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.
Looking for books?
You could visit the
Book Centre and look around.
This directory is centred on peradectids;
basal marsupials within
Alphadelphia. The scheme I'm presently following is based upon Case, Goin &
Woodburne, 2004. These authors (but others may disagree) divide
Marsupialia into three cohorts and an order of uncertain affinities. The
alphadelphians make up the first cohort. The other two, (
Ameridelphia and Australidelphia), can ultimately
be blamed on this group of opossum-like critters. Peradectidae includes two subfamilies;
Alphadontinae and Peradectinae.
Another view, (Cifelli, 2004), would be to extend Ameridelphia to include alphadelphians
and stem-taxa such as Kokopellia. However,
largely for convenience, I've decided to utilize this
paraphyletic cohort.
The first version of this webpage treated peradectids as Mesozoic members of Didelphidae
Gray, 1821 and their somewhat more distant relatives in Didelphimorphia Gill, 1872. That
isn't in accordance with recent research. Proper possums are didelphids. |
A. Alphadelphians? B. Alphadontinae
C. Peradectinae
| Taxon: none.
I'm not certain quite how these genera fit in with the concept of Alphadelphia, let alone
with Peradectidae.
Genera: Alphadon (partly = Turgidodon and
Varalphodon), Anchistodelphys (partly = Varalphadon),
Bistius, Delphodon (partly = Turgidodon),
Protalphadon (partly = Varalphodon), Turgidodon,
Varalphadon, other reports
Time-Line:
Upper Cretaceous: Bistius, Turgidodon, Varalphadon
Lower Cretaceous: trackways (other reports) |
| Genus:
Bistius Clemens WA & Lillegraven JA, 1986 |
| Species: | Bistius bondi Clemens WA & Lillegraven JA, 1986 |
| Place: | San Juan Basin, New Mexico |
| Country: | USA |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: |
Also may have a second species, (Alroy). A close relationship with Turgidodon? |
| Reference: | Clemens & Lillegraven (1986), New Late Cretaceous, North
American advanced therian mammals that fit neither the marsupial nor eutherian molds.
University of Wyoming Contributions in Geology Special Paper 3, p.55-85. |
| Link:
The Bisti Wilderness, Land of Hoodoos
The Bisti Wilderness
A short introduction to New Mexico’s Cretaceous Park. Here we learn that Bisti is an
English attempt of the Navajo name, Bis ta hi. It apparently means badlands. |
Genus:
Turgidodon Cifelli RL, 1990
Aka: Alphadon (partly); Delphodon (partly) |
| Species: | Turgidodon lillegraveni Cifelli RL, 1990 |
| Place: | Kaiparowits Formation, Utah
& Aguja Formation, Texas |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | The holotype, a jaw fragment, is at Oklahoma.
This species was relatively large, (Sankey JT 1998, p.136).
Unclear to me
I had assumed, hopefully correctly, that this species was based upon material previously
known as Alphadon lillegraveni, although I can't recall seeing confirmation of that.
A publication in 2009 leads me to suspect, but not know, this entry has just been
invalidated. Eaton reassigned two species, previously described as members of
Alphadon, to the newly established genus of
Eoalphadon, and one of them thus became E.
lillegraveni. At present, all I've seen is the relevant abstract. |
| Reference: | Cifelli (1990), Cretaceous mammals of southern Utah. I.
Marsupials from the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3),
p.295-319. |
| Species: | Turgidodon madseni Cifelli RL, 1990 |
| Place: | Kaiparowits Formation, Utah |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: |
A couple of jaw fragments are also in the Oklahoma collection,
including the type specimen. A fat mouse-weight of around 30g
(Alroy). |
| Reference: | Cifelli (1990), Cretaceous mammals of southern Utah. I.
Marsupials from the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3), p.295-319. |
| Species: | Turgiodon parapraesagus (Rigby JK & Wolberg DL,
1987) Cifelli RL, 1990 |
| Aka: | Alphadon parapraesagus Rigby JK & Wolberg DL, 1987 |
| Place: | San Juan, New Mexico |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: |
This specimen should be somewhere in the New Mexico Museum of
Natural History and Science collection, though it seems to have hidden from view. Its
known as NMMNH P-27705 and is part of a lower jaw with two teeth, (m3-m4, Morgan &
Lucas 1999, p.257). Its original catalogue number was UNM B-5338. |
| References: | Rigby & Wolberg (1987), The therian mammalian fauna
(Campanian) of Quarry 1, Fossil Forest study area, San Juan Basin, New Mexico. Geolog.
Soc. of America. Special Paper 209, p.51-80. |
| Cifelli (1990), Cretaceous mammals of southern Utah. 1. Marsupials
from the Kaiparowits Formation (Judithian), Journal of Vertebrate Paleontology 10,
p.215-319. |
| Species: | Turgidodon praesagus (Russell, 1952) Cifelli RL,
1990 |
| Aka: | Alphadon praesagus (Russell, 1952) Sahni, 1972;
Delphodon? praesagus Russell L, 1952 |
| Place: | Oldman Formation, Alberta & Judith River Formation,
Montana |
| Country: | Canada & USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | The following is
based upon my reading of Sahni, 1972. The author transferred the species to the
genus of Alphadon, and that's naturally the word he uses. Later, parts of
that genus were hived off into their present abode of Turgidodon.
Sorting out your alphadontids
Sahni concluded this species is much like Alphadon marshi
other than for being a bit larger (p.378). As it's now in a separate genus, subsequent
researchers presumably noted a greater degree of contrast. Be that as it may, as is
traditional for metatherians, there were four
molars per jaw half. The upper molars are heavily
involved in distinguishing between these critters, and the habits of a thing called
the stylar shelf matter in this regard. As the second half of the name indicates,
this can be thought of as a kind of shelf, and it extends out from the
buccal side of the main crown. And, much as books,
isolated bits of jigsaw puzzles, scraps of paper and half-eaten sandwiches are known
to grow by entirely mysterious means on book shelves, so these stylar shelves also
hold objects, with the stylar cusps being prime amongst them. And, as the details of
these differed between the various genera and species, they provide diagnostically
informative clues. For this reason, descriptions can be very keen on them.
A brief introduction
This is a relatively common species from the Campanian of North America. It has a
wide stylar shelf on the M3 molar, and a stylar cusp that's strongly developed for
the time of Earth. A short valley isolates this from stylar cusp B, which is the
largest of these things, has a ridge connecting it with the protocone, and another
behind running to stylar cusp C. That's a long cusp but smaller, and its direction
and position can vary in line with the molar position of the series. A still smaller
stylar cusp D comes behind, and a high ridge joins to a thing termed the metastyle
and the metacone of the trigon. Of the trigon cusps (these are found to the front
of the main crown, should the term be unfamiliar, and this means we've now wandered
off the stylar shelf), the metacone is the same height as, or a bit taller than the
paracone, and the protocone is lowly.
Upper molars
Each of the four positions have been kindly provided by the Judith River Formation.
Detailed descriptions are available in the paper.
M1 is the narrowest one (p.379). Stylar cusp A is the smallest stylar cusp and the
other comparative sizes (B-D) are as listed above. Stylar cusp C is located at the
centre of the stylar shelf, which is 'incipiently bilobate'. That refers to the
effects of a bay on the buccal shore line known as
the ectoflexus. When large enough, such a feature
causes the shelf to divide into two lobes. For this molar it's weak. The elongate
stylar cusp C is orientated diagonally.
M2 is proportionately middling in comparison to both its neighbours, and the stylar
shelf is divided unequal lobes. Put crudely, the constellation of the stylar cusps is
broadly similar to the one mentioned, but there are significant differences of detail.
As these are too detailed for my purposes and I've no wish to misexpress them. Besides,
anybody looking for technical information like that should certainly be looking in
the appropriate literature. (Mind you, that'd mean missing out on the architecture
of Bournemouth.) Turning to the trigon, the paracone and metacone are of
similar heights and, despite unfortunate damage to the specimen under interrogation,
it seems to have had a small lingual
cingulum to the front.
