EXPLORATION OF THE INFLUENCE OF ANATOMICAL DIFFERENCES IN DECOMPOSITION: AN ACTUALISTIC STUDY USING ARGENTINE TEGUS (SALVATOR MERIANAE)

The study of decomposition and its effects on remains in both the modern and fossil record is a fundamental cornerstone of the fields of paleontology, forensic anthropology, paleoanthropology, and zooarcheology. However, given the historical focus of these fields on mammalian decomposition, taphonomic studies of other clades remain comparatively underexplored. As a result, findings from mammalian studies are often applied to non-mammalian taxa without critical examination. Recent investigations into the taphonomic histories of dinosaurian “mummies” have raised important questions regarding the influence of intrinsic biological differences between mammals and reptiles during decomposition.

To replicate a selection of these foundational mammalian studies with a reptilian proxy and assess points of similarities and differences between the groups, we observed the natural decomposition of thirty Argentine tegus placed in an open-grid container in a wooded clearing in May 2023. Observations were made to track the stages of decomposition, insect succession, skeletal disarticulation, and weathering.

A year after placement, all specimens have retained significant amounts of skin, ranging from long strips to entire skin envelopes, contradicting previous assumptions that extensive skin preservation in fossils must rely on rapid burial. Retained skin also had downstream effects on the disarticulation and post-mortem posture of the animal, often limiting disarticulation within the skin envelopes. Depending on if the skin of the face adhered to the underlying cranial bones, insect activity concentrated in the cranial openings had the chance to allow the unfused skull bones in many specimens to disarticulate first, departing significantly from the limbs-first model of mammalian disarticulation. The dehydration of retained skin also offers a potential explanation for the iconic “death pose” seen in many dinosaurian taxa. These results stress the need for considering clade-specific anatomical differences when applying actualistic data to paleontological datasets.

This research was funded by the University of Tennessee Department of Earth, Environmental, and Planetary Sciences.