215 Coprolite Happens: Insights into Geobiology

Coprolites are significant sources of paleobiological data, providing insights into trophic ecology, migration, taphonomy, chemical cycling, and other geological/ecological fields. In this session, we invite talks about coprolite and other bromolite research.

Tuesday, 21 October 2025
1:30 PM - 5:30 PM
HBGCC, 304B

Community ecology from the Upper Triassic Chinle Formation, southwestern USA: insights from coprolite 𝛿13Corg and 𝛿15N stable isotope geochemistry

Paper number: 215-3
Program: Technical Sessions
Time: 2:10 PM – 2:25 PM

Authors

Abstract

Coprolites represent important evidence of trophic interactions in the fossil record. The organic carbon (𝛿13Corg) and nitrogen (𝛿15N) stable isotope compositions of excrement from extant animals provide evidence for reconstructing ecological interactions, but the application of stable isotopes for reconstructing ancient trophic dynamics from the coprolite record has been limited. In this project, we investigate external and internal coprolite anatomy along with 𝛿13Corg and 𝛿15N compositions of an assemblage of coprolites collected from a sequence of fossiliferous horizons in the Upper Triassic Chinle Formation of northeastern Arizona. This succession represents marginal fluviolacustrine paleoenvironments in the humid equatorial paleotropics of continental Pangaea approximately 225 – 205 million years ago. Here, we present coprolite anatomy and isotopic data from four localities and use this data to infer trophic structure (i.e. we focus on the relative contribution of terrestrial versus aquatic food sources) of the coprolite producers. The data occupy a broad isotopic space, with 𝛿15N values ranging from 8.7‰ to -2.8‰ and 𝛿13Corg ranging from -26.6‰ to -5.0‰, with the values separating in two distinct spaces, reflecting different trophic relationships. Additionally, we use the well resolved temporal and paleoclimatic constraints of these Chinle Formation localities to potentially link changes in trophic structure over time to the drying of the climate during the Late Triassic in central Pangea. Our results also test the fidelity of trophic data sourced from coprolite assemblages to the osseus vertebrate record derived from the same horizons, and this suggests biases towards preservation of coprolites from aquatic and carnivorous groups. These findings denote a significant development in the use of coprolite-derived stable isotopes from the Mesozoic Era to study trophic interactions and provide further details of ecological changes during the Late Triassic.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413226

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.