A helpful bit of maxilla came supplied with both the
other molars in the series. M3 is the larger of them but, as its stylar shelf
happened to be heavily worn, the details are obscured. Its A cusp is much smaller
than the B. A cingulum for this position is distinct but short, and travels from
the paraconule onto the front of the tooth.
M4s can be difficult to refer with safety as not many have been found in association.
It's smaller than M3 and the labial side of the
staylar shelf is expanded at the front. Its cingulum is much as with the previous
tooth.
Going downstairs to name that corpse
A fossil described by Russell in not 1952 was assigned to Delphodon? praesagus.
Subsequently, the m3 it contained pointed in the direction of Alphadon.
However, as alphadontids happened to be defined in terms of upper molars, and that
bit of lower jaw was unsurprisingly bereft of such things, certainty was lacking.
Isolated teeth and two jaw fragments from the Judith River Formation indicated the
conclusion was justified. The most common metatherian lower molars belong to the
same taxon as the most common uppers; Turgidodon
(Alphadon) praesagus. This material also reveals a tendency for the lowers to
be somewhat longer teeth (p.380).
Lower premolars
The basal number of premolars for metatherians is
three. Those available which probably belonged to this species are identified as
p3s but, as p2 is rather similar in size and shape, the bag could contain a mix.
The presence of particular cingula on the labial and lingual sides of the specimen
described, point to it being a p3 with a length of 2.4mm. This is consistent with
the molar size differentials of this species and A. marshi.
There's a large main cusp with a short lingual cingulum to the front. A valley
separates that cusp from a considerably smaller one behind. The rear
labial corner of the tooth has a further cingulum,
and the premolar is double-rooted.
Additionally, a deciduous premolar was also
identified.
Lower molars
Two possible m1s are more or less smaller versions of m2s, so we may as well skip
along the line.
The paraconid is the smallest of the
trigonid cusps of m2, and it's directed aggressively
forwards. Each of the three trigonid cusps is a cone with a broad base. A
cingulum runs to the front from the paraconid. At
the rear of the crown, the talonid exceeds the width
of the trigonid by a bit, and two of the talonid cusps -the hypoconulid and the
entoconid- are twinned in the typical Cretaceous
metatherian manner. (This wasn't the case for basal
members, so they must be considered atypical.) In other words, those cusps are
cuddled together. This cuspal friendliness is found on all lower molars of
typical Cret metas. Molar lengths are available: m1 (2 specimens) 2.5 - 2.6mm; m2s
(6 specimens) 2.8 - 3.3mm.
An isolated m3 has a trigonid that's "anteroposteriorly compressed". It looks as if
it's been squashed to make it shorter. The tallest cusp is the
paraconid, set a bit in advance of the metaconid
(p.381). A weak cingulum fringes the front of the tooth. This time, the trigonid
manages to beat the talonid for width: 2.0mm against 1.8
That width competition between the two contestants indicates a further isolated tooth
is an m4. The protoconid is again the highest cusp, with the other two being near
equal. Again, there's a cingulum adorning the front of the crown.
Holotype
NMC 114 is a lower right jaw held hostage at the National Museum of Canada. It was
kidnapped from southeast of Steveville, Alberta.
Additional notes
Gordon, 2003a (p.46) offers a bodyweight range of 200-210g (m1 only). |
| References: | Russell (1952), Cretaceous mammals of Alberta,
Bulletin of the National Museum of Canada, 126, 110-119. |
| Sahni (1972), The vertebrate fauna of the Judith River
Formation, Montana, Bulletin of the American Museum of Natural History, 147(6),
p.321-412. |
| Cifelli (1990), Cretaceous mammals of southern Utah. I.
Marsupials from the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3),
p.295-319. |
Extracting the teeth from
Judith
The following is based upon my reading of Sahni, 1972, a study which covers the
vertebrate fauna of the Judith River Formation as a whole. My interest centres on
the mammals. Lovers of dinosaurs, amphibians and etc should be able to find a link
to the paper below. The width of the subject matter is of epic proportions for a
single author.
Where Judith hangs out
The Judith River Formation is in northern Montana, and similar sediments also occur
over the border in Canada (although with different names). Remarkably or otherwise,
the Formation is name after the Judith River (p.325). This rock was laid down in the
Campanian part of the Upper Cretaceous, with its age being constrained by marine
fossils found in strata both below and above; the Claggett and Bearpaw shales
respectively. As these largely terrestrial Judithian deposits form the meat (or soya
substitute or cheese) in the sandwich, they were added chronologically between both
slices. Vertebrate fossils are concentrated
in the upper fifty foot (about 16 metres).
The collection of remains Sahni had available came from sandstone with a bias against
large animals. That may sound odd to some, but natural sorting of debris by the
thoroughly stupid librarians of rivers and streams can produce such results. Water
courses are frequently lazy, and reluctant to carry big, heavy material. They're keener
when it comes to small fry. As a result, similar sized stuff can often end up
concentrated together. Fifty foot of rock can be stingy with big dinosaurs but
generous when it comes to scraps of mammals (overwhelmingly isolated teeth), lizards
and other littlings. The paleoecology reflects the somewhat more recent Lance Formation
from the end of the Cretaceous, although the cast list contains somewhat different
actors for broadly parallel roles. It included at least five genera of
multituberculate mammals, three
metatherians and a single
eutherian. You, dear reader, are most probably a
eutherian yourself. As a third of a century has since elapsed, it wouldn't be wise
to assume that headcount has remained the same. Some subsequent Judith River localities
were deposited in different conditions; eg. the hadrosaurid nesting colony at Egg
Mountain.
Pioneers
The earliest reports on rocks in the area resulted from exploratory endeavours by Lewis
and Clark in 1804, as they were surveying territory for the government (p.328). (The
President was keen to learn what he presided over.) Fossils were first collected from
the Eagle Sandstone later during the 1850s. After two further decades, the area
near the mouth of the Judith River attracted the interest of Leidy, Cope, Marsh and
others. However, it didn't really hold it. This region was on the far side of the
back of beyond in terms of logistics, and the local residents weren't always
hospitable to strangers. Who can blame them, seeing as the strangers weren't always
exactly respectful? General Custer led an expedition n Montana in 1876, and that
resulted in the extinction of the 7th Cavalry. (As it happens, pioneer paleontologists
didn't encounter that sort of reception. They conducted themselves more
politely.)
However, it wasn't merely a matter of remoteness or logistical problems that dampened
the enthusiasm. The fact is that the pickings were richer elsewhere, and especially
in the Jurassic Morrison Formation of Wyoming. Judith River fossils were neither as
well preserved or as sexy, so researchers were aroused to sate their passions in beds
other than Judith's. Most of a century drifted quietly along her river.
The 60's generation
Research resumed with three campaigns from 1963 to 1965 in the counties of Chouteau
and Blaine (p.327). These undertakings involved more thorough methods than simply
scratching around the surface, and resulted in the recovery of numerous
microvertebrate remains. (A couple of millimetres of tooth hidden in sediment is
easy to overlook.) The most productive mammal locality was Clambank Hollow. Some
fossils were found on the surface, but most turned up by means of methodically
processing lots of sediment. Generally, half-a-dozen a ton is a pretty good rate for
mammal teeth. These efforts, though, brought more like eighty. There were also lots
of bits of reptiles, amphibians and fish.
Stratigraphy
The Montana Group is composed of various stratigraphic units which reflect conditions
when they were deposited. At is base is the Eagle Sandstone (p.333), and this starts
with a fossil poor rock laid down largely in the sea. The upper reaches are richer
in remains but, as they're also marine in origin, it's hardly surprising sampling
failed to uncover landlubbing vertebrates. It was reported a century ago that a
dinosaurs, Ornithomimus grandis, had come
from this sandstone, but that seems unlikely.
