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

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

ANALYZING ECOMORPHOLOGICAL SHIFTS IN THE STRIPED SKUNK (MEPHITIS MEPHITIS): FROM ICE AGE TO MODERN DAY

Paper number: 23-7
Program: Theme Sessions
Time: 9:00 AM – 6:00 PM

Authors

  • Lizbeth Jardon Presenting Author
    California State University - Long Beach, Long Beach, CA
  • Mairin Balisi
    Los Angeles County Natural History Museum, Los Angeles, CA

Abstract

The late Pleistocene may be known for its megafauna, but smaller animals also lived during this time –ones still with us today. The striped skunk (Mephitis mephitis) has persisted through the climate transition and megafaunal extinction that marked the end of the last Ice Age and is currently thriving in extant environments across North America. This study seeks to understand the ecomorphological changes these small carnivorans have undergone in response to ecological and environmental disturbances by comparing linear cranial and postcranial measurements of fossils of striped skunks from the Rancho La Brea asphalt seeps, Los Angeles, California and modern representatives from the same region in the collections of the Natural History Museum of Los Angeles County. We found shorter lower first molars, shorter carnassial blades, and larger dental grinding area over time, indicating smaller body sizes and decreasing carnivory from the Pleistocene to the present. The humerus also became more robust, suggesting increased strength in the forelimbs. No significant differences emerged across fossil deposits and across modern counties, suggesting skunks are very plastic and that the difference in environment between Pleistocene and present-day is greater than the difference across present-day geography and across the late Pleistocene itself.

As opportunistic feeders, extant striped skunks prefer more accessible prey, such as insects and roots, which require less slicing and more grinding. Having stronger forelimbs would assist in prey acquisition. The disappearance of Pleistocene megafauna removed potential competitors and predators for the striped skunk, possibly easing its access to such prey. Size differences also may reflect shifts in the skunk’s niche in response to megafaunal extinction, as the benefit of being larger (more intimidating) no longer justified metabolic cost. Ecomorphological shifts in mesocarnivores like the striped skunk likely result from a combination of top-down (from predators) and bottom-up (from prey and environment) pressure due to their mid-tier position in food webs. These insights can aid in understanding the extent of these small carnivorans’ adaptability, enabling improvements in efforts for their conservation and management, such as in pest control of modern populations.

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

doi: 10.1130/abs/2020CD-346004

© Copyright 2020 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.