MESOZOIC MAMMALS?; Monotremata, an internet
directory: |
PLEASE NOTE: THIS PROJECT IS NOT SCIENTIFIC. IT IS A HOBBY.
"I was looking for information on an old mammal and found this lot. What is this
project?"
It's got lots of information on old mammals. For a short bit of background information, see
here.
Monotremes include those Australasian egg-layers, the
duck-billed platypus and the echidnas. A couple of early representatives are known from
the Lower Cretaceous. The word means 'one hole'. The idea of egg-laying mammals is none
too surprising in itself. That’s evolution for you. Presumably all early
mammals did that sort of thing, the adult females
at least. But that some should persist with the habit today is extraordinary.
This is one aspect of monotremosity which mark these animals out as ‘primitive’. They also
have somewhat sprawling front legs and "just one anal opening that combines the
posterior end of the intestine, the ducts of the excretory system, and the genital ducts, a
common chamber known as the cloaca", -with thanks to
http://mammals.geozoo.org/mon/index.php. (It means they have only one hole for going
to the toilet and having sex, though not simultaneously.)
In other regards, these creatures are highly derived. In
contrast to the extinct multituberculates, the
construction of the skull is ‘properly’ mammalian. This would be easier to cope with if
the less derived multis had also been egg-layers. However, where known (very infrequently),
the narrowness of the pelvis suggests that at least some
representatives weren’t. |
(Achtung! The following paragraph is my own, ill-qualified speculation.)
This seems to imply to me that the trait of live birth may well have arisen at least twice
within mammalian history. Upon reflection, this wouldn’t be as surprising as it might sound.
Live birth isn’t restricted to mammals. Many
sharks do it, as well as
some bony fish.
Scorpions indulge.
And amongst reptiles, there’s a diverse array of adherents. The long gone ichthyosaurs
wouldn’t have been seen dead laying eggs. And various practitioners can be found among the
existing snake and lizard communities. Some families boast members who egg and others who
don’t. In the case of at least one lizard species, Bougainville’s skink, both techniques are
pursued, possibly according to temperature.
My Herp.Com
http://www.myherp.com/articles/other/egg.htm
The skink source.
Double D Reptiles
http://double-d-reptiles.tripod.com/birth.html
Further considerations on whether to be oviparous, ovoviviparous or viviparous.
|
A. Early Monotremes B.
Ornithorhynchidae C. Tachyglossidae
| Taxon: mostly presumably within Platypoda Gill, 1872
These genera bear more resemblance to the platypus line, Ornithorhynchidae, than to the
echidnas, Tachyglossidae. The fossil record of monotremes is very sparse. They’re first
known from the Lower Cretaceous of Australia, though they presumably evolved earlier, and
possibly much earlier. What they were up to for the next 45 million years is anyone’s
guess.
Genera: Kollikodon,
Kryoryctes, Steropodon,
Teinolophos, other reports
Time-Line:
Lower Cretaceous: Kollikodon, Kryoryctes, Steropodon,
Teinolophos |
| Genus: Kollikodon Flannery T,
Archer M, Rich TH & Jones R, 1995
'kollix tooth'
Remarks: Kollix is an ancient Greek word for a bread roll. The allusion is that the
strange teeth, when seen from above, resemble hot cross buns, traditionally toasted and
eaten on Good Friday. (Should it be of interest, we have a recipe available.) An
alternative name for this genus is Hotcrossbunidon. This was felt to be invalid in terms
of the rules of zoological nomenclature, and so Kollikodon was officially proposed.
The informal name actually makes more sense.
Family: Kollikodontidae Flannery et al, 1995 |
| Species: | Kollikodon ritchiei Flannery TF, Archer M, Rich TH,
& Jones R, 1995 |
| Place: | Lightning Ridge, New South Wales |
| Country: | Australia |
| Age: | Albian (middle), Lower Cretaceous |
| Remarks: |
This is based on an opalized fragment of dentary, with one
premolar and two molars
in situ. Like Steropodon, this genus was a relatively large mammal for the
Mesozoic. The molars have a length of around 5,5mm and a width of between about 4 - 6mm,
(Clemens et al, 2003). There were four in the series.
Musser & Archer, 1998 state that a large canal on the mandible would be consistent with
the presence of a beak, as with Steropodon, (p.1075).
A suggested possible bodylength for the complete animal is a full metre. If that's anywhere
near accurate, Kollikodon would easily be the largest Mesozoic mammal known.
Whether it's a very basal monotreme or something else is
presently unclear. (With thanks to David Marjanovic.) It's also possible the animal was at
least partly aquatic. The strange teeth would work well at crushing shellfish. (With thanks
to Tim Williams.) |
| Reference: | Flannery et al (1995), A new family of monotremes from the
Cretaceous of Australia. Nature 377, p.418-420. |
| Genus: Kryoryctes Pridmore PA,
Rich TH, Vickers-Rich P & Gambary PP, 2005
'Cold-temperature digger'
|
| Species: | Kryoryctes cadburyi Pridmore PA, Rich TH,
Vickers-Rich P & Gambary PP, 2005 |
| Place: | Dinosaur Cove, Victoria |
| Country: | Australia |
| Age: | Albian, Lower Cretaceous |
| Remarks: | The described remains are restricted to a single
humerus, although a partial tooth was found at the same
location. This bone is 'tachyglossid-like'. However, the
authors stay short of assigning it to Monotremata. The specialised characteristics have
much to do with digging abilities, and that's a hobby pursued by many mammals. It's broadly
in line with monotremes, but could belong to something else.
Time for a quick snack
The specific name honours the Cadbury-Schweppes company, who were in a position to supply
some much needed chocolate. Odd as it may seem, I'm not making that up. One of the
excavation team asked what she'd get if she struck mammal, and Rich TH promised a cubic
metre of the stuff. One of the links below provides a report.
With thanks to Tim Williams for posting notification of publication and some details to the
Dinosaur Mailing List. |
| Reference: | Pridmore PA, Rich TH, Vickers-Rich P & Gambaryan PP (2005),
A tachyglossid-like humerus from the Early Cretaceous of South-Eastern Australia, Journal of
Mammalian Evolution, 12(3/4), p. 359-378. |
| Genus: Steropodon Archer,
Flannery, Ritchie & Molnar, 1985
'lightning tooth' (With thanks to Dr Tom Rich)
Family: Steropodontidae Flannery TF, Archer M, Rich TH & Jones R, 1995 |
| Species: | Steropodon galmani Archer, Flannery, Ritchie &
Molnar, 1985 |
| Place: | Griman Creek Formation, Lightning Ridge, New South Wales |
| Country: | Australia |
| Age: | Albian (middle), Lower Cretaceous |
| Remarks: |
Another opalized jaw with three molars. Luo et al 2002,
(p.10): "the earliest-known representative of ornithorhynchid-like monotremes."
Big
This was a large mammal for the Mesozoic. Although only lower jaw and teeth are known, the
former owners were probably something like 40-50cm long. The molars "bear striking
resemblance to the tribosphenic pattern characteristic of living
therians...", (Pascual et al, 2002). However, they
also refer to previously reported differences. There's apparently no entoconid, (a funny
bump), and absence of wear suggests that the upper molars, (as yet unknown), didn't have a
protocone, (another funny bump).
Clemens et al (2003) provide the information that the lower molars are around 5 - 7mm in
length, with a width of 3 or 4mm. A length of 1 or 2mm is more typical for Mesozoic
mammals.
Holotype
Woodburne, 2003 (p.212) reports that the holotype is a right
mandible named AM F66763, which seems to work at the Australian Museum, Sydney. The
preserved molars are m1-m3. Page 237 includes: "In Steropodon, the mandibular
canal suggests the presence of a bill, with a bill also known in O. dicksoni and
O. anatinus." The O.s refer to Obdurodon and Ornithorhychus
respectively.
Further information has been provided by Musser & Archer, 1998. The genus was originally
referred to the platy family of Ornithorhynchidae. This was due to strong similarities of
the lower molars. However, molecular studies suggest that platties and echidnas diverged
after, (or at the end of), the Cretaceous. If Steropodon were included in the family,
then excluding echidnas would be artificial. As they say in the trade, the
taxon would be seriously
paraphyletic, and that's bad. A new family was subsequently erected to avoid that,
(p.1063).
More on teeth
Tim Morris (pers. comm., 2005) reports he's been reading a book on Lightning Ridge. This
mentions a further find which is probably from the same genus. The jaw concerned
carelessly lost its teeth, though the alveoli are naturally
present. Among these are sockets for two premolars and one incisor. There's no
information on the presence or absence of a canine. Many thanks for the information. |
| Reference: | Archer et al (1985), First Mesozoic mammal from Australia --an
early Cretaceous monotreme. Nature 318, p.363-366. |
| Genus: Teinolophos Rich et
al, 1999
'extended crest'
An interesting paper on this genus by a team of authors led by Tom Rich appeared in 2005.
It reported the presence of a postdentary trough on a new specimen of lower jaw, and
discussed the implications of that with regard to the evolution and construction of
mammalian middle ears. If correct, those implications made this a big deal as is chatted
about below.
However, their findings were called into doubt by a number of studies including Bever et
al, 2005 and Rougier et al, 2005. To some, there seemed to be doubts as to whether that
specimen actually belonged to this genus (fresh examinations indicate it does), and others
gave further reasons for supposing some of the reported observations could be wrong.
It also got further challenged by Rowe et al, 2008, and two of that author collective
happen to be Rich and Vickers-Rich; two of the team who originally reported a postdentary
trough. I'd falsely assumed that blew their original position out of the water. However,
2009 brings things into a different light (pers. comm.). Not all the authors involved in
the 2008 study shared the published views in all regards. Tom Rich informs me that he
still sees evidence for a shallow postdentary trough on the best preserved specimen, NVM
P212933. Nothing of the like is found on the other specimens, but this can be attributed
to breakage and abrasion resulting from natural transportation after death. A paper
discussing this is planned to appear at some stage.
Additionally, Averianov et al, 2005 accept without reservation that Teinolophos
is a monotreme. Nevertheless, from page 794: "However, attribution of this
specimen to Teinolophos is problematic, it may rather belong to an
ausktribosphenid." They don't provide
elaboration on this matter, perhaps as it's not of central concern to their study.
The fossil jaws they described are from
docodonts. I now have reasonable grounds for assuming they were incorrect
with that sentence. |
| Species: | Teinolophos trusleri Rich et al, 1999 |
| Place: | Flat Rocks, Victoria |
| Country: | Australia |
| Age: | Aptian, Lower Cretaceous |
| Remarks: | The following is partly based upon my reading of
Rowe et al, 2008 and thanks go to the supplier. Also relevant are Rich et al, 2005,
Bever et al, 2005, Rougier et al, 2005 and personal communication.
A controversy clears?
This genus became the subject of a complicated rumpus in 2005, and much smoke was billowing
over the battlefield. The first salvo was fired by the artillery of Rich et al, 2005.
They reported the presence of a postdentary trough on one specimen of lower jaw and, if
correct, that perhaps unexciting sounding feature would actually involve a rather remarkable
bout of parallelism concerning the evolution of the mammalian middle ear. As two of the
three small sound processors in your ear, the malleus and
the incus, were previously housed in a postdentary trough
owned by your ancient ancestors, apparently after the separation of the monotreme lineage,
the implication would be both your ancestors and those of a platypus independently reached
a tri-boned middle ear system. As it happened, I was familiarising myself with that paper
in the August sunshine at a Turkish hotel, and this perfectly logical bout of reasoning
nearly caused me to topple off my comfy chair and fall into the swimming pool in surprise.
Fortunately, such an accident was narrowly avoided, and I kept enough control of my senses
to fetch a reviving beer.
It sounded reasonable, fairly improbable but well-based. And, sometimes, improbable things
occur. For example, it's not likely you'll find somebody reading a paper about a Mesozoic
mammal jaw next to the swimming pool while on holiday, but that doesn't make it
impossible.
Bang
The next shots came from Bever et al, 2005. These authors didn't challenge the
identification of a postdentary trough. Rather, they questioned the affiliations of that
particular specimen, and correctly stated such a character hadn't been reported for any
other Teinolophos dentary. It would be strange beyond anybody's belief to have
different individuals of the same genus displaying such an astonishing degree of variation.
Therefore, they suggested, some non-monotreme,
australosphenidan as having owned the jaw instead.
However, further examination indicates the original identification was correct. That
being so it seems fair to say that Bever & Co missed the target. While the assignment of
critters both with and without postdentary troughs to the same genus may appear utterly
bizarre, there remains the possibility that the visible absence of troughs from specimens
could be the result of damage (Tom Rich, pers. comm., 2009).
Bang bang
And then, a bit later, came the barrage fired by Rougier, Forasiepe & Martinelli, 2005.
After examining all available specimens, these authors didn't question the identification
of the jaw as belonging to Teinolophos. Rather, they cast doubt upon the
interpretation of a postdentary trough being present. Instead, the observed feature
could be explained as: "... the floor of the large mandibular canal, which in broken
Teinolophos specimens continues anteriorly inside the
dentary at least up to the level of the antepenultimate
molar and would transmit the hypertrophied trigeminal
system, as in the platypus."
And then came Rowe et al, 2008. This new study involved treating three specimens to a free
ride though a High Resolution x-ray scanner in Texas, and the publication reports no
evidence at all indicated the presence of a postdentary trough or postdentary bones on
any of them. Rowe et al, 2008 appeared to corroborate the view of Rougier and colleagues.
This is complicated by the detail that two of the authors involved, Rich and Vickers-Rich,
happen to disagree with the published conclusion with regard to one specimen (Rich, 2009
pers. comm.).
Cease fire?
I thought the controversy concerning whether Teinolophos delivers evidence for supposing
parallelism of middle ear developments among mammals had ended. It turns out I was mistaken.
Merely most researchers presently accept such evidence isn't available.
If accepted as correct, the cladogram offered by Rowe & Co might be thought to also put the
brakes on parallelism based upon undoubted postdentary troughs of australosphenidans such
as Ausktribosphenos, as these
authors found monotremes aren't part of that grouping. That's actually a conclusion I'd
like to be true, but my preferences are less important than historical reality. However,
their alternative positioning of australosphenidans, close to the base of a clade involving
Zhangheotherium and me, also appears to
necessitate parallelism. This still requires that an ancestor of mine, more recent than
the last common ancestor of a platy and me, would've had a postdentary trough and all that
implies.
With regards to a further issue, not explicitly stated in the paper nor directly relevant
to it, it is interesting to see that this cladogram also provides no support at all
for placental affinities of Ausktribosphenos or
Bishops. In this instance, however, I wouldn't
assume that all the authors of that study accept all the implications of the
cladogram.
Still, at least as far as that there purported postdentary trough on a monotreme goes, I'm
somewhat relieved that particular can no longer contains quite so many wriggling worms
when opened. Many mammals like such things, but they don't feature as major items on my
shopping list. A controversy appears to have eased for most parties, and perhaps I won't have to
keep radically re-writing this article on a more-or-less annual basis.