The next layer in the cake is the Claggett Shale. This is a collection of mainly
marine shales. It contains a fauna of molluscs, some of which are informative as to
the age. Then comes the Judith River Formation (p.335). The ocean had ebbed when
these layers built up in most freshwater conditions. Vertebrate fossils occur at
all levels, but the mammal sites are concentrated towards the top. This Formation
is overlain by a return to marine rock; the sea closing the Campanian with the
Bearpaw Shale. It's not dissimilar to the Claggett below, but it's thicker, richer
and more diverse with fossils, and has evidence of some brackish conditions.
Over the border
Time nor tide awaits for no mammal, and this intermittent sea didn't give a damn about
future international borders (p.336). Its waves rippled merrily into Canada and, in
its most exuberant moods, as far north as it damned well pleased. Similar geological
conditions occur in Alberta and Saskatchewan, although the Formations have different
names. The rock was termed the Belly River Group. A section which Sahni then termed
the Oldman Formation is similar to the Judith River Formation of Montana, and contains
many of the same taxa (p.337). Conveniently, some radiometric dating had been
conducted in the overlying Bearpaw Shale, and that indicates the Oldman Formation
predates 72 million years ago (p.338).
Let's go on a clambank
Two localities back south in Montana yielded fossils, with easily the most generous
being Clambank Hollow on the ranch of the Halley family (p.339). This was probably
either a point where a river meandered or an oxbow lake, which would explain the
richness (p.342). A second locality was a quarry on Clayball Hill. This provided
less than 1% of the mammals, but this may partly reflect the difficulties posed there
for processing matrix. Its position happens to be inconvenient. Nine tons of
material were extracted from the first, more accessible, location.
Inconsiderate ants
Bizarre as it may sound seem, some ants are active participants in paleontology. A
red ant, Pogonomyrmex, can be a veritable enthusiast when it comes to collecting
microfossils. They drag them home and establish museums in their nests. However,
no such lucky breaks were encountered in this case. (It has to be said, that the
actions of primate paleontologists cause more breaks than luck for their insect
colleagues. Checking anthills for a fossil content is a slightly intrusive
line of enquiry, should a diplomat be explaining things. Take a spade and...
'Thoroughly destructive' is another way of expressing the result.
Mammals
Three grand groups of mammals lived in the area. Of these,
multituberculate teeth occur in much
greater numbers then those of metatherians (2nd
place) or the few eutherians (p.364). The mammals
have broad similarities with the later Lancian contingent, and some are at least
plausible ancestral forms.
Further information should be added to this entry (8.12.2006).
Further Mesozoic site summaries can be found at Localities.
|
| Species: | Turgidodon rhaister (Clemens, 1966) Cifelli RL,
1990 |
| Aka: | Alphadon rhaister Clemens, 1966; A. rhiaster |
| Place: | Lance Formation,Wyoming & Hell Creek Formation, Montana
& Alberta |
| Country: | USA & Canada |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: | Lofgren, 1995 includes information on speciemens
then referred to A. rhaister. These were collected from
Cretaceous-Paleocene,
McGuire Creek localities in Montana (p.107). Some were collected from Paleocene sites,
but they seem to have been reworked from Cretaceous strata by river action. They were
then referred to A. rhaister.
A difference between this species and similarly sized
Pediomys ones, as constituted in 1995, lies in the insection of a crest, the
cristid obliqua, with the trigonid on lower molars. For
T. rhaister this occurs below a notch between the
protoconid and metaconid. Six lowers came from
McGuire Creek localitis (p.108). Three were m1s while the others couldn't be assigned to
particular positions.
Length range
m1 (3 specimens) 3.14-3.29mm.
Holotype
UCMP 50292 is a partial upper jaw at the University of California, Berkely. It was obtained
from the Lance Formation.
As seen by Sahni
Sahni, 1972 referred some remains from the
Judith River Formation, Montana to A. cf. rhaister, a label which had already
been used for fossils from the Lancian Formation of Wyoming. While this isn't the
same as placing them in this species, it serves to give some information of
relevance.
The teeth indicate a large species for the genus, close in size to Boreodon,
a stagodont taxon of dubious worth which I presently
treat as a synonym of Eodelphis cutleri
(p.381). Regardless of its merits, the size doesn't alter. The Judith River fossils
are reported as perhaps representing one or more additional taxa, and the possibility
is cited that A. cf. rhaister could be synonymous with E. browni
(p.384).
Additional notes
Gordon, 2003a (p.46) offers 356-400g (M1 only). That equates to a
smallish
brown rat. Kemp 2005 (p.197) reveals upper jaw and teeth are known. |
| References: | Clemens (1966), Univ of Calif. Publications in
Geological Sci, 62. |
| Cifelli (1990), Cretaceous mammals of southern Utah. I. Marsupials from
the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3), p.295-319. |
| Species: | Turgidodon russelli (Fox RC, 1979) Cifelli RL,
1990 |
| Aka: | Alphadon russelli Fox RC, 1979a |
| Place: | Alberta & Judith River Formation, Montana,
Kaiparowits Formation, Utah & Wyoming |
| Country: | Canada & USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | Hunter, Heinrich & Weishampel reported on the
species also being recovered from the St Mary River Formation of Montana in 2010.
Holotype
This type fossil studies at the University of Alberta. Weighed
about two mice, 50g (Alroy). Or perhaps more like 121-156g (Gordon
2003a, p.45). |
| Reference: | Cifelli (1990), Cretaceous mammals of southern Utah. I.
Marsupials from the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3), p.295-319. |
| Species: | Turgidodon petiminis Storer JE, 1991 |
| Place: | Frenchman Formation, Saskatchewan |
| Country: | Canada |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: |
The suggested weight is a healthy 150g
(Alroy). Gordon & Cifelli, 2003 offer a more ambitious 245-314g, (p.96). |
| Reference: | Storer JE (1991), The mammals of the Gryde local fauna, Frenchman Formation (Maastrichtian: Lancian), Saskatchewan. J of Vert Paleont 11, p.350-369. |
Genus:
Varalphadon Johanson Z, 1996
Eaton (2005) reports the presence of this genus in the Santonian Straight Cliffs
Formation of Utah. A link to the abstract is included in the generic entry for
Alphadon.
Aka: Alphadon (partly); Anchistodelphys (partly); Protalphadon
(partly) |
| Species: | Varalphadon creber (Fox, 1971) Johanson Z, 1996b |
| Aka: | Alphadon creber Fox RC, 1971; Protalphadon creber (Fox, 1971) Cifelli RL, 1990 |
| Place: | Upper Milk River Formation, Alberta |
| Country: | Canada |
| Age: | Coniacian, Upper Cretaceous |
| Remarks: | |
| References: | Fox (1971), Zool. J. Linnean Soc 50, Supplement 1. |
| | Cifelli (1990), Cretaceous mammals of southern Utah. I. Marsupials from the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3), p.295-319. |
| Species: | Varalphadon crebreforme (Cifelli, 1990) Johanson Z, 1996b |
| Aka: | Protalphadon crebreforme Cifelli RL, 1990 |
| Place: | Wahweap Formation, Utah |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | A further species is possible. |
| Reference: | Cifelli (1990), Cretaceous mammals of southern Utah. II. Marsupials and marsupial-like mammals from the Wahweap Formation (Early Campanian). J. Vert. Paleo. 10(3), p.320-331. |
| Species: | Varalphadon wahweapensis (Cifelli, 1990), Johanson
Z, 1996 |
| Aka: | Alphadon wahweapensis; (Partly) Anchistodelphys
archibaldi Cifelli RL, 1990b; Protalphadon wahweapensis Cifelli RL, 1990a |
| Place: | Wahweap Formation, Utah |
| Country: | USA |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | Weighed about half a mouse, (
12g). Other Anchi archi material is still seen as a valid taxon. P. wahweap
can be admired in the Oklahoma Museum of Natural History. Specimens include a fragment of
dentary. |
| References: | Cifelli (1990a), Cretaceous mammals of southern Utah. I.
