MESOZOIC MAMMALS; ‘basal ungulates', an internet directory:
MESOZOIC MAMMALS; ‘basal ungulates', 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.
Simplistically put, ungulates are hoofed mammals, such as
horses, cows, goats, pigs etc. The word unguis is Latin for hoof. All these various
animals were traditionally corralled together in the taxon of
Ungulata. The difficulty with this group as traditionally used is that "it contains
some, but not all, descendants of a common ancestor," (with thanks to
Ungulates: Hoofed
Mammals, Berkeley University). It’s termed paraphyletic. The non-hoofed members are
generally missing; eg. whales. Whilst not usually fitted out with legs, their ancestors
were. According to molecular studies, the closest living relatives of whales are hippos.
As hippos are members of one of two main ungulate orders (Artiodactyla), logic demands
the same treatment for cetaceans such as Flipper. I'm not sure this will be followed by
those who study whales, as it may be less than relevant to their objectives. For reasons
of anatomy, whales are also sometimes linked with extinct terrestrial carnivores such as
the mesonychids, (Luo 2000). The other extant order consigned to Ungulata is
Perissodactyla, and that gang includes the horses, tapirs and rhinos.
Other living ungulates?
Various further candidates included elephants, rodent-like hyraxes, sea cows and aardvarks.
(Animal
Olympics, Aardvarks). However, molecular research is pointing to a separate origin
of these animals and a deep split inside of Placentalia. This will be addressed in the
following brief death announcement. It was sad news indeed, as this directory was
originally based on the systematical corpse.
Ungulatomorpha - an obituary
The following few paragraphs are derived from my reading of Averianov & Archibald, 2005
(p.595).
Back in 1996, it was thought traditional ungulates (the perissodactylans and artiodactylans)
belonged together in a monophyletic Ungulata; a
first ungulate and all of its descendants. This has been strongly supported by independent
molecular studies. However, it was further thought these animals were closely allied with
paenungulates (elephants, hyraxes, sea cows). All were cast into the cosy basket of
Ungulatomorpha along with a number of Cretaceous critters for company. Prime among those
are the 'zhelestids', and they can be petted on this page. Genetic comparisons indicate
the deep split within Placentalia led to two wide groupings called Laurasiatheria and
Afrotheria. Horses and friends are placed in the first field while elephants and relatives
herd into the second. The depth of the intervening ditch means they can't be closely
related. Ungulatomorpha was a pleasing idea but, (bearing in mind it was the baby of the
aforementioned Archibald JD), as Averianov and Archibald reject it emphatically, the
concept is as dead as a dodo. It was a no no.
Where to put your 'zhelestids' (and zalams)
As Ungulatomorpha has been discarded by even its daddy, 'Zhelestidae' can't be a family of
Cretaceous members. After all, the grouping has been erased. However, they still have
their ungulate-like teeth specialisations and, assuming this is due to common ancestry,
then logic demands a home within Laurasiatheria. The authors also discuss the affinities of
another Cretaceous group called zalambdalestids,
which I have an enclosure for on a different directory. In this scheme, zalams and
relatives continue to be referred to Euarchontoglires. That nomenclatural mouthful teams
them up with subsequent critters such as rodents and rabbits. Among other things, this
approach recognises both 'zhelestids' and zalams as fully-fledged
placentals.
Objections
This isn't universally accepted and will require further testing. The results obtained by
Meng and colleagues in 2003 left both families as stem-taxa; outside of crown-group
Placentalia. However, this discrepency of outcomes could reflect peculiarities of the
data used. Studies based on Cretaceous eutherians have
tended to incorporate only a pinch of later crown-group placentals. Meanwhile, those
heavy on such animals have been meagrely seasoned with Cretaceous mammals. The challenge
for the kitchen staff may be to blend the appropriate balance for the recipe required.
Should the feast be placed on a future table, I'm sure everybody concerned will have an
excellent appetite and, quite probably, find new bones of contention to chew over and
digest. |
|
The infracohort, Ungulatomorpha Archibald JD, 1996, is a bit broader still. This
includes the ancestors from the Mesozoic, and these proto-ungulates are the focus of this
directory. Ungulate evolution seems to have really got going later, during the Paleocene and
Eocene. That being so, it’s beyond my scope:
Early origins of modern birds and mammals: molecules vs. morphology
palaeo.gly.bris.ac.uk/publs/Benton/1999BioEssays.pdf
Professor Michael Benton’s a good writer. The original file was a pdf, which I don’t seem
able to open. |
| Links:
The Ultimate Ungulate Page
http://www.ultimateungulate.com/
A general look at ungulates and their history.
Mikko Haaramo's Basal Ungulatomorpha
Mikko Haaramo's Basal Ungulatomopha
"Note: Taxonomy and phylogeny of basal ungulates is quite a mess. A large number of
scientists have studied these animals over the years, but there is still no consensus about
the relationships of main ungulate groups."
Jeff Poling, Geologic Ages of Earth History
http://www.dinosauria.com/dml/history.htm
The Mesozoic. When men weren’t, women also weren’t and Zhelestes & Co were able
to graze in peace, as long as the predators kept away.
Palaeos: Ungulatomorpha
http://www.palaeos.com/Vertebrates/Units/510Ungulatomorpha/510.100.html
Toby White’s hobby is teaching himself vertebrate paleontology. He appears to be doing a
thorough job. (Having just established the link to this new version of the page, I feel oh
so humble. I have a 'Best on the Web' award! Then again, there's not that much
competition.) |
A. basal Ungulates B.
"Zhelestinae" C. K ungulates
A rather more derived ungulatomorph than the fossils on this
page. This old fashioned whale can be seen flying at the Senckenberg Museum, Frankfurt.
|
| Taxon: none.
Whilst these critters are not generally well-preserved, they clearly were geographically
widespread. At least most of them are 'zhelestids' of some kind or other.
A very misleading title
This directory section actually needs re-naming, but I've not yet thought of a more
appropriate choice. There are strong doubts as to whether most the listed genera
are actually placental mammals rather than more
basal members of
Eutheria. While many have previously been referred to as ungulates at one time
or another, non-placental mammals couldn't possibly have been anything of the kind.
Some ungulate-like tendencies don't suffice. Being an ungulate is a matter of direct
descent from earlier ones, and membership can't be obtained by convergent
characteristics on teeth for crushing food.
Genera: Alostera,
Aspanlestes, Avitotherium,
Eozhelestes, Gallolestes,
"Kumsuperus", Labes,
Lainodon, Sheikhdzheilia,
Sorlestes, Vallentinella,
Zalambdalestes (partly = Sorlestes), Zhelestes (partly =
Aspanlestes), other reports
Time-Line:
Upper Cretaceous: Alostera, Aspanlestes, Avitotherium,
Eozhelestes, Gallolestes,
"Kumsuperus", Labes, Lainodon, Sheikhdzheilia,
Sorlestes, Valentinella |
| Genus: Alostera Fox RC, 1989
|
| Species: | Alostera saskatchewanensis Fox RC, 1989 |
| Aka: | Allostera |
| Place: | Alberta, Saskatchewan & Montana |
| Country: | Canada & USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: |
The holotype is in the collection of the University of Alberta,
and the genus is known from isolated teeth. The animal weighed about the same as two mice,
(50g Alroy), and a second species is possible. The results obtained by Gordon & Cifelli,
2003, broadly concur: 27-45g, (p.96-97).
Alostera is also the name of a flowering cactus. Zoological and botanical
nomenclature are separate areas. |
| Reference: | Fox (1989), Palaeont Abt A 208(1-3). |
| Genus: Aspanlestes Nessov LA, 1985
Aka: Zhelestes (partly) |
| Species: | Aspanlestes aptap Nessov LA, 1985 |
| Aka: | Zhelestes bezelgen |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle - upper Turonian, Upper Cretaceous |
| Remarks: |
This is the smallest zhelestid from the Bissetky fauna.
A fragment of jaw and several other teeth from the overlying Aitym Formation, (which is
somewhat younger), are most like those of this species, (Averianov & Archibald 2003,
p.10-11). |
| Reference: | |
| Link:
Acta Palaeontologica Polonica, 42 (2), p.243-256, Abstract
http://www.paleo.pan.pl/acta/acta42-2.htm
Averianov, A.O. 1997. New Late Cretaceous mammals of southern Kazakhstan.
Remains from the lower part of the Darbasa Formation, including ?Aspanlestes sp.
|
| Genus: Avitotherium Cifelli
RL, 1990d
Aka: cf. Paranyctoides |
| Species: | Avitotherium utahensis Cifelli RL, 1990 |
| Place: | Kaiparowits Formation, Utah |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: |
Remains consist of teeth and a fragment of dentary.
Specimens are in the collection of the Oklahoma Museum of Natural History. This genus
might be a cimolestid, but that group’s not well-known either. They’re regarded as small
insectivores. John Alroy records it as ancestral to Alostera, and somewhat smaller,
(ca. 30g). He also mentions an unnamed, second species. |
| Reference: | Cifelli (1990), Cretaceous mammals of southern Utah. IV.
Eutherian mammals from the Wahweap (Aquilan) and Kaiparowits (Judithian) Formations. J. of
Vert. Paleont. 10(3), p.346-360. |
| Genus: Eozhelestes Nessov
LA, 1997
'dawn Zhelestes' |
| Species: | Eozhelestes mangit Nessov LA, 1997 |
| Place: | Sheikhdzheili local fauna,
Khodzhakul Formation |
| Country: | Uzbekistan |
| Age: | lower Cenomanian, Upper Cretaceous |
| Remarks: | The following is based upon my reading of Averianov
& Archibald, 2005.
This is presently the largest named mammal from this fauna. The size and morphology of the
first lower molar are broadly comparable with
Aspanlestes (p.601), but 'dawn Zhelestes' seems a
bit more primitive. Reasons include a trigonid which is
relatively higher than the talonid and a greater difference
in height between the protoconid and
metaconid. A partial
dentary (p.602) has a preserved length of around 1.3cm. As a small part at the front
and everything behind the first molar is missing, the original length was obviously more.
A healthy
mouse-size sounds like a realistic comparison.
Teeth
Alveoli attest to the presence of four
incisors and a fairly unimpressive, single-rooted
canine. That root goes back into the jaw until between the first two
premolars. There are five premolars, which is the number
known from basal eutherians,
and they're all double-rooted. The smallest of them is the p1. The p3, which was subsequently
consigned to the evolutionary dustbin, isn't much smaller than its immediate neighbours.
With regard to the molars, the m1 features a tall trigonid
with a distinct basin, while the talonid is a bit narrower and deeply basined. Some lengths
are available: m1 2.2mm; m3 talonid length 1.1mm - similar to the talonid length of m1
(p.603).
Holotype
CCMGE 26/12176 is a lower left molar (m1) in the care of Chernyshev's Central Museum of
Geological Exploration, Saint Petersburg. Other specimens include isolated teeth and
fragments of dentary, with a couple of premolars being milk teeth. Two further bits of
lower jaw are questionably referred. |
| Reference: | Nessov (1997), Cretaceous Nonmarine Vertebrates of Northern
Eurasia. In Golovneva LB & Averianov AO (eds), 218pp, (University of Saint Petersburg,
Institute of Earth Crust, Saint Petersburg). (In Russian.) |
| Genus: Gallolestes
Lillegraven, 1976
'Gallo thief' |
| Species: | Gallolestes pachymandibularis Lillegraven JA, 1976 |
| Place: | El Gallo Formation, Baja California |
| Country: | Mexico |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | Several dentaries
and lower molars are known. There have been difficulties
regarding the classification. What seems to be the final
premolar is a molariform tooth, and this is the
most worn one in the set. As m1 generally erupts before the last premolar in existing
mammals, this runs counter to expectations, (Archibald & Averianov 2001, p.11).
Nevertheless, expectations aren't always fulfilled.
One alternative suggested was that the genus is a
metatherian with four molars, rather than three. However, as the teeth look
eutherian, this is improbable. In which case, perhaps it's
an aberrant eutherian with a strange dental formula. A further suggestion was that the
premolar is actually a retained milk tooth. The difficulty with this is the well formed
roots; a feature not generally associated with disposable teeth. Finally, it's also been
proposed this genus could represent a separate therian
lineage but again, the teeth look eutherian.
One specimen of Paranyctoides aralensis
could be of relevance to this issue. It includes what's most likely to be a molariform
last premolar, (p5 in the terminology of Archibald & Averianov, 2001). As the
morphology is similar to the tooth in question, this may indicate it's the equivalent,
(p.13). If so, then this genus must be eutherian.