(Update: it's now 2009 and I'm having to re-write this article! And, when the new study
gets published, then...)
A controversy opens
Most researchers presently seem agreed about this postdentary trough business for
Teinolophos. Rather than a trough, breakage has exposed part of a bog-ordinary
hypertrophied mandibular canal, and part of it just happens to be in a trough-similar sort
of position. It's nothing particularly new, and rather like what could be found on a
platy following a persistent and destructive bout of interrogation. It provides strong
confirmation that this critter was a monotreme. Good and fine, except...
Except, while the platy has this hypertrophied what-not, its cousins the echidnas don't
share the extravagance to anything like the same degree. This suggests, according to Rowe
et al (p.1238), that Teinolophos is an ornithorhynchid, a platy, and the most
recent common ancestor shared with echidnas had already dropped dead prior to Teino's
hatching. That would be much earlier than previously supposed. Molecular based estimates
of platy-echidna divergence fall into some time between 17 to 80 million years ago, and
this would add at least a further 40 million to the upper extreme. Should that be correct,
then monotreme evolution would seem to run unusually slowly compared to that of most
mammals.
This tin may be a different can to the wormy one mentioned above, but it contains fresh
wriggling worms.
Suggestions of platy affinities have surfaced before (p.1239), but things weren't clear
cut. There are dental similarities shared specifically with platys and not with echidnas.
However, seeing as all known echidnas are toothless wonders, that's an inevitability.
Comparisons, when possible, with toothed echidna ancestors could perhaps show that
inheritance of those traits has to do with being a monotreme rather than just with
platy-ness. By the way, I'm aware that adult platys don't have teeth. Juveniles do.
Teinos go Tex
Curious as to their own affinities, three Teinolophos lower jaws decided to undertake
a study trip to Austin, Texas (p.1240). Two were toothless, one had three teeth, and all
came from the same Flat Rocks locality in Victoria. That latter point is hardly surprising
as, presently, that's the only source known. They chose to go to Texas as the
facilities had been recommended by some of their relatives. An adult and juvenile platy
and an Obdurodon skull had already enjoyed hospitality
there.
X-ray scanning revealed a large canal, a hypertrophied mandibular canal, running along the
length of the inside of the jaw. While some other living mammals have enlarged canals,
only the platy displays one that's hypertrophied along its full length. Its functional
purpose is a matter of much interest. It houses an artery and an enlarged branch of the
trigeminal nerve, and this is effectively wiring for the quite extraordinary perceptive
abilities stuffed into the most un-duck-like beak. This beak is a magnificent and audaciously,
outrageously ridiculous construction, and it's caused Australian researchers to develop a
technical description reflecting its uniqueness: "Cor strewth, mate, what a bloody beaut!"
Rather as with a well made pie it may be nice to look at, but the real joys emerge when
you cut into it and start eating. This analogy shouldn't be taken too literally.
The beak is home to impressive numbers of both mechano- (60,000) and electroreceptors
(40,000), and these enable a platy to successfully hunt underwater by day or night. Thanks
to an especial sneakiness, the availability of light is rendered utterly irrelevant by
the animal's determined preference for hunting with its aquatically
adapted eyes completely shut. Hunting with the eyes open has never been observed. Small
river shrimps and others possibly notice that this tactic is completely idiotic.
Their movements and giggles send out signals through the water. These are perceived by
the high-tech receptors in the beak at somewhat differing times, seeing as the mechanical
signals move more slowly than the electrical ones, and the nothing-seeing platy can work
out where its target is, how fast it may be moving, and the direction it's taking. The
greatly enlarged nerves allow e-mails to be sent from the beak to the platy central
processing unit in the skull, and the river shrimp soon has nothing left to laugh either
about or with.
Echidna abilities
Echidna beaks also work along the same principles, but to a much less well developed degree
or, and here's a snag, perhaps in a secondarily diminished way. I'm raising that
possibility. The authors use the relatively neutral: "but their sensitivity is far less
than in the platypus bill" (p.1241).
Before giving that matter a bit more consideration, a short introduction to echidnas would
seem to be a good idea. Imagine, if you will, a kind of fairly small anteater thing
mixed with a somewhat inflated hedgehog, stick a beak onto the front of the face and that'd
be getting on for somewhere in the rough direction. There are two living genera. The
long-beaked echidna, Zaglossus, is mostly at home in high
mountain forests of New Guinea, although it can be met at lower elevations in some parts.
Their beaks have a couple of thousand electroreceptors. Its short-beaked cousin,
Tachyglossus of New Guinea and Australia, is even less
perceptively receptive with this sense; only a few hundred per beak. This would appear to
match well with preferred living conditions, seeing as optimal use of this skill requires
plenty of water. The ground is a rather poor transmitter of electrical signals as, after
all, earth is earthed.
Trevor's quibbles
This ability, it seems to me, is odd for terrestrial mammals in any degree of development
excepting for one scenario; secondarily terrestrial descendants of semi-aquatic ancestors.
It presumably does provide some limited amount of information on moist ground, and such
conditions are more commonly encountered by rainforest zags rather than most tachys.
If my suspicions are correct with regards to semi-aquatic ancestry, then I'd also expect
those critters to have possessed more, probably many more, receptors in their beaks and,
regardless of the lack of available fossil evidence, that would likely have implications
for the optimal size of the mandibular canal. It would've been larger, perhaps much
larger. A word beginning with 'h' comes to mind.
This makes me wary of embracing a hypertrophied mandibular canal as being clearly, and
solely, an ornithorhynchid character. If it's legitimate to have doubts about affinities
postulated on the grounds of dental similarities between Teino and platys, and that on the
grounds of proto-echidna teeth being unknown, I also feel free to point to the severe
shortage of proto-echidna lower jaws from earlier than the Middle Miocene. However, two
factors should be kept in mind. Firstly, a semi-aquatic ancestor for echidnas has no
support whatsoever from the known fossil record, and is merely speculative. Secondly,
there are also those dental similarities adding further, albeit not unequivocal, support
for platy affinities. The case isn't built upon a single feature.
The authors state, and I can't see any reason to doubt they're correct, that the narrower
mandibular canals of echidnas reflect the: "...
plesiomorphic condition that is found in
Morganucodon and all therians sampled." They
continue: "Electroreception therefore appears to be an
apomorphic characteristic of Monotremata, whereas the evolution of a specialized
duckbill for high-resolution aquatic electroreception is unique to the platypus clade."
It certainly is now but, as you may have gathered, I'm not convinced that must always have
been the case. For example, should my hypothetical echidna ancestor have enjoyed
swimming, then enhanced electroreception
would obviously have been useful.
Anyway, Rowe et al take this hypertrophied canal as being indicative of a platy, and
refer Teinolophos to Ornithorhynchidae and the same, they say, applies for
Steropodon.
Affinities?
If you don't happen to be convinced about the case for platy affiliations for Teinolophos
but prefer, instead, to keep open the possibility of a deeper position within Monotremata,
some of the rest of the offered consideration is less compelling; particularly views on the
depth of time for platy and echidna divergence.
If that really occurred prior to Teinolophos, then it appears to show a
spectacularly slow rate of evolutionary change in comparison to the hastier habits of
similarly sized therian mammals. Mention is made (p.1242) of monotremes also having
considerably slower metabolic and ventilation rates as well, and their lower body
temperature. However, I fail to see a possible connection between those facts and a slower
rate of evolutionary development other than, perhaps, for them being reflections of it.
Most non-mammals have low-performance motors in comparison to monotremes, and I know of
nothing to indicate their lineages can't be radicals in terms of evolutionary change.
One point of undoubted relevance wasn't mentioned; slow birth rates. A female Tachyglossus
having sex more than twice within three years would be a nymphomani-tachy.
Platys and echidnas don't breed like rabbits, rats or opossums in many respects, and these
include sheer numbers of babies, aka fresh deliveries of random mutations.
Holotype
The holotype is a partial left dentary known as NMV P208231.
It came equipped with one molar, and now resides in the
Museum of Victoria, Melbourne.
Additional notes
Originally, this was thought to be a eupantothere.
Fuller research has revealed similarities to Steropodon, except in size. The animal
was around 10cm long. The species name honours the artist, Peter Trusler, (with thanks to
Dann Pigdon).
The following details are mainly from my reading of Woodburne, 2003.
The lower molar is broadly similar in morphology to the m2 of
Steropodon. The trigonid
is compressed and the talonid has no basin. It's about one
sixth of the size of Steropodon, Wear facets indicate an 'orthal' occlusion with the
upper molars, (p.209). The construction of the lower jaw differs to existing monotremes.
Amongst the contrasts: the condyle is well above the tooth row, (instead of at about the
same height); the ascending ramus is also higher. Woodburne also mentions further
distinctions, but much subsequent information was unavailable to him. That features below.
Also different is that Teinolophos probably had a strong bite, (p.210).
A unique feature for known toothed monotremes is that the trigonid is tall, whilst the
talonid is set much lower, (p.211). This is more like the general mammalian arrangement.
The molar is double-rooted, which is plesiomorphic
when compared to ornithorhynchids, but is a shared characteristic with Steropodon
and Kollikodon. Subsequent monotreme molars are
multi-rooted, (p.212). | |
| References: | Rich et al (1999), Early Cretaceous Mammals from Flat Rocks,
Victoria, Australia. Records of the Queen Victoria Museum, Launceston. |
| Rich TH, Vickers-Rich P, Trusler P, Flannery TF, Cifelli RL,
Constantine A, Kool L, & Nicholas Klaveren N (2001), Monotreme nature of the
Australian Early Cretaceous mammal Teinolophos, Acta Palaeontologica Polonica
46(1), p.113–118. |
| Links:
Rowe et al, 2008
http://www.pnas.org/cgi/content/abstract/105/4/1238
Rowe et al (2008), The oldest platypus and its bearing on divergence timing of the platypus
and echidna clades, PNAS, 105(4), p.1238-1242.
Life in the Shadows, Non-reptilian life in Mesozoic Australia
http://www.alphalink.com.au/~dannj/non-rept.htm
See Polar Fuzz-balls: Mesozoic Mammals. Part of Dann Pigdon's project.
University of Chicago Medical Center, 11.2.2005
http://www.innovations-report.de/html/berichte/biowissenschaften_chemie/bericht-40188.html
Weirdness update: Prehistoric jawbone reveals evolution repeating itself.
It appears that the standard mammalian arrangement of three bones in the inner ear
may have developed twice. A new jaw specimen has a suspicious trough present on it, and this would
be consistent with 'extra' jaw bones still being attached to the
dentary. If so, then presumably neither a
malleus nor an incus were
present in early monotreme ears.
From the linked article:
<<Many paleontologists have doubted that such a seemingly complex adaptation could have
originated more than once in mammals, but according to the authors of the paper, the
evidence of T. trusleri indicates that it did. "Nothing like that has ever been
found before," said Tom Rich, Ph.D., lead author of the paper and curator of
vertebrate paleontology at Museum Victoria in Melbourne, Australia. "These jaws may be
the oldest evidence of monotremes on Earth," Rich said. "Some of these jawbones
show facets for what scientists call accessory bones – bones that humans and most other
mammals do not have.">>
Mammalian hearing and homoplasy
The following is based upon my reading of Martin & Luo, 2005, and more thanks are due
to the generous supplier.
As there are now doubts about the identity of the jaw
bone described by Rich et al in 2005, (doubts that it belongs to a monotreme, for
example, let alone Teinolophos), that should definitely be taken into
consideration while perusing the following.
Update to the update
2008 has arrived, and there now seems to be a reasonable level of consensus that the
specimen under discussion is indeed Teinolophos. However, there's a catch. A
wide agreement has also emerged that it doesn't have a postdentary trough and, by
implication, would've had three sound processing bones in its middle ear. This should also
be taken into account whne reading what follows.
The paper mentioned is an accompanying commentary for Rich et al, 2005, which concerned
Teinolophos. A homoplasy is a quaint term for the results of convergent evolution;
a similar condition arising independently in separate lineages. For example, both birds
and mammals are endothermic, ('warm blooded'), but not as a consequence of common descent.
This is a homoplasy.
When such convergences occur with relatively simple characteristics, (eg, similar shapes
of tooth to deal with similar types of food), they're not all that surprising. If you
enjoy gnawing things, then chisel-like incisors would be
ideal, and they've been developed by a variety of mammals including
multituberculates, rodents and some primates.
However, proposing that astounding similarities in something as complex as mammalian inner
ears are homoplasies is in a different league. This fully merits being called
counter-intuitive. The again, if that's what the evidence suggests... It may be
extraordinary, but extraordinary things sometimes happen.
At least two lines of mammals appear to have independently evolved remarkably similar
inner ears, (p.861).
Uses of jaws
If you think about your jaws, you might notice you do various things with them. I use
mine as storage space and the engine room for my teeth. But they also play a role in
speaking and other forms of communication. Passionate kissing is part of human
reproductive strategy, and the jaws are essential for this purpose. Moving the mouth is
recommended for serious snogging, and I speak (happily) from personal experience. Most
mammals don't use their jaws for such an activity, and they're missing out.
I don't know of any evidence for passionate snogging among non-mammalian
eucynodonts, but their reproductive strategies clearly
worked well, as they persisted until about 115 million years ago. Nevertheless, they also
had somewhat unorthodox uses for their jaws. Some bones, (the
angular, articular and
quadrate), were involved in the sense of hearing. Generally, there was a trend among
therapsids for the tooth-bearing dentary to increase in
size, but early mammals also retained most of the
'non-mammalian' elements. Some of these were the forerunners of our inner ear bones, and
their separation from the mandible happened subsequently
to the appearance of mammals.
Triconodonts
Even after the ear bones had left the jaw, it would seem logical to expect there must've
been a stage when they were still connected, and such a condition has been found in some
Chinese triconodonts, (eg. Repenomamus).
It presently appears this lineage emerged after monotreme
and therian ancestry had diverged. If so, then triconodonts
are presumably more closely related with me than with a platypus.
An early pionear
The genus Teinolophos dates from the Lower Cretaceous, but the separation of ear
bones from the jaw already had an ancient history for some mammals. With Lower Jurassic
Hadrocodium, there's no trace of a trough on
the inside of the dentary, (p.862). As that taxon is
otherwise anatomically more primitive than any monotremes, a similar separation seems to
have taken place at least three times; in the ancestors of Hadro, in my predecessors and
within Monotremata.
Controversial australosphenidans
There was no way these authors would have failed to have commented on
australosphenidans. They point to "an uncanny resemblance" with
Teinolophos, as the mandibular trough is a common feature. Its primitiveness
contrasts with their derived tribosphenic
molars. |
| Other reports:
Salamanca Formation, Patagonia, Argentina
http://exa.unne.edu.ar/eventos/congresos/paleontologia/public_html/programa1.htm
A monotreme femur was reported. This formation dates from
the Paleocene, as does Monotrematum.
