Wilson-Leonard An 11,000-year Archeological Record of Hunter-Gatherers in Central Texas Volume V: Special Studies

Study of the archeology of the Wilson-Leonard site has opened broad new vistas for the reexamination and improved interpretation of regional prehistory. Beyond that, it is of national importance in terms of both data and interpretation (for example, on the Paleoindian era) and the concepts used in its excavation and analysis. It is unique in other ways. In most cases, deep, stratified, multicomponent sites of this integrity are rarely excavated (in Texas, at least) more than once and the potential for long-term research is not fully met. As the reader will learn, Wilson-Leonard was first excavated on a large scale by archeologists of the Texas Department of Trans-portation (TxDOT) from 1982-1984 but was not formally published. Much attention went, deservedly, to the discovery of a Paleoindian burial at the site. Beginning in 1991, the Texas Archeological Research Laboratory was contracted by TxDOT to evaluate the records from the excavations and to make recommendations on the preparation of a comprehensive report. Given the many changes that had occurred in the technology of archeological excavation and the rise of new theoretical and analytical approaches, the TxDOT data appeared to be insufficient for more than a descriptive study. Yet, it was clear that the rich body of information from Wilson-Leonard warranted more than that. Thus, Michael B. Collins and his staff recommended that a second major excavation be undertaken in order to provide a better context for the TxDOT materials. Further, the findings from both excavations would then be fully integrated into a final report. Thanks to the foresight of Kenneth Bohuslav and Ann Irwin at TxDOT, this proposal was accepted and excavations directed by Collins were carried out in 1992-1993

The extinction of Equidae and Proboscidea in South America. A test using Carbon isotope data

Carbon isotopes, preserved in 166 samples of fossil teeth and bone, provide key data for understanding the ecology of extinct horses and gomphotheres during the Plio-Pleistocene in South America. To analyze the patterns of dietary partitioning throughout this time we divided the samples into 19 groups, taking into account the genus and the age of the corresponding localities. In this study, the diets of both groups are assessed to test extinction hypotheses. The strong resource partitioning among herbivores assumed under Co-evolutionary disequilibrium hypothesis is supported by isotopic data of horses from latest Pleistocene. <i>Hippidon</i> and <i>Equus</i> had very different diets. In contrast, species of gomphotheres from late Pleistocene in South America seem to have had less specialized diets containing a broad mix of both C<sub>3</sub> and C<sub>4</sub> plants, which is in line with the dietary assumptions of the mosaic-nutrient hypothesis, but does not support the assumptions of Co-evolutionary disequilibrium hypothesis.<br><br>Los isótopos del carbono preservados en 166 muestras de dientes y huesos fósiles son un dato clave para entender la ecología de los de caballos y gonfoterios durante el Plio-Pleistoceno en América del Sur. Para analizar los cambios en las reconstrucciones de la dieta durante este lapso temporal hemos dividido las muestras en 19 grupos, teniendo en cuenta la sistemática y la cronología de cada localidad. En este estudio, las dietas de ambos grupos son evaluadas para probar las hipótesis sobre su extinción. El alto fraccionamiento en el uso de los recursos entre los herbívoros que asume la hipótesis del desequilibrio co-evolutivo es sustentada por los datos isotópicos de los caballos del Pleistoceno tardío. <i>Hippidion</i> y <i>Equus</i> tenían una dieta muy diferente. En contraste, las especies de gonfoterios de finales del Pleistoceno parecen tener una dieta menos especializada con una combinación de plantas C<sub>3</sub> y C<sub>4</sub>, que está en consonancia con los supuestos de la hipótesis del mosaico de nutrientes, pero no admite los supuestos de la hipótesis de desequilibrio Co-evolutivo