2 Interdisciplinary Paleontology: New approaches to solving complex paleontological problems (Part I)

Paleontology is increasingly drawing upon insight from other disciplines to solve complex problems and generate more accurate reconstructions of past life. This session will illustrate novel interdisciplinary research and provide tools to develop such approaches.

Monday, 18 May 2026
8:00 AM - 12:00 PM
Alvarado F

Late Hemingfordian-Barstovian Mammalian Biostratigraphy of the Tesuque Formation (Middle Miocene), Española Basin, North-central New Mexico

Paper number: 2-8
Program: Technical Sessions
Time: 10:40 AM – 11:00 AM

Authors

Abstract

The middle Miocene was a period of climatic, ecological, and depositional change that shaped terrestrial ecosystems across North America. The Tesuque Formation of the Española Basin in north-central New Mexico preserves a fossil-rich record spanning the late Hemingfordian through the Barstovian North American Land Mammal Ages (NALMAs). However, the complex tectonic history and facies variability within this west-tilted half-graben of the Rio Grande Rift have long complicated stratigraphic correlation. To address these issues, an 836-m-thick composite stratigraphic section was constructed within the Bureau of Land Management’s Sombrillo Area of Critical Environmental Concern (ACEC), integrating fossil occurrences with laterally traceable volcanic ash beds. This framework provides temporal control for evaluating faunal and paleoenvironmental change across the Miocene Climatic Optimum (MCO; ~17–14.5 Ma) and the subsequent Miocene Climatic Transition (MCT; ~14.5–13.9 Ma).

During the MCO, the Española Basin experienced warm, humid conditions that coincided with alluvial-fan and fluvial basin-floor deposition and the presence of diverse browsing faunas, including camelids, equids, rhinocerotids, and oreodonts. Progressive cooling immediately after the MCO is marked by retrogradation of alluvial-fan facies, regional floral turnover, including palm extirpation, increased antilocaprid abundance, and the appearance of gomphotheres. Four discrete faunal turnover events (17.241 Ma, 16.322 Ma, 15.343 Ma, 14.397 Ma) correspond closely with climatic and depositional shifts. The final turnover, coincident with the MCT, records a transition from ecosystems dominated by C3 feeders to communities containing mixed feeders that incorporate C4 plants into their diets. Integrating lithostratigraphy, biostratigraphy, and paleoecology refines the temporal framework for middle Miocene mammalian evolution in the southwestern United States and strengthens regional biochronologic correlations across the late Hemingfordian–Barstovian interval.

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410691

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