23 La Brea Tar Pits: Old Bones and New Insights (Posters)

Wednesday, 13 May 2020
9:00 AM - 6:00 PM
Fountain Ballroom

ASSESSING MIGRATION IN PLEISTOCENE HERBIVORES AT RANCHO LA BREA – YEA OR NEIGH?

Paper number: 23-5
Program: Theme Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

The asphaltic seeps at Rancho La Brea (RLB) have preserved the remains of local inhabitants for 50,000 years. Over 3.5 million fossils have been recovered from RLB preserving large herbivores such as Bison antiquus, Equus occidentalis, and Camelops hesternus. From these fossils, migratory patterns can be investigated, shedding light on paleoecological, climatic, and floral changes through time. Based on previous publications, B. antiquus was a seasonal migrant at RLB. This is supported by calculated age profiles showing annual clusters of juveniles and serially sampled enamel isotopes indicating dietary shifts between winter and summer months. However, such patterns could also be caused by seasonal seep activity and seasonal changes in vegetation; therefore, it is necessary to compare these data against supposed non-migratory species in order to conclusively infer migratory behavior of B. antiquus. In this study, we sought to test whether the inferred non-migratory taxon E. occidentalis and C. hesternus (taxon with unknown migration patterns) comprise a continuous spectrum of age classes reflecting year-round occupation at RLB. We calculated age profiles of E. occidentalis and C. hesternus using progressive tooth wear and tooth eruption sequences and compared our results to previously published age profiles of B. antiquus. E. occidentalis age profiles differ from that of B. antiquus, with individuals representing a wide range of ages, indicating that E. occidentalis did not migrate and became entrapped at RLB year-round, consistent with previous research based upon serially sampled enamel isotopes. These results support annual clusters of juveniles in B. antiquus are consistent with migratory behavior, indicating age profiles can be a useful technique to assess migration patterns in extinct taxa. In C. hesternus where migratory patterns are unknown, we found age profiles are more similar to those of B. antiquus with an annual cluster of juveniles, consistent with migration at RLB. Our data suggest age profiles can be applied to other paleontological sites to assess faunal interaction and migration throughout the Pleistocene.

Geological Society of America Abstracts with Programs. Vol. 52, No. 4

doi: 10.1130/abs/2020CD-347079

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