91涩漫

Biography

Research interests

I am a vertebrate paleontologist specializing in the evolution of mammals during the time of dinosaurs. Specifically, my research focuses on understanding evolutionary dynamics and morphological changes in mammals during the Cretaceous Period, from 100–75 million years ago. This was a time when ecosystem reorganization was taking place, leading to the emergence of modern flora and fauna, including modern mammalian groups. As such, the exact timing of when modern mammalian groups emerge is of some dispute; molecular clock methods point towards an earlier divergence around 100 million years ago, but fossil data suggests a much later emergence at 65 million years ago. To understand this disconnect, I utilize a combination of fieldwork and morphological descriptions to fill in gaps in the fossil record to better understand the exact timing of modern mammalian groups.

I also research the response of mammalian communities to major events, such as extinction events and climate change. The end of the Pleistocene in North America saw dramatic ecological upheaval, including climate change at the end of the last Ice Age, the arrival of humans onto the continent, and a megafaunal extinction event. To tease apart how organisms respond to these major events, I study the end Pleistocene mammalian megafauna from the Rancho La Brea Tar Pits Museum over the last 50,000 years. The Tar Pits Museum has the largest Late Pleistocene collection of fossils since the last Ice Age, which allows for a highly detailed record of the megafauna. This allows for multiproxy techniques to be used, such as morphology, tooth wear, radiocarbon dating, and stable isotopes analysis to determine paleoecological roles and changes within species and the community during the end of the Late Pleistocene.

Research projects

Students interested in joining my lab may become involved in a variety of discovery-based research. These projects will provide a strong basis in learning anatomy and evolutionary concepts and will be a good fit for students interested in pursuing graduate programs in ecology and evolution and pre-health careers, including students interested in applying to medical, dental, and veterinary schools. Student researchers will learn skills including morphological observations and diagnosis, interpretation of computed tomography (CT) imagery, data management, field techniques, and systematics. Projects include, but are not limited to:

1. Data collection by sorting through and identifying microvertebrate fossiliferous matrix from fossil localities that range from 100–75 million years ago.
2. Fieldwork and fossil collection primarily from Late Cretaceous rock units in southern Utah.
3. Taxonomic and systematic studies of middle Cretaceous vertebrates.
4. Reconstructing skeletal and skull elements using microCT data.

Selected publications

Eberle, J., Cohen, J., Foster, J., Hunt-Foster, R., & Heckert, A. (2024). A new Late Cretaceous metatherian from the Williams Fork Formation, Colorado. PLoSOne, 19(10), e0310948.

O’Keefe, F. R., Dunn, R. E., Weitzel, E. M., Waters, M. R., Martinez, L. N., Binder, W. J., Southon, J. R., Cohen, J. E., Meachen, J. A., DeSantis, L. R. G., Kirby, M. E., Ghezzo, E., Coltrain, J. B., Fuller, B. T., Farrell, A. B., Takeuchi, G. T., MacDonald, G., Davis, E. B., & Lindsey, E. L. (2023). Pre–Younger Dryas megafaunal extirpation at Rancho La Brea linked to fire-driven state shift. Science, 381(6659).

Frederickson, J., Cohen, J., Engel, M., Hunt, T., Wilbert, G., Castañeda, O., & Czaplewski, N. (2022). The paleoecology of the Late Miocene mammals from the Optima Local Fauna of Oklahoma, USA. Acta Palaeontologica Polonica, 67(1), 221–238.

Cohen, J. E., DeSantis, L. R. G., Lindsey, E. L., Meachen, J. A., O’Keefe, F. R., Southon, J. R., & Binder, W. J. (2021). Dietary stability inferred from dental mesowear analysis in large ungulates from Rancho La Brea and opportunistic feeding during the late Pleistocene. Palaeogeography, Palaeoclimatology, Palaeoecology, 570, 110360.

Cohen, J. E., Davis, B. M., & Cifelli, R. L. (2020). Geologically oldest Pediomyoidea (Mammalia, Marsupialiformes) from the Late Cretaceous of North America, with implications for taxonomy and diet of earliest Late Cretaceous mammals. Journal of Vertebrate Paleontology, 40(5), e1835935.

Cohen, J. E. (2018). Earliest divergence of stagodontid (Mammalia: Marsupialiformes) feeding strategies from the Late Cretaceous (Turonian) of North America. Journal of Mammalian Evolution, 25(2), 165–177.