Holotype
The holotype, LACM 42633, is a partial mandible with
remains of the last premolar and m1-m3. I think the acronym refers to the Natural History
Museum of Los Angeles County.
Body mass of around 70g. A third species is indicated. |
| Reference: | Lillegraven (1976), A new genus of therian mammal from the
Late Cretaceous "El Gallo Formation", Baja California, Mexico. Journal of
Paleontology, 50 (3), p.437-443. |
| Species: | Gallolestes agujaensis Cifelli RL, 1994 |
| Place: | Aguja Formation, Texas |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: |
"Upper molars referred to G. agujaensis are of
eutherian design and, assuming generic referral is
correct, support placement of Gallolestes within the Eutheria," (Cifelli,
1994). The dating of the Fundstätte is apparently supported by the presence of particular
ammonites and bivalves.
A number of specimens live in the Oklahoma Museum of Natural History, including at least
one dentary fragment. |
| Reference: | Cifelli (1994), Therian mammals of the Terlingua local fauna
(Judithian), Aguja Formation, Big Bend of the Rio Grande, Texas. Contributions to Geology,
vol 30(2). |
| Genus: "Kumsuperus"
Nessov LA, 1984 |
| Species: | "Kumsuperus avus" Nessov LA, 1984 |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle-upper Turonian, Upper Cretaceous |
| Remarks: | This could be synonymous with Eoungulatum
kudukensis, (Averianov & Archibald 2003, p.15). |
| Reference: | |
| Genus: Labes Sigè 1992, in Pol C,
Buscalioni AD, Carballeira J, Francés V, López Martinez N, Marandat B, Moratalla JJ, Sanz
JL, Sigé B & Villatte J, 1992
Remarks: According to Averianov & Archibald 2003, (p.17-18), the known chronological
range of Labes is Campanian - Maastrichtian. |
| Species: | Labes garimondi ?Sigé in Pol et al, 1992 |
| Place: | Champ Garimond |
| Country: | France |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | Isolated teeth. |
| Reference: | |
| Species: | Labes quintanillensis ?Sigé in Pol et al, 1992 |
| Place: | Quintanilla del Coco |
| Country: | Spain |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: | Teeth. |
| Reference: | Pol et al (1992), Reptiles and mammals from the Late Cretaceous
new locality Quintamilla del Coco (Burgos Province, Spain). Neues Jahrbuch für Geologie und
Paläontoligie 184, p.279-314. |
| Genus: Lainodon Gheerbrant E
& Astibia H, 1994
Remarks: This genus belongs in or near Zhelestidae. "Gheerbrant and Astibia (1999)
interpreted the more compressed trigonid of the Asian
zhelestids as the ancestral state; however, Nessov et al. (1998) and Archibald (1996)
argued that the less antero-posteriorly compressed trigonid
such as in the European zhelestids is ancestral because this state is found more widely in
both early metatherians and
eutherians", (Averianov et al, 2003, p.149). |
| Species: | Lainodon orueetxebarriai Gheerbrant E &
Astibia H, 1994 |
| Place: | Lano |
| Continent: | Spain |
| Age: | ?Campanian, Upper Cretaceous |
| Remarks: | There are similarities between the fossil fauna of Lano and the
Maastrichtian strata of Madagascar, from where a possible close relative has been identified.
Shared taxa include a snake, Madtsoia, and
titanosaurid sauropods. A Gondwanan incursion is suggested by various other localities in
France and Romania.(Averianov et al, 2003, p.149).
Holotype
The holotype, a lower molar (LIAT 14), is in the collection
of the Museo de Ciencias Naturales de Alava, Spain. |
| Reference: | Gheerbrant & Astibia (1994), Un nouveau mammifère du
Maastrichtien de Lano (Pays Basque espagnol). Comptes Rendus de l'Académie des Sciences.
Série II, 318, p.1125-1131. |
| Link:
Emmanuel Gheerbrant, Le Paléogène et la radiation des mammifères
http://www.cnrs.fr/cw/dossiers/dosevol/decouv/articles/chap2/gheerbrant.html
As my French is limited, I concentrated on trying to follow the gist of this article,
rather than to admire the doubtlessly interesting details of the landscape. As the title
attests, it concerns the radiation of mammals after the end of the Mesozoic.
It explores some intriguing territory over which this project doesn't seek to roam; namely,
the findings of researchers into the mammalian molecular clock, and the state of the fossil
record. At the heart of this story is a question: when did modern
placental orders evolve?
Some molecular clockists have found good reasons to maintain that key branches sprouted
during the Upper Cretaceous. DNA studies have led to the establishment of two wide taxa
within Placentalia; Afrotheria and Laurasiatheria. Both are said to contain a number of
our modern orders within their ranks.
However, the fossilists point out that there's no sign of this in the known record. If
modern orders were being established 110 million years ago or so, identifiable traces
should be visible somewhere. What the fossil record does show is a picture of rapid,
post-Cretaceous diversity. For example, found in the Upper Cretaceous deposits of Montana
are apparently, (unless I'm misreading the article. It sounds rather a lot to me!), 23
species of placental mammal. Two million years after the K-T, the count has rocketed to
70.
It may be that the molecular clockists haven't yet mastered the intricacies of their
timepieces. On the other hand, there might be significant gaps in the fossil record, (eg.
for much of the southern hemisphere). Of course, a bit of both might also apply.
The publication of Eomaia added welcome spice to
the soup last year. This undoubted eutherian is 125
million years old.
Some possible ancestors of modern orders are known from the Cretaceous, but not yet
representatives of the orders themselves. As well as the perhaps ungulatomorphs on this
page, the article also mentions Zalambdalestes,
(from Asie rather than Amérique du Nord), which may be associated with rodents and bunnies;
Cimolestes, who has been blamed for giving rise
to carnivores; and Paranyctoides, which
could be associated with insectivores. A further view sees that genus as closer to 'zhelestids',
Archibald & Averianov, 2001).
Even given my linguistic limitations vis a vis Francais, the link has much of interest. It
also contains a photo of a lower molar of Lainodon. |
| Genus: Sheikhdzheilia
Averianov AO & Archibald JD, 2005
'for Sheikh Dzheili'
Remarks: The generic name honours the Sheikhdzheili Range, which is where the remains came
from. This in turn presumably commemorates a generally forgotten local notable. If the
Sheikh would like to give some account of his doings, (especially with any spicy details),
then I would happily add a brief biog or obit. Extensive research by myself revealed no
trace of a blog or personal homepage.
Also included in the following entry is mention of material reassigned from the now defunct
genus of Otlestes. This is presently designated cf. Sheikhdzheilia, which
suggests it could represent a closely related animal, but isn't necessarily part of the
same species or genus. Further remains of Otlestes have been granted a new home as
specimens of a ?zalambdalestoidean named
Bobolestes. |
| Species: | Sheikhdzheilia rezvyii Averianov & Archibald, 2005 |
| Place: | Sheikhdzheili local fauna,
Khodzhakul Formation |
| Country: | Uzbekistan |
| Age: | lower Cenomanian, Upper Cretaceous |
| Remarks: | The following is based upon my reading of Averianov
& Archibald, 2005.
Among known 'zhelestids' (p.599), this genus probably has the largest number of
basal traits, although it possesses some relatively
derived features as well. It also has the honour of being
the smallest 'zhelestid'.
Sizes, downers and (close) uppers
The preserved fragment of dentary has the impressive length
of around 8mm (p.600), and the entire article would've been even longer. Lengths of two
fully preserved teeth are also known: p5 1.5mm and m1 1.9mm. Two fragments of upper jaw
have been referred to as close to this genus (on a cf. basis), and they're refugees from
the former concept known as Otlestes. However, while the dental morphology is
appropriate for the lower teeth, at least one specimen appears to be a bit too large.
Strictly speaking, the holotype is presently the sole fossil for this genus.
Lower postcanines of Sheikhdzheilia
The final premolar, (p5 in the terminology of this study),
isn't that much shorter than the first molar. Its
lingual side has a cingulum running along most of its length,
and two shorter ones can be found towards the front and rear of the
labial face. For the molars, the talonid of m2 is a
bit wider than the one of m1.
Uppers of cf. Sheikhdzheilia
The P5 premolar is about as wide as the M1 molar. This premolar has three roots and can be
termed 'at least semimolariform', seeing as the authors do precisely that. The first two
molars share similar structure with each other, but the shape of the external sides vary.
A kind of bay called the ectoflexus is shallower on M1.
Another feature, the metastylar lobe, points further forwards on that tooth as well. Both
have a narrow stylar shelf and lower metacones than protocones (p.601). There are no
cingula ridges on the lingual side.
Family issues
These molars resemble those of 'zhelestids', as they have common features which seem to
result from shared ancestry. The resemblance with
Aspanlestes is particularly close. These include a protocone which is
proportionately larger than that of
Bobolestes. The absence of lingual cingula is in contrast to other 'zhelestids'.
To reiterate, the upper material appears a bit too large for the lower jaw, so two distinct
yet related taxa may well have been the donors.
Holotype
The holotype, ZIN 88438, is a partial dentary with a p5,
m1 and the talonid of m2.
Alveoli are also present for the p4 and m3. It's looked after at the Zoological
Institute of the Russian Academy of Sciences, Saint Petersburg. The specific name refers
to Anton S Rezvyi, who discovered this specimen. |
| Reference: | Averianov AO & Archibald JD (2005), Mammals from the
mid-Cretaceous Khodzhakul Formation, Kyzylkum Desert, Uzbekistan, Cretaceous Research 26,
p.593-608. |
| Genus: Sorlestes Nessov LA,
1985
Aka: Zalambdalestes (partly)
Remarks: This genus is a further zhelestid. |
| Species: | Sorlestes budan Nessov LA, 1985 |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle-upper Turonian, Upper Cretaceous |
| Remarks: | If the faunal list of Archibald
& Averianov, 2005 is correct, this species seems to be treated as a junior synonym of
Zhelestes temirkazyk. I think I'll await something more
substantial than a fauna list (p.11), but it doesn't presently seem to merit a distinct
taxnomic status.
Be that as it may, S. budan is based on a
dentary which resides at Chernyshev's Central Museum of
Geological Exploration, Saint Petersburg, (CCMGE 3/12176).
Z. mynbulakensis is a fragmentary lower left jaw with one
molar, (Wible et al 2004, p.16). This was held to be a
synonym of Sorlestes, but seems to have mutated into
Parazhelestes mynbulakensis. |
| Reference: | |
| Species: | Sorlestes kara Nessov LA, 1993 |
| Place: | Aschikol |
| Country: | Kazakhstan |
| Age: | Turonian, Upper Cretaceous |
| Remarks: | A skull length of about 1,7cm. |
| Reference: | |
| Species: | Sorlestes mifunensis Setoguchi T, Tsubamoto T,
Hanaura H & Hachiya K, 1999 |
| Place: | Mifune Group, Kyushu |
| Country: | Japan |
| Age: | upper Cenomanian- lower Turonian, Upper Cretaceous |
| Remarks: | A jaw fragment with a lower left
molar, this fossil "is the oldest zhelestid yet
recorded," (see abstract). With thanks to Dr Tsubamoto for the citation. |
| Reference: | Setoguchi et al (1999), An early Late Cretaceous mammal from
Japan, with reconsideration of the evolution of tribosphenic molars. Paleontological Research,
vol. 3, no. 1, p.18-28. |
| Genus: Valentinella
Tabuce R, Vianey-Liaud M & Garcia G, 2004
'for Valentin'
Remarks: The name honours Xavier Valentin, who discovered the fossils. |
| Species: | Valentinelly vitrollense Tabuce R, Vianey-Liaud
M & Garcia G, 2004 |
| Place: | Arc Basin |
| Country: | France |
| Age: | lower Masstrichtian, Upper Cretaceous |
| Remarks: | The following is based upon my reading of Tabuce
et al, 2004.
Remains include a fragmentary, partial right dentary with
five teeth, (p3 - m3), and a couple of further bits of lower and upper jaw. In terms of
European, uppermost Cretaceous mammals, that makes this an extensive find. As the continent
was largely under water at the time, the European record is paltry, (p.347). This is only
the third eutherian. Its assignment to 'Zhelestidae' is
tentative and the state of preservation isn't good.
