30-5 Intra-Specimen Variability in Cellular and Soft Tissue Preservation Within a Fossil Bone: Evidence and Implications

Session: Laws of the Grave: Advances in Taphonomy Across the Paleontologic Record (Posters)

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Abstract:

Since the 2007 discovery of cells and soft-tissue microstructures retaining peptides of endogenous proteins within the femur of a Tyrannosaurus rex, numerous studies have sought to explore the extent of this style of exceptional preservation across the fossil record—recovering cellular and soft-tissue microstructures such as osteocytes and blood vessels as well as, occasionally, traces of their component proteins, carbohydrates, and lipids. Few researchers, however, have tested whether there is spatial variability in the preservation of such organic microstructures throughout a single fossil skeletal element. Therefore, we performed a pioneering case study to explore this question, using 0.5 M ethylenediaminetetraacetic acid pH 8.0 to demineralize 12 samples excised from the midshaft and epiphyses of a tibia from a partial Edmontosaurus annectens skeleton recently collected from the Cretaceous Hell Creek Formation in Montana. Any potential cells and/or soft tissue microstructures remaining after demineralization were identified morphologically based on their similarity to extant vertebrate cells and tissues. Our demineralization assays revealed moderate variability in both the quantity and preservation quality of osteocytes, blood vessels, and fibrous matrix among the 12 samples, including among those from different regions of the bone with comparable histologic structure (i.e., porosity). For example, fewer blood vessels were recovered from samples taken from the distal epiphysis of the bone than from its proximal epiphysis, and vessels were found to range in color among these same samples from light orange to dark brown, potentially indicative of chemical heterogeneity in their preservation. Similarly, the four samples taken from the proximal epiphysis exhibited surprisingly variable preservation of osteocyte filopodia, between basically lacking filopodia to retaining long and intricate filopodia with multiple levels of ramifications. In contrast, osteocytes and fibrous matrix were found to present a narrower range of colors than vessels throughout the bone, with most exhibiting a light tan color. Our study thus represents the first rigorous investigation into the spatial variability of cellular and soft tissue preservation within a fossil bone, revealing that preservation of such potentially-endogenous microstructures can be heterogeneous rather than uniform throughout a single specimen. Broader sampling throughout fossil bones could enhance both knowledge of the fossilization mechanism(s) driving cellular/soft-tissue preservation within bone and the ability of researchers to identify and select optimal regions for future paleomolecular analyses.

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

doi: 10.1130/abs/2025AM-9442

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