Reference: Forasiepi AM & Martinelli (2002), Fémur de un monotrema (Mammalia,
Monotremata) del Paleoceno Temprano (Formación Salamanca de Patagonia, Argentina. VIII
Congresso Argentino de Paleontologia y Bioestratigrafia, Corrientes, Argentina -(October
2002). |
A. Early Monotremes B.
Ornithorhynchidae C. Tachyglossidae
| Taxon: Ornithorhynchidae Gray, 1825
The duckbilled platypus and its forebears. Between Monotrematum (above) and
Obdurodon there’s another gap in the fossil record of about 40 million years.
Monotreme, monotreme, wherefrom art thou?
The origins of monotremes have been the subject of much discussion. One of the most recent
views, (Luo, Cifelli & Kielan-Jaworowska (2001), Dual origin of tribosphenic mammals.
Nature 409: 53-57), combines these animals into a monophyletic
taxon, (ie. derived from a common ancestor), with some other strange mammals of the
Australian Cretaceous called ausktribosphenids.
This proposal, Australosphenida Luo et al 2001,
also includes a couple of Jurassic, southern-hemisphere members, (Ambondro and
Asfaltomylos from Madagascar and Argentina respectively), with a sister-line
represented by Shuotherium, known from China and England.
As expressed in a subsequent paper on Shuotherium, Kielan-Jaworowska, Cifelli &
Luo 2002, p.484 (see Bibliography): "Based on the limited evidence available, however,
we suggest that Shuotherium is a viable sister-taxon to Australosphenida. Their last
common ancestor presumably had molars of
"symmetodont" construction...",
(and, as crudely summarized by my self, lived some time before the Bathonian age of Shuo and
Ambondro).
Thus, monotremes are also australosphenids and descended from some kind of Lower or Middle
Jurassic 'symmetrodont' or other. Easy. Perhaps too easy?
Australosphenida is essentially a widened alternative to Ausktribosphenida Rich TH,
Vickers-Rich P, Constantine A, Flannery TF, Kool L & van Klaveren N, 1997, which Rich
et al view as possibly being within Placentalia. If
correct, monotremes can't possibly be their immediate relatives or descendants, simply
because they're in no way placentals.
Then there's a paper by Pascual et al, 2002, on Monotrematum (see Bibliography).
This seems to imply preference for Australosphenida, (rather than Ausktribosphenida), but
they "suggest that monotremes should be excluded from the Australosphenida,"
(p.490).
Earlier on the same page is: "Accordingly, the pseudo-triangular molar pattern of
Steropodon galmani is, in our view, most plausibly derived from the linear,
tricuspate pattern, as seen in Morganucodon,
which is universally accepted as ancestral for the Mammalia." To Pascual and Co then,
monotremes must've evolved from something with some Morganucodon-like gnashers.
According to Woodburne, 2003, the placement of Monotremata within Australosphenida has an
apparently insurmountable problem, (p.195): "An abundance of evidence points to the
conclusion that monotremes are phyletically allied with pretribosphenic, rather than
tribosphenic, mammals." If correct, then they can neither be australosphenidans nor
their descendants. For the lower molars: "The
talonid is composed of the pretribosphenic hypoconid,
hypoconulid, and cristid obliqua. There is no evidence for a tribosphenic entoconid, nor
for a talonid basin. There was no tribosphenic protocone" (on the upper molars). These
sorts of detail suggest alliance with something anatomically like, or between,
Amphitherium and perhaps Peramus, (p.235). That seems to suggest to me
placement within or near to Zatheria.
As Woodburne's paper is concerned specifically with monotremes, I'll attempt to utilize his
observations to enrich the entries as appropriate. However, he also provides a reasonably
concise explanation of terminology, (p.197): "In the following discussion, the term
tribosphenic refers to a mammalian dental morphology in which the protocone of the
upper molars is developed and occludes with a talonid basin of the lower molar that
possesses an entoconid in addition to a pretribosphenic hypoconid and hypoconulid. The term
tribosphenic also applies to Mammalia that possess
a dentition considered to have been modified subsequently
from that condition. The term pretribosphenic is reserved for those Mammalia having
upper molars composed of a paracone, metacone, and stylocone; lower molars are composed of
a protoconid, paraconid, metaconid, hypoconulid and, in some cases, hypoconid."
However, that isn't the only possible definition of tribosphenic molars. Martin &
Rauhut, 2005 state it's conceivable that dual-functional molars in australosphenidans
didn't necessarily have a functional protocone. They retain the traditional terminology
for tribosphenic teeth in their study, but do so in a descriptive sense, (p.414). More on
their thinking can be read in the entry for
Asfaltomylos.
Identifying an ancestral line for monotremes is seemingly not a problem. Recognizing the
correct one's the tricky bit.
Woodburne, 2003 (p.230) also points out that, since the Paleocene, monotreme teeth show only
infrequent scratches when highly magnified. This suggest a diet of soft food. In contrast
to the Cretaceous genera, (Teinolophos and Steropodon - I don't know about
Kollikodon in this respect), jaw mechanics were modified: "By the Paleocene,
orthal shear apparently had been largely replaced by propalinal apical grinding of
soft-bodied prey that left few abrasion facets or scratches on the molar surface",
(p.237).
Genera: Dermipus (= Ornithorhynchus),
Ektopodon (not a monotreme!), Obdurodon,
Ornithorhynchus, "Platypus"
(= Ornithorhynchus), Monotrematum,
other reports
Time-Line:
Today: Ornithorhynchus
Miocene: Obdurodon
Oligocene: Obdurodon
Paleocene: Monotrematum |
| Genus: Ektopodon Stirton RA,
Tedford RH & Woodburne MO, 1967
Remarks: This genus was once thought to be a monotreme, but isn't. It finally admitted to
being a phalangeroid marsupial in disguise. |
| Species: | Ektopodon serratus Stirton RA, Tedford RH &
Woodburne MO, 1967 |
| Place: | Tirari Desert, South Australia |
| Country: | Australia |
| Age: | Middle Miocene |
| Remarks: | The misidentification is cited in Woodburne &
Tedford, 1975 (p.1). It should never have claimed to be a monotreme in the first place.
Naughty marsup. |
| Reference: | Stirton et al (1967), A new Tertiary formation and fauna from
the Tirari Desert, South Australia, Rec. South Australian Museum, 15(3), p.427-462. |
| Genus: Monotrematum
Pascual R, Archer M, Juareguizar EO, Prado JL, Godthelp H, & Hand SJ, 1992 |
| Species: | Monotrematum sudamericanum Pascual et al, 1992 |
| Place: | Punta Peligro, Patagonia |
| Country: | Argentina |
| Age: | Lower Paleocene |
| Remarks: |
A platypus tooth from South America. Update: three teeth, two lower and one upper,
(Pascual et al, 2002). This is the only known non-Australasian
taxon. The two new specimens were discovered in 1992, but
they've only just been described.
"The preserved enamel in the central region shows that the crown pattern is almost
identical to that of Obdurodon (Fig. 2A): it is composed of two V-shaped lobes, the
anterior of which is wider, separated from the posterior one by a valley that connects the
lingual and buccal sides of
the crown separating the anterior and posterior lobes," (Pascual et al, 2002). The
main difference, apart from continent and age, is the size. The M. teeth are around
twice as large as O..
Woodburne, 2003 (p.218) adds that the holotype is called MLP 91-I-1-1. This charming
molar resides in the Museo de La Plata, Argentina. It seems
to be a right, upper molar. This is fairly worn, but the subsequently identified specimens
are in better condition. The familial affinities of this genus are confirmed in Musser &
Archer, 1998 (p.1063). |
| Reference: | Pascual et al (1992), First discovery of monotremes in South
America. Nature 356, p.704-706. |
| Genus: Obdurodon Woodburne MO &
Tedford RH, 1975
'enduring tooth'
Remarks: The generic name refers to the teeth being both larger and more robust than the
molars of the platypus, and their probable longer retention. Platypussies throw theirs
away while still juvenile. |
| Species: | Obdurodon insignis Woodburne MO & Tedford RH,
1975 |
| Place: | Etudunna Formation, Tirari Desert, South Australia |
| Country: | Australia |
| Age: | Middle Miocene (or Upper Oligocene) |
| Remarks: | The following is based upon my reading of Woodburne
and Tedford, 1975.
At the time of writing only two teeth were available, and the authors identified them as
being probably upper molars from the right side. This turned
out to be incorrect. They're lowers from the left side. As the fossils were described in
both an upside-down and wrong-sided sort of way, the other orientations were vindicated;
anterior, posterior, labial and
lingual.
Obdurodon insignis claimed a notable distinction despite only providing a couple of
molars. This was the first Tertiary monotreme discovered (p.1). Eight years previously,
Ektopodon serratus had tried to claim the prize but it was
rightly disqualified. That usurper was a phalangeroid
marsupial. The first two Obdurodon teeth were both arrested in South Australia,
although from locations about 300 kilometres apart. This was roughly north of Adelaide;
about 700km north for the first (1971), and less so for the holotype in the following year.
The age is similar in both cases but not precisely clear. The authors were tempted by Middle
Miocene (p.3). I think I've read the age is actually somewhat older, but I can't presently
remember where. Further fossils of the species have since been found.
Distinctions
There was only one reasonable comparison to be made in 1975, and that was with the platypus.
Obdurodon's molar is larger, has a higher and more
complex crown (bearing in mind the comparison was with an upper rather than lower tooth),
and the crown is proportionately shorter. When viewed from the
occlusal perspective the molar is a longish rectangular shape, but with the width
narrowing towards the rear. Two lophs run across the crown (p.5). A broad
cingulum is at the front of the tooth while a narrower
one can be found at the back.
Baking lophs with the Mesozoic Eucynodont chef
As 'loph' may be less than familiar to some, a bit of an explanation will be attempted.
The demystification of this term requires (to feed four): a large enough rectangular baking
pan and suitable quantities of roast chicken, mushrooms, carrots, maize, stock, bacon and
perhaps some garlic and black pepper. You'll also need some pastry and an oven. This
requires preheating to 220°C.
Everything but the pastry, stock and oven should be chopped up and flung in the also-not-to-be-chopped
pan. Now add the stock and then roll out the pastry. Most of this should be used for the
pie roof, but we need some left for decorative purposes. Form this into two sausages of an
appropriate length, lay them across the pie and mould them into a couple of ramp-like
structures. Those are lophs.
Now place your model Obdurodon molar into the oven for 20-25 minutes, and then you
should have something well worth chewing over.
Back to the tooth
The foremost loph is more diagonally directed than the rear one, and comprises a trio of
cusps; a tall lingual one and a pair of lower labial ones. Each of those latter two connects
with their lingual friend by means of a crest. A deep valley separates this loph from the
rear one.
The posterior loph is simpler; a labial and a lingual cusp connected by one crest. This
area of the molar is narrower than the front of the crown, and the rear loph is similarly
narrower than its anterior colleague. Its cusps are higher, with the labial one being
relatively more massive, and the course of the loph is less slanted.
Roots
Typically, mammalian molars are double-rooted teeth, but unorthodoxy isn't particularly
rare. Single- and multi-rooted versions also occur. Being a monotreme, O. insignis
took things further than most. The m1 has six roots; three per side. These are generally
rather slender, but the final labial root is stouter and
near quadratic in cross-section. The front one is the best developed of the
lingual trio, with the middle being the least impressive.
It spends its time supporting the end of the inter-loph valley (p.7), while its colleagues
look after the cusps. The labial roots are set inwards of the crown margin, and less
directly associated with cusps.
(Platypus molars are also multi-rooted, and these grow through a layer of epithelium prior
to being accommodated by depressions in the bone. I'm not sure what epithelium is, but
it nevertheless plays an important role. As the teeth are dispensed with, this is the stuff
which forms into the horny plates of adult platy mouths.)
Comparisons and dimensions
Comparisons were made with upper teeth from a platypussy, which are smaller and less
complicated (p.9). The broad morphological similarities point to related animals. However,
as the Obdurodon molars turned out to be lowers, the detailed comparisons lost some
of their bite.
The dimensions obviously remain unaffected by that development. The type fossil is 7.15mm
long with the width of the lophs being 5.45 (front) and 4.45 (back). About a third of the
lingual side of the second specimen was absent without leave, so the measured widths are
incomplete for that one: length 7.35, loph widths 4.7 (front) and 4.35 (back). The authors
suggest adding about 30% for the live breadths.
Holotype
The type fossil, SAM P18087, is a lower left m1 in the collection of the South Australia
Museum, Adelaide. It was originally thought to be an upper right molar. The specific name
translates as 'distinguishing mark'. This is in recognition of the species providing the
first evidence of a Tertiary monotreme. When described, this was the oldest monotreme as
well, but Cretaceous (and Paleocene) material has since turned up.
Additional notes
Teeth and fragments of jaw and pelvis are known.
According to Woodburne 2003, (p.220) a new cuspid (NC1) is present on the
talonid; 'new' in comparison to Steropodon, which
might have had a much smaller precursor of the condition. This feature is also well
developed in the Paleocene Monotrematum, (p.222). An m2 seems to have had four
foots.
Musser & Archer, 1998 state that a second, undescribed species has been found at a site
called Mammalon Hill in the same formation, (p.1063). Compared to O. dicksoni, the
beak of O. insignis was relatively smaller, although more substantial than is known
from the modern platypus, (p.1075). |
| Reference: | Woodburne & Tedford (1975), The first Tertiary Monotreme
from Australia. American Museum, Novitates Number 2588, p.1-11. |
| Species: | Obdurodon dicksoni Archer M, Jenkins FA, Hand SJ,
Murray P, & Godthelp H, 1992 |
| Place: | Riversleigh |
| Country: | Australia |
| Age: | Lower-Middle Miocene |
| Remarks: | The following is based largely upon my reading of
Musser & Archer, 1998.
The species is known from an almost complete skull, several fragments of
dentary and a number of isolated teeth. Overall, it's very
reminiscent of the modern platypus but there are significant differences. A not particularly
important one is that it's somewhat larger.
Significant differences are listed on pages 1064-1066. The jaw bones, (which strutted far
out to supported the beak), are comparatively long and wide in O. dicksoni, and
they're not as strongly fused. A bone termed the
septomaxilla is clearly distinct from the premaxilla,
which it overlies. The top of the skull is flatter and both the angular and coronoid
processes of the dentary are well developed. The front of the snout has a prominent,
centrally located, oval shaped hole which is more or less fully surrounded by bone. In a
modern platy, the equivalent is a V-shaped feature, which isn't enclosed at the front. The
jaws of O. dicksoni are equipped with functional, shallow-rooted cheek teeth,
whereas adult platties depend largely upon keratinized pads for processing foodstuff.
What does that mean?
To add a bit of detail for some of those funny terms, the septomaxilla isn't generally
present in mammalian mouths, but at least some authors have regarded this as homologous
with the feature known in 'reptiles', therapsids, various
basal mammals, (eg. docodonts), and even some
placental edentates, (p.1066). In Obdurodon dicksoni, it's particularly large, and
this reflects the presence of a hypertrophied beak. In living platties, this bone helps
support a cartilage, and that was presumably similar in this case.