Fossils of terrestrial Europeans of this sort of age come from a few former islands. These
are located in Iberia-France and Transylvania, and date from the Campanian to Maastrichtian
stages. The record of eutherians is impoverished, and definite specimens had only been
recovered from four sites in Western Europe. Excavations near Vitrolles in southern France,
(northwest of Marseilles), provided the fifth location. These specimens were found with
bits of fish, dinos and further reptiles, fragments of eggshell and convenient molluscs.
Along with magneto-stratigraphic information, this collectively indicates an early
Maastrichtian age. The mammal remains represent a new genus, which appears to be at least
related to 'zhelestids'.
'Zhelestid' teeth
The diagnosis on page 348 offers information on the generalized 'zhelestid' condition, (and
some possibly strange words). "Valentinella presents the classic
"zhelestid" features: the teeth are characterized by developed crushing function,
the paraconid is lingually or sublingually positioned with
a clear appression to the metaconid, the entoconid and the hypoconulid are twinned, and the
talonid is expanded labio-lingually. Valentinella
differs from the Asian "zhelestids" by the molarization of the ultimate
premolar, and is distinct from
Avitotherium and Gallolestes by its simple,
bulbous p3 and by its larger metaconid and entoconid on lower
molars, respectively. Valentinella differs from Labes
and Lainodon in having a mesio-distally compressed
trigonid."
As if being dead wasn't enough to contend with, the buried jaw also had to put up with the
actions of plant roots, (p.349). Displaying no respect whatsoever, they contrived to distort
the fossil. However, at least the dentine and enamel are better preserved, and provide
useful information.
Dentition and size
Five double-rooted teeth are present on the jaw, and they range in length from 2.3 (p3) to
3.5mm (m2). The second one is either a premolar or its
deciduous predecessor. The first option is considered
more likely. The molars are more poorly preserved. Given that the bone fragment is about
2.5cm long, this was presumably an animal sized more like a rat rather than a mouse. A
further fragment is probably from a maxilla and contains
bits of teeth; most notably canines.
A large, three-cusped talonid is indicative of Theria, while
twinned entoconids and hypoconulids are reminiscent of
Metatheria. However, this condition isn't unknown in
eutherians. The presence of only three molars and further details, (including a
reduced paraconid), confirm Eutheria. Among other things,
the wear pattern is associated with a crushing function. Along with the relatively large
size, these are characteristics known from 'zhelestids', (p.351).
In some early 'zhelestids', (Aspanlestes and
Sorlestes), five lower premolars were present. The third of
these, (which could've been a retained milk tooth), seems to have been dispensed with over
the course of time. This renders the p3 and p4 of this genus as homologues of the original
p4 and p5 respectively. When making comparisons, this sort of detail is both a nuisance and
important.
Enamel
As enamel is highly mineralized, its structure is less prone to significant alteration
caused by fossilization, (p.352). In this case, small fragments are well preserved. The
outer coating (up to about 15 to 20% of the thickness) was prismless. The remainder, however,
was prismed and true enamel prisms are restricted to mammals. Without going into detail
here, the authors mention the possibility that the morphology may indicate a herbivore, but
this is adorned with a question mark, (p.354). They also state that radial prisms observed
in primitive condylarths, (Protungulatum and
Molinodus), are reminiscent of the arrangement in this genus. However, as that kind
of structure is basal for placental mammals, it's not overly
useful for assessing relationships. The microstructure does nothing to contradict a genuine
association between 'zhelestids' and condylarths.
The final sentence of the Conclusion is worth bearing in mind: "The phylogenetic
position of Valentinella remains uncertain, but it appears that this genus could be
a "zhelestid"."
Holotype
The holotype is a damaged right dentary known as ISEM/VLP-2, which is in the collection of
Montpellier University. The species name refers to the town of Vitrolles, which is near
the fossil location. |
| Reference: | Tabuce R, Vianey-Liaud M & Garcia G (2004), A eutherian
mammal in the latest Cretaceous of Vitrolles, southern France, Acta Palaeontologica
Polonica, 49(3), p.347-356. |
| Other reports:
Sheikhdzheili local fauna, Uzbekistan
Averianov & Archibald, 2005 report a relatively large zhelestid was on the prowl, but
it's presently elusive (p.603). There are a couple of bits of lower jaw with
alveoli for postcanine
teeth (p.604). As the preserved length of one amounts to about 2.4cm, a 'large zhelestid' still
denotes a small mammal.
One of these dentaries came from the equivalent of a
pensioner. The length, depth and robustness are all attributes earned by a long life.
This is supported by the narrow pulp cavities for the roots of
premolars p2 and p4. The p3 had been lost and the
alveoli plugged with bone, so as to leave a notable
diastema. Towards the rear of the jaw, the coronoid process is steep. This, and the
general shape of the massetic fossa, are characters associated with 'zhelestids'.
A fossil which was named Oxlestes could be part
of this critter, despite having been referred to as a
metatherian. By the standards of this mammalian fauna, this was a relatively large
axis from the spine. This fits sensibly with an animal, whose skull length was somewhere
around 7 or 8 centimetres, and that's also plausible for the dentary remains (p.605). I
think I'll invoke a large
rat as a rough model for the dimensions.
A reasonably well preserved petrosal was also identified,
but the identity of the owner is unclear. The authors suggest a 'zhelestid' could be a
candidate, although a zalambdalestid might also
put in a claim. Should the owner wish to be reacquainted with this bone, then I'm sure
they'd be welcome to apply. The address (in this ear case) is the Zoological Institute,
Saint Petersburg. Ask for ZIN 88691. |
A. basal Ungulates B.
"Zhelestinae" C. K ungulates
| Taxon: "Zhelestinae"
Further finds and studies have shown that Zhelestidae Nessov LA, 1985 is also probably
paraphyletic. I’m using this proposed sub-family, because it’s convenient. These were
small, Asiatic herbivores which might or might not have been related to their North American
and European 'brethren'. Still further finds and studies are required.
Reportedly in 2000, Novacek MJ observed: "This suggests the possibility that the new
dentition is assignable to a new
taxon of zalambdalestid. Such an assignment in combination with the striking dental
similarity between the Red Rum taxon and zhelestids suggests that the latter, which are
presently unknown from skulls, are closely related to zalambdalestids. This argument would
either undermine the proposed affinity between zhelestids and ungulates, or indicate a
close affinity of a zhelestid-zalambdalestid clade with ungulates." He favoured the
first view; ie. zhelestids are not closely alinged with ungulates. Others presumably
favour the second possibility. |
| Link:
David Marjanovic, DML, 23.5.2001
http://www.cmnh.org/dinoarch/2001May/msg00796.html
M. J. Novacek: New eutherian mammal from the Late Cretaceous of Mongolia and its bearing on
the origins of the modern placental radiation, JVP 20(3) SVP Meeting Abstracts September
2000, p. 61A. (As typed and posted by David, and thanks for letting me know!)
Genera: Eoungulatum,
Parazhelestes, Zhelestes,
other reports
Time-Line:
Upper Cretaceous: Eoungulatum, Parazhelestes, Zhelestes
|
| Genus: Eoungulatum Nessov
LA, Archibald JD & Kielan-Jaworowska Z, 1998
'dawn ungulate'
Remarks: According to Archibald & Averianov, 2005 (p.11), this may be synonymous with
Parazhelestes. |
| Species: | Eoungulatum kudukensis Nessov LA et al, 1998 |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle-upper Turonian, Upper Cretaceous |
| Remarks: | Archibald & Averianov, 2005 (p.11) have this
as possibly synomynous with Parazhelestes.
This is both the largest and most derived zhelestid from
the Bissekty fauna, (Averianov & Archibald 2003, p.13). Further, similar material has
been recovered from the overlying Aitym Formation. This consists of a worn, lower
molar and a dentary fragment. |
| Reference: | Nessov et al (1998), Ungulate-like mammals from the Late Cretaceous
of Uzbekistan and a phylogenetic analysis of Ungulatomorpha. Bulletin of the Carnegie
Museum of N H, 34, p.40-88. |
| Link:
Archibald J David, San Diego State University
http://www.bio.sdsu.edu/faculty/archibald.html
Professor Archibald’s university homepage. What he and his students have been getting up to,
including their research at Dzharakuduk, in the Kyzylkum Desert of Uzbekistan.
Recent research concluded: "Although Zhelestidae is also supported, it is not as well
supported"… (as Zalambdalestidae)… "and may include Paranyctoides and
Gallolestes," (Archibald et al, 2001, see Bibliography). |
Genus: Parazhelestes
Nessov LA, 1993
'beside Zhelestes'
Aka: Parazenlestes and perhaps Eoungulatum
and Kumsuperus.
| Reassigned species: P. minor Nessov LA, Archibald JD &
Kielan-Jaworowska Z, 1998 see P. mynbulakensis | |
| Species: | Parazhelestes robustus Nessov LA, 1993 |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle - upper Turonian, Upper Cretaceous |
| Remarks: | This larger species is based on part of an upper
jaw (CCMGE 70/12455), which resides in the collection of Chernyshev's Central Museum of
Geological Exploration, Saint Petersburg.
Several, similar upper molars have been recovered from the
overlying, (and thus younger), Aitym Formation. |
| Reference: | Nessov et al (1998), Ungulate-like mammals from the Late Cretaceous
of Uzbekistan and a phylogenetic analysis of Ungulatomorpha. Bulletin of the Carnegie
Museum of N H, 34, p.40-88. |
| Species: | Parazhelestes mynbulakensis |
| Aka: | P. minor Nessov LA, Archibald JD &
Kielan-Jaworowska Z, 1998; Zalambdalestes mynbulakensis Nessov LA, 1985 |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle - upper Turonian, Upper Cretaceous |
| Remarks: | This species is included in the fauna lest of
Archibald & Averianov, 2005 (p.11). It apparently includes P. minor.
Presumably, it has a connection with "Zalambdalestes" mynbulakensis
Nessov, 1985, which I had listed as a synonym for Sorlestes. |
| Reference: | Nessov et al (1998), Ungulate-like mammals from the Late Cretaceous
of Uzbekistan and a phylogenetic analysis of Ungulatomorpha. Bulletin of the Carnegie
Museum of N H, 34, p.40-88. |
| Bissekty Formation, Dzaharakuduk
The following is based upon my reading of Archibald and Averianov, 2005.
The Kyzylkum Desert of Middle Asia offers a number of localities with terrestrial fossils
from the Upper Cretaceous, most of which are in Uzbekistan. The oldest form the
Sheikhdzheili local fauna with an age of something
like 95 million years. (It's Cenomanian.) The Bissekty fauna is much more numerous and
diverse, and dates to thr Turonian (p.9). That's around 90 million years old. There's
also the five million year younger Aitym local fauna. Despite the difference in age, the
Aitym mammals are broadly similar to their Bissekty predecessors.
Diversity
Bissekty has so far provided 15 species and, unusually for the time of Earth, we
eutherians were the dominant mammals. We account for a
dozen species, while our metatherian cousins apparently
muster but one. The other two mammals are comparative rarities; an archaic spalacotheriid
'symmetrodont' and a lonely
multituberculate. This contrasts radically with Turonian localities in the USA, where
eutherians are more or less (and perhaps completely) absent. North American
Mammalia was heavily infested with by multis and
metatherians. Disregarding the somewhat disputed
Montanalestes, eutherians start turning up there from about 80 million years ago.
If the present fossil record is an accurate reflection of events, then the initial blossoming
of my ancestry occurred in Cretaceous Asia.
Bissekty Formation
The Bissekty has contributed over a thousand mammalian fossils, and such generosity merits
appreciation (p.10). These remains were obtained from 1978 until 2003. For the first two
decades researchers concentrated their attentions on the scouring the surface. However,
from 1998 five field seasons involved extensive attempts at screenwashing techniques; various
forms of sieving with and without the assistance of water. This allowed much larger
quantities of matrix to be thoroughly processed for fossils, with the total quantity examined
reaching about 145 tons. Thousands of remnants of non-mammals were also recovered.
The basis of dating this fauna as Turonian is indirect. Marine deposits are found both
above and below (p.13), and they're fossil rich. The age of the Bissekty mammals must be
between both slices, as it's in the middle of the sandwich.
Bissekty local fauna
The relevant rock strata were laid down largely by river action, and fifteen localities
have so far been found, with four being particularly rich. In terms of stratigraphy, 70
metres separate the highest and lowest sites in the sequence, but this doesn't have a
discernable impact on the faunal composition (p.16). Although not all localities could've
been strictly contemporaneous, all have been assigned to a single local fauna.
