28 D13. Recent Advances in Paleoecology/Taphonomy (Posters)

Sunday, 22 September 2024
8:00 AM - 5:30 PM
Hall D

SEASONAL DIET ECOLOGY OF RANCHO LA BREA DIRE WOLVES

Paper number: 28-23
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Dire wolves were large-bodied hypercarnivores that lived during the Pleistocene epoch. We investigated whether Rancho La Brea dire wolf diets varied seasonally and if these variations can be explained by wolf or prey migration. We collected serial samples from 10 dire wolf teeth which were analyzed for their δ13C and δ18O isotope values. δ13C acts as a measure of both diet and, to a lesser extent, climate. For predators such as dire wolves, C isotope compositions reflect the herbivores they consume, and the herbivores’ isotopic composition is reflected by the plants they consume. The δ13C value of a plant varies based on several factors, most notably, its photosynthetic pathway. C3 plants are adapted for cooler, wetter areas and have lower δ13C values around -14.5‰. Conversely, C4 photosynthetic plants are adapted for warmer, drier climates and have higher values around 2.5‰. Oxygen isotopes, on the other hand, are derived from drinking water and record seasonality and climate. Low δ18O values reflect cool periods while warmer temperatures produce higher δ18O values. The average δ13C value in the teeth we have sampled is -8.3±1.2‰ (±1σ) while the average δ18O value is -3.9±1.4‰. These values are similar to previously published isotope compositions for RLB herbivores (horses, bison), which suggests a very small percentage of C4 plants in the diet of dire wolf prey, consistent with Rancho La Brea as a primarily C3 ecosystem. We also found an inverse relationship between carbon and oxygen isotope compositions within individual teeth. This suggests a dietary shift towards more open-habitat prey during warmer periods. A shift to greater fat consumption in dire wolf diets during warm periods could also cause this inverse relationship, as fat is depleted in 13C. Both of these interpretations imply a seasonal component to diet choices, which may be due to movement of prey, wolves, or both. However, given the small amount of variation in both δ13C and δ18O compositions in the teeth sampled, it is most likely that these seasonal changes are not due to substantial movement of dire wolves. As such, we predict that dire wolves did not follow migrating animals, and instead remained within the area around Rancho La Brea year-round. Future work will expand on these data with increased sample sizes and with other isotopic systems such as nitrogen and strontium.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-401783

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.