The angular and coronoid processes are found towards the back of the lower jaw. The coronoid
process slants upwards towards the cheek from just behind the final
molar, and its angular colleague slants backwards and slightly downwards behind and
below it. These are attachment structures for muscles, and are at least much reduced in
platties. The eating techniques of the platy no longer depend upon those muscles. This also
helps explain why the platy skull is flatter on the sides, as extra space isn't required.
In slightly technical terminology, the zygoma is relatively expansive in the older species.
Relative body size
As Obdurodon dicksoni isn't known from many specimens, the size range is unclear. It's
comparatively larger than platties. Some isolated teeth show other individuals were bigger
still, (p.1066). Nevertheless, the skull is from an adult individual.
Teeth
As with the platy, there are features called secateuring ridges towards the front of the
jaw, and not an incisor or
canine in sight. These are comparatively shorter and start further back along the
jaw. On the dentary, a gap is then followed by two,
single-coned premolars, and three
molars. The m1 has six roots, m2 boasts five and the m3 but
one, (p.1069). Although undescribed, a couple of probable m3s have been found at
Riversleigh, and they appear to be vestigial teeth.
The upper jaws have two premolars and only two molars; a six-rooted M1 and a four-rooted
colleague. Although those root numbers sound impressive, these are shallow and less than a
third the height of the crown. So far, molars have only be found in isolation from jaws.
This suggests they weren't strongly anchored in place. In both uppers and lowers, there is
a stark differentiation in morphological shape between premolars and molars, (p.1070).
Beak
"The bill in Or. anatinus is used both as a sense organ and as a tool for
breaking the ground when burrowing", (p.1075). Strangely enough, it's also equipped with
electroreceptors. It was thought to play some role in navigation back in the 1930s, but
these features weren't identified until 1986. As numerous, corresponding forimina are also
present along the beak in Obdurodon, it was presumably also a highly perceptive
organ.
Lifestyle?
The relatively flat skull and dentary, (and other features), suggest a somewhat different
lifestyle to the platypus, (p.1076). The shape may have been better suited for foraging at
a higher level in the water, whereas a platy feeds mostly on the beds of rivers. The beak
of the modern animal slopes more downwards, and this may enhance its performance when
shovelling through low lying debris for food.
Dental developments
"Three correlated trends in dental evolution leading to and within the ornithorhynchid
line can be seen: (i) elaboration and multiplication of the transverse shearing blade; (ii)
progressive reduction of the roots of the molars; and (iii) increased role of the oral
epithelium in dental function through production of horny pads", (p.1976).
The tongues of all living monotremes come fitted with spines of keratinized tissue, and
these assist with breaking down food items.
Holotype
The holotype resides in the Queensland Museum, Brisbane. It's a near complete skull with
premolars in place. It's supplemented by further material from Riversleigh. According to
this study, the holotype is QM F20568. For some reason, Woodburne, 2003 gives the type as
QM F20654, (p.225). I find it difficult to believe they're both correct! Satisfyingly,
both papers agree on the tooth formula: Uppers: 0,0,2,2; Lowers: 0,0,2,3. |
| Reference: | Archer et al (1992), Description of the skull and non-vestigial
dentition of a Miocene platypus (Obdurodon dicksoni n. sp.) from Riversleigh,
Australia, and the problem of monotreme origins. p. 15-27 in M.L. Augee (ed.)
"Platypus and Echidnas", Royal Zoological Society of New South Wales. |
| Genus: Ornithorhynchus
(Shaw, 1799) Blumenbach JF, 1800
'bird snout'
Aka: Dermipus Wiedemann, 1800; Ornithorinchus Artaud, 1803;
"Platypus" ('flat foot') Shaw, 1799
Remarks: Allow me to introduce the duckbilled platypus. The original name was
preoccupied by a beetle described by Herbst, 1793. A drawing by Bertuch JF, published in
1798, was labelled O. paradoxus, and featured in a picture encyclopedia, Bilderbuch
für Kinder. The illustration of the skull goes into some detail, but there was no attempt
at a scientific description.
Those curious about how platypussies find their way around under water, might find the
introdctory piece below of interest. An article on distribution and lifestyle is also
available at:
The platypus, a mammalian megastar.
The following is based upon my reading of Pettigrew et al, 1998.
A platy approach to making sense of things.
The focus of these directories centres on Mesozoic animals, and the platypus doesn't fit
the bill. I'm not going to attempt a general introduction, as there are plenty of other
pages available on the web. Nevertheless, it deserves homage for its daring
eccentricity.
Platypussies are generous, aquatic mammals, and they love helping shrimps and other
invertebrates avoid problems associated with overcrowding. The bill is important for this
challenge, as it can be used for rummaging through mud and debris on the stream bed.
However, as a platy keeps its eyes closed when hunting, the bill is of far greater
significance. It's equipped with receptors to detect movements. In the 1980s, it was also
found guilty of picking up electrical impulses as well. The bill may in part be a shovel,
but this is an impressively high-tech implement.
Hearing
Platy hearing shows no obvious aquatic adaptations, (p.1200). It works best with sounds
travelling through the air. They're not very talkative animals. When awoken, 'tremulous
growling' has been noticed, and that applies for me as well. They've also been known to
offer a soft squeak of protest when rudely injected. This sense is probably of more
importance for the ground-dwelling echidnas.
Sight
There is evidence of aquatic specialisation in the eye, which is very small. The cornea is
flattened, and the front of the lens has a restricted curvature. The back, in contrast, is
strongly curved. This combination is found in other water-loving mammals; eg otters and
sea lions. The location and concentration of large ganglion cells on the temporal retina
would be effective for a relatively near-sighted predator, (p.1201). Visibility isn't
usually good under water, so it's of benefit to make the most of what light is available.
However, a platy does its best to get around these potential advantages. They rarely open
their eyes under water, and this has only been observed happening when the animal has been
about to surface. They never look at their prey, and this habit renders the adaptations as
being close to useless.
Why does a mammal with specialized vision hunt with its eyes closed?
This has nothing to do with liking a challenge or giving crustaceans an overly sporting
chance of survival. It could make sense in an evolutionary scenario. If platy ancestors
depended more upon vision, then the present state of affairs could be a remnant. This has
a potential parallel among echidnas, which also have receptors for detecting electrical
impulses. Tachyglossus, (the short-beaked echidna),
would appear to derive no particular benefit from them, and it boasts of only a small
number. Zaglossus, (the rain-forest dwelling long-beaked
echidna), is between its two relatives in this respect.
In this instance, the very limited fossil record means this possibility is presently
barely testable, but the authors do provide posterity with some pointers. If platy
ancestors made more use of vision, then they would presumably have possessed larger
orbits for their eyes. Should they have been less reliant on
their beaks, then the septomaxilla in the upper jaw
and the trigemal nerves would probably have been smaller, (p.1202).
For the while, published Cretaceous remains consist only of lower jaws and teeth from three
named genera. The oldest taxon for which such details are
available is Obdurodon. Its bill is actually more strongly
developed. Nevertheless, it's very conceivable that extinct monotremes were more diverse
than their surviving relatives. The Upper Cretaceous is entirely blank for this group.
There's a gap in the record of about fifty million years.
Raising hair
Platys are fond of fur, as are many water-loving mammals. Areas not covered are the beak,
the webbing on the feet and the lower side of the tail. The coat is at its most dense on
the front of the body, and it's organised into semi-circular bushels. The centre of each
is marked by one large hair, and this has between three to five clusters congregated around
it. Each cluster contains ten to sixteen finer hairs. These complete units have one or
two apocrine glands in the skin, (p.1203), and they're associated with the large hair.
That's also where the relevant nerves are concentrated.
At its thickest, there are around 750 hairs per square millimetre, 12-13 of which are large
ones. (For purists, the range is between 600 and 900 per square millimetre, and
geographical and seasonal factors are probably of significance.) When it comes to density,
the platypus wins the silver medal for mammalian furriness. It's only beaten by the sea
otter, (Enhydra lutris), which manages a phenomenal 1,250.
Always check the bill
I've nothing against ducks, (especially when served with orange sauce), but claims of
similarity for the beaks don't stand up to scrutiny. A platy bill is packed with sense
receptors and, as demonstrated by Schleich and colleagues in 1986, these include
electrosensory receptors. It's a highly sensitive subject. Quite how it works its wonders
isn't fully clear. It functions more effectively than crude calculations suggest it should,
so there may be some elegant data processing going on in the brain, (p.1204). Information
collected by the bill provides precise indications as to where a potential meal is, and
sensitivity is increased by repeated movements. Should a shrimp elect to wave its arms,
it'd be asking for trouble.
Somehow, the bill doesn't simply just pick up movement and electricity. It enables the
owner to construct the three-dimensional context. Both forms of receptors work in
conjunction.
Mechanoreceptors
These are found all over the bill. They can be recognized as small domes in a living
animal viewed under a microscope, and become better exposed when wet. These receptors are
aquatically adapted. When a prey animal moves, water displacement advertises the fact, and
a nearby platy could make sense of the transmission.
Electroreceptors
The beak has thousands of electroreceptors. Calculations suggest that the full-field
strength of a large shrimp should be detectable from a distance of around ten centimetres.
Observed behaviour shows platys can actually manage up to (and sometimes over) three times
that performance, (p.1205).
Part of the puzzle could be the electrical field produced by the lucky recipient of the
platy's attentions. Such fields are complex rather than uniform, and simple measurements
may fail to detect particular concentrations. There could also be a relatively poor
correlation between an artificial stimulus generated in laboratory work and what actually
happens in the outside world.
The number of electroreceptors is put at 40,000, and all can be picking up signals from the
same source.
A sense of direction
Should you happen to have a platypus, a large tank and some way of providing an electrical
signal, you might like to try this out at home. In response to a stimulus from above, the
platy would raise its head. It would also show suitable appreciation for signals from any
direction. It can sense the location of a single pulse. Electric fish can't manage that.
However, if you continually seek to entertain the animal from the same position, it also
has the ability to get bored, and completely ignore your unimaginative efforts. Its
detection rate is least effective with signals coming from either directly below or in
front.
Teamwork
Thanks to the combination of mechano- and electroreceptors, the platy can't only
figuratively hunt shrimps with its eyes closed. That's precisely what it does. Calling
such a mammal primitive, because it refuses to reproduce with live birth, would be
outrageous. It does indeed have some charming basal
qualities, but its bill is astonishingly derived and
un-duck-like.
Tank testing
The authors filled a 60x40x20cm tank with water, and a live crustacean (Cherax
quadricarinatus) agreed to help out by providing both mechanical and electrical
impulses, (p.1207). (Actually, it required prods and squeezes of encouragement.) They
used appropriate artificial sensors, but sometimes placed a platy beak near them, in case
it could somehow act as a damper. Its presence made no appreciable difference, (p.1208).
Mechanical disturbances were detected over forty centimetres away. There was also a clear
difference in the time required for both forms of signal to be registered. The electrical
signal arrived earlier. The distances tested ranged from five to sixty centimetres. Those
time-lags are a source of information a platy could use, in order to sense how far away its
next meal is. Knowledge of direction and distance is valuable for platy power.
Writing this article has been fun, and the opportunity has been provided by Pettigrew JD,
Manger PR & Fine SLB (1998), The sensory world of the platypus, Philosophical
Transactions of the Royal Society B, 353, p.199-1210. The paper is freely available
on-line:
The sensory world of the platypus.
There's a link to the pdf at the end of the Abstract.
| Reassigned species: O. agilis de Vis CW, 1895 and O. brevirostris
Ogilby, 1832 and O. crispus McGillivray, 1827 and O. fuscus Péron, 1807 and
O. laevis McGillivray, 1827 and O. novaehollandiae Lacépède, 1800 and O.
paradoxus Blumenbach, 1800 see O. anatinus | |
| Species: | Ornithorhynchus anatinus (Shaw G, 1799) Blumenbach
JF, 1800 |
| Aka: | O. agilis de Vis CW, 1885; O. brevirostris Ogilby,
1832; O. crispus MacGillivray, 1827; O. fuscus Péron, 1807; O. laevis
Macgillivray, 1827; O. novaehollandiae Lacépède, 1800; O. paradoxus
Blumenbach, 1800; O. rufus Péron, 1807; "Platypus anatinus"
('flatfoot duck-like') Shaw, 1799 |
| Place: | In or near the river bank |
| Country: | Australia |
| Age: | Still swimming |
| Remarks: |
One of my favourite creatures. Should you have some at home, you
may keep them in a platypussary. Whilst the females express their non-conformity by laying
eggs, the males are amongst the very few kinds of poisonous mammals. They produce venom in
a spur on the foot.
Teeth?
Despite some accounts to the contrary, platypussies aren't toothless. (Echidnas are).
Platties have highly modified teeth. The basic formula is
incisors 0/5, canines 1/1,
premolars 2/2, molars 3/3, and the first premolars are
replacements for deciduous ones. Adults are less toothy:
no incisors or canines, P 1/0, M 2/3. Taking into account both sides of the jaw, that's
twelve teeth in all. They're highly modified, not absent, (Woodburne 2003, p.303).
However, different authors provide differing reports on the presence or absence of teeth.
Every source confirms young platties have them. Musser & Archer, 1998 (p.1068)
contains: "Teeth are absent in adult Or. anatinus... although juveniles retain
vestigial molars until about one month after leaving the burrow". This appears to
contradict the dental formula found in Woodburne 2003, (above). I don't know if this
reflects a genuine difference of interpretation or simply different terminology. I suspect
the latter is more probable, as the alternative suggests somebody managed to count absent
choppers. What constitutes a tooth may be in the eye of the beholder.
Be that as it may, Musser & Archer provided a sketch on page 1067. Towards the front
of the jaws can be found secateuring ridges. There's one per side both up and down. They're
in the sort of position more usually reserved for incisors, and are longer than their
equivalents in the older Obdurodon dicksoni. These are followed by a significant
gap, where premolars might be expected in normal mammals.
Towards the back of the jaw is a slightly shorter and more complex construction called a
kerantinized dental pad. It's the platty equivalent of cheek teeth. At least some authors
see teeth in there somewhere. As some mammals use keratin for horns, these are often
termed horny pads. |
| References: | Shaw (1799), The duck-billed platypus. The Naturalist's
Miscellany 10: Plates 385, 386. |
| ?Blumenbach, (I assume!) (1800), Phil. Trans. XC. 432 My
opportunities of examining the Ornithorhynchus were procured through Sir Joseph
Banks. |
| Blumenbach (1800), Abbildungen naturhistorischer Gegenstande (v.
5, no. 41). |
| de Vis (1885), On an extinct monotreme, Ornithorhynchus agilis
. Proc. Roy. Soc. Queensland II p.35-38, pl. IV, figs. 1-3. |
| Links:
Melbourne Zoo, Platypus
http://www.zoo.org.au/animal_page.cfm?area_id=27&zoo_id=1&animal_id=41
A short introduction, with an e-postcard.
