12-1 An Investigation of Enamel Degradation in Teeth of the Homestead Site Microvertebrate Assemblage of the Garita Creek Formation (Late Triassic: Norian) New Mexico

Session: Advances in ichnology: walking in Memphis and other records of behavior (Posters)

Poster Booth No.: 86

Presenting Author:

James Bartlinski

Authors:

Bartlinski, James Joseph¹, Heckert, Andrew B.², Lauer, Bruce H.³, Lauer, Rene⁴

(1) Appalachian State Univ, Belk Library, Fayetteville, NC, USA, (2) Appalachian State University, Boone, NC, , (3) Lauer Foundation of Paleontology, Science, & Education, Wheaton, IL, , (4) Lauer Foundation of Paleontology, Science, & Education, Wheaton, IL, ,

Abstract:

The Homestead Site in the Upper Triassic Garita Creek Formation of New Mexico contains a high degree of diversity in its microvertebrate assemblage, including teeth attributed to phytosaurs preserving a variety of different forms of enamel degradation that are historically attributed to digestion or erosion. This study examines this enamel degradation and categorizes it based on patterns of enamel loss. The two main types of enamel loss identified are “pitting,” or teeth characterized by irregularly distributed ~circular pits that have an average diameter of ~0.2mm and are often associated with deposits of calcium carbonate (CaCO₃) powder, and “thinning,” or teeth characterized by the total or near total loss of enamel, with any remaining enamel in elongate strips. Additionally, the teeth with thinned enamel can be further divided by grades of enamel loss, with one extreme displaying only a small amount of thinning of the surface enamel and the other extreme showing complete enamel loss, such that the entirety of the preserved tooth is the dentine core. The pitted teeth are hypothesized to either represent traces of bacterial biofilm formation on the surface of the teeth or else symptomatic of an individual with hypomineralized teeth, a condition observed in modern crocodilians. The CaCO₃ deposits appear to be the result of CaCO₃ precipitating out of an alkaline sediment. The thinning is hypothesized to be caused by the teeth being consumed by an organism with an especially long digestive period, resulting in digestive fluids completely removing the enamel. While the agent responsible for the pitting remains unknown due to a lack of similar traces being reported in the literature, the thinned teeth are very similar to those that have been attributed to both modern and fossil crocodilian digestion. At the Homestead site, these could be the result of digestion by phytosaurs or temnospondyls, both of which are known from the site and apparently converged upon a similar body plan and mode of life to crocodilians. The thinning is informative for reconstructing a food web of the site, as it displays direct evidence of feeding interactions between organisms. The pitting could highlight an additional convergent feature shared by phytosaurs and modern crocodilians.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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