129-69 Niche Partitioning Between Small-Bodied Insectivorous Mammals During Early Eocene Climate Fluctuation, Willwood Formation (56-52 Ma), Bighorn Basin, WY

Abstract:

The early Eocene (56-52 Ma) is a paleontologically significant time period characterized by the appearance and proliferation of ancestors and relatives of modern mammalian groups as well as climate fluctuations analogous to modern climate instability. Analysis of modern and fossil taxa is instrumental for understanding early Eocene faunal ecology and adaptations, and the results in turn can be used to inform conservation efforts for modern mammals. Focusing on Bighorn Basin, Wyoming, Willwood Formation, fossil taxa, this study examines the potential for competition and niche partitioning between two early Eocene faunivorous small-bodied mammals: Haplomylus, an extinct relative of today’s elephant shrew (Order Macroscelidea) in Africa, and omomyid primate Tetonius in the lineage that gave rise to modern tarsiers in Asia along with modern monkeys, apes, and humans. It compares characteristics including distribution, locomotion, diet, activity, and body mass responses to well-documented thermal temperature fluctuations (PETM) using literature review, analysis of Haplomylus and Tetonius dental morphology, and geospatial analysis of fossil distribution using specimens and data from the Colorado State University Primate Origins Lab. Results show partial niche overlap in areas of diet, distribution, and body mass alongside diverging adaptations in other areas. This indicates indirect competition and increasing niche partitioning related to environmental stressors, which informs these animals’ evolutionary pathways and responses to significant climate fluctuations, thus providing insights applicable to conservation strategies for their modern descendants.

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