Baiotomeus
Encyclopedia
Baiotomeus is a genus of mammals from the extinct order of Multituberculata
. It is known from the Paleocene
of North America
.
The genus
Baiotomeus was formally named by Krause in 1987 (Krause, 1987), and has also been known as Mimetodon
(partly), Neoplagiaulax
(partly), and Ptilodus
(partly).
and Wyoming
in the United States
, in strata of the Gidley Quarry dated to the Torrejonian stage
of the Paleocene
.
The species was originally named Ptilodus
douglassi by Simpson in 1935 (Simpson, 1935), but it has been reclassified several times:
It was finally assigned to Baiotomeus by Hartman in 1986 — which is before Krause formally established the genus in 1987.
Several specimens, including the holotype
, are at the Peabody Museum of Natural History at Yale. Collected in 1958 and 1965, these were originally described as belonging to Mimetodon
. It was given its current name in 1987 by Krause (Krause, 1987). B. lamberti has also been confused with Ptilodus
montanus.
, Canada, in Cochrane 2 of the Paskapoo Formation, which has been dated to the lower Tiffanian stage of the Paleocene.
Remains consist of nine upper premolars, (P4), which average nearly 2.5 mm
in length. This is smaller than the teeth of other genus members; from front to back, approximately 45% less than B. douglassi and 40% less than B. lamberti. The rows of cusps also display a strong curvature and the cuspate anterolabial lobe is better developed. There is more variation in the height of the cusps among the middle row. These particular premolars — P4s — have three rows of cusps, of which there seem to be about 15 or so in all. In addition, "the enamel is weakly wrinkled on all specimens". (Scott et al., 2002)
According to the same authors:
The species name honours L. S. Russell "for his pioneering research on the mammals from Cochrane 2". All presently identified remains are part of the collection of the University of Alberta
.
Cochrane 2 has also been interpreted as correlating to the Porcupine Hills Formation, but recent studies suggest that it is part of the Paskapoo, as originally concluded by Russell in 1929.
Multituberculata
The Multituberculata were a group of rodent-like mammals that existed for approximately one hundred and twenty million years—the longest fossil history of any mammal lineage—but were eventually outcompeted by rodents, becoming extinct during the early Oligocene. At least 200 species are...
. It is known from the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
.
The genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Baiotomeus was formally named by Krause in 1987 (Krause, 1987), and has also been known as Mimetodon
Mimetodon
Mimetodon is a small mammal from the Paleocene of North America and perhaps Europe. It was a member of the extinct order Multituberculata within the suborder Cimolodonta and family Neoplagiaulacidae....
(partly), Neoplagiaulax
Neoplagiaulax
Neoplagiaulax is a mammal genus from the Paleocene of Europe and North America. In the case of the latter continent, there may possibly be some slightly earlier, Upper Cretaceous material too. It existed in the age immediately following the extinction of the last dinosaurs...
(partly), and Ptilodus
Ptilodus
Ptilodus is a genus of mammals from the extinct order of Multituberculata, and lived during the Paleocene in North America.Ptilodus was a relatively large multituberculate of in length, which is about the same size as a squirrel...
(partly).
B. douglassi
Baiotomeus douglassi is a fairly substantial multituberculate weighing almost 200 g. Remains have been found in MontanaMontana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, in strata of the Gidley Quarry dated to the Torrejonian stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
of the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
.
The species was originally named Ptilodus
Ptilodus
Ptilodus is a genus of mammals from the extinct order of Multituberculata, and lived during the Paleocene in North America.Ptilodus was a relatively large multituberculate of in length, which is about the same size as a squirrel...
douglassi by Simpson in 1935 (Simpson, 1935), but it has been reclassified several times:
- MimetodonMimetodonMimetodon is a small mammal from the Paleocene of North America and perhaps Europe. It was a member of the extinct order Multituberculata within the suborder Cimolodonta and family Neoplagiaulacidae....
douglassi in 1940, by Jepsen - NeoplagiaulaxNeoplagiaulaxNeoplagiaulax is a mammal genus from the Paleocene of Europe and North America. In the case of the latter continent, there may possibly be some slightly earlier, Upper Cretaceous material too. It existed in the age immediately following the extinction of the last dinosaurs...
douglassi in 1974, by Schiebout
It was finally assigned to Baiotomeus by Hartman in 1986 — which is before Krause formally established the genus in 1987.
B. lamberti
Remains of Baiotomeus lamberti have been discovered in Montana in the United States, in the Medicine Rocks of the Tongue River Formation, which have been dated to the Paleocene.Several specimens, including the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, are at the Peabody Museum of Natural History at Yale. Collected in 1958 and 1965, these were originally described as belonging to Mimetodon
Mimetodon
Mimetodon is a small mammal from the Paleocene of North America and perhaps Europe. It was a member of the extinct order Multituberculata within the suborder Cimolodonta and family Neoplagiaulacidae....
. It was given its current name in 1987 by Krause (Krause, 1987). B. lamberti has also been confused with Ptilodus
Ptilodus
Ptilodus is a genus of mammals from the extinct order of Multituberculata, and lived during the Paleocene in North America.Ptilodus was a relatively large multituberculate of in length, which is about the same size as a squirrel...
montanus.
B. russelli
Baiotomeus russelli has been discovered in AlbertaAlberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, Canada, in Cochrane 2 of the Paskapoo Formation, which has been dated to the lower Tiffanian stage of the Paleocene.
Remains consist of nine upper premolars, (P4), which average nearly 2.5 mm
1 E-3 m
To help compare different orders of magnitude this page lists lengths between 10−3 m and 10−2 m .Distances shorter than 1 mm* 1.0 mm — 1/1000 of a metre* 1.0 mm — 0.03937 inches or 5/127...
in length. This is smaller than the teeth of other genus members; from front to back, approximately 45% less than B. douglassi and 40% less than B. lamberti. The rows of cusps also display a strong curvature and the cuspate anterolabial lobe is better developed. There is more variation in the height of the cusps among the middle row. These particular premolars — P4s — have three rows of cusps, of which there seem to be about 15 or so in all. In addition, "the enamel is weakly wrinkled on all specimens". (Scott et al., 2002)
According to the same authors:
- At present, P4s are the only specimens from Cochrane 2 that we can identify as pertaining to B. russelli. Although knowledge of this species is limited, we consider its naming to be justified based on the diagnostic morphology of ultimate fourth premolars in ptilodontids generally (Krause 1982, 1987) and the unique structure of these teeth.
The species name honours L. S. Russell "for his pioneering research on the mammals from Cochrane 2". All presently identified remains are part of the collection of the University of Alberta
University of Alberta
The University of Alberta is a public research university located in Edmonton, Alberta, Canada. Founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta and Henry Marshall Tory, its first president, it is widely recognized as one of the best universities in Canada...
.
Cochrane 2 has also been interpreted as correlating to the Porcupine Hills Formation, but recent studies suggest that it is part of the Paskapoo, as originally concluded by Russell in 1929.