Taphonomy

Taphonomy is a multidisciplinary, multitasking body of knowledge that studies the processes affecting organic remains after death—that is, the transition of these remains from the biosphere into the lithosphere. Taphonomic studies are key to paleobiology, paleontology, archaeology, geology, and geography, among other disciplines, as they impinge directly on our capacity to reconstruct paleoenvironments and past biotas. They do so by understanding the postmortem processes on biological materials and how they affect the fossil record—broadly defined as the set of nonliving remains and traces of organisms—and the information therein.

The term taphonomy, from the Greek taphos and nomos (the “laws of burial”), was coined by Ivan Efremov in 1940, although such inquiries had been carried out well before, notably by German paleontologists in the late 19th and early 20th centuries. These researchers focused primarily on paleoenvironmental reconstruction, while Efremov and others emphasized information loss and biases introduced in the fossil record. Other researchers, especially after the input by Anna Behrensmeyer, Susan Kidwell, and Diane Gifford, have focused on the “positive” contributions of taphonomy as well. These emphasize the preservation of the fossil record and the paleoecological and paleobiological information contained in the signatures of the processes that have affected it through time. Moreover, all the recycling pathways of biologically derived materials are informative to taphonomic enquiry.

The processes affecting organic remains from death to final burial, such as carnivore scavenging of vertebrate carcasses, are different from those occurring from final burial until recovery, as is the case with mineral replacement in different organic remains. The former are known as biostratinomy and the latter, as diagenesis, and both constitute taphonomy. On infrequent occasions, as in the case of severe floods and catastrophic death, rapid burial of organisms lead to large concentrations of exceptionally well-preserved fossils, known as fossil lagerstätten.

Taphonomists study both direct and indirect evidence—that is, not only the organic remains themselves but also the traces of different organisms, such as the tooth marks of a predator on bones or a leaf imprint on a sedimentary matrix. These traces or signatures of activity by an organism are also known as ichnofossils and commonly inform us of the interactions with its environment. Finally, they study the geological context where the fossils and traces are deposited as well.

To understand and interpret all these lines of evidence, taphonomic principles are needed. As in other historical sciences, the most powerful [Page 2776]strategy for doing so is actualism—that is, the study of contemporary, observable taphonomic processes producing effects analogous to those observed in the fossil record, and their causes. This strategy has been key in taphonomy since the German Aktuopaläontologie (invertebrate) program in the early 20th century. Observing present-day processes and their contexts links causes and effects, thereby generating models that can be applied to the fossil record by analogy. In some cases, experiments can help understand the effects of some processes as well. Such studies require assuming that the processes operating in the past are essentially the same as those operating in the present, although their rates and configurations and their interactions may well have changed through time. This methodological assumption is called uniformitarianism.

...