During my time at the University of Oregon, I mostly worked in central and eastern Oregon collecting in the John Day and Owyhee Basins. This work has ben undertaken in collaboration with Dr. Samantha Hopkins and Dr. Edward Davis (UO) as well as the John Day Fossil Beds National Monument.
Leptarctines are enigmatic, yet common, mustelids in the North American and Asian fossil record. No consensus has yet been reached about their paleoecology. Differing interpretations of dental and cranial features and a lack of available postcranial elements have left the diet and locomotor habits of this subfamily uncertain. Initial interpretations of their ecology include coati-like omnivory, badger-like carnivory, kinkajou-like frugivory, and koala-like herbivory. The comparison to a koala-like diet implied a strongly arboreal lifestyle for leptarctines. Most recently, the cranial and dental morphology have been interpreted as evidence for a crushing omnivorous diet.
We have been studying a partial skeleton of a late early Hemphillian (7.5 – 6.7 Ma) leptarctine from the Rome fauna of Malheur County, Oregon as well as a nearly complete skull of Leptarctus oregonensis, a small Leptarctus from the Mascall Formation of central Oregon (early Barstovian, 15.9 – 14.8 Ma) with the goal of improving our understanding of the Leptarctine paleoecology.
Preliminary results have been presented by Winifred Kehl at the Geological Society of America annual meeting in Portland (2009) and the Oregon Academy of Sciences annual meeting in Portland (2010).
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