Paleobiology of a large mammal community from the late Pleistocene of Sonora, Mexico

Rachel A Short,Arturo Baez,Jeff M Martin,Nicholas A Famoso,Jim I Mead,Sandy L Swift,Laura G Emmert

doi:10.1017/qua.2020.125

Abstract

AbstractA paleontological deposit near San Clemente de Térapa represents one of the very few Rancholabrean North American Land Mammal Age sites within Sonora, Mexico. During that time, grasslands were common, and the climate included cooler and drier summers and wetter winters than currently experienced in northern Mexico. Here, we demonstrate restructuring in the mammalian community associated with environmental change over the past 40,000 years at Térapa. The fossil community has a similar number of carnivores and herbivores whereas the modern community consists mostly of carnivores. There was also a 97% decrease in mean body size (from 289 kg to 9 kg) because of the loss of megafauna. We further provide an updated review of ungulates and carnivores, recognizing two distinct morphotypes ofEquus, includingE.scottiand a slighter species; as well asPlatygonus compressus;Camelops hesternus;Canis dirus; andLynx rufus;and the first regional records ofPalaeolama mirifica,Procyon lotor, andSmilodoncf.S.fatalis. The Térapa mammals presented here provide a more comprehensive understanding of the faunal community restructuring that occurred in northern Mexico from the late Pleistocene to present day, indicating further potential biodiversity loss with continued warming and drying of the region.

Highlights

Conservation paleobiology aims to use knowledge of the past to make informed predictions about the future of Earth’s threatened biodiversity (Dietl and Flessa, 2011, Dietl et al, 2015, Barnosky et al, 2017)
From the mammalian fauna found at Térapa, we provide descriptions for eight species in seven genera, including Equus, Platygonus, Camelops, Palaeolama, Canis, Procyon, Lynx, and
Camelops, and Canis are well-represented at sites across the North American desert region and, Platygonus and Lynx are sparsely represented in northern Mexico, they have extensive records in the southwestern US, making them expected at Térapa during the Rancholabrean

Summary

Introduction

Conservation paleobiology aims to use knowledge of the past to make informed predictions about the future of Earth’s threatened biodiversity (Dietl and Flessa, 2011, Dietl et al, 2015, Barnosky et al, 2017). Other similar work has documented the presence of Bison in the Grand Canyon region (Martin et al, 2017), inspired interagency conservation and management plans for Bison today (Plumb and McMullen, 2018), and encouraged restoration of threatened plant species in Hawaii (Burney and Burney, 2007). Xeric landscapes, such as those in the southwest US and northwest Mexico, are challenging for natural resource management (Sayre et al, 2013). Large animals and plants are disproportionately important for ecosystem function (Enquist et al, 2020), and changes in these communities can indicate environmental change (Blois and Hadly, 2009)

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