Megamammals

El león americano Panthera atrox, fue un importante componente de la megafauna del Pleistoceno Tardío en América del Norte. Aquí documentamos un nuevo registro de P. atrox para Chiapas con base en un m1 izquierdo parcialmente completo, rescatado de la localidad La Simpatía, en el municipio de Villa Corzo. Con este nuevo ejemplar se contabilizan tres registros para el estado, constatando que P. atrox fue un  depredador común en esta región de México durante el Pleistoceno Tardío.
The American lion Panthera atrox, was an important component of the late Pleistocene megafauna in North America. Here we document a new record of P. atrox from Chiapas, based on a partially complete left m1 collected from La Simpatia locality, Villa Corzo municipality. With this new specimen there are accounted three records for Chiapas, which evidence that P. atrox was a common predator in this region of Mexico during the Late Pleistocene.

RESUMEN

Se describen por primera vez los restos fósiles rescatados en los sedimentos cuaternarios que afloran en Villaflores, Chiapas, y se confirma la presencia de los megamamíferos Eremotherium laurillardi, Glyptotherium floridanum, Mammuthus columbi, Cuvieronius hyodon, Equus conversidens y Odocoileus  virginianus. El conjunto faunístico es asignado a la edad biocronológica Rancholabreano (Pleistoceno Tardío). Con base en los taxones presentes en las localidades de Villaflores (fauna y polen), se infiere que durante el Pleistoceno Tardío predominó un pastizal abierto con zonas de árboles bajos. Probablemente la región central de Chiapas pudo haber servido como refugio estacional, además de ser un paso obligado durante el intercambio de megamamíferos entre Norteamérica y Sudamérica.

This is an excerpt from chapter 5 of the out-of-print book by G. Haynes, The Early Settlement of North America: The Clovis Era, (c) 2002 by Cambridge University Press. The chapter discusses megamammal-hunting by fluted-point-makers in North America.

During the latest Pleistocene-earliest Holocene, South American terrestrial vertebrate faunas suffered one of the largest (and probably the youngest) extinction in the world for this lapse. No megamammal and most of the large mammals survived in the continent, and several complete ecological guilds and their predators were erased. A giant terrestrial turtle also went extinct. The mammal extinction had been attributed mainly to overkill, climatic change or a combination of both. We propose human overhunting as the main cause of the extinction in South America. However, according to our interpretation, the slaughtering of mammals had to have been accomplished in a particular frame. During most of the middle and late Pleistocene, dry and cold climate and open areas predominated in South America. Nearly all of those megamammals and large mammals that became extinct were adapted to this kind of environments. The periodic, though relatively short, interglacial increase in temperature and humidity had provoked the dramatic shrinking of open areas and extreme reduction of the biomass (not diversity) of mammals adapted to open habitats. Many populations were surely close to a minimum level of population viability. During the longer glacial periods, mammals populations recovered. This alternation of low and high biomass of mammals from open and closed areas is what we refer to as the Zig-Zag. During the present interglacial, humans entered South America and broke the Zig-Zag when killed all the megamammals and almost all the large mammals during their less favourable periodic lapse.

El registro arqueológico de la región pampeana (Argentina) indica la supervivencia de mamíferos de gran tamaño hasta ca. 7500 años AP, hasta el momento representado exclusivamente por xenartros. En las últimas décadas, análisis específicos sobre xenartros fósiles han permitido formular hipótesis paleobiológicas que podrían ayudar a comprender esta situación. Los estudios del aparato masticatorio, incluyendo área de la superficie oclusal dentaria, hipsodoncia y ancho relativo del hocico, han provisto hipótesis sobre dietas, hábitos alimenticios y preferencias de hábitat. Los resultados de estas líneas de investigación permiten proponer que los xenartros, en especial gliptodontes y perezosos terrestres, habrían consumido y explotado una gran variedad de recursos vegetales y hábitats y, por lo tanto, la coexistencia de varias especies herbívoras de xenartros pudo sustentarse a través del consumo diferencial de un amplio rango de recursos alimenticios. El objetivo de este trabajo es evaluar cómo los aspectos biológicos inferidos para estas especies pudieron haber representado ventajas en ambientes recientemente modificados, como aquellos de la transición Pleistoceno-Holoceno, en comparación con otros taxones (e.g., Artiodactyla, Perissodactyla), conduciendo, entre otras cosas, a la supervivencia diferencial de especies. Se presenta para ello información arqueológica, contextual, cronológica, así como los resultados derivados de los análisis paleobiológicos de estas especies.

Abstract

Paso Otero 5 (Pampean region, Argentina) is characterized by the presence of extinct megamammals and modern species in association with fish-tail projectile points chronologically located ca. 10,450-10,200 years BP. The purpose of this paper is to summarize and discuss the results from several lines of evidence carried out for the last 10 years, particularly archaeological, chronological, geological, and paleonvironmental studies for the Pleistocene-Holocene transition. These results, integrated to regional information from other early sites, enable to highlight the main contributions of Paso Otero 5 to understanding hunter-gatherers adaptation and ways of life. In this sense, results indicate that a) human colonization occurred under cold, arid-semiarid, severe, and fluctuating climatic conditions; b) a great diversity of extinct species were recorded in a critical transitional period; c) megamammal bones were used as fuel; d) a planned and complex lithic technological strategy were developed; e) a good knowledge of the landscape and of resources distribution was acquired; f) wide home ranges and social interaction networks, both at a regional and extra-regional scale, were established by the Pleistocene-Holocene transition .