Of multis and 'symmetrodonts'
Only eight out of the thousand specimens are from
multis, and all belong to the same species of
Uzbekbaatar kyzylkumensis. As well as the holotype, (a p4
premolar), there are toothless bits of jaw and a few
pieces of skeleton. The spalacotheriid,
Shalbaatar, is represented solely by an
edentulous fragment of dentary.
Metatheria
Three taxa have been established over the years, but the
total number of specimens has since increased to thirty, which allowed a review. All fossils
seem to belong to the same species, with differences being a matter of variation. This is
a deltatheroidan named
Sulestes. Deltatherus (formally Deltatheroides) Kyzylkumensis
and Marsaia aenigma are seen as synonyms (p.17).
Eutheria
'True beast' fossils tally up to 977, and that's over 96% of all mammalian specimens. This
overwhelming domination is produced by a dozen species. In terms of eutherian diversity,
North America had to wait until the Paleocene to reach this figure in a single fauna. Even
sites from the very latest Cretaceous provide no more than a maximum of seven species.
Midgets
Four species of mini-mammals were assigned by the authors to
asioryctitheria. These are the genera of
Daulestes and
Bulaklestes, and opinions vary on their affinities. Among these specimens is a
nearly complete skull with a length of around 1.5cm. In the view of Archibald and Averianov,
these animals were most closely related with fossils from the Mongolian Campanian. (An updated
summary on these critters is below.)
Zalams
There are probably two species of a zalambdalestid called
Kulbeckia. The larger is K. kulbecke with a skull length of about
3.5cm. This big
mouse-sized critter is the most common mammal in the fauna, as it contributes 96
specimens (10%). Previously, it was the earliest zalam known, but that honour has since
been claimed by unnamed remains from the
Sheikhdzheili local fauna (p. 18).
'Zhelestid'-ness
Also well represented are 'zhelestids'. Five species have donated
227 fossils. Zhelestes was a bit larger than the just
mentioned Kulbeckia, and perhaps qualifies as modestly
rat-sized). An
interesting feature of 'zhelestids' is their dentition. The cheek teeth have low crowns
and bulbous cusps, the trigonid is low in comparison with
the talonid, and the upper
molars are adorned with narrow cingula on the
lingual side. These possibly baffling words all point in
a similar direction. These details are specialisations for grinding and crushing at the
expense of cutting abilities.
Getting ready to roam
Presently completing the eutherian Bissekty club is
Paranyctoides, a genus of uncertain affinities. This genus probably includes a
partial jaw previously referred to as Marsasia sp. and, perhaps, an upper molar
called Sailestes quadrans (an m1). What makes Paranyctoides all the more
intriguing is that this animal's been found loitering in Campanian faunas from North
America. It appears to have participated in an invasion along with other
vertebrates. As it was one of my closest relatives from
those times, I've no doubt it led the charge.
Aitym local fauna
This smaller fauna is from a single locality about 30 metres stratigraphically above the
Bissekty Formation. That makes it a bit later (upper Turonian or perhaps Coniacian -p.19).
The mammalian wildlife is less extensive, but there are strong overlaps. Aitym features
cf. Shalbaatar, Uzbekbaatar, a deltatheroid metatherian and five eutherians.
All of these also occur in the Bissekty fauna, although there are possible distinctions at
the level of species.
Utah
At present there are two localities for mammals from beyond Asia, which are close enough in
age to be sensibly compared. Both are in southern Utah. The composition is very different;
up to seven multis, two ''symmetrodonts', some kind
of therian and five metatherians. Instead of a healthy
dozen eutherians Utah can offer none. Montanalestes was described as a Lower
Cretaceous eutherian, although Averianov has doubts about this being correct (p.20). Even
if it is an early North American representative, the next oldest known is Paranyctoides
from the lower Campanian. A possible 'zhelestid', Avitotherium,
was providing some company from the middle Campanian.
Asioryctitherians of Bissekty
This résumé is based upon my reading of Archibald and Averianov, 2006.
An increased sample of fossils is gradually bringing clearer resolution to the Turonian mammal
fauna of Dzharakuduk in Uzbekistan. Most mammals at the time were engaged in insect, grub
and worm-baiting, and the asioryctitherians weren't exceptions in this regard. Four are
presently recognized in the fauna with their sizes spread across the entire range between
small and not quite as big as that; Daulestes kulbeckensis, D. inobervablis,
Uchkudukodon nessovi and Bulaklestes (p.351). Their relatives from elsewhere
in Asia include Asioryctes,
Ukhaatherium and Kennalestes. That
trio are united in the family of Asioryctidae whereas the Uzbek representatives are simply
referred to Asioryctitheria. For those not familiar with the significance of that (the vast
majority of people in the world), these little critters were fairly early
eutherians (relatives of
placental mammals.)
Minis
The giant of the Uzbek asiorycties is Bulaklestes,
and it fully earns the epithet 'small'. At the other extreme comes
Uchkudukodon.
Molar lengths amount to a millimetre in some cases, and that's less than most therians,
contemporary or otherwise. It is about the same as known from
Batodon from later in the North American Cretaceous, and I wonder how it'd compare
to the extant
Etruscan shrew. That mammal enjoys an advantage over many other fearsome predators.
Should the intended victim flee into a worm hole, then the Etruscan shrew sometimes has the
option of following it
Further Mesozoic site summaries can be found at Localities.
Meet the Mammals of the Bissekty Formation
The mammalian Fauna so far described include (Stand: March 2005, p.11-12):
'Symmetrodonta':
Shalbaatar bakht
Multituberculata:
Uzbekbaatar kyzylkumensis
Metatheria:
Sulestes karakshi
Eutheria:
Bulaklestes kezbe;
Daulestes kulbeckensis; "Daulestes"
nessovi; D. inobservabilis;
Uchkudukodon nessovi (new genus from 2006);
Paranyctoides aralensis (listed as Eutheria intercerta sedis though
probably close to "zhelestids", Placentalia).
Placentalia:
"Zalambdalestidae" - Kulbeckia kulbecke;
Kulbeckia new smaller species
; Sheikhdzheilia rezvyii;
"Zhelestidae" - Aspanlestes aptap;
Eoungulatum kudukensis (= Parazhelestes robustus);
Parazhelestes mynbulakensis; Parazhelestes robustus;
Sorlestes budan; Zhelestes
temirkazyk.
Kulbeckia and 'zhelestids', lend me your ears
Among the mammalian fossils recovered from Bissekty are twenty isolated
petrosals. Comparisons with the content of the local fauna
and more complete specimens known from elsewhere, indicate these are most likely the remains
of 'zhelestids' and Kulbeckia, (a 'zalambdalestid'). "The "zhelestid"
petrosal retains several characters ancestral to eutherians
(if not more basally in the mammalian phylogeny), including
a prootic canal, a lateral flange, and a less eliptical fenestra vestibuli. The only other
eutherian taxon to retain these structures is the Early
Cretaceous Prokennalestes", (p.161).
No structures unique to both 'zhelestids' and ungulates were identified.
Petrosals referred to Kulbeckia were found to have similarities with
'zalambdalestids', and also Asioryctes and
Kennalestes.
A reasonable sounding question is: how on Earth can such small material be confidently
assigned to a family and even genus, when all the fossils were found in isolation? Such
referrals aren't always possible but there are methods worth trying, and none rely upon
psychic abilities. Of course, (p.162), the authors know what taxa have been identified in
the Bissekty formation. Most might be represented only by isolated teeth, but they're
still worth taking into account. Only Daulestes kulbeckensis is known from dental
remains found in association with a petrosal.
As an initial step, the fossils were compared with each other. They form two, distinct
groups which were originally termed type I and type II. Variations of size within each
group suggest the remains may be from closely related species, rather than from one taxon.
Among the methods available for closer identification are comparative anatomy, frequency
and size. A number of features indicate these are probably
therian fossils; eg. the cochlear canals are
coiled at least near to 360°. This allows non-therian taxa to be eliminated. The presence
of "an ascending canal for the superior ramus of the stapedial artery" is known
in eutherians but not in their sister lineage. This, in
conjunction with other factors, excludes metatherians.
As both the identified types differ significantly to the petrosal known from Daulestes,
that genus can also be declared not guilty. Because the teeth of Bulaklestes are
very similar to those of Daulestes, it has a credible alibi too. From the faunal
list above, only 'zalambdalestids' (all referred to Kulbeckia), 'zhelestids' and
Paranyctoides, (which seems to be an accomplice of the 'zhelestid' gang), can give
no account of their whereabouts at the time of the crime, (p.163).
Another method of cross-examination worth trying is the comparison of specimen numbers.
The more extensively a location has been sampled, the better the chances are of a
significant, statistical correlation. However, the results in this line of enquiry weren't
clear cut. In the paper, Table 1 shows a preliminary list which: "includes all
specimens identified to the species level through the 2000 field season", with a few
exceptions as reported, (p.163). 79 are from 'zhelestids' and 47 represent 'zalambdalestids'.
Therefore, a 63 / 37% ratio would've been convenient. Amongst the petrosals though, the
split was 11 (type II) to 9 (type I). That's 55 / 45% and doesn't seem informative, but
the sample numbers aren't great. (My mouth's got 28 teeth.)
Comparing the sizes of groups of petrosals to groups of teeth can also be indicative,
(p.164). In this case, the area of a lower molar (m3) and part of
the petrosal (promontorium) were interrogated. The reason for this choice is that those
figures were available from six Cretaceous, therian eyewitnesses from elsewhere in Asia.
They provide a useable set of data for both comparison and control, and allow differing
ratios for different bodysizes to be taken into account. (Generally, but not always, the
promontorium area in type II is significantly larger than in type I petrosals.)
A calculation was then made for an expected m3 area. For type I, the arithmetical range
obtained was 2,8 - 4,4 mm². As this is consistent with the sample of the available
'zhelestid' teeth, 'zhelestids' are probably guilty.
The five larger type II specimens are in line with Kulbeckia. Furthermore, the
morphology of those petrosals is similar to
Zalambdalestes, which supports the case for blaming 'Zalambdalestidae'. It
shouldn't be ignored that four type II petrosals fall below the size range known for
Kulbeckia, including the undescribed, smaller species. Nevertheless, the anatomy
suggests they're at least 'zalambdalestid'.
In summary: Morpho type I probably = 'zhelestid'; Morpho type II probably =
Kulbeckia, (and / or related taxa). I don't think that's enough to obtain a
conviction, but further sampling of the Bissekty Formation and other localities, will
supply evidence for testing the validity of these referrals.
Ekdale et al, 2004 isn't limited to the allocation of fossils to this or that taxon. Much
more space is dedicated to description. It's thorough, complex stuff. For anything more than
a very scant flavour refer to the paper, (linked below).
The remains studied are tiny. The larger specimens pictured on page 166 appear to have
maximum lengths of about 4mm and maximum widths of roughly 3mm. Nevertheless, the state of
preservation allowed reconstructions of soft tissue features. The various holes, canals and
channels give information on the former wiring; nerves, veins and arteries, (p.170-173).
Link
Acta Palaeontologica 49 (1), p.161-176
http://app.pan.pl/acta49/app49-161.pdf
Ekdale, Archibald & Averianov, Petrosal bones of placental mammals from the Late
Cretaceous of Uzbekistan. |
Genus: Zhelestes Nessov LA,
1985
| Reassigned species: Z. bezelgen Nessov LA, 1987 see
Aspanlestes aptap | |
| Species: | Zhelestes temirkazyk Nessov LA, 1985 |
| Place: | Bissekty Formation,
Dzharakuduk |
| Country: | Uzbekistan |
| Age: | middle-upper Turonian, Upper Cretaceous |
| Remarks: |
The holotype is a maxilla.
|
| Reference: | Nessov (1985a), New mammals from the Cretaceous of Kyzylkum.
Vestnik Leningradskogo Universiteta. Seriya 7(17), p.8-18. (In Russian.) |
| Other reports:
Xxxxxxxxxx
Xxxxxxxxxxxxxxx |
A. basal Ungulates B.
"Zhelestinae" C. K ungulates
Unlike the other fossils on this page, these genera have been placed within Ungulata
Linnaeus, 1766. They include some possibly Cretaceous (K) representatives, but are better
known from post-Mesozoic strata. At least, they've been referred to as ungulates
in the past (doubts have been expressed by others), and remains have been found in
Cretaceous deposits. However, in most the North American cases, they probably
ended up there due to reworking from overlying, Paleocene sediments.