What is a Platypus?
http://www.rentcomputers.com/platwhat.html
An on-line resource guide. Not surprisingly, there are loads of links available.
Jeff Allender's House of Checklists
http://ourworld.compuserve.com/homepages/allender/24natu.htm
A listing of John Player cigarette cards from 1924. Both the platypus and an echidna were
featured.
The Brain Museum, Platypus
http://www.brainmuseum.org/Specimens/monotremata/platypus/index.html
An opportunity to look at the brain. Not for the squeamish.
Evolutionists Claim that the Platypus Links Birds and Mammals?
http://www.amazon.com/exec/obidos/ASIN/0801057744/104-3361527-2501525
"Evolutionists insist that the duck-billed platypus is an evolutionary link between
mammals and birds." This piece of twaddle comes from The Collapse of Evolution
by Scott M Huse, which first appeared in 1983. Reportedly, over 100,000 copies have been
sold. The third edition was published in 1998 and is still readily available. A review at
Amazon.com, posted on 8.10.2001, makes clear that the above untruth is still in it.
We’re all capable of writing or saying stupid things and we all get things wrong, but that
doesn’t explain how someone can knowingly perpetuate a falsehood for nigh-on twenty years.
|
| Species: | Ornithorhynchus matinus |
| Place: | |
| Country: | |
| Age: | |
| Remarks: |
The Natural History Museum in London have a pickled juvenile
specimen with this name, and they possess a stuffed head. This cannot surely be a valid
species. |
| Reference: | |
| Species: | Ornithorhynchus severini |
| Place: | |
| Country: | |
| Age: | |
| Remarks: |
This is listed on the Biosis Index, but I have no further information. |
| Reference: | |
A. Early Monotremes B.
Ornithorhynchidae C. Tachyglossidae
| Taxon: Tachyglossidae Gill, 1872
Whilst the platypus has a worldwide fan base, far fewer people have heard of echidnas.
There are two existing genera and they’re fun. Perhaps because monotremes enjoy confounding
and confusing people, female echidnas come equipped with a basic pouch. This doesn’t make
them marsupials. Nor does it mean that monos were
somehow ancestral to marsups.
Genera: Acanthoglossus (= Zaglossus), Acanthonothus
(= Tachyglossus), Bruijia (= Zaglossus), Bruynia (= Zaglossus)
, "Echidna" (= Tachyglossus), Echidnopus (= Tachyglossus),
Megalibgwilia (= Zaglossus?), Mymecophaga
(= Tachyglossus), Proechidna (= Zaglossus), Prozaglossus
(= Zaglossus), Syphomia (= Tachyglossus),
Tachyglossus, Zaglossus ,
other reports
Remarks: As can be seen, the book-keeping is somewhat confusing. Luckily, there’s…
Links:
Rád: Monotremata Bonaparte, 1837
http://savci.upol.cz/spec/ptak_syn.htm
A well researched page on monotrematic nomenclature. This is in Czech and attests to the
advantages of using standard scientific names.
Geozoo Mammals, Echidnas
http://mammals.geozoo.org/mon/tac/
This is an introduction to echidnas. I particularly enjoyed the sex as reported on a former
page:
"During the breeding season, a group of males often walks in lines behind a single
female, forming an "echidna train." They may follow the female for a few days,
until she is ready to mate. The courtship process may last six weeks, yet only one male gets to mate.
When the female is ready, she grabs a tree with her legs. The males walk around the tree in
a circle, stopping now and then to dig a trench. Finally, one lucky male mates with the
female."
Echidnas on the Web
http://www.isidore-of-seville.com/echidnas/
Tim Spalding pays homage to echidnas; info, topics, images, inspiration and so on. He also
has a soft spot for Komodo dragons -the ambitiously sized monitor lizards of Indonesia.
Time-Line:
Today: Tachyglossus, Zaglossus
Pliocene-Pleistocene: Megalibgwilia, Zaglossus |
| Genus: Tachyglossus (Shaw
G, 1792) Illiger, 1811
'rapid tongue'
Aka: Acanthonothus Goldfuss, 1809; "Echidna" Cuvier G, 1797?/8?;
Echinopus Fischer G, 1814; Mymecophaga Shaw 1792; Ornithrhynchus sp.;
Platypus sp.; Syphomia Rafinesque, 1815
Remarks: More commonly known as the spiny anteater. Echidna Forster, 1788 is a
moray eel genus,
(thank you Aquadex.) Syphomia was meant as a replacement name for Echidna
Cuvier.
Several sub-species are widely recognized; eg. T. a. lawesi
from NG. The number of names is impressive, but not a record. Shaw’s original attempt from
1792 positioned this animal as a species within the anteater genus, Myrmecophaga
Linnaeus, 1758. Ten years later, Home had a bash and recognized the anatomical similarities
with the platypus, Ornithorhynchus. Their odd mode of reproduction makes this relationship
obvious now but, until the 1880s, European scientists didn’t know about echidna eggs.
In Australia in 1789, shortly after a slight disagreement with most the crew of HMS Bounty,
the deposed Captain Bligh apparently sketched a specimen, shortly before dinner. There's
no prize available for guessing what they ate.
The specific name apparently means 'with points'.
| Reassigned species: T. lawesi Ramsay, 1877 and T. setosus
(Geoffroy, 1803) and T. typicus see T. aculeatus | |
| Species: | Tachyglossus aculeatus (Shaw G, 1792) |
| Aka: | Acanthonotus myrmecophagus Goldfuss, 1809; Echidna
acanthion Collett, 1884; E. aculeata Shaw (two refs. from 1934); E.
australiensis Lesson, 1827; E. australis Lesson, 1836; E. breviaculeata
Tiedemann, 1808; E. corealis Krefft, 1872; E. hobartensis Kowarzik, 1909;
E. hystrix (ref. from 1935); E. longiaculeata Tiedemann, 1808; E.
novaehollandiae Lapécède, 1799; E. orientalis Krefft, 1872; E. setosa
Geoffroy, 1803; E. sydneiensis Kowarzik, 1909; Myrmecophaga aculeate Shaw G,
1792; Ornithorhynchus eracinius Mudie, 1829; Ornithorhynchus hystrix Home,
1802; Platypus longirostris Perry, 1810; T. lawesi Ramsay, 1877; T.
setosus (Geoffroy, 1803); T. typicus |
| Place: | On land |
| Country: | Australia, Indonesia & Papua New Guinea |
| Age: | Still rummaging. |
| Remarks: | The following is based upon my reading or Rismiller
PD & McKelvey MW, 2000. This has been supplemented by Attenborough D, 2003 (p.15-18),
Honders J (Gen. Ed.), 1975 (p.68-70), Rismiller PD, 1992 and a webpage: Parker J, 2000,
Echidna Love Trains,
Scribblygum.
A tachy tale of sex
I've been reading about Australians and sex, and it was hot stuff. It concerned goings on
at a place called Pelican Lagoon on Kangaroo Island, which is 100km southwest of Adelaide.
In winter, (July to August), some of the residents get extremely randy and partake in
public parades. For some reason, this island is popular with tourists. Should readers be
looking for sex, this article is packed with it. Kangaroo Island has 10,000 human
residents, but it's the short-beaked echidnas who really know how to have a good time.
Tachyglossus is the most widespread monotreme in the world. Although competition for
this honour is none too fierce, it surely deserves some applause. It lives all over
Australia, (p.1), and also in New Guinea. That may sound geographically unimpressive, but
Australia is much bigger than some people give it credit for, and the scope of habitats is
remarkably varied. Assuming you're in Australasia, should you be near a desert, a
rainforest, an open plain, a valley, 1,500 metres up a mountain, at a cricket ground or
anywhere in between, you could well be close to Tachyglossus. Regardless of what the
terrain is like, if it can support ants, termites and other creepy crawlies, then the
short-beaked echidna is adaptable enough to call it home sweet home.
Despite its range in a country with plenty of skilled observers, the habits of the echidna
make it elusive. The population levels before the arrival of Europeans is unsurprisingly
not known, but nor are the current numbers. As they live alone on territories which can
reach nearly 200 hectares, that's a lot of land for a mammal of between two and seven
kilos.
It's not even possible to tell the sexes apart without hands-on examination, as all the
informative bits are stored internally. Whether the individual is a male or female has no
obvious bearing upon the weight, size or colour. As these animals usually refuse to breed
in zoos, little knowledge existed about reproduction rates.
Live long and keep cool
Echidnas have been known to celebrate Golden Jubilees in captivity, which is fifty years.
Even in the perils of the wild, one individual reached the age of at least forty-five.
The only mammals with lower body temperatures are either platypuses or dead. Generally,
the operating temperature is between 31-33°C, but this can change by as much as 10° during
a single day. As echidnas don't like being too hot, their presence in much of Australia
might seem puzzling. However, the variety of habitats is a testimony to adaptability. They
don't mind being diurnal, nocturnal or both, and can hibernate. Five subspecies are
recognised. Of these, two in cooler conditions and one in a more Mediterranean climate
practice some form of hibernation. Those in alpine areas switch off for much of the
winter, but they reawake every couple of weeks to attend to any necessary business.
Make a date for the love train
In autumn or winter, an adult echidna's heart yearns for companionship and sex. They become
social, and do so with determination, (p.2). Should a female be enticing, a male may begin
to follow her around. Often, she'll collect up a club of fans. The result is known as an
echidna train, and there are usually three or four males in the procession. Presently, the
longest ever reported was a file containing eleven individuals. These trains can be caught
from the middle of May until September. Often, the single female is the largest animal,
and she enraptures her followers with a pheromone perfume. This can carry on for over five
weeks.
Getting down to business
All Australian echidna mating occurs between July and September. Given their usually
secluded way of life, little was known about mating in the wild until the 1980s. At what
age they begin to breed was a mystery, as were the frequency and survival rates of babies.
It was thought that a female probably wouldn't give birth annually, but systematic
observation was immensely difficult. Rismiller and McKelvey came up with a way of
improving the picture. The work they reported on was carried out during a seven year
project, and required many human helpers. Volunteers from the Earthwatch Institute and the
Australian Trust for Conservation Volunteers devoted over 70,000 person hours of careful
effort to the undertaking.
Location
Kangaroo Island is in South Australia. As it's surrounded by water, the environment has
been less disturbed by more recent arrivals than elsewhere. The study area was Pelican
Lagoon, which is a peninsula on the eastern side. It's five kilometres long and offers
around a thousand hectares of land. Much of the flora is pristine Australia, and it's a
rabbit and fox free zone. It also has a variety of habitats; woods, shrubland, open grass
and both freshwater and coastal swamps. The climate is temperate or Mediterranean, and
some areas are semi-arid.
First catch your echidnas
Echidnas don't lead settled lives or follow regular routines. They also avoid baited traps
and aren't partial to recorded noise. As the study was to be as thorough as practical, the
obvious place to look was more or less everywhere. With the assistance of volunteers, three
hundred hectares were explored on foot. When a specimen was encountered, it was approached
with care and bare hands.
A friendly method of grabbing an echidna involves kneeling down behind one, and placing
the hands below the shoulders and legs. Keep a firm grip and wait until it relaxes, (which
would be difficult to assess with protective gloves). You can then lift the echidna, and
it will curl itself round your hands. Luckily, the presence of your flesh will prevent the
animal inadvertently spiking its delicate underside. Less considerate methods were
avoided.
Echidnas can't be bothered with trying to run away. If the ground permits, they have the
ability to dig themselves in vertically at speed. On harder surfaces they roll up. Their
spikes are effective.
Timespan and echidna freebies
87 individuals took part in the survey, which ran from November 1990 until December 1997.
All adult residents were probably registered by 1995, as no additional ones were found
later. Each was injected with a small electronic transponder, (p.3), which they were
allowed to keep for their lifetime. These enable unambiguous identifications. However, as
reading them necessitates using a scanner, it can be disruptive. Discrete colour coding
was also employed. All the females and juveniles were presented with radio transmitters,
as were some males. Over time these get lost. When fully kitted out, the residents were
set free where they were found.
Keeping track
At any one time during the seven years, a maximum of thirty residents were kindly providing
radio reports on their whereabouts. Despite conforming to mammalian norms by possessing
seven neck vertebrae, echidnas don't have much of what could be termed necks, so collars
aren't an option. Instead, small transmitters were glued onto a couple of snipped spines
on the lower back. These generally remained in place for a couple of years, and required
new batteries every nine months.
The privileged males found a further use for their transmitters. They provided extra grip
when mating, and were much appreciated. In the understandable excitement, these sex aids
sometimes fell off. The emergence of new spines also caused difficulties. Both factors
meant transmitters had to be checked more carefully in the winter and spring.
Systematic espionage
It was known from experience that tracking and observation necessitate discretion, should
the objective be not to influence natural breeding behaviour. I doubt I'd perform in
quite the same way if an unexpected third party were making notes and taking photos. This
meant assistants required training so as to use factors such as wind, the lie of the land,
sound and light efficiently. Working in relay, animals could be monitored at intervals
around the clock for over five days continuously. Hides and natural cover helped during
daytime, and low-level light enhancers and infrared equipment were useful during darkness.
As the study was concerned primarily with love life, monitoring became more intensive with
the commencement of courtship. Instead of checking the location of a mature female once a
day, she was subjected to a sighting every four hours. With the beginnings of heavy
petting, (ie. when she failed to raise her spines at the approach of a male), she was
voyeuristically viewed hourly. Copulation was followed by a relaxation; two-hourly. Once
the female had resumed her more usual solitary lifestyle, derived primates inspected her
pouch each couple of days after the fifteenth post-mating day. We really are the nosiest
animals on the planet.
The progeny were fitted with transmitters whenever possible. Their need to eventually
find a new range for themselves means they can travel considerable distances. They
sometimes led their human spies off the peninsula.
Sex and age
Echidnas are well practised at telling the crucial difference, but it's more problematic
for humans, (p.4). When not in use, all sex organs are stored tidily inside the body.
However, gentle feeling of the appropriate region can reveal the existence of a penis.
Those individuals are male. Monitoring showed the assessments were accurate. Both sexes
can display the beginnings of a pouch, should they contract the correct muscles. In
lactating females, the enlargement of the mammary glands causes it to increase in size, so
as to provide a hatchling with accommodation.
Both boy and girl echidnas possess spurs of bone on the back of the foot, and these are
covered by juvenile sheaths. They are lost between the ages of 14 and 48 months, and no
individuals with sheathed spurs were seen mating. This feature helps establish the
approximate age, but it doesn't provide information on the sex.
Telling the age of an adult echidna is presently impossible, unless it's been monitored
since birth. As most hatch in August or September, and are then weaned by about 200 days,
any unknown individual with juvenile spurs found in November must be about 14 to 16 months
in age. It's known that they leave home when about a year old, so such animals were
probably immigrants.