Marsupials from the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3), p.295-319. |
| Cifelli (1990b), Cretaceous mammals of southern Utah. II. Marsupials
and marsupial-like mammals from the Wahweap Formation (Early Campanian). Journal of
Vertebrate Paleontology, 10(3), p.320-331. |
| Johanson (1996), Revision of the Late Cretaceous North American
marsupial genus Alphadon. Palaeontographica Abt. A, 242, p.127-184. |
| Other reports:
Trackways, North America
Some footprints in British Columbia have been given the name, Duquetteichnus kooli. Reportedly, William Sarjeant calls these, "...the oldest marsupial tracks found anywhere in the world". These are about Aptian in age and there's a picture below. (With thanks to Ray Stanford).
I'm further informed that, in a separate article, (I don't know which), Sarjeant stated
that D. k. was "probably a creature much like the surviving Australian
brush-tail possum, a tree-climbing, leaf- and fruit-eating creature with a long, thick tail,
much like a cat-sized squirrel." This interpretation isn't universally accepted.
Sadly, William Sarjeant died of cancer during 2002.
Reference: W.A.S. Sarjeant and R.A. Thulborn, 1986. Probable marsupial footprints from the
Cretaceous sediments of British Columbia. Canadian Journal of Earth Sciences, vol. 23, no.
8, p.1223-1227, figs. 1-3.
Very recently, (May 2002), prints have been found at a location in the USA, which seem to
be similar to opossum tracks. Whether these can be clearly referred to any particular
group, or even to Mammalia, remains to be seen. These ichnofossils look something like
this left rear foot: |
A. Alphadelphians? B. Alphadontinae
C. Peradectinae
Note: At least, that's how it was
described. As the state of preservation isn't good, Lockley & Foster, 2003 are
uncertain it's mammalian, (p.273).
| Taxon: Alphadontinae Marshall, Case & Woodburne, 1990
A family has also been proposed; Alphadontidae Eaton, 1993. Case et al, 2004 have it as a
subfamily within Peradectidae.
Genera: Albertatherium,
Alphadon, Eoalphadon,
Protalphadon,
other reports
Time-Line:
Paleocene: ?Alphadon
Upper Cretaceous: Albertatherium, Alphadon, Eoalphadon,
Protalphadon |
| Genus:
Albertatherium Fox RC, 1971
'Alberta beast' |
| Species: | Albertatherium primus Fox RC, 1971 |
| Place: | Upper Milk River Formation, Alberta |
| Country: | Canada |
| Age: | Santonian, Upper Cretaceous |
| Remarks: | Alberta University holotype. |
| Reference: | Fox (1971), Zool Jour Linn Society 50, Supplement 1. |
| Species: | Albertatherium secundus Johanson Z, 1995 |
| Place: | |
| Country: | |
| Age: | |
| Remarks: | Further information welcome. |
| Reference: | |
| Genus:
Alphadon Simpson GG, 1927
'first tooth'
Remarks: There are a great many species names, and different authors assign some of them
to differing genera. A species has been reported from the Santonian Straight Cliffs
Formation of Utah. The abstract of Eaton, 2005 is linked below.
Lofgren, 1995 includes information on some fossils which were then referred to the genus.
He was aware that much needed revisions were in progress by other authors, but wasn't able
to take them into account. In part, they concerned the status of A. wilsoni.
Lofgren thought that species was probably synonymous with A. marshi (p.106), and
this turned out to be vindicated. In the paper he refers to it consistently as "A.
wilsoni", with the inverted commars being significant. His intentions didn't include
duplicating work already being undertaken by others.
| Reassigned species: A. austinum Sigé, 1971 see
Peradectes austinum; A. clemensi see Eoalphadon
clemensi; A. creber Fox, 1971 see
Varalphadon creber; A. lillegraveni see
Eoalphadon lilligraveni; A. lulli Clemens, 1966 see
Protalphadon lulli; A. marshi (partly) see
Nortedelphys magnus;
A. parapraesagus Rigby & Wolberg, 1987 see
Turgidodon parapraesagus; A. praesagus
(Russell, 1952) see Turgidodon praesagus; A. rhaister
Clemens, 1966 see Turgidodon rhaister,
Ectocentrocristus foxi and
Hatcheritherium alpha; A. russelli
Fox, 1979 see Turgidodon russelli; A. sahnii
Lillegraven & McKenna, 1986 ?see A. halleyi; A. wahweapensis
see Varalphadon waheapensis; A. wilsoni
Lillegraven, 1969 see A. marshi | |
| Species: | Alphadon marshi Simpson GG, 1927 |
| Aka: | Alphadon wilsoni Lillegraven JA, 1969 |
| Place: | Wyoming, Montana, New Mexico, North Dakota,
Utah, Wyoming & Alberta, Saskatchewan |
| Country: | USA & Canada |
| Age: | Campanian - Maastrichtian, Upper Cretaceous - ?Puercan |
| Remarks: | Lofgren, 1995 contains some information on
specimens obtained from Cretaceous-Paleocene,
McGuire Creek localities in Montana. He referred to them as "A. wilsoni" as
that species hadn't then been formally synonymized with A. marshi (p.106). Some of
these fossils came from sites that actually date from the Paleocene, but they'd probably
been reworked due to river action. If so, then the owners dropped dead during the
Cretaceous.
Four upper and six lower molars were interpreted as belonging
to "A. wilsoni". The uppers had large stylar cusps in the C position, and these
were well separated from the B cusps. That's part of the distinction from
Protalphadon lulli. Lofgren anticipated that these
specimens would require transferral to other species.
Distinctions between individual Alphadon species had often been based upon size
and proportions. However, as larger collections of samples built up, the once apparently
clear distinctions started to melt in some cases. Specimens turned up which could
logically be fitted into more than one supposedly distinct species, and that suggested
the logic involved couldn't have been in good health.
Sizes
The relevant specimens corresponded to others already assigned to "A. wilson" in terms
of size and proportions, and could be distinguished from A. marshi as then defined.
The significance of those distinctions was being undermined by increasing sample sizes.
Reported lengths were as follows:
Uppers: M1 (3 specimens) 1.96-2.06mm; M2 (1 sp.) 2.49mm.
Further McGuire Creek fossils were referred directly to A. marshi. While welcomed
with open arms, they added little detail to the already established picture. At least one
of these also came from a Paleocene locality (p.107), and was presumably also reworked.
It was a lower molar with a length of 2.38mm.
Holotypes
The holotype of A. marshi, YPM 13659, is a right upper molar from the Lance Formation of
Wyoming. It attends Yale University.
The type fossil of Alphadon wilsoni is a fragmentary upper jaw studying at the
University of Alberta. It enjoys being called UA 3681. The specimen was arrested for
loitering in the Scollard Formation in Alberta.
Additional notes
Weight estimates of around
30g (Alroy), or about 67-86g (Gordon & Cifelli 2003, p.94-95, M1 only).
The holotype, YPM 13659, came from Niobrara County, Wyoming and presently studies in the
Peabody Museum, Yale. Material has also been reported from South Dakota, (Hunter &
Archibald 2002, p.196). |
| Reference: | Simpson (1927), Mesozoic Mammalia. VIII. Genera of Lance
mammals other than multituberculates. American Journal of Science (5) 14, p.121-130. |
| Lillegraven (1969), Latest Cretaceous mammals of upper part of
Edmonton Formation of Alberta, Canada, and review of marsupial-placental dichotomy in
mammalian evolution. Paleontological Contributions, University of Kansa 50, p.1-122. |
| Species: | Alphadon halleyi Sahni, 1972 |
| Aka: | ?Alphadon sahnii Lillegraven & McKenna, 1986 |
| Place: | Utah, Montana, Texas, New
Mexico, Wyoming & Oldman Formation |
| Country: | USA& Canada |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | The following is based upon my reading of
Sahni, 1972, an extraordinarily wide ranging romp through all the vertebrates of the
Judith River Formation of Montana. While attempting to digest the description, one
detail struck me as somewhat odd, and that's the specific name. I think it's
incorrect and should be emended. I'll mention my reasoning below under the
'Holotype' subheading. However, unless a correction ever appears in an appropriate
journal, the name penned by Sahni will certainly remain valid, and shouldn't be
arbitrarily written otherwise.
