215-8 Plumbing the Depths of the Niobrara: Prey Size and Preservation in Coprolites of the Smoky Hill Chalk Member

Session: Coprolite Happens: Insights into Geobiology

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The Smoky Hill Chalk (Coniacian-Santonian) boasts a varied assemblage of coprolites, which are broadly attributed to teleosts and tetrapods. However, while these trace fossils have the potential to unveil crucial paleoecological and taphonomic insights into the overall Niobrara assemblage, they have only received limited comprehensive study in the published literature. Preliminary CT imaging and analyses have determined that vertebrate bones are typical inclusions found within non-spiraled Smoky Hill coprolite morphotypes. Moreover, studies of modern marine fecal inclusions have indicated that vertebral dimensions (length, width, and height) can serve as a correlate for prey body size. This study employed non-destructive X-ray microscopy and digital segmentation analyses to explore the dimensions and taphonomic attributes of fifty vertebral inclusions within six ~38-59 mm long by ~15-29 mm wide tapered-morph coprolites. To determine the prey size range of the tapered coprolites’ producer, vertebral inclusion dimensions from the coprolites were compared to measurements from 125 vertebrae of twenty coeval taxa (obtained from museum specimens and the published literature) using Principal Components Analysis (PCA). The PCA indicated that the measured coprolite vertebrae were often smaller and shorter than the measured museum and literature vertebrae, suggesting that coprolites may serve as a preservational refuge for smaller vertebrate remains that would otherwise be damaged or destroyed through taphonomic processes in the surrounding deposits. Moreover, this work provides a clearer picture of the feeding behaviors and prey preferences of the producer of a subset of the Niobrara coprolites whilst simultaneously capturing unique paleoecological and paleoenvironmental information within the Smokey Hill Chalk.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9532

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