Osseous anomalies of the cryptobranchid Eoscapherpeton asiaticum (Amphibia: Caudata) from the Late Cretaceous of Uzbekistan

Abstract

Osseous anomalies/pathologies in the Late Cretaceous cryptobranchid salamander Eoscapherpeton asiaticum from the Turonian Bissekty Formation of Uzbekistan are analyzed using gross morphological description, microCT, and histologic analysis. These pathologies result from trauma (fractured and subsequently healed dentary and femora; hematoma on femur), possible infection due to trauma (prearticular with exostosis and necrotic cavities; anterior trunk vertebra and fused vertebra with pathological enlargements formed during reactive periosteal growth) and congenital disorders (hemivertebra and fused vertebrae with shortened asymmetrical centra and abnormal arrangements of transverse processes). The origin of the pathologies of two atlantal specimens (enlargement of transverse processes) is unclear. Our report of hemivertebra in Eoscapherpeton is the first occurrence of this congenital pathology in a fossil lissamphibian. The occurrence of several traumatic femoral pathologies in Eoscapherpeton could be a result of intraspecific aggressive behavior. Bone pathologies are described for the first time in fossil salamanders.