Remains of A. halleyi were not exactly extensive; a lower and an upper
molar (p.381). That wasn't much to make a meal from,
but it was a start and some further servings have since been added from elsewhere.
It's a smaller species than Turgidodon (Alphadon)
praesagus but, had the owner lived some millions of years longer, then it
would've been large enough to have considered bullying A. lulli.
Lower molar
The most obvious distinction from T. (A.) praesagus is the length; 2.1mm is
well below the range for its fellow alphadontid. Some cusp characteristics are
given in the study, and the talonid heel is
characteristic for the genus. It qualifies by being deeply basined with a ridge
(the crista obliqua) directed in the appropriate fashion. The hypoconulid is further
from the entoconid than was generally the case for American marsups of the time. The
talonid and trigonid share the same width, 1.2mm.
Upper molar
A partial upper is the appropriate sort of size for this species, and presumably
belongs. Its width of 1.7mm is probably about the same size as the original length.
The metacone and paracone are as high as one another, with the protocone being low.
Remains of the stylar shelf show its D cusp was larger than C. Sahni accuses the
owner of being perhaps ancestral to A. lulli.
Holotype
The type fossil, AMNH 77367, is a lower molar held at the American Museum of Natural
History, New York. It's "named in honour of the Warren Halley family", and they
owned the ranch on which much of the prospecting work was conducted. They thoroughly
deserve a Cretaceous marsup pet.
The problem with the name is one of Latin grammar, which is enthusiastic about
genders. Should it have been named for Warren Halley then, as he's a single male
weirdly derived primate, halleyi would be fine. But it isn't. The
name's in honour of a family of weirdly derived primates which, given the usual
customs of Montana, contains members of at least two sexes. In such a case (and
I've sought the advice of somebody far better acquainted with Latin grammar than I
am), the final i ought to be replaced by orum. I'm not even going to
informally write the word as I think it should appear because, as stated above, the
name as written by the author is the valid one even if it's incorrect.
A further Cretaceous mammal from Montana scampered into a similar problem a few
years ago. Montanalestes keeblerorum
was inadvertently christened M. keebleri, despite the Keebler family not
consisting of a single male.
Additional notes
Several specimens, A. sahnii, are at Oklahoma Museum
NH. The Museum of the Rockies, Montana, lists a fossil as A. hallei, which I’m
assuming is a typo. This was a critter of around 20g (Alroy),
or even larger than that, 44-90g, (Gordon 2003a, p45).
Whilst on the subject of Montana: "Two relatively complete lower
jaws of Alphadon halleyi have previously been reported from Egg Mountain (Montellano,
1988)," (Montellano et al 2000, p.334). |
| Reference: | Sahni (1972), The vertebrate fauna of the Judith River
Formation, Montana, Bulletin of the American Museum of Natural History, 147(6),
p.321-412. |
| Species: | Alphadon attaragos Lillegraven JA & McKenna
MC, 1986 |
| Aka: | A. altaragos |
| Place: | Montana, ?Utah, Wyoming
& Alberta |
| Country: | USA & Canada |
| Age: | Campanian, Upper Cretaceous |
| Remarks: | Some specimens are in the Oklahoma collection. A
modest 10g. The Alberta material is mentioned in Foote et al, 1999. |
| Reference: | Lillegraven & McKenna (1986), Fossil mammals from the
"Mesaverde" Formation (Late Cretaceous, Judithian) of the Bighorn and Wind
River basins, Wyoming, with definitions of Late Cretaceous North American land-mammal
"ages". American Museum Novitates, 2840, p.1-68. |
| Species: | Alphadon jasoni Storer, 1991 |
| Aka: | A. jaysoni (in Foote et al, 1999 |
| Place: | Hell Creek, Montana, Wyoming & Alberta, Saskatchewan |
| Country: | USA & Canada |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: |
A macho 30g (Alroy) or 73-191g,
(Gordon & Cifelli 2003, p.94). |
| Reference: | |
| Species: | Alphadon perexiguus Cifelli RL, 1994 |
| Place: | Aguja Formation, Texas |
| Country: | USA |
| Age: | Maastrichtian, Upper Cretaceous - ?Puercan, Paleocene |
| Remarks: |
Specimens at Oklahoma include the holotype, a left molar.
Weighed perhaps around four paperclips, (8g according to Alroy),
Gordon 2003a, offers 25-32g, (p.45, m1 only). |
| Reference: | Cifelli (1994), Therian mammals of the Terlingua local fauna
(Judithian), Big Bend of the Rio Grande, Texas. Contributions to Geology, University of
Wyoming, 30, p.117-136. |
| An Upper Maastrichtian Location in
Saskatchewan, Canada (Upper Cretaceous)
The following is based upon my reading of Tokaryk & Bryant, 2004.
This paper concerns the last home of Scotty, (p.1). Given the familiar name, I suppose I'll
refer to a him. Scotty wasn't a mammal. He was a good natured Tyrannosaurus rex who
growled and tore chunks out of friends and neighbours sixty-five million years ago. Seeing
as a Tyrannosaurus was about 100 times larger than most of the contemporary mammals,
I doubt they had much to fear from him, so long as they kept out the way of his feet.
Scotty's known from a partial skeleton now housed in the collection of the Royal Saskatchewan
Museum. He was recovered from a quarry which is part of the Frenchman Formation. Bits of
him first turned up in 1991, (p.2), though excavations began in earnest in June 1994. At
the end of the following year, researchers thought they'd found all there was, but more
bones came to light later. Although focused on finding remains of a monster, prospectors
also kept their eyes open for smaller fossils. As studies are on-going, the fauna list in
the paper is provisional.
The neighbours
Impressions, (p.2-3), attest to the presence of a number of gastropods and bivalves, while
fragments represent indeterminate insects. Unsurprisingly, there were fish in them there
waters, and part of an amphibian jaw was also harvested. This is probably from
Opisthotriton, which is known from other Frenchman locations and is common in the
coeval Hell Creek Formation, (p.4).
Among the resident reptiles are several individual champosaurs and a small tooth shows the
presence of a crocodile, (which must've been attached to it at some point -p.5). Several
turtle families are represented. A tibia may be referable to
Basilemys. Although incomplete, this bone's over 8.5cm long. As upper Maastrichtian
North American turtles go, this was big, (p.6).
Scotty wasn't the only meateating dinosaur on the block, but he was excessively large. The
mammals might've been more concerned about the dromaeosaurids. If, as is likely, an isolated
tooth does represent Dromaeosaurus, this would be the first record of that genus from
this formation.
Scotty
On page seven come some remarks on that Tyrannosaurus. The skeleton's disarticulated
but the skull is nearly complete. Remains of the rest of the animal include much of the
vertebral column, parts of the shoulder and front legs, the pelvis and a rear leg. A
description of the specimen is in preparation.
Scotty had to have something to eat, so he would have been interested in the planteating
dinos. Most common are remains of ceratopsians such as Triceratops. Also present
are rarer fossils of hadrosaurs. This is the usual pattern for the Frenchman Formation, from
which only one hadrosaur, (or indeed large ornithischian), has been formally described to
date; Edmontosaurus saskatchewanensis. One tooth seems to indicate the presence of
the thick-headed Pachycephalosauridae in the community. If correct, this would be only the
second such instance in the formation fauna.
The dinosaur digest is completed by one or two bits of bird leg, (p.8). It probably won't
be possible to identify the affinities of those remains. One bird which is known from the
near-by Gryde fauna is Cimolopteryx, and various indeterminate fragments have been
found there too.
A partial right dentary has been referred to the
marsupial Alphadon, and it seems to be closest
to A. jasoni. This species is already known from both the Gryde and Wounded Knee
localities. There's a partial left dentary too. Eutherian
mammals were also around; Gypsonictops. This
is represented by a further lower jaw. Another mammalian specimen, (so far indeterminate),
is being studied by Fox RC.
