Tepexpan

Tepexpan
Name	Tepexpan
Settlement type	Village / Archaeological site
Country	Mexico
State	State of Mexico
Municipality	Acolman

Tepexpan Tepexpan is a village and Pleistocene–Holocene archaeological site near Valle de México, notable for early human and fauna remains. The site has been central to debates involving radiocarbon dating, stratigraphy, and Pleistocene paleontology that engaged researchers from institutions such as the National Autonomous University of Mexico, the Smithsonian Institution, and the Peabody Museum of Archaeology and Ethnology. Its finds have been compared with assemblages from sites like Tepexpan Lake and regional localities including Tlapacoya, Tizayuca, and Chalco (altépetl).

Geography

The site lies in the lacustrine plain of the former Lake Texcoco within the Basin of Mexico City, situated in the municipality of Acolman, State of Mexico (state), near the town of Acolman de Nezahualcóyotl and the modern Mexico City metropolitan area. Tepexpan's geomorphology is part of the closed basin that also contains Texcoco (lake), Chalco (Lake) and sedimentary sequences correlated with sequences from Toluca and the Valle de Toluca. The regional hydrology and volcanic context involve the Nevado de Toluca, the Popocatépetl volcanic complex, and the Basin's Pleistocene lake systems monitored by geologists from the Instituto de Geología (UNAM).

Archaeological discoveries

Excavations at the site produced lithic and faunal remains recovered from lacustrine silts and clays, including stone tools comparable to those from Coxcatlán Cave, Santa Isabel Iztapan, and Tehuacán Valley sequences studied by archaeologists associated with the Instituto Nacional de Antropología e Historia and the Peabody Museum. Finds include worked chert and obsidian flakes related to procurement networks linked to sources near Otumba and Pachuca as well as heavy fauna remains similar to those reported at Zacapu Lagoon and Tlapacoya. Excavation reports were disseminated through venues such as the Proceedings of the National Academy of Sciences and monographs by researchers affiliated with UNAM and the Smithsonian Institution.

Tepexpan Man and human remains

A prominent discovery often called "Tepexpan Man" comprises partial adult human skeletal remains recovered in lacustrine sediments; recovery involved workers collaborating with archaeologists from INAH and paleoanthropologists connected to the Peabody Museum of Archaeology and Ethnology and the Museo Nacional de Antropología (Mexico City). Comparative osteological analyses referenced collections at the American Museum of Natural History, the Natural History Museum, London, and the Museo Nacional de Antropología to assess morphology, pathology, and taphonomy. Debates have compared the remains with Early Holocene and Late Pleistocene individuals from sites such as Hoyo Negro, Monte Verde, Piedras Blancas, and Beringia sample contexts.

Chronology and dating controversies

Chronometric work at Tepexpan has produced contested dates using radiocarbon methods debated by specialists at University of Arizona, University of Oxford, and Caltech. Initial age estimates placed some remains in the Late Pleistocene, prompting comparisons to Clovis culture chronologies and pre-Clovis claims from Monte Verde and Meadowcroft Rockshelter. Subsequent reassessments invoked diagenetic alteration, reservoir effects in closed basins like Lake Texcoco, and sample contamination issues documented in literature from Radiocarbon (journal), the Journal of Archaeological Science, and reports by laboratories such as the University of Groningen Radiocarbon Laboratory and the Arizona AMS Laboratory.

Paleoenvironment and fauna

Faunal assemblages from Tepexpan include megafauna and smaller vertebrates whose identifications were cross-checked with collections from Museo de Paleontología (UNAM), regional studies in the Valle de México and comparative faunas from Tequixquiac, Tlapacoya, and Coahuila localities. Taxa reported encompass proboscideans and large ungulates similar to those documented in Cenozoic Research and paleontological surveys by the Instituto de Geología (UNAM), with paleoenvironmental reconstructions invoking fluctuating lacustrine levels influenced by late Pleistocene climatic events such as the Last Glacial Maximum and Younger Dryas analogs discussed in paleoclimatology work at INAH and the IPCC regional studies.

Cultural context and artifacts

Artifacts from the site—flaked stone, hearth features, and worked bone—were contextualized with regional lithic traditions including parallels to assemblages from Tlapacoya, Coxcatlán Cave, and early Holocene horizons of the Tehuacán Valley sequence excavated by teams from UNAM and the Smithsonian Institution. Interpretation of cultural behavior drew on frameworks developed in comparative research at Monte Albán, Teotihuacan, and early sites in Central Mexico by scholars from UNAM, INAH, and international collaborators at institutions like the University of Cambridge and the Max Planck Institute for Evolutionary Anthropology.

Research history and interpretations

Research at the site began in the mid-20th century with fieldwork by Mexican and international teams, including investigators associated with INAH, UNAM, the Peabody Museum, and the Smithsonian Institution, followed by analytical studies published through venues such as the Journal of Archaeological Science and regional monographs. Interpretive debates involve chronology, site formation processes, and the implications for peopling of the Americas—dialogues that reference contrasting models advocated by researchers connected to Clovis-first proponents and pre-Clovis proponents who cite Monte Verde and Gault Site evidence. Ongoing work involves multidisciplinary contributions from paleontologists, geochronologists, and archaeologists at institutions like the University of Michigan, University of California, Berkeley, and the National Museum of Natural History.

Category:Archaeological sites in Mexico