Poebrotherium

''Poebrotherium'' ( ) is an extinct genus of camelid, endemic to North America. They lived from the Eocene to Miocene epochs, 46.3—13.6 mya, existing for approximately .

Discovery and history

''Poebrotherium'' was first named by scientist Joseph Leidy in 1848, and its relationship to other White River fossils was later expanded by him in 1853. Fur trapper Samuel Culbertson was working in Nebraska in pursuit of fur bearing mammals, and found a collection of strange fossil animal bones. He sent a box of these bones to his family back east, and not knowing what to make of them, they forwarded the remains to Leidy for identification. Several animals' remains were included in this package, but one of the most interesting was that of a small mammal, about the size of a small deer or sheep. In addition to a partial skull, a portion of a forelimb was found. The portions that Leidy was able to examine helped him determine it was likely related to modern llamas, even though there was a paucity of new material available after his 1848 diagnosis. This package spawned Leidy's interest in the White River badlands and its fauna, and he eventually sent collectors from the American Museum west to expand his collection. Between 1848 and 1853, cases of new material were shipping back to Leidy. Maddeningly, only three more ''Poebrotherium'' tooth samples were among the remains recovered.

Etymology

The term ''poebrotherium'' comes from grc, ποιηβόρος (, "grass-eating") and (, "wild animal; animal; "beast"), in Latinised form. The specific epithet is the Latinised name of a person or place, or a Latin adjective denoting a postulated characteristic of the species.

Species

*''Poebrotherium wilsoni'' can be translated as " r. ThomasWilson's grass-eating beast".
*''Poebrotherium chadronensis'' can be translated as "grass-eating beast from Chadron ormation.
*''Poebrotherium franki'' can be translated as "Frank's grass-eating beast".
*''Poebrotherium eximium'' can be translated as "Extraordinary grass-eating beast"
*''Poebrotherium labratrum'' can be translated as "Chief grass-eating beast" or "Royal grass-eating beast"

Description

''Poebrotherium'' looked more like modern camels than its predecessor ''Protylopus'', but at in height, it was roughly the size of a modern sheep. Its skull resembled that of a modern llama, while its limbs ended in hooved toes and were more built for speed than the feet of ''Protylopus''. Despite this apparent adaptation to the open plains, ''Poebrotherium'' has been found in all major White River environments, including forests and river overbank deposits, indicating that it was not tied to one particular environment. The teeth of ''Poebrotherium'' were more generalised than those of modern camelids. In fact, despite the name meaning "grass-eating beast" it is likely that ''Poebrotherium'' was either a browser or a mixed-feeder, and grass may have played a minimal role in the diet of ''Poebrotherium''.


Unlike its modern cousins, which are either adapted for desert or alpine conditions, ''Poebrotherium'' took the place of a gazelle or deer in the White River Fauna ecosystem. This trait was taken to an extreme in later camels, notably ''Stenomylus''. Fossil evidence has shown that ''Poebrotherium'' was a popular prey item for the entelodont ''Archaeotherium''. Remains of partial ''Poebrotherium'' carcasses have been found fossilized, and appear to have been killed and cached by ''Archaeotherium'', the only animal known from the White River ecosystem that could have made the feeding marks found on the bones of ''Poebrotherium''.

Relationships

''Poebrotherium'' lies within the clade Camelidae, which can be defined as (Stenomylinae + ( Miolabinae + ( Protolabinae + Camelinae))) + ''Poebrotherium''. As such, ''Poebrotherium'' lies outside the Camelinae proper. In fact the definition of Camelidae is the most recent common ancestor of ''Poebrotherium'' and ''Camelus'', and all of its descendants.

Several authors offer characteristics to define ''Poebrotherium''. These include a long neck; an adult height of around ; relatively unspecialized teeth; moderately long legs; long, unsplayed, unfused, and proximally wider-than-deep metapodials; a pes lacking digits 1, 4, and 5; and a typical ungulate stance but lacking in a foot pad.Whistler, DP & SD Webb (2005), New Goatlike camelid from the Late Pliocene of Tecopa Lake Basin, California. Contrib. Sci. No. 503, 40 pp

References

{{Taxonbar, from=Q783416

Prehistoric camelids
Eocene even-toed ungulates
Oligocene even-toed ungulates
Rupelian genus extinctions
Paleogene mammals of North America
White River Fauna
Prehistoric even-toed ungulate genera
Taxa named by Joseph Leidy
Fossil taxa described in 1847