Great Basin Mylagaulidae

research5mylagaulids

Mylagaulids are abundant burrowing rodents in Miocene faunas from western North America. Recent taxonomic revisions of mylagaulids from the Great Plains suggest that their systematics may be best understood on a regional basis. Previous studies have addressed the taxonomy and evolutionary history of mylagaulids from the Great Basin, but recent discoveries of specimens, new phylogenetic data, and more detailed stratigraphic information necessitate a thorough reanalysis of their relationships and occurrences. We therefore present a revision of the systematics of the mylagaulids from the Great Basin.

The results of our research were presented at the Oregon Academy of Sciences annual meeting in Portland (2010) and are part of my M.S. thesis at the University of Oregon. The resulting paper is published in the Zoological Journal of the Linnean Society.

Calede J.J., and S.S.B. Hopkins. 2012. Intraspecific versus interspecific variation in Miocene Great Basin mylagaulids: implications for evolutionary history. Zoological Journal of the Linnean Society 164:427–450.
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Collaborator: Samantha Hopkins

Antelope astragali

research3antelopes

The Hemphillian (~8Ma) Thousand Creek Fauna of northwestern Nevada contains three species of closely related antilocaprids in two genera, Ilingoceros alexandrae, Ilingoceros schizoceras, and Sphenophalos nevadanus. These species were diagnosed on the basis of their distinct horn morphology, but the little work done comparing their dental or postcranial morphology showed no clear separation between the species, leading to a hypothesis that the two Ilingoceros were age classes and that Ilingoceros and Sphenophalos represented sexual morphs within one species. We used multivariate morphometric comparison of eight linear dimensions of >200 antilocaprid astragali from Thousand Creek to find out if there is enough variation to support the presence of more than one species.

Preliminary results have been presented by Dr. Edward Davis at the annual meeting of the Society of Vertebrate Paleontology in Austin (2007). The results of this research project are published in Palaeontologia Electronica.

Davis, E. B., and Calede, J.2012. Multivariate analysis of Hemphillian (Late Miocene) and recent antilocaprid astragali indicates little divergence between Ilingoceros and Sphenophalos in the Thousand Creek Formation, Nevada. Paleontologia Electronica 15.1.1A.
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Collaborator: Edward Davis