Amongst other locations, many of these genera are known from the
Ferris Formation of
Wyoming. The link leads to a brief summary of localized goings on there, from between the
uppermost Cretaceous until the Puercan stage of the Paleocene.
North American "condylarths"
Snippets of info have now been added by a paper by Lofgren from 1995. He pointed out that
a number of "archaic condylarths" were established for fossils from Montana, some originally
regarded as Cretaceous, but descriptions of them were frequently short (p.122). Lofgren
felt sympathy enough to offer fuller information on some. This was a consequence of his
research at McGuire Creek. What he sensibly didn't do is to repeat details that were
already adequately known. I've got Lofgren's work but often not the original
descriptions.
Genera: Baioconodon, Earendil
(= Mimatuta), Kharmerungulatum,
Loxolophus (partly = Baioconodon),
Mimatuta, Oxyprimus,
Perutherium, Protungulatum, Ragnarok
(= Baioconodon), other reports
Time-Line:
Paleocene: Baioconodon, Mimatuta, Oxyprimus, Protungulatum
Upper Cretaceous: ?Baioconodon, ?Mimatuta, Kharmerungulatum,
?Oxyprimus, Perutherium, ?Protungulatum |
| Genus: Baioconodon Gazin,
1941
Aka: Ragnarok Van Valen LM, 1978
Remarks: A mention of this genus from the Maastrichtian of West North America
is contained in the fauna table of Averianov & Archibald 2003, (p.18). No further
details are given.
Ragnarok is apparently a term from Norse mythology. It translates as akin to 'doom of the
gods', (with thanks to Mark Isaak).
| Reassigned species: B. antiquus (Simpson, 1936) is Oxyclaenus
antiqqus; B. harbichiti Middleton, 1983 see B. nordicus | |
| Species: | Baioconodon denverensis Gazin CL, 1941 |
| Place: | South Table Mountain, Denver Formation,
Colorado, Montana,
Wyoming & Rav W-1 Saskatchewan |
| Country: | USA & Canada |
| Age: | lower Puercan, Lower Paleocene |
| Remarks: | The following is based on my reading of Eberle,
2003 (p.154-155).
This is a primitive species of the genus, and Eberele's description concerned an additional
specimen from South Table Mountain, which is where the holotype was found. The new
material is an isolated left molar (m3).
The tooth is very similar to the m3s of B. jeffersoni, but the
talonid is proportionately narrower in this species. The
talonid also has a pair of additional cuspules, but this is often the case and can occur
on any of the lower molars. It's a variable feature.
Holotype
The holotype, USNM 16621, is an employee of the Smithsonian Institute, Washington DC. It's
a fragment of a right dentary with the teeth m2-m3.
Additional notes
It reached the size of an opossum probably weighed about 4 kilos or so. |
| Reference: | Gazin (1941), Paleocene mammals from the Denver Basin,
Colorado, Washington Academy of Sciences Journal, 31, p.289-295. |
| Link:
The Canadian Museum of Nature on line!
http://www.nature.ca/discover/field/eberle/2000/denvr2_e.cfm
Jaelyn Eberle and companions report on crawling over a parched desert. This is where B.
denverensis slept and played 64 million years ago, nibbling plants and perhaps the
occasional bit of meat. Although those big and loud dinosaurs had disappeared, mammalian
life wasn't necessarily idyllic. There were crocodiles to avoid. An accessibly written
report, with several good pics. |
| Species: | Baioconodon nordicus (Jepsen GL, 1930) Middleton,
1983 |
| Aka: | B. harbichiti Middleton, 1983; Loxolophus nordicus
Jepsen, 1930; Ragnarok nordicum (Jepsen, 1930) Van Valen L, 1978; Ragnarok
harbichti Van Valen L, 1978 |
| Place: | Mantua Lentil, Wyoming, Harbicht Hill and upper Hell Creek,
Montana |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | The ever helpful Lofgren, 1995 contained information
on this genus in its varying taxonomic costumes. He was dealing mainly with fossils from
McGuire Creek localities in Montana, but took the opportunity to review specimens found
previously. At the time, he used the name of Ragnarok nordicum.
One of the goodies Lofgren provides is a sketch of a partial dentary. According to me,
that has a preserved length of around 6.5cm. In life then, the owner's head would've
been somewhat longer. I'm not sure how many friends you could feed with one, but a
smallish rabbit
sort of size sounds about right.
Aka B. harbichti
This species was supposed to differ from B. nordicus on account of having smaller
talonids on its lower molars. However, when re-questioned
upon this point, it admitted that the difference was at most minimal and perhaps
non-existent (p.140).
Anyway, as specimens from McGuire Creek resembled both B. nordicus and B.
harbichti, Lofgren could find no grounds for recognizing both species and proposed
synonymity under the older specific name (p.144). At that time and, as far as I know,
still, Middleton hadn't formally published his suggested synonymity at the generic
level. That explains why Lofgren was still using the name of Ragnarok.
Postcanine lengths
Tooth sizes are in tables found on pages 142, 143 and 147. The information for lowers
listed here combines specimens from McGuire Creek, Harbicht Hill and Mantua Lentil
localities. Uppers come from McGuire C and Mantua L.
Uppers: P2 (1 specimen) 3.22mm; P3 (1 sp.) 3.80mm; P4 (1 sp.) 4.30mm; M1 (6 sp.) 4.80-5.50mm;
M2 (7 sp.) 5.64-6.03mm; M3 (7 sp.) 4.21-5.94mm.
Lowers: p4 (8 sp.) 4.22-4.93mm; m1 (11 sp.) 4.78-5.25mm; m2 (20 sp.) 5,29-5.92mm; m3
(18 sp.) 5.98-7.02mm.
Lower teeth
Prior to Lofgren's contribution much of the tooth-work of this species hadn't been described,
so he naturally took the opportunity to change that situation (p.145). A lower
canine and the first three premolars were paraded on a
fairly complete bit of jaw. Mental foramina, naturally occurring holes for nerves and
such stuff, were on view beneath the front root of p2 and the rear one of p3. The canine
was large and rose to a height considerably superior to that attained by the premolars.
Its root curves back into the jaw beneath the first of those teeth, from which its crown is
separated by a shot gap in the tooth row.
The first of the premolars is single-rooted and somewhat
procumbently directed. A rear cusp is small while a basal front one, positioned slightly
lingually, is even less impressive. The p2 is more
strongly developed and double-rooted. Its central cusp is higher, and there's a weak,
cusped talonid. No cusp developed at the front in this
instance. The third premolar had two roots and some doubtlessly fascinating crown
architecture. Sadly, however, the crown's been lopped off. No
diastemata occur between the premolars, and no further teeth of this specimen are
discussed.
Having just perhaps upset the lovers of p4 lowers, let alone to speak of disappointed
molar maniacs, there were p4s among the collection eager to assist with information. The
main cusps are described as being "large" (metaconid and
paraconid or "massive" (
protoconid). The paraconid isn't as tall as the metaconid, and it's positioned more
lingually. A common feature, but not an always well developed one, is a ridge termed the
protolophid. A strong buccal
cingulum inhabits the rear area with a weaker one to the front, and these cingula are not
brought into connection by the protoconid. The well-developed talonid boasts a cusp that
some may term a hypoconid, given its position.
This p4 is longer than that worn by other Hell Creek Formation "archaic condylarths"
excepting for Protungulatum gorgun (p.146). However,
it's wider than the p4 of that species, and other differences concern crown proportions
and cingula developments. As a set, the presence of diastemata also distinguishes
Ragnarok (aka Baioconodon).
Lower molar
Trigonids are low with fat cusps, especially on their
sides. The metaconid is just the highest, and larger than the protoconid. The paraconid
is small and close to the metaconid.
Talonid cusps are strong but low. Excepting for third molars, the hypoconid is the
largest but it's smaller on m3s. A lingual cingulum is strong at the talonid notch, but
not usually present at other points.
These teeth are larger than those of Protungulatum gorgun, with lower trigonids
that are nevertheless wider. Another distinction is that Ragnarok paraconids show
not, or but little, inclinations towards projecting forwards.
Upper jaw
Part of a damaged maxilla was kind enough to present the
premolars, most of which fell off during excavation. They survived the experience.
Unfortunately, the state of the jaw bone doesn't allow them to be replaced accurately.
Nevertheless, the gesture is appreciated.
Upper premolars
The first was only known from its single root, and that suggests a size similar to its
lower partner. The other premolars are double-rooted. P2 is very simple and not
particularly interesting. The follower improves matters but, despite being more
molar-like, it fails to go as far as possessing a metacone. It does boast a large,
chubby paracone and makes some attempt towards having a bi-lobed stylar shelf, although
the front lobe isn't really much to be proud of. The potential protocone area isn't
preserved but, if there were a cusp there, then it can't have been anything other than
small. P4 makes a more fulsome attempt with the front lobe of the stylar shelf, but still
failed to go in for a metacone. At least it's known there was a protocone on this crown,
and it's a fairly large one (p.151). The paracone, however, is bigger.
Upper molars have paracones and metacones that are fatter
than those sported by Protungulatum gorgun. The larger and broader protocones and
metacones result in these teeth having a more quadratic occlusal
outline.
Holotypes
The type fossil of B. nordicus is PU 12385, part of an upper jaw sitting exams at
Princeton University. It began its fossil career as Loxolophus nordicus in 1930,
and put in for a generic transfer half a century later. It demanded its own genus and a
sex change operation in line with the attitudes of Latin gradmas. However, other
researchers suggested it could try out for Baioconodon. That necessited a second
sex change for the specific name.
Additional notes
The Montana site is Puercan, though they may also be some reworked fossils from the Upper
Cretaceous there. This species weighed something like 1,5 kg (Alroy), or
511-597g, (Gordon & Cifelli 2003, p.97 - R. barbichti).
Some fossils are in the Peabody Museum collection, Yale. Middleton's study is an
unpublished thesis produced under the auspices of the University of Colorado, Boulder. |
| References: | Jepsen (1930), Stratigraphy and paleontology of the Paleocene of
northeastern Park County, Wyoming. Proc. of the American Phil. Soc. 69 (7), p.463-528. |
| | Van Valen LM (1978), The Beginning of the Age of the Mammals,
Evolutionary Theory 4, p.45-80. |
| Link:
Ragnarokhorde.com
http://www.ragnarokhorde.com/
A group of further derived Ragnarokers. Jontho the drummer informs me they'll be appearing
in Mexico in December 2003, and plans are in place for gigs in Italy, Sweden, England and
Russia for next year. |
| Species: | Baioconodon engdahli (Archibald, 1982) Middleton,
1983 |
| Aka: | Ragnarok engdahli Archibald, 1982 |
| Place: | Hell's Hollow Local Fauna, Montana |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | This was a smaller species of around a kilo in
weight. |
| Reference: | |
| Species: | Baioconodon wovokae (Van Valen, 1978) Middleton,
1983 |
| Aka: | Ragnarok wovokae Van Valen, 1978 |
| Place: | Leidy Quarry, Wyoming |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | |
| Reference: | |
| Species: | Baioconodon middletoni Eberle & Lillegraven,
1998 |
| Place: | Hanna Basin, Wyoming |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | |
| Reference: | |
| Species: | Baioconodon jeffersoni Eberle JJ, 2003 |
| Place: | South Table Mountain,
Colorado |
| Country: | USA |
| Age: | lower Puercan, Lower Paleocene |
| Remarks: | The following is based upon my reading of Eberle,
2003.
This species is represented by at least three partial
dentaries from the same site. It's closest in both size and form to B. deverensis,
(p.153). However, the p4 (a premolar) is larger and wider,
and the talonids on the molars
are also wider. Meanwhile, the trigonids are narrower
than the talonid, and that's more like the situation in Loxolophus. The central
position of the paraconid on the m2 is a further
characteristic more in keeping with that genus.
Developmental matters in summary
The teeth of Baioconodon are transitional between the less
derived Protungulatum and its more immediate relatives,
the loxolophines. Furthermore, characters in this species are intermediate between
B. denverensis and L. hyattianus and L. priscus. Both those species
are known from the middle Puercan, and so are later.
On page 154, Eberle points out the similarities with B. denverensis may indicate
that is the ancestral species, or these are sister taxa
derived from a common predecessor. Furthermore, B. jeffersoni is cited as a
possibly plausible candidate for the ancestry of the aforementioned Loxolophus
species. L. hyattianus occurs further south in Colorado at Corral Bluffs. Although
L. priscus hasn't yet been found in the state, it has turned up in both Wyoming and
New Mexico.