Flora and climate
A wide variety of plant remains have also been identified; ferns, fruits, seeds, logs and
possible water lily roots among them, (p.9). Page ten contains some brief consideration on
living conditions at the time. It appears to have been an area mostly free of frost in the
winters but subject to seasonal rainfall. Summers were adorned with lush, mixed vegetation
of deciduous trees and conifers. And then things turned really inhospitable for Scotty and
Co.
Further Mesozoic site summaries can be found at Localities.
|
| Species: | Alphadon eatoni Cifelli RL & de
Muizon C, 1998 |
| Place: | North Horn Formation, Utah |
| Country: | USA |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: |
The following is based on my reading of Cifelli & de Muizon, 1998.
The specimen described is a lower left jaw. It includes an unusually complete row of teeth;
two incisors (there were at least three originally), a
canine, three premolars
(the third is a milk tooth), and one erupted and another unerupted
molar. Somewhat inconveniently, Cretaceous marsupials tend to be diagnosed on the
basis of the upper molar structure. Being a dentary, these
teeth aren't present. However, the authors are confident enough to establish a distinct
species.
As well as having a nice collection of in situ teeth, A. eatoni is also a
rarity because of the biological age of the individual. They estimate it to have been
only about nine or ten weeks old, based on comparisons with patterns of tooth eruption and
replacement in a couple of existing marsupials. Other than for one piece of upper jaw,
(Pediomys hatcheri, such young animals from North America are only known from
isolated teeth, (p.533).
Other fossils found in this fauna include a rare occurrence of a North American, Maastrichtian
sauropod dinosaur, Alamosaurus. The locality seems to have had a semi-arid climate
at the time, (p.532), and about 40 vertebrate
taxa have so far been identified, (p.535). Amongst them are
eight mammals, although only Pediomys hatcheri is also known from a reasonably
complete jaw specimen.
The type fossil is named OMNH 27380, and it's an inmate of the Oklahoma Museum of Natural
History collection. It's approximately 1.6cm in length. (John Alroy offers a bodyweight
estimate of 10g.) Other fragmentary specimens may also represent this species, but they
haven't been formally referred, (p.535). The specific name honours Jeffrey G Eaton in
recognition of his work on the Cretaceous mammals of Utah. |
| Reference: | Cifelli & de Muizon (1998), Marsupial mammal from the
Upper Cretaceous North Horn Formation, Central Utah. Journal of Paleontology, vol 72 (3),
p.532-537. |
| Genus:Eoalphadon
Eaton JG, 2009
'Dawn Alphadon'
Aka: Alphadon (in part); Turgidodon (perhaps?)
Remarks: Eaton established this genus for a new species from Cedar Canyon, Utah, and
two species previously assigned to Alphadon. However,
these speices appear to be too basal for inclusion there,
and a new genus was required.
This leaves me unclear about the significance, if any, of a taxon called
Turgidodon lillegraveni, as that's also the name of one of the species
transferred here in 2009. I'm also uncertain as to which the type species of this new
genus is. |
| Species: | Eoalphadon woodburnei Eaton JG, 2009 |
| Place: | Cedar Canyon, Utah |
| Country: | USA |
| Age: | Cenomanian, Upper Cretaceous |
| Remarks: | This species is based upon fossils from a pair
of newly worked localities. Of the three members of this genus, E. woodburnei rates
as the most primitive, and that could indicate it lived at a slightly earlier time.
According to the abstract, which is all I've presently seen, the newly available fossils
came from "a relatively small amonunt of matrix (~1,000 kg)" that's so far been processed.
If you'd like to know how relatively small 'relatively small' may be, then a
European supermarket could be a good place to enquire. Politely ask them to set up a
thousand standard bags of sugar for your inspection. That's the sort of amount. Of
course, should they then be agreeable to opening the bags and pouring the whole lot
out onto the floor, turning the heating system up as far as it'll go, and sprinkling a
few corns of black pepper somewhere or other into the sugar, you could then simulate
fossil hunting for mammals in Utah. Although black pepper corns are relatively large...
Wild guesses
If I had to bet on which the type species of the genus is, then I'd back this one. I'll
also risk guessing that the specific name must be in honour of Michael O Woodburne. |
| Reference: | Eaton JG (2009), Cenomanian (Late Cretaceous) mammals from
Cedar Canyon, southwestern Utah, and a revision of Cenomanian Alphadon-like
marsupials, pp. 97-110 In Albright LBI (Ed.), Papers on Geology, Vertebrate Paleontology,
and Biostratigraphy in Honour of Michael O Woodburne, Museum of Northern Arizona
Bulletin 65. |
| Species: | Eoalphadon clemensi (Eaton JG, 1993) Eaton JG,
2009 |
| Aka: | Alphadon clemensi Eaton JG, 1993 |
| Place: | Colorado Plateau |
| Country: | USA |
| Age: | Cenomanian, Upper Cretaceous |
| Remarks: | A weight estimate suggests around 10g. |
| Reference: | Eaton JG (2009), Cenomanian (Late Cretaceous) mammals from
Cedar Canyon, southwestern Utah, and a revision of Cenomanian Alphadon-like
marsupials, pp. 97-110 In Albright LBI (Ed.), Papers on Geology, Vertebrate Paleontology,
and Biostratigraphy in Honour of Michael O Woodburne, Museum of Northern Arizona
Bulletin 65. |
| Species: | Eoalphadon lillegraveni (Eaton JG, 1993) Eaton JG, 2009 |
| Aka: | Alphadon lillegraveni Eaton JG, 1993 |
| Place: | Colorado Plateau |
| Country: | USA |
| Age: | Cenomanian, Upper Cretaceous |
| Remarks: |
45g (Alroy). This is presumably the same material as
Turgidodon lillegraveni, which is known from the Campanian of Utah. |
| Reference: | Eaton JG (2009), Cenomanian (Late Cretaceous) mammals from
Cedar Canyon, southwestern Utah, and a revision of Cenomanian Alphadon-like
marsupials, pp. 97-110 In Albright LBI (Ed.), Papers on Geology, Vertebrate Paleontology,
and Biostratigraphy in Honour of Michael O Woodburne, Museum of Northern Arizona
Bulletin 65. |
| Genus: Protalphadon
Cifelli RL, 1990
'first Alphadon'
Aka: Alphadon (partly)
Remarks: McKenna & Bell, (1997), treats this genus as a synonym of Alphadon.
| Reassigned species: P. creber (Fox, 1971) see
Varalphadon creber; P. creberforme Cifelli, 1990 see
Varalphadon creberforme; P. wahweapensis Cifelli, 1990 see
Varalphadon wahweapensis | |
| Species: | Protalphadon foxi Johanson Z, 1996b |
| Place: | Hell Creek Formation, Montana |
| Country: | USA |
| Age: | Maastrichtian, Upper Cretaceous |
| Remarks: | |
| Reference: | |
| Species: | Protalphadon lulli (Clemens, 1966) Cifelli RL, 1990 |
| Aka: | Alphadon lulli Clemens, 1966 |
| Place: | Marshalltown Fm, New Jersey, Montana, Lance Fm, Wyoming |
| Country: | USA |
| Age: | Campanian - Maastrichtian, Upper Cretaceous |
| Remarks: |
I have seen a reference to material from Alberta, but I don’t know what the present
thinking is on that.
Gordon, 2003a (p.45) offers a bodyweight range of 53-61g, (upper Molar
only). The lower jaw and teeth are also known, (Kemp 2005, p.197). |
| References: | Clemens (1966), Fossil mammals of the type Lance Formation,
Wyoming. Part II. Marsupialia. University of California Publications in Geological Science,
62, p.1-122. |
| Cifelli (1990), Cretaceous mammals of southern Utah. I. Marsupials from
the Kaiparowits Formation (Judithian). J of Vert Paleont 10(3), p.295-319. |
| Other reports:
Xxxxxxxxxxxxxxxxxxxx
Xxxxxxxxxxxxxxxxxx |
A. Alphadelphians? B. Alphadontinae
C. Peradectinae
| Taxon: Peradectinae Crochet, 1979
Peradectidae is an unusually long-existing marsupial
family, if all members have been correctly assigned. McKenna & Bell, 1997, has this
subfamily within Didelphidae, (p.69), which contains proper opossums. In that version, it
ranges from the Cretaceous until the Miocene of Asia. They also included further genera,
but I don't know whether these placements would be in line with the concept used by Case
et al, 2004.
