Soft Tissue and Biomolecular Preservation in Vertebrate Fossils from Glauconitic, Shallow Marine Sediments of the Hornerstown Formation, Edelman Fossil Park, New Jersey

SIMPLE SUMMARY: Original organics and soft tissues are known to persist in the fossil record. To date, these discoveries derive from a limited number of ancient environments, (e.g., rivers, floodplains), and fossils from rarer environments remain largely unexplored. We studied Cretaceous–Paleogene fossils from a peculiar marine environment (glauconitic greensand) from Jean and Ric Edelman Fossil Park in Mantua Township, NJ. Twelve samples were demineralized in acid to remove the mineral component of bone. This treatment frequently yielded products that are visually consistent with bone cells, blood vessels, and bone matrix from modern animals. Fossil specimens that are dark in color exhibit excellent microscopic bone preservation and yielded a greater recovery of original soft tissues, whereas light-colored specimens exhibit poor microscopic preservation and yielded few to no soft tissues. Additionally, a well-preserved femur of a marine crocodilian was found to retain original bone protein by reactions with antibodies. Our results: (1) corroborate previous findings that original soft tissue and proteins can be recovered from fossils preserved in marine environments, and (2) expand the range of ancient environments documented to preserve original organics and soft tissues. This broadens the suite of fossils that may be fruitful to examine in future paleomolecular studies. ABSTRACT: Endogenous biomolecules and soft tissues are known to persist in the fossil record. To date, these discoveries derive from a limited number of preservational environments, (e.g., fluvial channels and floodplains), and fossils from less common depositional environments have been largely unexplored. We conducted paleomolecular analyses of shallow marine vertebrate fossils from the Cretaceous–Paleogene Hornerstown Formation, an 80–90% glauconitic greensand from Jean and Ric Edelman Fossil Park in Mantua Township, NJ. Twelve samples were demineralized and found to yield products morphologically consistent with vertebrate osteocytes, blood vessels, and bone matrix. Specimens from these deposits that are dark in color exhibit excellent histological preservation and yielded a greater recovery of cells and soft tissues, whereas lighter-colored specimens exhibit poor histology and few to no cells/soft tissues. Additionally, a well-preserved femur of the marine crocodilian Thoracosaurus was found to have retained endogenous collagen I by immunofluorescence and enzyme-linked immunosorbent assays. Our results thus not only corroborate previous findings that soft tissue and biomolecular recovery from fossils preserved in marine environments are possible but also expand the range of depositional environments documented to preserve endogenous biomolecules, thus broadening the suite of geologic strata that may be fruitful to examine in future paleomolecular studies.