Habitat preferences in the fossil record


We tested hypotheses of drivers of mammalian evolution through an examination of apparent competitive replacements of burrowing rodents at a regional scale in the middle to late Miocene fossil record of the northern Great Basin. At that time, mylagaulids became very abundant within the burrowing herbivore niche, including all burrowing rodents. This peculiar group of subterranean small mammals is most abundant in the Hemingfordian through Clarendonian NALMAs (17.5 to 9 Ma) and declines in the Hemphilian (9 to 5 Ma), giving way to the now very abundant family Geomyidae. We tested the hypothesis that this turnover of the most abundant group within the guild was associated with changes in habitat.

The results of this research were presented at the annual meeting of the Society of Vertebrate Paleontology in Pittsburgh (2010) by Dr. Samantha Hopkins and are part of my M.S. thesis at the University of Oregon. The article has been published in Palaeogeography, Palaeoclimatology, Palaeoecology.

Calede, J.J., S.S.B., Hopkins, E.B., Davis. 2011. Turnover in burrowing rodents: the role of competition and habitat change. Palaeogeography, Palaeoclimatology, Palaeoecology 311:242-255.
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Collaborators: Samantha Hopkins, Edward Davis

Great Basin Mylagaulidae


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