Caravans of love
Echidna trains only form during the breeding season. The earliest sighting was in April
and the latest in September. Sometimes, they failed to reach Sexual Congress Station. Each
year, at least one female attracted admirers who proved less than enthusiastic. There
were never more than two, and they deserted her company within 48 hours. One female led
trains over a period of 44 days, but this didn't end with a fertilized egg. Skipping briefly
forwards to page 11, she attracted males on two occasions during that time.
For those who mated at Pelican Lagoon, courtships lasted between seven and 37 days. The
number of births varied from year to year, but not in line with the total number of females:
1990, 4 monitored females, (1 birth); 1991, 8 (3); 1992, 10 (1); 1993, 19 (6); 1994, 19
(9); 1995, 10 (1); 1996, 11 (1), (Table 1, p.5)
In the vintage years ('93 and '94) successful echidna trains hit the rails in June or July,
and the station was reached between mid June and late July. (As this is Australia, that's
winter.) Not all trains were spotted though, as three females were fond with incriminating
babies in their pouches. If possible, all individuals in a group were weighed. However,
no insight was gained into whether bodymass had an effect on the closeness of a male with
the female. They were sometimes found in more of a huddle than a procession, with the
female in the centre.
The six birthers of 1993 had been accompanied by three to five suitors. Weight figures
were acquired for five of these trains, and the female was the heaviest animal in three
cases. The lightest female had the shortest courtship of seven days, (p.6). In the
following year, trains featuring a male as the heaviest member were found more frequently.
Furthermore, when more breeding females were available, trains tended to be shorter. None
of the ladies in 1994 attracted more than three companions.
Fickle fans
Some males were less committed than others, and changed allegiances. They left one
train and hopped on another. There doesn't appear to be an advantage for heavyweights.
The largest male recorded doted after a female called RHC in both most productive years,
but he didn't get to make a contribution to the increased birth rate on either occasion.
As he was also spotted in other trains, perhaps she felt offended.
Four steps to heavenly bliss
The first stage of courtship is relatively shy. Males stay close to the object of their
desires, but the association is a fairly loose three to five metres. When taking a break,
the animals will go into a huddle. Otherwise, no touching is allowed.
Things bolden for stage two, and some gentlemen will walk beside or directly behind the
female, and there will be contact. This is also when proceedings begin to get a bit rough,
as pushing and shoving are employed in order to obtain the most prized positions. During
both these stages, males will switch trains, and even wander off on their own for a rest or
forage, only to resume the activity later.
By the third stage, things are getting serious and the excitement rises. Males remain
close to the interesting female. They'll attempt to entice her with beak-nudging and jab
or caress her body with their eager paws. Should it all get a bit much, she may dig into
the ground and erect her spines in protest. This causes all suitors to move back.
Stage four and bingo
When the lady can resist no longer, she'll lie prone with relaxed spines, and this shows
she wants sex. What actually occurs is strongly influenced by the number of her fans.
Should there be but one, he'll romantically dig a hole next to her, (p.7), while stroking
her with his front feet. He'll then attempt to push her tail up with his back feet. This
is very much how I approach love making.
If more males are present, the process is rather more complicated. They all start digging,
while shoving each other aside. As this can result in a 25 centimetre deep circular trench,
and serious barging until only one male remains, passionately enflamed female echidnas
sometimes need patience. Anyway, once all that's sorted out and there's been a bit more
digging, their tails will touch and so will their cloacae. The penis will enter her body.
Was it worth the wait?
This may not be everybody's idea of a good time, but echidnas seem to enjoy it. The female
will be pleasured by a four-headed penis. As she has sex less than once a year, it's
important to make a thorough job of it. The couple may be thus occupied for half-an-hour,
but that would be quick for echidnas. This intimate union can last for three hours.
Should you wish to watch these animals in action, it's a matter of both persistence and
luck. They may make love behind foliage, in caves, in tunnels among tree roots and
quite frequently in darkness. Despite plenty of persistence, this behaviour was only seen
eight times in seven years. Although mating may take several hours, it doesn't leave the
couple bonded by love. Before the end of two days, male and female will have gone their
separate ways, and he might have joined another train to a different station. In all known
instances, mating resulted in an egg.
Giving birth
Eggs are laid 15 to 23 days after the train finally derailed and all its passengers
wandered elsewhere. In this study, they were found between 22 and 24 days. Much excitement
resulted from the demonstration attempted by YGBL. She was seen sitting with her tail
curled in the direction of the pouch. This meant her cloaca was above the front edge.
Observers noticed an interesting contraction. Within half-a-minute, YGBL resumed a more
familiar pose and strolled off. A body search revealed a white egg and, ten days later,
it was hatching.
Among observed mothers, eight preferred to shelter in one place when incubating eggs, while
two were more mobile. Locations included crevices, below tree roots and in excavated
holes. The animals were generally also actively looking for food. All hatching was
complete within nine to eleven days.
Congratulations! It's a puggle.
Should you want to cause an outcry at a Scrabble tournament, new born echidnas are known
as puggles. Weights ranged from 0.23 to 0.37 grammes and bodylengths were 2.2 to 2.5
centimetres. (These measurements were for babies which had hatched within 48 hours. In
most cases, the individuals were less than 24 hours old, and this applied for the second
largest.) If a puggle wants to succeed, it first has much growing to do. A 600-fold
weight gain in about two months would be an adequate start.
Sexual maturity and appetite
25 females took part in the survey, and 17 became mothers. 22 puggles hatched. Of the
other females, six found less than enthusiastic fans, and two were either nuns, incredibly
ugly or something else. Only two reproduced in consecutive years, (p.8), and RHC set a
record with three. Unfortunately, she failed to increase in weight over the summer, and
died during wintry August.
Four of the mothers participated for the full seven years. Two gave birth twice, one
once, and the fourth stirred some moderate interest but never mated. It's known that she
must have been at least ten years old.
GTC provided some indication of the onset of maturity. When first met in 1990, she was
probably between 15 and 27 months old. As she mated in 1994, she would have been
approximately five.
Raising puggles
A growing puggle gets heavy and prickly, so the mother puts it in a nursery burrow at 45
to 55 days. These may be built to take advantage of natural facilities, or dug personally.
The mother always closes up the entrance when she goes shopping. Her trips take time.
Apparently, a puggle never leaves the burrow, and depends entirely upon the milk deliveries.
(This is supported by analysis of recovered droppings.) It only gets a meal every five to
six days, and can drink up to 40% of its own bodyweight per feed.
Echidnas take a cold turkey approach to breaking milk addiction, and this occurs between
mid January and late February. The mother returns from the shops, opens the burrow and
brings the puggle outside for a drink. She then walks off and parental duties are over.
Weaning is achieved by disappearing.
Growing up
Deserted puggles are vulnerable. 22 hatchlings were monitored over the seven years, and
only eight definitely reached ages of a year or more. At 12 to 18 months, an echidna has
to move to pastures new. A pair of the survivors were dead before their second birthdays.
Of those who moved out, all travelled at least six kilometres before trace was lost or the
transmitter fell off. One got as far as thirty kilometres, but the winner managed at least
45. Among those who failed to reach the weaning stage, three fell victim to monitor
lizards called goannas, and four met with feral cat accidents. (An island with 10,000
humans is very liable to have feral cats.) What happened to the other seven is unknown,
(p.9). There was no obvious correlation between the loss of a puggle and the readiness
of the mother to try again the following year, but this did occur in two cases.
Newcomers
As young echidnas leave their area of birth, new recruits arrive from elsewhere. These
animals take genetic diversity seriously. A total of seventeen unfamiliar subadults
turned up, while no marked local juvenile was found. Of these immigrants, six perished
during the survey; cats -two, suspected accidental poisoning with herbicide -two, unknown
causes -two.
Further afield
It's not only on Kangaroo Island that Tachyglossus love involves conga lines.
Echidna trains have also been seen in Victoria, New South Wales, Queensland and the
Capital Territory, (p.12). Things may work differently above the snow line. No trains
were spotted in the mountains of the Kosciusko National Park, NSW. In cold climates,
echidnas pair up and seek out a burrow in late winter, (August and September). Maternal
care also differs. The mother remains with the puggle, and doesn't venture out until it's
about three weeks old, (p.13).
As echidnas breed infrequently and their rituals are complicated, it's hardly astonishing
that births in captivity are rare. The first instance was recorded in Berlin in 1908.
This was only noticed when the baby fell out of the pouch in May. It died in August. At
the time of publication, 75 short-beaked echidnas lived in 37 zoos outside of Australia,
and only three had been born in captivity. None of those had become parents.
As the breeding season is much the same all over Australia, it doesn't have an obvious
environmental trigger, (p.15). June to September is the rainiest time of the year in the
south, but it's the driest in the north. One factor which may be involved is seasonally
restricted light levels, as it's winter at the same time. Intriguingly, zoo inmates in
the northern hemisphere also follow this pattern, (p.16). Their minds turn most readily
to sex between the winter solstice and the spring equinox; ie. during the northern
winter. |
| Reference??????: | Shaw G & Nodder FP collaborated on The Naturalist's
Miscellany, or coloured figures of natural objects; drawn and described from nature,
(1789-1813).
The text was Dr Shaw’s responsibility, whilst Nodder or, (after about 1800), Nodder junior
supplied the illustrations. I don’t know that this is the source, but there are some nice
pictures from the 1792 edition at:
http://pages.1700-1900aaaantiques.com/5042/InventoryPage/1062443/1.html |
| Species: | Tachyglossus setosus (Geoffroy, 1803) |
| Aka: | T. selosus |
| Place: | Tasmania |
| Country: | Australia |
| Age: | Still chewing |
| Remarks: | Many authors see this as a subspecies;
T.aculeatus setosus. |
| Reference: | |
| Genus: Megalibgwilia
Griffiths M, Wells RT & Barrie DJ, 1991
Remarks: Doubts exist as to whether this is a separate genus from Zaglossus.
|
| Species: | Megalibgwilia oweni |
| Aka: | Zaglossus oweni |
| Place: | |
| Country: | |
| Age: | |
| Remarks: | A possibly synonym of M.-Z. ramsayi. |
| Reference: | |
| Species: | Megalibgwilia ramsayi (Owen R, 1884) Griffiths M,
Wells RT & Barrie DJ, 1991 |
| Aka: | Echidna ramsayi Owen, 1884; Zaglossus ramsayi (Owen,
1884) |
| Place: | NSW & South Australia |
| Country: | Australia |
| Age: | Middle Pleistocene |
| Remarks: | Several near complete skulls. A body length of
around 75cm. |
| References: | Owen (1884), Evidence of a large extinct monotreme (Echidna
ramsayi, Ow.) from the Wellington breccia Cave, New South Wales. Philos Trans Roy Soc
London CLXXV. p.273-275, pl. XIV. |
| Griffiths et al (1991), Observations on the skulls of fossil and extant
echidnas (Monotremata: Tachyglossidae). Australian Mammalogy 14, p.87-101. |
| Species: | Megalibgwilia robusta (Dun WS, 1895) Griffiths M,
Wells RT & Barrie DJ, 1991 |
| Aka: | Ornithorhynchus maximus Dun WS, 1895; Zaglossus robusta
Dun WS, 1895; Z. robustus? |
| Place: | |
| Country: | Australia |
| Age: | Upper Pliocene - Upper Pleistocene |
| Remarks: | A length of perhaps 65cm or so. (The skull was
about 16cm long. This is 2cm, (11%), less than for M. ramsayi. Basis of guestimate:
75 x 0,89.) |
| Reference: | Griffiths et al (1991), Observations on the skulls of fossil
and extant echidnas (Monotremata: Tachyglossidae). Australian Mammalogy 14, p.87-101.
|
| Genus: Zaglossus Gill, 1877
'great tongue'
Aka: Acanthoglossus Gervais, 1877; Bruijnia Thomas, 1883;
Bruynia Dubois, 1882; Echidna sp.; Ornithorhynchus sp.;
Proechidna ('before Echidna') Gervais, 1877; Prozaglossus
('before Zaglossus') Kerbert, 1913; Tachyglossus sp.
Remarks: This genus is now restricted to New Guinea, (Indonesia and Papua NG), though
fossil remains have been reported from Australia. Mostly, these now get assigned
to Megalibgwilia. Proechidna is still sometimes
used for this genus.
At last I can attempt a more fitting entry for this genus
The following is based upon my decade late reading of Flannery & Groves, 1998, and
thanks are due to somebody for posting the link.
These notes are being written in September 2007. Given the welcome and sudden
arrival of flocks of recent papers on Mesozoic mammals and their allies, I've
naturally resolved to concentrate my attentions on those. However, something has
prompted me to turn to this study of long-beaked echidnas from 1998. Firstly, I've
wanted to write something with substance on this genus for years. An informative
source, however, was as elusive as a Zaglossus, animals whose hobbies include
hiding, not being seen, and attempting invisibility. As they're also generally
anti-social, nocturnal, live in inaccessible places and rare to the point of being
endangered, they happen to be very good at their hobbies and extremely hard to
study.
Secondly, despite having been published nine years ago, Flannery & Groves' paper
has suddenly become seductively sexy for mammal fanciers. I couldn't resist its
charms any longer, lay down in bed and waited for it to have its way with me. The
experience proved most pleasurable. This was brought about by the rediscovery of
the smallest and most elusive member of the genus. Z. attenboroughi, named
after St David of the BBC, has just been sighted wandering around with a placard:
"Reports of my extinction were exaggerations." When these authors established
that species in 1998, the last signs of activity had been detected in 1961. That's
when the future holotype and, for many years, the only known specimen had been
granted relief from its responsibilities; a diplomatic phrase meaning 'brutally
murdered'. ('Collected' is the actual word used, and it perhaps lived for a bit
longer.) Anyway, it was the remains of a stiff when F & G found it.
It turns out that there have actually been a couple of detections in the last few
years. The first reported encounter was lost to science, but researchers were
advised this individual had been very tasty. As the echidna failed to survive its
unexpected invitation to dinner, the correctness of the identification is somewhat
tricky to assess. Nevertheless, a secure 2007 report shows that Z. attenboroughi
is in a healthier state than has generally been thought. It's merely on the brink
of extinction rather than beyond it.
The 2007 expedition involved a researcher by the name of Johnathan Baille. Pleasingly,
he's put some comments on-line in a blog, and a link can be found below in the
specific entry for Z. attenboroughi. Reportedly, there are grounds for some
cautious optimism. Firstly, a number of locals informed him of echidna sightings
in the area over the last few decades, and at least one of them could recommend the pleasant
taste of the things. Descriptions were consistent with this species; eg small
and straight-beaked. All such reports came from surprisingly low elevations; 300
metres at the most. That naturally suggests it isn't restricted to tall peaks, and
this would mean the potential territory must be somewhat larger than feared.
Another encouraging sign is that the local name of the animal is still known to
some. Baille was told it's payangko.
Echidnas -elegance beyond mere fashion.