Holotype
The holotype is known affectionately as DMNH 43208, and it resides in the collection of
the Denver Museum of Nature and Science. It has a couple of other specimens for company.
The specific name honours both Jefferson County and Jefferson County Open Space, who
purchased the land. This ensures it's protected from development. |
| Reference: | Eberle (2003), Puercan mammalian systematics and
biostratigraphy in the Denver Formation, Denver Basin, Colorado, Rocky Mountain Geology,
38(1), p.143-169.
|
| Species: | Baioconodon cannoni |
| Place: | Littleton Local Fauna, Denver Formation,
Colorado |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | This is probably awaiting publication, though I
have seen it credited to Middleton, 1983. As that study is an unpublished doctoral thesis,
a description hasn't yet officially appeared. |
| Reference: | |
| Link:
Eric W Dewar
http://www-unix.oit.umass.edu/~dewar/research/SVP97poster.html
Dietary inferences for archaic ungulates from the Early Puercan Littleton Local Fauna
(Denver Formation, Colorado)
Last year (2002), Eric was kind enough to inform me that many of the species from this
fauna haven't yet been described. As B. cannoni is mentioned as 'n. sp.', it
may be amongst them. |
| Genus: Kharmerungulatum
Prasad GVR, Verma O, Sahni A, Parmar V & Khosla A, 2007
'Kharmer ungulate'
Remarks: The generic name is based upon the Kharmer River. |
| Species: | Kharmerungulatum vanvaleni Prasad GVR,
Verma O, Sahni A, Parmar V & Khosla A, 2007 |
| Place: | near Kisalpuri, Andhra Pradesh,
Deccan Traps |
| Country: | India |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: | The following is based upon my reading of Prasad,
Verma, Sahni, Parmar & Khoslar, 2007, and thanks are due to the supplier.
Normally, I'd have abbreviated that list of authors just cited but, given the present
number of studies presently emerging from India, that could produce some confusion
later. If living in interesting times has to be seen as a curse, then it's one I'm more
than happy to be suffering from at the moment. This is the second new genus of the year
from the stables of Prasad and colleagues, and they might launch more at any moment.
Great efforts have gone into scouring Central India for
vertebrate fossils from close to the final curtain of the Cretaceous, and they've
been rewarded with new information. As is often the case, this new addition is described
in terms of an isolated tooth. However, the search for more fossils and localities
continues and, should fuller Maastrichtian mammals be awaiting discovery somewhere in a
local cemetery, then they'll almost certainly be disturbed in their graves at some time.
A speckle of sites is separated by between a few kilometres from each other or, in one
case, 700km. That's now a large area to search. Fortunately, vertebrate paleontologists
are among the most determined of animals.
Hoof-tooth
As only a single molar has been found, the title of the
paper, 'A Cretaceous hoofed mammal from India', could pose a puzzle for some. How can
anybody be sure the ancient owner had hoofed feet? Naturally enough, they can't. These
are more like figurative hoofs. Paw taste in fashion is actually beside the point. The
molar is strongly similar to others from mammals called condylarths, and they stand
accused of having a close relationship with extant ungulates such as horses, deer, pigs,
sheep, hippos and whales. As Flipper would be only too pleased to demonstrate for a fish,
ungulate affinities don't literally require hoofs. (I appreciate your book might not
count dolphins as ungulates. However, I didn't write it. Moreover, studies indicate the
closest living relatives of cetaceans happen to be hippos; ungulates.)
Ungulate orgins?
The Prasad & Co paper is only a page long, and the sense of its title reflects the
assumption that ungulates are related to at least some condylarths. That seems likely
enough. However, a significant point isn't addressed: "The earliest definitive ungulates
represented by Protungulatum,
Oxyprimus, Baioconodon and
Mimatuta (...) come from the Early Paleocene (Puercan) of north-eastern
Montana", (reference numbers omitted).
There are a couple of details to confront that sentence with. Least important is the
reported presence of a condylarth in the Maastrichtian Frenchman Formation of
Saskatchewan (eg. as in Fox et al, 2007 p.1). It's about the same age as the Indian
genus.
More importantly, one study cited in the references of the paper would, if correct, blow
any connection between Protungulatum and Oxyprimus completely out of the
water. According to the findings of Wible et al, 2007, those genera can't possibly have
bonked ungulates into existence. This is because they failed to qualify even for
Placentalia in that analysis. Doubts about connecting
"zhelestids" with condylarths are cited by Prasad and Co, but there's no mention of the
possible non-placental affinities of Protungulatum and friends. That strikes me
as being a weakness. However, a single page doesn't allow much space, and Wible et al
published only a few months before Science accepted the description of
Kharmerungulatum for publication. Those factors shouldn't be forgotten.
A further Deccan eutherian
In the view of these authors, the new tooth shows most resemblance with fossil genera
such as Protungulatum, and they refer it to Condylarthra: "... a
paraphyletic group regarded as an ancestral or sister
taxon to the living ungulate mammals...".
It's a modestly large mammalian molar for the time of Earth, with a length of 2.5mm.
Some considerably larger specimens are, however, known from mammals of that age, and it's
also rather small for morphologically similar teeth from the Paleocene. The
trigonid is asymmetrically built, and larger than the
talonid in terms of length and width. It's also a touch
taller; something future generations would remedy. Its cusps are fat with the
buccal protoconid taking
up around twice the room allocated to the metaconid.
As for the talonid, its entoconid is smaller than the hypoconulid, and their bases merge
together. The buccally positioned hypoconid is a larger cusp than either of that
pair.
Crusher
Condylarth molars are about crushing and grinding abilities. The height similarity of
trigonid and talonid, the chubbiness of the cusps (more like rounded hills than craggy
mountains), and the enlarged hypoconid all point that way, and the wear patterns
agree. Kharmerungulatum, however, was at an earlier stage of development in this
trend. Its cusps are bunodont, but less so than future models. It's also small. Some
of its basal traits sometimes occur among the likes of
Protungulatum; a somewhat taller trigonid, a paraconid set slightly in from the
lingual edge of the crown and clearly separated from
the metaconid, and further details. It seems most closely comparable with two North
American species, Protungulatum gorgun and Baioconodon
Conclusions
The final paragraph of the paper, in my view, appears to involve some ambitious
speculation based upon one molar. However, I don't know what else may have been harvested
but not yet described. The authors make no mention of further relevant Deccan
specimens; neither yes or no.
Assuming archaic condylarths are ungulates, then this is justifiably the earliest known
from Gondwana and, more questionably, could be the oldest yet found anywhere. However,
(and bearing in mind the following points are preceded by the word 'may'):
"The presence of an archaic ungulate in the latest Cretaceous of India may reflect that
(i) archaic ungulates had a pan-Gondwanan distribution, and their absence in other land
masses may be an artifact of limited field investigations;"
This possible "pan-Gondwanan distribution" is founded on remains from only India. The
somewhat earlier Patagonian faunas of Argentina (probably Campanian) haven't yielded any
eutherians, let along archaic ungulates. Furthermore,
South America remained an ungulate free-zone for millions of years after the Cretaceous,
with many of the equivalent niches being filled by notoungulates that weren't actually
ungulates. This would presumably be a "pan-Gondwanan distribution" without SAm (and
perhaps the rest of Gondwana other than India).
"(ii) Kharmerungulatum immigrated to India from Western Asia, which had a
diversified assemblage of zhelestids (85 million years ago)
regarded by some as ancestral to archaic ungulates (5), although any connection is
disputed (6);"
Assuming ungulates are connected with archaic condylarths and, in turn, they're
descended from some 'zhelestid' or other, immigration from Asia sits in odd company with
a possible "pan-Gondwanan distribution". While the two possibilities need not be
mutually exclusive, if they both turn out to be justified I'd be astonished. Immigration
from Asia and a limited Gondwanan distribution would be more likely, in my opinion.
"(iii) the drifting Indian subcontinent may have served as a center of origin for many
mammalian orders and other vertebrate and plant groups."
I suppose it have, but I find it improbable for major groups. India may make for a very
large country, but it's rather small if viewed as a continent. It seems unlikely it
could've given rise to mammalian orders that went on to dominate the faunas of much
larger landmasses. The authors don't actually go as far as stating that possibility, so
perhaps their speculation is limited to small orders and groups rather than, say,
ungulates.
Filling in unknowns
The main reason so much room is open for speculation is the sparse Gondwanan fossil
record. For example, the Upper Cretaceous and Paleocene pages of Africa are little more
than blank. There must be localities around somewhere. Until 1988, Cretaceous mammals
weren't known from India either. That picture has been changed with some luck, but much
more by determination and the working out of likely places to sample. A great service has
already been provided by both native and foreign paleontological researchers in India.
Their continuing success throws down a challenge to the other former landmasses of
Gondwana.
Holotype
The sole specimen referred to the genus is VPL/JU/IM/31, and it works, rests and plays at
Jammu University, India. The specific name honours Leigh Van Valen, a researcher of
North American mammal fossils. |
| Reference: | Prasad et al (2007), A Cretaceous hoofed mammal from
India, Science, 318, p.937. |
| Genus: Mimatuta Van Valen, 1978
Aka: Earendil Van Valen, 1978
Remarks: A mention of this genus from the Maastrichtian of West North America is contained
in the fauna table of Averianov & Archibald 2003, (p.18). No further details are
given.
For those unacquainted with the works of Tolkien, Eärendil is the father of Elrond, (with
thanks to Mark Isaak). |
| Species: | Mimatuta makpialutae van Valen, 1978 |
| Place: | Leidy Quarry, Wyoming |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | This holotype is also in the Peabody collection. |
| Reference: | Van Valen LM (1978), The Beginning of the Age of the Mammals,
Evolutionary Theory 4, p.45-80. |
| Species: | Mimatuta minuial Van Valen L, 1978 |
| Aka: | M. minuiel; Earendil undomiel Van Valen, 1978 |
| Place: | Mantua Lentil, Wyoming & Montana |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | When alive, the creature weighed about 600 g.
'Minuial' is of course Elvish: 'the twilight of the dawn', (further thanks to Mark Isaak).
The holotype, (YPM 14211), is another Yale student. |
| Reference: | Van Valen LM (1978), The Beginning of the Age of the Mammals,
Evolutionary Theory 4, p.45-80. |
| Species: | Mimatuta morgoth Van Valen L, 1978 |
| Place: | Harbicht Hill & upper Hell Creek Formation, Montana |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | Lofgren, 1995 contains information on this
species thanks to fossils from the McGuire Creek localities, Montana. These few additional
uppers increased numbers of specimens but added little new information (p.151).
Postcanine lengths
Uppers are from Harbicht Hill (an M2) and McGuire Creek. All lowers mentioned are from
McGuire Creek (p.152-154). I've combined the information here.
Uppers: M1 (2 specimens) 4.05-4.57mm; M2 (2 sp.) 4.76-4.77mm; M3 (6 sp.) 3.85-4.32mm.
Lowers: canine (2 sp.) 2.08mm; p1 (1 sp.) 1.54mm; p2 (1 sp.) 2.50mm; p3 (1 sp.) 3.16mm;
p4 (4 sp.) 3.44-3.80mm; m1 (3 sp.) 3.92-4.05mm; m2 (4 sp.) 3.97-4.56mm; m3 (3 sp.)
4.90-5.43mm.
An examination of a diagnostic matter was conducted (p.152), seeing as the larger number
of relevant specimens allowed for it. The proposal had been that the more
bucally positioned protocone of M2 allows a difference to
be distinguished for this species, in comparison to
Protungulatum donnae, a similarly sized taxon.
This was confirmed.
However, the lower teeth are less cooperative. Postcanines are annoyingly similar to those
of a sister species, Mimatuta minuial. The
metaconid on the p4 from that species is meant to be "rather strong" whereas it's
reportedly "rather weak" for M. morgoth. On this basis, four
dentary fragments from McGuire Creek were assigned to this
species, with a fifth facing charges of belonging to M. morgoth (p.153). Lofgren
couldn't recognize any distinguishments for the molars whether in terms of either
structure or size. Isolated molars couldn't be securely assigned to either species.