The additional taxa concerned are:
Armintodelphys Krishtalka & Stucky, 1983, Eocene of North America;
Mimoperadectes Brown & Rose, 1979, Paleocene-Eocene of NAm; Nanodelphys
McGrew, 1937 (including Didelphidectes Hough, 1961), Eocene to Oligocene (and perhaps
the Miocene) of NAm; Alloeodectes Russell LS, 1984, Eocene (and perhaps Miocene) of
NAm; and Siamperadectes Ducrocq, Buffetaut, Buffetaut-Tong, Jaeger,
Jongkanjanasoontorn & Suteethorn, 1992, Miocene of Thailand. Further material is
reported for Europe and Africa.
Though they're all doubtlessly charming, I'm going to stick with genera which have a
possibly Cretaceous record.
Genera: Alphadon (partly = Peradectes) Herpetotherium (partly
= Peradectes), Nanodelphys (partly = Peradectes),
Thylacodon (= Peradectes), other reports
Time-Line:
Eocene: Peradectes
Paleocene: Peradectes
Upper Cretaceous: ?Peradectes |
| Genus: Peradectes Matthew
& Granger, 1921
'persisting biter'
Aka: Alphadon (partly); Herpetotherium (partly); Nanodelphys
(partly); Thylacodon
Remarks: If all the fossils ascribed to this genus have been correctly interpreted,
it would have been a remarkably long-lived and cosmopolitan one. It's also been reported
from the Lower Eocene of Africa and Europe.
|
| Reassigned species: P. pauli see P. elegans |
| Links:
UNEP, World Heritage Sites, Grube Messel Lagerstätte
http://www.unep-wcmc.org/sites/wh/messel.html
Peradectes sp. is known from Messel, Germany, (Eocene, ca. 50Ma). An example works
in Vitrine (the glass display case) 43 of the
Geiseltalmuseum,
Halle-Wittenberg. A couple of other marsupial genera have also turned up, including
Amphiperatherium, (another Geiseltaler), and an impressively complete, small
opossumy thing of some kind, which is 26cm long and resident in the Hessisches
Landesmuseum of Darmstadt, Me 8035, (von Koenigswald & Storch, 1998, p.64).
Messel is an absolute treasure trove with some surprising gems; a furry hedgehog, an
anteater, a tapir. One of the mini horses, Propaleotherium parulum, is obviously a
female. She was pregnant. The legs of a male lemur have also been found, inclusive of a
small supporting bone for the penis. There are also several early rodents, which seem to
have first appeared in the Paleocene. I thought they were later than that, but
Koenigswald & Storch, 1998 -see bibliography- shows I was wrong. Then there's
Leptictidium, a bipedal, roughly cat-with-spectacularly-long-tail-sized hunter of
small reptiles, mammals and insects. The stomach contents of L. nasutum have been
preserved. All this is non-Mesozoic, but who cares? Finds from this site featured in the
first episode of the BBC series, Walking with Beasts.
On the subject of Euro-marsups
A brief list of some Eurosupials is given by Smith & Smith, 2004. Peratherium
matronese occurs in the French Eocene of Condé-en Brie. At least two further
species have been arrested during the Paleocene-Eocene transition at Dormaal,
Belgium: Peratherium constans Chardin T de, 1927 and Amphiperatherium
brabantense Crochet, 1979. While these might have little relevance to the
genera listed on this directory, not including the information would be entirely
pointless. I'd happily plug more reports of the perishers, should information
come to hand.
Senckenberg Museum Frankfurt, Fossilien aus der Grube Messel
http://www.senckenberg.uni-frankfurt.de/sm/messel.htm
Almost completely off-theme and in German, this page contains some photos of other Messel
fossils. Säugetier = mammal; Urpferd = original horse; Vögel = birds; Schlangen = snakes;
Schildkröten = tortoises; Fische, you'll have to translate for yourself, but they feel
unhealthy out of water. |
| Species: | Peradectes elegans Matthew & Granger, 1921 |
| Aka: | P. pauli Gazin CL, 1956 |
| Place: | San Juan Basin, Colorado, Wyoming & Paskapoo Formation, Alberta
|
| Country: | USA & Canada |
| Age: | Tiffany - Clarkforkian, Paleocene |
| Remarks: |
Weighed about 13g (Alroy). P. pauli
was synonymized with P. elegans by Holtzmann, 1978 (Alroy, web).
The Alberta material is mentioned in Macrofossils. Their localities in Alberta Canada, (with
notes on adjacent areas of British Columbia, LeBlanc JE, 2000, (free and on-line at:
Macrofossils of Alberta, page 64).
Holotype(?)
Lofgren, 1995 reports the type fossil of the genus as being AMNH 16414, a frgment of lower
jaw from New Mexico. It's difficult to see how that wouldn't also be the type of this
species, but that's not explicitely stated. It's a guest of the American Museum of Natural
History in New York. |
| Reference: | Matthew & Granger (1921), New genera of Paleocene mammals.
American Museum Novitates 13, p.1-7. |
| Species: | Peradectes protinnominatus McKenna MC, 1960 |
| Place: | Colorado |
| Country: | USA |
| Age: | Wasatchian, Eocene |
| Remarks: | Weighed about 12g (Alroy).
Was previously seen as a synonym of P. chesteri. |
| Reference: | |
| Species: | Peradectes austrinum (Sigé B, 1971) |
| Aka: | Alphadon austrinum Sigé B, 1971 |
| Place: | Laguna Umayo |
| Country: | Peru |
| Age: | ?Upper Cretaceous |
| Remarks: | I've seen this material
listed as coming from Alberta. Unless someone's been moving bits of Canada about, that
seems to be incorrect. This is based on an isolated upper
molar. Further species may be represented at this location, but the fossils are too
incomplete. The stratum is about two hundred metres below Chulpas, from whence
Chulpasia has been recovered.
A further upper molar has also been identified at Tiupampa, (de Muizon & Cifelli 2001,
p.95). |
| Reference: | Sigé (1971), Les Didelphoidea de Laguna Umayo (Formation
Vilquechilco, Crétacé Supérieur, Pérou), et le peuplement marsupial d'Amérique du Sud.
Comptes Rendus de l'Académie des Sciences, Paris, 273, p.2479-2481. |
| Links:
How did Plate Tectonics affect the Evolution of Marsupials? by Paul Talise
http://www.bol.ucla.edu/~ptalise/marsupialrules.html
"Peru and Bolivia reported fossils from the late Cretaceous. These are mostly composed
of tiny insectivorous and carnivorous forms that originated from the north. An example is
the Peradectes which was discovered to be a descendant (?) of the
early Oligocene Peradectes of North America (Szalay, 1994)."
A very interesting article with some great pics. Sugar gliders, flying squirrels...
How a 'Cretaceous' critter can be descended from Oligocene ancestors is not something I'm
inclined to ponder upon.
Palaeos, M Alan Kazlev, The Paleocene Epoch
http://www.palaeos.com/Cenozoic/Paleocene/Paleocene.htm
Peradectes is in the tree, watching the happenings below. |
| Species: | Peradectes californicus (Stock, 1936) |
| Aka: | Nanodelphys californicus Lillegraven, 1976; P. californicum
Stock, 1936 |
| Place: | California & Cypress Hills, Saskatchewan |
| Country: | USA & Canada |
| Age: | Uintan - Duchesnean, Eocene |
| Remarks: | A tiny critter of about 5g
(Alroy). |
| Reference: | |
| Links:
Alf Museum of Paleontology, The Goler Project
http://www.alfmuseum.org/collect2a.html
Fossils from the Goler Formation of California, which is largely Paleocene. This brief
report features a photo of an upper molar.