Cleaning the echidnas
The systematics of Zaglossus have caused an impressive number of headaches
over the last century or so. They're rare, difficult to study and rather variable
in some ways. You can come across differing colour tones, thickness of fur, lengths
of quills, numbers of claws and so on. However, as some of these differences are
due to age or result from adaptations for seasonal and other environmental factors
(eg. the altitude of the home range), which of them might actually be informative
for identifying species isn't necessarily obvious. And things can get further
obscured by shortages of specimens and some less than ideal bookkeeping. For
example, if you're not sure about where particular animals came from, then you'll
have difficulties with assigning them to their correct population. Record keeping
sometimes got a low priority.
The authors undertook the widest survey of individuals they could manage, and this
involved globetrotting around the museum collections of the planet, measuring and
examining along the way. By concentrating on the more reliable locality data, they
came up with more Zag diversity than expected; three species including a newly
described one (p.367). Z. bruijnii resides in western New Guinea and Z.
bartoni, split into four species, is spread around through much of the mountainous
middle and on down to the southeast. A third species, little Z. attenboroughi,
seems to be restricted to its enclave of the Cyclops Mountains, which are found
roughly near the middle of the north coast. The only representative then available,
or what was left of it, was actually found lurking in Leiden, the Netherlands.
Variety is the spice of life
There are two fairly similar genera of echidna;
Tachyglossus (Australia and New Guinea) and Zaglossus (New Guinea).
Zaglossus-like critters used to inhabit Australia as well, although these
are mostly referred to their own genus these days (
Megalibgwilia). Zags tend to be larger than tachys, but that isn't
always the case. This genus has a preference for worms rather than ants and
termites, as far as is known. Its beak is proportionately longer, thus long-beaked
echidna, and curves downwards (p.368). The shorter tachy equivalent is also
straighter. Differences also lie in the construction of the skull.
Captive zags have been known to reach about 17 kilos in weight. From beak tip to
tail end lengths of perhaps a metre have been exceptionally seen, but this could
be an exaggeration of the size of things caused by possibly stretched skins. Some
adult zags are no larger than adult tachys.
Sex
If Lewis Carol had included explicit sex scenes in Alice in Wonderland, then he'd
probably not have managed to compete with the bizarreness achieved by some tachy
behaviour; games of follow my leader going on for days, competitive hole digging by
the multi-headed penis fraternity, bush grabbing by the willing bride, copulations
lasting several hours... It all makes a game of croquet played with flamingos
and hedgehogs seem rather mundane. What customs may accompany zag courtship and
conquest is only known by the participants themselves. They've never given public
performances. Puggles (babies) have also remained successfully out of sight.
Taxonomic history
This area is potentially confusing. Peters and Doria kicked things off in 1876 by
describing a skull from northwest New Guinea. They nominated it as representing a
new species of the already known echidna, and named it Tachyglossus
bruijini. That wasn't unreasonable, and nor was its elevation to a generic
level in the following year. While these echidnas are broadly similar, clear
distinctions are present. To great public acclaim Gill launched Zaglossus.
Unfortunately, perhaps deafened by the applause, Gervais failed to hear about that
and suggested Acanthoglossus for the same thing (p.369).
Du Bois stepped forward in 1882 and, whether from luck or talent, managed to make
an inspired muddle. Unaware of the original proposal, he concluded the second one
could be invalid due to its preoccupation by a beetle with a different name:
Acanthoglossa. He wasn't sure whether such similar names are allowed. They
are, as it happens. Nevertheless, his uncertainty led him to propose a possible
replacement one, should such a thing perhaps be required. Quite magnificently, he
managed to misspell it as Bruynia (in honour of Bruijin, the collector).
There was a further point Du Bois didn't appreciate. Should a generic name
require emendation or replacement, then this has no relevance at all for the
specific one. He felt B. tridactyla would do well enough.
Why he didn't simply check the ICZN regulations on the internet is something I find
difficult to understand. (Please don't try and explain. That sentence is meant to
be silly.)
Matters then turned to the establishment of new species and species based upon
differences of fur and spines. These led to a series of proposed species and subspecies,
and that was despite little being known about variations due to age or seasonal
factors. The number had reached five by 1913. More caution would've wise, and it
was called for by some, but there were visible differences that were well worth
thinking about. Simply ignoring distinctions you can see is technically termed
stupidity.
A researcher named Kerbert had doubts about the significance of variable fur colour,
thickness, spine details and the like and, instead, paid more attention to the
number of claws per paw. As far as he was aware, all known members of "Z. bruijni"
from eastern New Guinea have five claws on all feet, whereas those to the west have
three. This isn't quite accurate. Nevertheless, it served as the basis for
establishing Prozaglossus bartoni for the 'five-clawed' lot. Others
concluded a separate genus was going a bit too far, and revised it to Z.
bartoni.
Eventually, however, in a 1969 paper I've coincidently not yet written any notes on,
van Duesen and George felt a single species was a sensible provisional solution.
To go any further than that would require a through examination of available
specimens, and that could perhaps then allow significant differences to be threshed
from the chaff of individual variation. That's rather what Flannery and Groves
attempted. Ideally, some forms of genetic testing would also have been helpful but,
given the elusive lifestyle and rarity of Z., and the condition of the
available remains, that wasn't a practical option.
Measurements, age and sex
Of all the specimens volunteered as holotypes at one time or another, only
Z. villossissima managed to remain beyond reach. Measurements of some skull
details were impaired by their habitual fragility, and statistical analyses were
generally restricted to adults. The joins between individual skull bones helpfully
fade from view with advancing age, and that habit allows for the identification of
kids. Further aspects of maturation serve to provide confirmation on the issue
(p.371).
Living individuals can be sexed by decidedly impolite probing of certain physical
properties, although it isn't as straightforward as many humans might imagine.
Reproductive equipment is generally stored away internally when not in use. Still,
encouragement can excite clarity. However, such an approach doesn't help with
deadlings in museum collections. Cutting them up could be revealing, or less
intrusive examinations are possible in some cases. What could be a reasonably sure
sign is the presence, or absence, of a spur of bone on the back of the ankle. This
is the preserve of males among adults with platypussies and tachy echidnas.
Unfortunately, zags simply aren't well enough known for complete clarity. Conceivably,
some females could perhaps retain such things, as this spur does come supplied with
at least some girls. Not enough adult females have been examined. However, this
probably was the basis used for many museum specimens and, given a lack of
alternatives, museum records were accepted as presumably correct.
This gang of echidnas was divided into geographical subsets; localized populations.
Six were identified, but only one of them contained a reasonable number of both
males (six) and females (six). Sex had no obvious influence upon dimensions of
the skull or body weight. A couple of possible distinctions were found in the skull
and jaw of individuals referred to Z. bartoni, but these were no more than
"slight", and there were some non-conformists. For example, males would tend to win
beak length competitions, but not against all female rivals.
A range of weights is given for some once trapped members of Z. bartoni
from three subspecies (p.372): males 3.3 - 8.0 kilos (11 individuals); females 7.3
- 9.9 (5 individuals).
Geography
Seven potentially geographically distinct groups were identified and, given my blissful
ignorance concerning the layout of New Guinea, the map provided on page 368 is much
appreciated. I'm adding approximate locations in brackets. The scope of areas
actually varies greatly, and the difference between New Guinea (all the island) and
Papua New Guinea (the eastern parts) shouldn't be overlooked.
1, Nanneau Range (eastern Papua New Guinea); 2. Owen Stanley Range (west of group
1); 3. Huron Peninsula (northeast New Guinea); 4. central cordillera (central New
Guinea); 5. western New Guinea; 6. Cyclops Mountains (roughly the middle of the
north coast); 7. lowlands of southern Chumba Province.
Sample 7 showed no particular differences to sample 2, and these geographical
groups were combined into sample 2.
Claws
Kerbert's assertions concerning differing claw numbers had been based on individuals
consigned, in this study, to sample 5 and samples 1 and 4 (east to central). Generally,
members of sample 5 do have only claws per paw and the easterners five (p.374).
However, the five skins available for sample 4 tend to have only four on rear
feet (3 out of 5 specimens). That count can also occur for the front paws of the
western group, albeit rarely. This prompted a demarcation into two species: Z.
bruijni (west) and Z. bartoni. The latter was further divided into
subspecies, and this was supported by distinctions in proportional skull
measurements. There's now an aggressively echidna-hostile zone in the Paniai Lakes
region found between both species. It's heavily populated by people, and much forest
has been cleared (p.377). While one or both species may previously have frequented
that area, it's no longer anything like hospitable.
Some comments on the various taxa can be found in the specific entries below.
| Reassigned species: Z. bubensis Laurie, 1952 see
Z. bartoni | |
| Species: | Zaglossus bruijini (Peters & Doria,
1876) |
| Aka: | Acanthoglossus goodfellowi Thomas, 1907; Bruynia
tridactyla Du Bois, 1882; Proechidna nigroaculeata Rothschild, 1892;
Proechidna nigroaculeata Rothschild, 1892; Proechidna villossissima Du Bois, 1884;
Tachyglossus bruijni Peters & Doria, 1876; Zaglossus bruijinii gularis
Rothschild, 1922; Z. b. pallidus Rothschild, 1922 |
| Place: | New Guinea |
| Country: | Indonesia & Papua New Guinea |
| Age: | Still snuffling |
| Remarks: | The following is based upon my reading of
Flannery & Groves, 1998.
This is the most westerly found Z. species, and occupies the middle size
range for the genus. Unlike others, members are typically owners of but three claws
per foot or, occasionally, four (p.379). Further distinctions occur with relative
proportions of skull bones (p.380).
It lives to the east of the Paniai Lakes in Indonesian New Guinea, and is unusually
capable of coming to terms with a broad range of elevations. The spectrum runs
from near sea level to heights of over 2000 metres. Other Zaglossus favour
only the heights. It's this factor that probably led to the amount of variation of
fur. Lower livers tend to be lightly furred, whereas a dense hippy approach can
hide spines from view in peak areas. Fur colour varies from black to dark (perhaps
also light) brown. Paler heads and feet are popularly sported.
Indeed, the variability is brightly reflected by the impressive number of
synonyms. A number of those arose for such reasons.
Holotype
GE 1623 is a skull from the Arfak Mountains of New Guinea, and now lives (in a very
non-living sort of way) in the Museo Civico di Storia Naturelle Giacomo Doria,
Genoa. The specific name's for AA Bruijn, the collector of it.
Additional comments
Somewhat better known as the long-beaked echidna. Imagine inflating a European hedgehog up
to about the size of a football, (spikes inclusive), and you've got a reasonable
approximation of the dimensions. Please don't try this.
Zaglossus is restricted to rainforest habitats, and favours the highlands.
It's largely nocturnal. |
| References: | Bois, A du (1882), Remarques sur l'Acantho buijinii,
Bull. Soc. Zool. France, 6, p.266-270. |
| Bois, A du (1884), Description d'un Échidné et d'un Perroquet
inédits de la Nouvelle-Guinée, Bull. Mus. Hist. Nat. Belgique, 3, p.109. |
| Rothschild W (1892), Description of two new mammals from New
Guinea, Proceedings of the Zoological Society of London, p.545-546. |
| Thomas MO (1907), A new Acanthoglossus from the island
of Salawatti, Ann. Mag. Nat. Hist. London, 20, p.498-499. |
| Rothschild W (1922), In Ann. Mag. Nat. Hist., 10,
p.131. |
| Species: | Zaglossus bartoni Thomas, 1907 |
| Aka: | Acanthoglossus bartoni; Z. bubuensis Laurie,
1952 |
| Place: | |
| Country: | New Guinea |
| Age: | Still chomping worms |
| Remarks: | The following is based upon my reading of
Flannery & Groves, 1998.
This species shows a fairly high degree of variation, and that's prompted it to be
sliced up into subspecies. For one reason or another, these now live isolated
from each other in different parts of the island. Western New Guinea has a different
species all to itself, Z. bruijni.
In contrast to its western cousin, front paws of this species are always adorned
with five claws (p.381), and please, nobody fetch a pair of pliers to demonstrate
the contrary can occur. Behave! Generally, five are also found on the rear feet,
but there can be only four in some instances. It's at home to the east of the Paniai
Lakes in mountain forests, and four localized subspecies are recognized. This was
done mostly on the basis of abosolute and relative sizes.
The specific holotype, for those who crave such information, is the same individual
as for the subspecies of Z. bartoni bartoni. The name Thomas used in 1907
was Acanthoglossus bruijinii bartoni. This was for an individual with thick
fur from Papua New Guinea.
Z. bartoni bartoni Thomas, 1907
The territory of this subspecies is found in mountain forests across south and
central Papua New Guinea (p.381). If it weren't for the presence of a lot of people
forming a barrier, then it might perhaps feel like overlaping with members of
Z. b. diamondi, a population most living to the northwest. However, echidnas
aren't known to frequent the relevant areas of Chimbu and the Eastern Highlands,
so any such social gatherings appear improbable. Besides, western reports of
Z. b. bartoni typically come from lower mountain areas, where as easterly
found diamonds have always been from higher places. Forests, which formerly
provided cover between those zones, have largely disappeared thanks to the
activities of strange primates, and this factor probably now isolates the two
subspecies.
Living levels for bartoni range from around 600 metres, in Chimbu Province,
to between 2000 - 3200 further east. At least, they do if the Chimbu population
actually belong. They happen to be scantly known, with knowledge of their
external appearance provided by a single photo.
Fur variation is less pronouncedd than with the fashion concious members of Z.
bruijni. These echidnas mostly favour long, thick fur that hides the quills
along the back (p.382). Black is the most popular colour although dark brown has
some adherents. All agree that white quills are a must, and they like to show
these off along their flanks when not engaged in successfully hiding, an
extrmely popular activity.
Z. bubensis was supposed to differ by having shorter, brown fur, light brown
paws and a straighter jaw. However, these fashion statements turned out not to be
unique, and seem to be of no particular significance. The individual concerned was
just mildly odd.
Holotype
The type speciemn of the species and subspecies is the skin of an adult female from
Mount Victoria. She presently resides in the Natural History Museum, London, and
would like to be able to answer to any name including BMNH 7.7.17.5. Unfortunately,
deathness makes that impossible. Mount Victoria is part of the Wharton Range in
Papua New Guinea.
Zaglossus bartoni clunius Thomas & Rothschild, 1922
This subspecies is found north of Z. b. bartoni towards the northeastern
coast (Rawlinson Mountains of Huon Province). That's a relatively restricted
territory with heights ranging from 2100 to 2700 metres (p.382). It's comparatively
small for a Zaglossus and always has five claws per paw.
Dry lowlands isolate this subspecies from other populations. All known members
sport long black fur and white spines. The quills on the middle of the back are
generally rendered invisible beneath the hair, a tendency shared with my ears.
Holotype
BMNH 28.10.1.33 is a skin and skull at the Natural History Museum, London.
Z. bartoni smeenki Flannery & Groves, 1998
As well as being the most easterly of New Guinea's Zaglossus inhabitants,
they reside in the Nanneau Range, smeenkis also earn merit by being among the
smallest. All known specimens happen to be male (p.384), but their fathers must've
found some feminine company at some time or other.