Few news
As lower teeth available to Lofgren mostly conformed well to the norms of previous
descriptions, there wasn't much point in him engaging in repetition of details. Exceptions
came at the front of the jaw. One specimen related that its robust
canine was vertically implanted (p.154), and rose in height to reach the level of the
central cusp of the third premolar. That left it free to look down upon the first two
premolars. It's not an especially frightening looking tooth, has a single root, and this
curves pronouncedly back into the jaw below the p1. That premolar's a rather pathetic,
simple feature set at a slightly jaunty angle. In contrast to its colleagues, but in
sympathy with the canine, it's also single-rooted.
Diastemata occur both to its fore, between the canine and p1, and to its aft, between
p1 and the larger, much better developed p2.
Holotype
UMVP 1560 is a partial upper jaw attending the University of Minnesota, Minneapolis.
Additional notes
Remains of this species have been identified from
the Hell Creek Formation, which is Upper Cretaceous. However, there has been some
reworking of fossils. The critter weighed about half a kilo (Alroy); or
247-256g, (Gordon & Cifelli 2003, p.97, m1 only).
Van Valen was evidently rather keen on Tolkien. 'Morgoth' is the 'dark enemy of the world'.
|
| Reference: | Van Valen LM (1978), The Beginning of the Age of the Mammals,
Evolutionary Theory 4, p.45-80. |
| Genus: Oxyprimus Van Valen L,
1978
Remarks: A mention of this genus from the Maastrichtian of West North America is contained
in the fauna table of Averianov & Archibald 2003, (p.18). No further details are
given. |
| Species: | Oxyprimus erikseni Van Valen L, 1978 |
| Aka: | O. eriksoni |
| Place: | Harbicht Hill & Upper Creek Formation, Montana, ?Ravenscrag
Formation, Sasksatchewan |
| Country: | USA & ?Canada |
| Age: | Puercan, Paleocene |
| Remarks: | Lofgren, 1995 had specimens of this species from
McGuire Creek localities, Montana, and provides some information on them.
Sizing things up
Figures on pages 136-138 give measurements for specimens from both McGuire Creek and
Harbicht hill. I've combined the legth ranges. All uppers come from McGuire Creek and only
m1s were available from HH.
Uppers: M1 (7 specimens) 3.17-3.93mm; M2 (4 sp.) 3.64-3.90mm; M3 (3 sp.) 3.07-3.23mm.
Lowers: p4 (3 sp.) 3.00-3.45mm; m1 (7 sp.) 3.03-3.38mm; m2 (7 sp.) 3.35-3.64mm; m3 (7 sp.)
3.83-4.52mm.
Lofgren also writes about similarly sized teeth from Mantua Lentil. He found they could
be distinguished, and justified thier status as representing a separate species named
O. galadriela.
Upper postcanines
Such teeth hadn't previously been described for O. erikseni (p.135), but McGuire
Creek ones were identified by comparisons with the very similar O. galadrielae.
Distinguishing between the two is difficult to impossible. However, should a locality
house only one species, as could be determined by the presence of sufficient lower molars,
then it would be extremely odd if the uppers had some other owner.
The upper M1 and M2 molars are also much like those of
Protungulatum donnae, although they are smaller. There
are also distinctions of proportions. With O. erikseni the parastylar lobe is
relatively smaller, the hypocone larger and the protocone has a steeper slope on its
lingual side.
The original descriptions of both O. erikseni and O. galadrielae were
approaching minimalist in terms of thoroughness and, reportedly, an identifiable difference
had to do with the shape of the metaconid. This was
said to be more conical for the first cited species, and elongated for the second.
Re-examination found the metaconids of O. galadrielae are of equal or longer
length. The suggested diagnosis failed to work and a new one was required, if distinctions
were available (p.137).
A few features do differ for lower postcanines (p.138). talonids
are a bit narrower for O. erikseni, and p4 and m1 are close in terms of length. The
first molar is longer for O. galadrielae. Usually, but not always, the p4
metaconid is larger for erik. That's a relatively minor matter, seeing that p4 metaconids
don't always behave oblingingly in this respect. Even less difference occurs for upper
molars. Those of erik may be a touch wider, although not be much.
Holotype
UMVP 1561 is a lower molar teaching at the University of Minnesot, Minneapolis.
Additional remarks
A weight of about 130g (Alroy), or 76-114g,
(Gordon & Cifelli 2003, p.97). |
| Reference: | |
| Species: | Oxyprimus galadrielae Van Valen L, 1978 |
| Place: | Mantua Lentil, Wyoming, North Dakota,
Colorado, Montana |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | Lofgren, 1995 has information on specimens
obtained from McGuire Creek localities, Montana. He reviewed the health of this taxon
as a distinct species, and found it could be justified on account of the morphology of
lower molars.
Size
Lofgren includes the following postcanine lengths for the species:
lowers: p4 (3 specimens) 2.80-3.99mm; m1 (4 sp.) 3.21-3.26mm; m2 (3 sp.) 3.76-4.31mm.
Some comparative points are contained in the entry above housing O. erikiseni.
Holotype
Material, including the holotype, is in the collection of the Peabody
Museum, Yale, (YPM 16866). This is a left maxilla with
premolars and molars,
(Hunter & Archibald 2002, p.199).
Additionally
Named in honour of the elf Lady Galadriel, (with
more thanks to Mark Isaak). John Alroy offers an age range of between 66-63 million years
ago, which cuts across the K-T border.
"However, because the genus Oxyprimus has been regarded by Luo (1991) as
possessing more primitive character states than Protungulatum and Mimatuta,
we regard this taxon as a useful comparative element for
basal "condylarths"", (Muizon C & Cifelli
RL 2000, p.52). |
| Reference: | Van Valen LM (1978), The Beginning of the Age of the Mammals,
Evolutionary Theory 4, p.45-80. |
| Species: | Oxyprimus putorius Van Valen L, 1978 |
| Place: | Mantua Lentil, Wyoming |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | Lofgren, 1995 has this speices as being very poorly
represented and possibly dubious (p.138). Upper 'molars' (the singular would be more
appropriate) are narrower than those of other species in the genus, at least in as far as
sample sizes allow for that to be tested. The only know lower specimen is in very poor
condition, and of little use (p.139).
Holotype
PU 167045 is an upper left molar residing at Princeston University, New Jersey.
Additional notes
Of questionable validity according to Martin Jehle. |
| Reference: | Van Valen LM (1978), The Beginning of the Age of the Mammals,
Evolutionary Theory 4, p.45-80. |
| Species: | Oxyprimus albertensis |
| Place: | Purgatory Hill, Montana |
| Country: | USA |
| Age: | Puercan, Paleocene |
| Remarks: | This species is contained in the fauna list of
Weil, 1999, (p.166). |
| Reference: | |
| Genus: Perutherium Thaler L,
1967
'Peru beast' |
| Species: | Perutherium altiplanense Thaler L, 1967 |
| Place: | Laguna Umayo |
| Country: | Peru |
| Age: | Upper Cretaceous |
| Remarks: | It's assigned to this age in McKenna & Bell,
1997 (p.450) and noted as perhaps a dilodontid or a primitive notoungulate. Notoungulate
herbivores flourished in South America after the Cretaceous. The authorship above is the
form they have listed. Why the reference should have more authors isn't clear to me. I
could think up a plausible explanation, but that would be pointless.
Simpson, 1980 (p.38) has a paragraph on the location and genus: "So the present
positive knowledge of this history starts with the scanty handful of fragments of mammals
from late Cretaceous strata. These were found in 1965 and 1967 by a French expedition on
the tremendous high Andean plateau of Peru not far from Lake Titicaca and near the small
Laguna Umayo. The first specimen found was a fragment of a lower jaw with the posterior half
of the first molar and the anterior half of the second molar.
Later a small fragment of an upper molar apparently of the same species was found. This
animal was with high probability a primitive hoofed mammal, a condylarth rather like the
Didolodontidae, the condylarth family known from later faunas. It is not much like anything
known from the late Cretaceous of North America but does somewhat resemble some later
(Paleocene and Eocene) North American, European, and Asiatic condylarths. The French
paleontologist Louis Thaler named it Perutherium altiplanense."
Simpson also indicates the metatherian, Alphadon, is in the same collection. To the
best of my knowledge, this was subsequently emended to
Peradectes austrinum.
The genus also receives mention in Muizon & Cifelli, 2000. Periptychid affinities
have been suggested in the past, (p.69), which is a further family of condylarths. They
refer to it as "poorly known". |
| Reference: | Grambast LM, Martinez M, Mattauer M & Thaler L (1967),
{Perutherium altiplanense}, nov. gen., nov. sp., premier Mammifere mesozoique
d'Amerique du Sud, C. R. Acad. Sci. Paris, Vol. 264, p.707-710. |
Genus: Protungulatum Sloan
& Van Valen, 1965
'before-ungulate'
Remarks: P., a form of ancestral ungulate, has been found in association with
isolated dinosaur scraps. This indicates the possibility of an Upper Cretaceous age, but
could also be due to secondary deposit of fossils. Isolated dino remains do occasionally
turn up in younger rock. The question is how they got there.
| Reassigned species: P. mckeeveri Archibald, 1982 see P. donnae
| |
| Species: | Protungulatum donnae Sloan & van Valen, 1965 |
| Aka?: | P. mckeeveri Archibald, 1982 |
| Place: | Bug Creek Anthills and ?lower Tullock, Montana,
Colorado, Wyoming
& ?Frenchman & Ravenscrag Formations, Saskatchewan? |
| Country: | USA & Canada? |
| Age: | lower Puercan, Lower Paleocene |
| Remarks: | The start of this entry is derived from my reading
of Eberle, 2003.
Eberle, 2003 (p.150) includes a description of a
further specimen from the Plains Conservation Centre in Colorado, which was found by
Nicole Boyle. The possible Saskatchewan fossils may be Upper Cretaceous. Material from
Hanna Basin, Wyoming is middle and (perhaps) upper Puercan.
The fossil Eberle described, is a fragment of lower jaw with the p4 and two
molars. They're worn, but the m2 is very similar to its
counterparts from Bug Creek. The simplest way of telling the difference between this
taxon and its close relatives,
Oxyprimus erikseni and O. galadrielae, is that this species is larger. The
p4 and m2 are both longer and wider. In this case, the m1 was so eroded that the length
could only be estimated. The m2 has a paraconid situated
on the lingual half of the crown, whereas it's nearer the
middle in O. erikseni.
Holotypes
The holotype, SPSM 62-2028, is a resident of the Saint Paul Science Museum, Minnesota. It's
part of a left dentary with
premolars and molars, (p2-m3), and was found in the Anthills.
UCMP 121782, meanwhile, hangs out at the University of California, Berkely. It claims
to be a species called P. mckeevi. However, lots of doctors who hear this going
on have their doubts about the sanity of this particular inmate.
About the size of things
Lofgren, 1995 contains a series of molar measurements for specimens from McGuire Creek,
Montana (p.124-125). The lengths cited are as follows:
Uppers: M1 (3 specimens) 3.50-3.80mm; M2 (4 sp.) 3.69-4.78mm; M3 (1 sp.) 4.50mm.
Lowers: m1 (8 sp.) 3.61-4.10mm; m2 (15 sp.) 3.68-4.52mm; m3 (7 sp.) 4.42-5.56mm.
The upper molars of P. donnae are similar in size to the corresponding teeth of
Mimatura. They differ in the slope of protocones on the
lingual side, which are both steeper and shorter for this species. Lower molars,
unsurprisingly, are also similarly sized. Those of Mimatura tend to have somewhat
wider talonids. More significantly, paraconids are positioned
further bucally for Mima.
P. mckeevi
Lofgren rated this species as perhaps distinct from P. donnae, or maybe not (p.127).
It was poorly represented by only a single bit of lower jaw, and some differences were
cited. These were largely matters of proportion and minor details. The paraconid of
lowers is also somewhat smaller. Lofgren rated synonymity as being probable but not
certain.
For what it's worth, Lofgren measured its teeth as well.
Lowers: m1 4.00mm; m2 4.40mm; m3 4.90mm.
Further notes
A Yale specimen from Montana is dated as Upper Cretaceous. It might well have been around
on either side of the K-T border. It weighed about the same as a very obese rat, 530g
(Alroy), or maybe 181-304g, (Gordon & Cifelli 2003, p.97).
P. mckeeveri is also within that range. |
| Reference: | Sloan & Van Valen (1965), Cretaceous mammals from Montana,
Science, 148, p.220-227. |
| Links:
Origin of Conscious Life on Earth, Piers Clement
http://www.geocities.com/piers_clement/origin.html
The extinction of the dinos, II. A theory that Protungulatum actually arrived from
another planet. I'm not totally convinced this is correct.