Journal of Vertebrate Paleontology, 16(4), 1996
http://www.vertpaleo.org/jvp/16-770-774.html
The marsupials of the Lac Pelletier Lower Fauna, Middle Eocene (Duchesnean) of Saskatchewan.
Rothecker J & Storer JE (1996), JVP, 16(4), p.770-774.
An abstract on the marsupials of Saskatchewan. |
| Species: | Peradectes chesteri (Gazin CL, 1952) |
| Aka: | Herpetotherium chesteri Crochet, 1978 |
| Place: | Wyoming |
| Country: | USA |
| Age: | Wasatchian - Bridgerian, Eocene |
| Remarks: |
Started out as P., became H. and was then returned to P. It weighed
about 5g (Alroy). |
| Reference: | |
| Species: | ?Peradectes marandati Crochet JY & Sigé B, 1983 |
| Place: | Hainin |
| Country: | Belgium |
| Age: | Upper Paleocene |
| Remarks: | |
| Reference: | Crotchet & Sigé (1983), Les Mammiferes Montiens de Hainan
(Paleocene moyen de Belgique) Part III: Marsupiaux. Palaeovertebrata 13, p.51-64. |
| Species: | Peradectes pusillus (Matthew & Granger, 1921) |
| Aka: | Thylacodon pusillus, Matthew & Granger, 1921 |
| Place: | New Mexico, Colorado,
Montana & Wyoming |
| Country: | USA |
| Age: | Maastrichtian - Puercan, Upper Cretaceous - Paleocene |
| Remarks: |
McKenna & Bell, 1997 lists T. as a synonym of Peradectes.
A number of other authorities don't seem to share this view, as shown by John Alroy's
database, (linked towards the end of this page). Alroy's weight estimate of
50g also suggests this is a significantly larger animal than
Peradectes. In this case, I've decided not to follow the guidance of M & B,
1997.
Lofgren, 1995 reported the collection of molars from
Cretaceous-Paleocene,
McGuire Creek, Montana (p.109). He referred to them as being P. cf pusillus
rather than formally assinging them to a species. In effect, they compare closely but
could belong to a different taxon. |
| Reference: | Matthew & Granger (1921), New genera of Paleocene mammals.
American Museum Novitates 13, p.1-7. |
| Xxxxxxxxxxxxxx
Xxxxxxxxxxxx |
| Help:
Should anybody have any further information, I'd be pleased to hear of it.
Regarding references and Bibliography:
I haven't and can't verify all the references, so beware. Traditional papers used in
constructing this page are in the bibliography. If you feel these are too few, then send
some more.
With thanks to all the featured sources.
back to top
Trevor Dykes, March 2002. Latest update: 10.3.2010
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 source of much of the above information, including weight estimates.
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, 2003a (p.45-46). CynThis Gordon's 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. As they were New World marsupials, I'll
include the range of estimates based upon Didelphidae. These calculations were derived
from a. m1 Length, b. m1 L x Width, c. M1 L and d. M1 L x W.
A third source is Gordon & Cifelli, 2003 (p.93-97). The methods are as for Gordon,
2003.
A rough system of measurement is employed in these directories. A standard mouse = 25g, a
brown rat counts as 400 whilst a beaver equals about 25 kilos.
The Prehistoric Data Files
http://www.angellis.net/Web/PDfiles/marsups.pdf
A much appreciated resource.
Martin Jehle, Paleocene mammals of the world, Class Mammalia
http://www.paleocene-mammals.de/pal1.htm
Part of an interesting project centred on the immediate post-Cretaceous fauna.
John H Burkitt, Mammals, A World Listing of Living and Extinct Species
John H Burkitt's Mammals
This impressive listing has returned on-line. It'll take a while to open, as it's a large
pdf file.
BIOSIS, The Index to Organism Names
http://www.biosis.org.uk/triton/indexfm.htm
The Society of Vertebrate Paleontology BFV Online, (John Damuth)
http://www.bfvol.org/
The Peabody On-line VP Catalogue
http://george.peabody.yale.edu/vp/ |
Bibliography:
Case JA, Goin FJ & Woodburne MO (2004), "South American" marsupials
from the Late Cretaceous of North America and the origin of marsupial cohorts, Journal of
Mammalian Evolution, 11(3/4), p.223-255.
Cifelli RL (2004), Marsupial mammals from the Albian-Cenomanian (Early-Late
Cretaceous Boundary, Utah, Chapter 5 of Bulletin of the American Museum of Natural History,
285, p.62-79.
Cifelli RL & Muizon de C (1998), Marsupial mammal from the Upper Cretaceous
North Horn Formation, central Utah. Journal of Paleontology, 72 (3), p.532-537.
Foote M, Hunter JP, Janis CM & Sepkoski JJ (1999), (Supplementary material for)
Evolutionary and preservational constraints on origins of biologic groups: divergence times
of eutherian mammals, Science 283.
Gordon CL (2003a), A first look at estimating body size in dentally conservative
marsupials, p.4-55 (In) Functional Morphology and Diet of Late Cretaceous Mammals of North
America, Ph.D. Dissertation, University of Oklahoma, p.i-xiv and 1-177.
Gordon CL (2003b), Molar morphology and diet of Late Cretaceous therian mammals of
North America: a preliminary analysis, p.149-177 (In) Functional Morphology and Diet of
Late Cretaceous Mammals of North America, Ph.D. Dissertation, University of Oklahoma,
p.i-xiv and 1-177.
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 reappraisal 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.
Kemp TS (2005), The Origin and Evolution of Mammals, Oxford University Press,
pp.331.
Koenigswald von W & Storch G [eds.] (1998), Messel, ein Pompeji der Paläontologie.
Thorbecke Species Band 2.
Lockley M & Foster J, (2003), Late cretaceous mammal tracks from
North America, Ichnos, 10, p.269-276.
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.
McKenna MC & Bell SK (1997), Classification of Mammals Above the Species Level.
Columbia University Press.
Montellano M, Weil A & Clemens WA (2000), An exceptional specimen of
Cimexomys judithae (Mammalia: Multituberculata) from the Campanian Two Medicine
Formation of Montana, and the phylogenetic status of Cimexomys. Journal of
Vertebrate Paleontology 20 (2), p.333-340.
Morgan GS & Lucas SG (1999), Type specimens of fossil vertebrates in the New
Mexico Museum of Natural History and Science. New Mexico Museum of Natural History and
Science Bulletin 16, p.253-259.
Muizon de C & Cifelli RL (2001), A new basal "didelphoid" (Marsupialia,
Mammalia) from the Early Paleocene of Tiupampa (Bolivia), Journal of Vertebrate Paleontology,
21 (1), p.87-97.
Sahni A (1972), The vertebrate fauna of the Judith River Formation, Montana,
Bulletin of the American Museum of Natural History, 147(6), p.321-412.
Sankey JT (1998), Vertebrate Paleontology and Magnetostratigraphy of the Upper Aguja
Formation (Late Campanian), Talley Mountain Area, Big Bend National Park, Texas, Ph.D.
Dissertation, Louisiana State University, p.1-251.
Smith R & Smith T (2004), Les Mammiferes de l'Ypresien Moyen du Bassin de
Paris (niveau-repere MP8-9) sont-ils presents des la limite Paleocene/Eocene de
Dormaal (niveau-repere MP7, Belgique)?, Oryctos, 5, p.75-82.
Tokaryk TT & Bryant HN (2004), The fauna from the Tyrannosaurus rex
excavation, Frenchman Formation (Late Maastrichtian), Saskatchewan; in Summary of
Investigations 2004, Vol 1. Saskatchewan Geological Survey, Sask. In. Resources, Misc.
Rep. 2004-4.1, CD-Rom, Paper A-18, 12p.
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. |
