Soft Tissue Preservation in Terrestrial Mesozoic Vertebrates

Exceptionally preserved fossils—i.e., those that retain, in some manner, labile components of organisms that are normally degraded far too quickly to enter the fossil record—hold the greatest potential for understanding aspects of the biology of long-extinct animals and are the best targets for the search for endogenous biomolecules. Yet the modes of preservation of these labile components, and exactly what remains of the original composition, are not well understood. Here, I review a selection of cases of soft tissue preservation in Mesozoic vertebrates, examine chemical and environmental factors that may influence such preservation, explore the potential of these fossils for high-resolution analytical studies, and suggest clarification of terminologies and criteria for determining the endogeneity of source and the degree of preservation of these well-preserved tissues.