Gamely, the author, who now describes this article as a youthful folly (pers. comm.), has
no objections to this link. It does not reflect his present views, (and certainly
not those of Dr Smit, who simply supplied information), and "includes an implicit
disclaimer against any idea that it might be a contribution to science!" Nevertheless,
I found it entertaining.
NAFMS, Bug Creek West
http://flatpebble.nceas.ucsb.edu/nam/listfiles/Bug_Creek_West.html |
| Species: | Protungulatum gorgun Van Valen L, 1978 |
| Place: | Harbicht Hill, Montana & Wyoming |
| Country: | USA & Canada |
| Age: | Paleocene |
| Remarks: | Lofgren, 1995 helps out here as well.
These teeth are morphologically similar to those of P. donnae, sometimes known from
the same localities, but they are significantly larger (p.126). That was the reason for
their assignment to a separate species. It was originally based on specimens from
Harbricht Hill. Lofgren was dealing with further specimens from McGuire Creek localities
from Montana. Measurements of those are found on pages 128-129.
Postcanine lengths (McGuire Creek)
Uppers: M1 (4 specimens) 4.09-4.64mm; M2 (12 sp.) 4.62-5.38mm; M3 (4 sp.) 5.34-6.16mm.
Lowers: p2 (1 sp.) 2.97mm; p3 (1 sp.) 3.24mm; p4 (1 sp.) 4.38mm; m1 (3 sp.) 4.09-4.64mm;
m2 (4 sp.) 4.62-5.05mm; m3 (3 sp.) 5.57-6.16mm.
This species was the least known of Montana's then published "archaic ungulates" (p.128),
and little description had been published even in the original description. A shortage of
specimens obviously hadn't helped matters. Prior to Lofgren the upper dentition hadn't
been dealt with at all. The McGuire Creek specimens provided the opportunity for
improving matters.
Lower jaw
The bone in front of the final premolar was available for
interview on a specimen named UCMP 134558, a new resident of Berkeley University. Mental
foramina are located beneath a gap separating p2 and p3 and beneath the rear root of p3.
The crown of the canine had obviously made plans to go
elsewhere, although its root decided to stay in place (p.129). That root is larger than
those of the first two premolars, and it curves down into the jaw below the p1.
Lower premolars
The first of the gang is also an absentee. The slant of its
alveolus, however, kindly indicates it must have been somewhat procumbent in
inclination. A short diastema intervenes between it and
p2, and a larger one separates the latter from p3. Should I be understanding things
correctly, the first premolar is single-rooted while the remaining three are
double-rooted.
The crown of p2 proudly sports a large cusp at its centre, a couple of weak ridges and a
small cusp to the rear. Its p3 neighbour has a larger main cusp and, the show off, a small
additional cuspule to the front. Breakage left some room for mystery behind that point.
A further scrap of jaw does preserve the final premolar. Its front cusp is larger and its
central one is tall and strong. The rear cusp remains small and low. This tooth has a
broad, short talonid featuring a single cusp; the
hypoconid.
In comparison to teeth then assigned to Ragnarok (sneered at on this directory by
being regarded as a junior synonym of Baiocondon, but
not including the Norwegian rock band with the same name), the premolars are relatively
short and narrow (p.130). But they are proportionately longer and wider than for
Protungulatum donnae and
Mimatuta morgoth. The crown shape closely accords with P. donnae,
albeit as a larger version. A difference occurs with the larger diastema between the
second and third premolars; nigh on twice the length as the other premolar diastema. The
talonid of p4 is better developed for this larger species.
Lower molars
These teeth are significantly larger than the corresponding millstones of P. donnae,
but otherwise similar. The cusps are stronger for P. gorgun, and there's a clearer
separation between the paraconid and
metaconid, with the first of those cusps generally
being located in a more buccal position. The hypoconid of the
talonid is more dominant. Compared to members of Ragnarok (again, not the
Norwegian rock band), these teeth are smaller and have proportionately higher
trigonids. Cusps are less bulbous, and there is a
distinct forwards projection of the paraconid.
Upper molars
Only isolated uppers were found. Both size and morphology is appropriate for lowers from
the same localities, but their referral is regarded as tentative (p.132).
M1s are more or less a scaled up version of the tooth known from P. donnae, although
the protocone is proportionately larger, and the postcingulum and hypocone are weaker.
The protocone of M2 is taller and larger and, consequently, it has steeper and longer
sloping sides (p.134). This tooth is also relatively wider. M3s only differ between
the species significantly in terms of size.
Holotype
AMNH 35987 is a guest at the American Museum of Natural History, New York. It's an
isolated M2 upper molar.
What's in a name?
As regards the specific
name: "Gorgun was the name for Orcs that Ghan-buri-Ghan, the leader of the Wild Men of
the woods, used.". With thanks to the The Tolkien Index,
(
http://www.geocities.com/the_tolkien_index/index.html). Middle Earth meets Mesozoic. |
| Reference: | Van Valen (1978), The beginning of the age of the mammals,
Evol. Theory 4, p.45-80. |
| Species: | Protungulatum sloani van Valen L, 1978 |
| Place: | Purgatory Hill, Montana & Wyoming |
| Country: | USA |
| Age: | Maastrichtian, Upper Cretaceous - Puercan, Paleocene |
| Remarks: | A cast specimen is at the Peabody. |
| Reference: | |
| Link:
What Wiped out the Dinosaurs?, Discover Vol 23 (6), June 2002
http://www.discover.com/june_02/featdino.html
The extinction of the dinos III. A recent and reasonably in-depth item on the Hell Creek
fossil location. This focuses more on the micro-residents of the time, including the
mammals. Doubts are raised about the mono-causual killer-meteorite theory.
|
| Other reports:
Xxxxxxxxxx
Xxxxxxxxxxxxxxx |
| 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 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, June 2002 Last updated: 30.5.2008
Ktdykes@arcor.de |
| With further thanks due to...
Weight estimates
Dr John Alroy, North American Fossil Mammal Systematics Database
http://www.nceas.ucsb.edu/~alroy/nafmsd.html
The completeness and reliability of Dr Alroy’s database is very impressive.
Weight estimates have generally, when not otherwise stated, been shamelessly stolen from
John Alroy's internet site. When other sources are available, this may produce disparities.
I've got two comments to offer.
Firstly, if you were to claim that some European hedgehogs (Erinaceus europaeus)
weigh 400 grammes, you'd be correct. If I were to add that some reach 1,2 kilos, I'd also
be correct. Some hedgehogs are bigger than others.
Secondly, the estimates partly depend upon the questions posed. If a calculation is based
upon an insectivore model, the answer may be 50g. Choose a South American opossum, and it'd
perhaps be closer to 150. Think primate, and 300g might result.
A further source is Gordon & Cifelli, 2003 (p.93-97). This research offers various
alternatives. These depend upon which tooth is used, (lower molar 1 or Upper Molar 1),
and which group of animals it's compared to. I'll include the range of estimates based
upon insectivores, (though my intuition suggests they might be somewhat low). These
calculations were derived from a. m1 Length, b. m1 L x Width, c. M1 L and d. M1 L x W.
A rough system of measurement is employed in these directories. A standard mouse = 25g, a
rat counts as 400 whilst a beaver equals about 25 kilos.
The Prehistoric Data Files
http://www.angellis.net/Web/PDfiles/marsups.pdf
Another valuable resource.
BIOSIS, The Index to Organism Names
http://www.biosis.org.uk/triton/indexfm.htm
The thrilling animated graphics are courtesy of
HitBox Central,
Animation Library and
best animations.com.
|
Bibliography:
Archibald JD & Averianov AO (2001), Paranyctoides and allies from the
Late Cretaceous of North America and Asia, Acta Palaeonotologica Polonica, 46 (4), (Proof
Version).
Archibald JD & Averianov AO (2005), Mammalian faunal succession in the Cretaceous
of the Kyzylkum Desert, Journal of Mammalian Evolution, 12 (1/2), p.9-22.
Archibald JD & Averianov AO (2006), Late Cretaceous asioryctitherian eutherian
mammals from Uzbekistand and phylogenetic analysis of Asioryctitheria, Acta Palaeotnologica
Polonic, 51(2), p.351-376.
Archibald JD, Averianov AO & Ekdale EG (2001), Late Cretaceous relatives of
rabbits, rodents and other extant eutherian mammals. Nature 414, p.62-65.
Averianov AO & Archibald JD (2003), Mammals from the Upper Cretaceous Aitym
Formation, Kyzylkum Desert, Uzbekistan. Cretaceous Research 00 (2003), p.1-21.
Averianov AO & Archibald JD (2005), Mammals from the mid-Cretaceous Khodzhakul
Formation, Kyzylkum Desert, Uzbekistan, Cretaceous Research 26, p.593-608.
Averianov AO, Archibald JD & Martin T (2003), Placental nature of the alleged
marsupial from the Cretaceous of Madagascar. Acta Palaeontologica Polnica 48(1), p.149-151.
Eberle JJ (2003), Puercan mammalian systematics and biostratigraphy in the Denver
Formation, Denver Basin, Colorado, Rocky Mountain Geology, 38(1), p.143-169.
Ekdale EG, Archibald DJ & Averianov AO (2004), Petrosal bones of placental
mammals from the Late Cretaceous of Uzbekistan. Acta Palaeontologica Polnica 49(1),
p.161-176.
Fox RC, Scott CS & Bryant HN (2007), A new, unusual therian mammal from the Upper
Cretaceous of Saskatchewan, Canada, Cretaceous Research, 'Article in Press' edition,
p.1-9.
Gheerbrant E (webpage), Le Paléogène et la radiation des mammifères (In) Le
déroulement de l'évolution, sa chronologie et l'histoire des millieux, presently available
at:
http://www.cnrs.fr/cw/dossiers/dosevol/decouv/articles/chap2/gheerbrant.html.
Gordon CL & Cifelli RL (2003), Estimating body size in Late Cretaceous therian
mammals of North America, p.56-148 (In) Functional Morphology and Diet of Late Cretaceous
Mammals of North America, Ph.D. Dissertation, University of Oklahoma, p.i-xiv and 1-177.
Hunter JP & Archibald JD (2002), Mammals from the end of the age of the
dinosaurs in North Dakota and southeastern Montana, with a reapprAsial of geographic
differentiation among Lancian mammals, in Hartman JH, Johnson KR & Nichols DJ
(eds.), The Hell Creek Formation and the Cretaceous Tertiary boundary in the northern
Great Plains: An integrated continental record at the end of the Cretaceous, Boulder,
Colorado, Geological Society of America Special Paper 361, p.191-216.
Lofgren DL (1995), The Bug Creek Problem and the Cretaceous-Tertiary Transition at
McGuire Creek, Montana, University of California Publications Geological Sciences, vol.
140, 185pp.
Luo Z-X (2000), In search of the whales' sister. Nature 404, p.235-239.
McKenna MC & Bell SK (1997), Classification of Mammals Above the Species Level.
Columbia University Press.
Muizon de C & Cifelli RL (2000), The "condylarths" (archaic Ungulata,
Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of
the South American ungulates. Geodiversitas 22(1), p.47-150.
pdf-file available at:
http://www.mnhn.fr/publication/geodiv/g00n1a4.pdf
Prasad GVR, Verma O, Sahni A, Parmar V & Khosla A (2007), A Cretaceous hoofed
mammal from India, Science, 318, p.937.
Simpson GG (1980), Splendid Isolation, The Curious History of South American Mammals,
Yale University Press, pp266.
Tabuce R, Vianey-Liaud M & Garcia G (2004), A eutherian mammal in the latest
Cretaceous of Vitrolles, southern France, Acta Palaeontologica Polonica, 49(3), p.347-356.
Weil A (1999), Multituberculate phylogeny and mammalian biogeography in the Late
Cretaceous and earliest Paleocene Western Interior of North America, Ph.D. Dissertation,
University of California, Berkeley, p.1-243.
Wible JR, Novacek MJ & Rougier GW (2004), New data on the skull and dentition
in the Mongolian Late Cretaceous eutherian mammal Zalambdalestes, Bulletin of the
American Museum of Natural History, 281, p.1-144.
Wible JR, Rougier GW, Novacek MJ & Asher RJ (2007), Cretaceous eutherians and
Laurasian origin for placental mammals near the K/T boundary, Nature, 447,
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