Elevations range from between 200 to 1670 metres, and one note suggests a critter
may have been spotted 2000 metres still higher. It's conceivable that further
information could merit raising this taxon to a distinct species. However, there're
presently insufficient grounds for doing so.
Holotype
AM M968 22 is a skin and skeleton in the employ of the Australian Museum. The
subspecific name honours Dr Chris Smeenk of Leiden. As well as providing much
assistance to the authors, they also accuse him of showing courtesy and hospitality
that are "legendary".
Z. bartoni diamondi Flannery & Groves, 1998
These particular jewels among echidnas presently supply the largest
monotremes in the world (p.385). One zoo-based thug managed a weight of 16.5
kilos. Front paws are always equipped with five claws, but the count sometimes
decreases to four at the rear. Its geographical range encompases the eastern
highlands of Papua New Guinea (p.386), and continues westwards ho across central
Indonesian New Guinea until the Paniai Lakes. Recorded elevations of territory
span from 1300 to 4150 metres. Colours provide a spectrum from black to mahogany
brown. Some quills peep through the dense fur on the back, and the stomach area
remains spine free. While most of the quills are white, small black tips can
sometimes be present.
Although large and geographically wide-ranging, the subspecies isn't very well
known even for this generally not very well known genus.
Holotype
The star of this subspecies, AM M7955, frequents the Australian Museum. Its sparkling
subspecific name shines tribute upon the gem of a contribution to the understanding
of Melanisian biology performed by no lesser diamond than Jared Diamond, a Professor
glittering at the University of California. |
| References: | Thomas MO (1907), On the occurrence of Acanthoglossus
in British New Guinea, Ann. Mag. Nat. Hist. London, 20, p.293-294. |
| Thomas & Rothschild (1922), On a new subspecies of Zaglossus,
with remarks on other species of the genus, Ann. Mag. Nat. Hist. London, 10,
p.129-131. |
| Laurie EMO (1952), Mammals collected by Mr Shaw Mayer
in New Guinea 1932-1949, Bull. Brit. Mus. (Nat. Hist.) Zoology, 1, p.271-318. |
| Flannery & Groves (1998), A revision of the genus
Zaglossus, with description of a new species and subspecies. Mammalia 62,
p.367-396. |
| Species: | Zaglossus hacketti (Glauert, 1914) |
| Place: | Western Australia |
| Country: | Australia |
| Age: | Upper Pleistocene |
| Remarks: | This species was a large monotreme with a length
of about a metre. A weight estimate suggests around thirty kilos. Extinction set in
around 15,000 years ago. Although Captain Bligh was probably the first European to attempt
a sketch of a monotreme, an ancient artist depicted Z. hacketti far earlier, (Oakes
2003, p.72). |
| Species: | Zaglossus attenboroughi Flannery &
Groves, 1998 |
| Place: | Cyclops Mountains |
| Country: | New Guinea |
| Age: | At least 1963-2007 and hopefully much longer |
| Remarks: | The following is based largely upon my
reading of Flannery & Groves, 1998.
This is the smallest known Zaglossus species (p.387), and its continuing
residence of the Cyclops Mountains of New Guinea's north coast was widely doubted.
The holotype had been arrested in 1961, and no more were recorded for nigh on fifty
years. Originally, this directory entry contained a single word: 'extinct'. Sometimes,
it's great to be proved wrong. Even when described, it was considered likely to be
as energetic as the average dodo; happy birthday and RIP before it had a chance to
blow any of the candles on the cake out.
A comparative tiddler
A couple of measurements help illustrate the smallness of the specimen of unknown
sex. However, as the sample size involved is only one, it's possible the type could
be atypical. Beak length is 70mm (81 - 127.5 for other zags). The
dentary manages 107.5 (compared with 118 - 157).
The beak is straighter than usual as well as shorter, and five claws adorn all
paws. Fur is short, thick and fine with colours ranging from "raw umber" (on the
back) to fawn (stomach). Being somewhat colour blind and astonishingly unobservant
with such matters, I think those are tones of what I term brown.
This is in the usual size bracket of Tachyglossus
rather than the zags, and that comparison suggests a weight of something like two
or three kilos (p.388). Two, should you fancy a quick rummage in a supermarket, can
be experienced by picking up a standard sized packet of sugar in much of Western
Europe.
Body bits
The five-clawed rear feet both show indications of spurs on the back of the ankle.
From comparisons to relatives, that suggests this was a hechidna rather than a
she. However, while it seems overwhelmingly probable the species follows all other
known monotremes with this mark of sexual dimorphism, the lack of a sufficiently
large sample means the possibilities of some adult females perhaps retaining these
spurs can't actually be assessed.
Quills on the back are sparse and hidden by the short fur, and some areas to the
middle of the back are spineless. They become more thickly represented towards the
bum (UK slang usage) while none occupy the tum.
The skull's only partly present (p.389). Some of the suture between the nasal and
frontal bones can be seen through the somewhat translucent bone, but the join has
nevertheless closed. Sutures elsewhere are all closed as well. Despite being a small
zag, this was a lusty adult male (probably), and I hope he was fresh from an
appointment with an attractive shechidna when that cad, P van Royen, put an end to
his sex life on July 4th 1961. I bet his middle name's Shame!, and I don't mean
the echidna's. Perhaps that very postulated copulation meant the species still has
a pulse in 2007.
Free to bonk
Some Cyclops echidnas or other were still left with an eye for getting together with
the complimentary sex, as an individual was spotted by an expedition to the region
in 2007. It's still echidna country. As fortune would have it, I happen to visit
a forum with a posting that mentioned the blog of echidna fancier, Johnathan Baille.
He'd just returned from the EDGE expedition and, before nipping off to discuss other
issues with mammals in Mongolia, found time to upload some news. It's time for a
couple of links.
The Extinction Forum
http://extinctanimals.proboards22.com/index.cgi
Deadlings, rediscoveries, conservation...
Johnathan Baille's Blog, Search for Attenborough's echidna
http://www.edgeofexistence.org/edgeblog/?cat=11
A five part extravaganza with loads of photos, but not of echidnas, and background
information on the EDGE expedition in May, 2007. Part one is located towards the
foot of the blog-page.
Payangko is given as the local name of the critter. Furthermore, one witness
reported having seen a small, straight-beaked echidna in 1980 at 200 metres in the
hills near the village of Yongsu. Other sightings also came to light, and all were
oddly below elevations of 300 metres. The significance of this includes an
extension of the usable living area for the animal, seeing as this species was
previously thought to be restricted only to high peaks.
The payangko
Returning to Flannery & Groves (p.389), the presence of any echidna in the Cyclops
Mountains was originally a surprise. Being roughly near the middle of the north
coast, this is part of a large, otherwise echidna-free zone. While there are
further mountain ranges around, the nearest known echidna population resides a
couple of hundred kilometres south towards the middle of the island. Back in 1999,
researchers hadn't encountered local hunters with direct experience of such critters.
One, a 30+ resident of the Cyclops Mountains, had heard of them from oldsters, but
never seen them himself and couldn't recall the local name (p.390). He stated it
only lived on high and remote peaks although, as mentioned just above, Johnathan
Baille has now found good reasons to have doubts about that.
Holotype
RMNH 17301 flies the flag for this species in the National Naturhistorisch Museum,
Leiden. The specific name honours David Attenborough for his contributions to the
public appreciation of wildlife in New Guinea. In case anybody happens to be
reading this in the long distant future, we used to have things called televisions.
These were boxes for looking at, and there were extremely dusty glass screens at the
front. This Mr Attenborough bloke would often climb into them, and start talking
about animals. He showed pictures as well, and these performances usually involved
getting crapped on by bats. |
| Reference: | Flannery & Groves (1998), A revision of the genus
Zaglossus, with description of a new species and subspecies. Mammalia 62,
p.367-396. |
| Species: | Zaglossus harrisoni Scott HH & Lord CE, 1922 |
| Place: | Tasmania, I presume |
| Country: | |
| Age: | Upper Pleistocene |
| Remarks: | Certainly extinct and may not be a valid species.
This is a possibly synonym of M-Z. ramsayi. |
| Reference: | Scott and Lord (1922), Studies in Tasmanian mammals, living
and extinct. No. V. Zaglossus harrissoni, sp. nov. Papers Proc. Roy. Soc. Tasmania
1921, p.13-15, pl. V. |
| Bonus Links:
Theodore Nicholas Gill (1837-1914)
http://www.mnh.si.edu/vert/fishes/baird/gill.html
Prototheria Gill: Gill was an eminent American fishologist, (aka ichthyologist).
Monotremes were something of a sideline.
Charles-Lucien Bonaparte (1803-1857), The Emperor of Nature
http://www.upenn.edu/pennpress/book/13374.html
Monotremata Bonaparte: Bonaparte was a French naturalist, termed "the father of
American descriptive ornithology." His uncle was active in other fields; eg. ones
near Austerlitz and Waterloo. |
What I never knew I wanted to know about platypus sperm:
Having given some consideration to eggs, it seems only fair to make mention of monotreme
sperm. Thanks are due to Herr Walter Kleesattel, (see Bibliography).
"Auf zellulärer Ebene zeigt sich, dass beispielsweise die Spermien des Schnabeltiers
ähnlich denen vieler Reptilien einen fädig ausgezogenen Kopfteil besitzen, während die
Anordnung der innnerzellulären Bewegungsorganellen, die der Mikrotubuli, typisch für
Säugerspermien sind. Auch bei den Chromosomen zeigt sich eine Mischung von Säuger- und
Kriechtierkennzeichen. Kloakentiere besitzen zum einen große, säugertiertypische
Makrochromosomen und zugleich kleine Mikrochromosomen, wie sie ganz typisch für Kriechtiere
sind und sonst bei Säugertieren nicht vorkommen."
Apologies in advance. This inelegant translation is my own. Any misrepresentations of Herr
Kleesattel's views are down to me.
"It can be seen at the cellular level that the sperm of the platypus, for example, are
similar to those of many reptiles, in that they possess an elongated thread-like head, whilst
the internal cellular organs of movement, those of the Mikrotubuli, are typical for
mammalian sperm. The chromosomes also show a mixture of mammal and reptilian characteristics.
Monotremes have the typical macrochromosomes of mammals whilst also possessing
microchromosomes typical of reptiles, and otherwise not found amongst mammals."
|
| Help:
Should anybody have any further information, I'd be pleased to hear of it.
Regarding references and Bibliography:
I haven't and can't verify all the references, so beware. Traditional papers used in
constructing this page are in the bibliography. If you feel these are too few, then send
some more.
With thanks to all the featured sources.
back to top
Trevor Dykes, January 2002 Latest update: 17.3.2009
Ktdykes@arcor.de |
Bibliography:
Attenborough D (2003), Das geheime Leben der Säugetiere, Scherz Verlag.
Averianov AO, Lopatin AV, Skutschas PP, Martynovich NV, Leshchinskiy SV, Rezvyi AS,
Krasnolutskii SA & Fayngertz AV, (2005), Discovery of Middle Jurassic mammals from
Siberia, Acta Palaeontologica Polonica, 50(4), p.789-797.
Bever GS, Rowe T, Ekdale EG, Macrini TE, Colbert MW & Balanoff AM, (2005),
Comment on "Independat origins of middle ear bones in monotremes and therians",
Science, 309, p.1492a.
Clemens WA, Wilson GP & Molnar RE (2003), An enigmatic (Synapsid?) tooth
from the Early Cretaceous of New South Wales, Australia, Journal of Vertebrate
Paleontology, 23 (1), p.232-237.
Flannery TF & Groves CP (1998), A revision of the genus Zaglossus
(Monotremata, Tachyglossidae), with description of new species and subspecies,
Mammalia, 62(3), p.367-396.
Honders J [General Editor] (1975), The World of Mammals. Peebles Press.
Kielan-Jaworowska Z, Cifelli RL, & Luo Z-X (2002). Dentition and relationships of
the Jurassic mammal Shuotherium. Acta Palaeontologica Polonica 47(3), p.479-486.
Kleesattel, W (2001), Die Welt der lebenden Fossilien, (p.35). Theiss Verlag.
Luo Z-X, Kielan-Jaworowska Z & Cifelli RL (2002), In quest for a phylogeny of
Mesozoic mammals. Acta Palaeontologica Polonica 47 (1), p.1-78.
Martin T & Luo Z-X (2005), Homoplasy in the mammalian ear, Science, 307,
p.861-862.
McKenna MC & Bell SK (1997), Classification of Mammals Above the Species Level.
Columbia University Press.
Musser AM & Archer M (1998), New information about the skull and dentary of the
Miocene platypus Obdurodon dicksoni, and a discussion of ornithorhynchid
relationships, Philosophical Transactions of the Royal Society of London B, 353,
p.1063-1079.
Oakes T (2003), Menschen gegen Monster - Der Kampf um unseren Planeten, Egmont vgs
verlagsgesellschaft.
Pascual R, Goin FJ, Balarino L & Udrizar Sauthier DE (2002), New data on the
Paleocene monotreme Monotrematum sudamericanum, and the convergent evolution of
triangulate molars. Acta Palaeontologica Polonica 47(3), p.487-492.
Pettigrew JD, Manger PR & Fine SLB (1998), The sensory world of the platypus,
Philosophical Transactions of the Royal Society B, 353, p.1199-1210.
Rich TH, Hopson JA, Musser Am, Flannery TF & Vickers-Rich P (2005), Independent
origins of middle ear bones in Monotremes and therians, Science, 307, p.910-914.
Rich TH & Vickers-Rich P (2004), Diversity of Early Cretaceous Mammals from
Victoria, Australia, Chapter 3, Bulletin American Museum of Natural History, 285,
(p.35-53).
Rismiller PD (1992), Field observations on Kangaroo Island echidnas
(Tachyglossus aculeatus multiculeatus) during the breeding season, p.101-105 in
Platypus and echidnas (Augee ML ed.), The Royal Zoological Society of New South Wales,
Sydney.
Rismiller PD & McKelvey MW (2000), Frequency of breeding and recruitment in the
short-beaked echidna, Tachyglossus aculeatus, Journal of Mammalogy, 81(1),
p.1-17.
Rougier GW, Forasiepi AM & Martinelli AG (2005), Comment on "Independent origins
of middle ear bones in monotremes and therians", Science 309, p.1492.
Rowe T, Rich TH, Vickers-Rich P, Springer M & Woodburne MO (2008), The oldest
platpus and its bearing on divergence timing of the platypus and echidna clades, PNAS, 105,
p.1238-1242.
Thulborn T & Turner S (2003), The last dicynodont: an Australian Cretaceous
relict, Proceedings of the Royal Society B, 270, p.985-993.
Vickers-Rich P & Rich TH (2004), Dinosaurs of the Antarctic, Scientific American,
p.40-47.
Woodburne MO (2003), Monotremes as Pretribosphenic Mammals, Journal of Mammalian
Evolution, 10 (3), p.195-248.
Woodburne MO & Tedford RH (1975), The first Tertiary Monotreme from Australia.
American Museum, Novitates Number 2588, p.1-11. |
