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The Smoky Hill Member of the Niobrara Chalk (Late Coniacian to Early Santonian), Kansas is renowned for its diverse assemblage of bromalites including coprolites, enterospirae, and even rare regurgitates. Producers of these fecal products are atributed to sharks, teleost fish and marine reptles based on their variously spiraled and non-spiraled morphologies, containing a range of invertebrate and vertebrate inclusions. Traditonally, examinaton of these fossils has necessitated sub-sampling via consumptve techniques like disaggregaton or dissoluton on either portons or the entrety of the specimen. Three-dimensional imaging techniques such as X-ray tomographic microscopy (µCT) offer a non-destructve alternatve to reveal both macroscopic and microscopic inclusions. Due to the minimal diagenetc alteraton of specimens from this locality, µCT imaging and segmentaton facilitates the extracton of structural and taphonomic informaton potentally obscured by physical extracton methods. This study employes non-destructve methods to explore the diversity of gross morphotypes represented by coprolites and a possible regurgitate from this member alongside their internal structure and inclusions. Preliminary results from segmented specimens offer insights into the taphonomic atributes of the coprolites and their ability to preserve exceptonally delicate structures, with remains of vertebral columns stll partally artculated. Lightly to non-mineralized inclusions, possibly crustaceans and scale remains, represent a hidden component of the assemblage rarely preserved otherwise. Virtual renders also enable quanttatve analysis of the inclusions with respect to the degrees of fragmentaton, the orientaton and alignment of boney inclusions relatve to the longitudinal axis of the specimen, and the relatve proportons of bone, pore space, and phosphatc matrix. This work offers a rare glimpse into the feeding, digestve, and excretory behaviors of producers whilst simultaneously capturing unique paleoecological and paleoenvironmental informaton.
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X-ray tomographic microscopy of Eocene coprolites from Pipestone Springs Main Pocket, southwest Montana
The Eocene Pipestone Springs Main Pocket (Renova Formation, Jefferson County, Montana, United States of America) is a locality renowned for its diverse Chadronian (late Eocene; ∼38–33.9 million years ago) mammalian fauna and abundant coprolites. Two distinct coprolite size classes were previously identified in the trace fossil assemblage from which we selected representatives to investigate feeding behaviors and dietary selection of the producers. A subset of the selected coprolites was analyzed based on their compositional and taphonomic attributes using non-destructive x-ray tomographic microscopy in combination with more traditional methods including thin-section petrography, scanning electron microscopy, and energy dispersive spectroscopy. Among the features extracted in the tomographic data were skeletal fragments, including those showing evidence of bone-crushing; delicate hair molds; encrusted lithic fragments; and several irregular pores and cracks throughout the coprolites. Segmentation and volumetric renders permit quantitative assessment of the relative proportions of inclusions, revealing porosity as a primary volumetric element aside from the matrix and bone inclusions. There was no significant difference in the total volume of bone extracted between coprolite size class, though the smaller coprolites preserved a relatively higher volumetric proportion of undigested skeletal material. This multi-visualization approach provides a means to observe and evaluate differences in the coprolite gross morphology and inclusions across the two size classes, thereby offering valuable insights into the broader paleoecology of the Pipestone Springs Main Pocket coprolite producers and holding promise for comparable paleo-dietary studies of other coprolite-rich deposits.
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- Award ID(s):
- 1917031
- PAR ID:
- 10482710
- Publisher / Repository:
- Frontiers
- Date Published:
- Journal Name:
- Frontiers in Earth Science
- Volume:
- 11
- ISSN:
- 2296-6463
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/feart.2023.1130107
