217-6 An Actualistic Study of Crocodylian Decomposition: Preliminary Observations and Implications for Archosaurian Decomposition

Session: Paleontology, Paleoecology/Taphonomy

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Abstract:

Reptilian decomposition historically has been severely understudied when compared to mammals. Recent research on decomposition patterns in larger-bodied squamates has found that reptiles vary from mammalian models in some respects (e.g. patterns of disarticulation and skin retention) while remaining similar in others (e.g. insect succession and weathering stages). However, the question remains whether these patterns are consistent across reptilian groups.

To expand this long-term study into archosaurs, four American alligators (Alligator mississippiensis) and two African dwarf crocodiles (Osteolaemus tetraspis) were left to decay naturally in a wooded clearing in Knoxville, Tennessee, U.S.A., starting in June of 2025. They were placed in caged boxes, allowing small invertebrates to retain access to the carcasses while preventing larger vertebrate scavengers from wholly removing them. The four alligators were left intact when emplaced; however, the two crocodiles were set out dismembered. Although observations of decomposition progression, disarticulation, and insect activity were made daily during the early stages, visit frequency decreased once later stages of decomposition were reached and the rate of observable changes slowed. Motion-activated trail cameras were also placed to track any macro-vertebrate activity.

Preliminary observations have revealed broadly similar patterns to those seen in the Argentine tegus (Salvator merianae); however, there were some key differences. The progression of decomposition in crocodylians was slower, most likely because of the size differences between the species. The disarticulation patterns differed as well, starting with the back legs rather than the skull-first due to the concentration of maggot activity around the cloacal region, partnered with the more highly fused skull within crocodylians. Furthermore, patterns of insect activity were broadly similar, but exhibited higher diversity in the later stages of decomposition in the crocodylians. In the original tegu study, observations were made of the external layer of skin detaching from the underlying dermis and creating small air pockets. In the crocodylians, this pattern was more extreme, with the epidermis shedding from the dermis and exposing the osteoderms to earlier weathering. The scalation pattern present on the overlying epidermis persisted on the exposed dermis, with implications for impression-style preservation of reptilian skin. These results suggest that significant variation in patterns of decomposition is present both between reptiles and mammals and within major reptilian groups.

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

doi: 10.1130/abs/2025AM-9487

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