Insights on the Cranial Anatomy and Osteohistology of Cyonosaurus

This study investigates the cranial anatomy and life history of the small-bodied gorgonopsian Cyonosaurus. Previous research on gorgonopsians has disproportionately focused on larger members of the clade, leaving smaller forms relatively understudied. This gap has led to several unresolved questions, the most pressing of which concerns gorgonopsian ontogeny. Specifically, it remains unclear whether small-bodied gorgonopsians represent genuinely diminutive adult individuals or juveniles of larger species. The specimen NHCC LB1087 presents an ideal opportunity to address this issue and gain new insights into the biology of small-bodied gorgonopsians. The first chapter focuses on cranial anatomy. Due to the specimen’s preservation, many taxonomically important features were obscured by surrounding rock. To overcome this, NHCC LB1087 was CT scanned and digitally segmented, revealing internal structures that are rarely preserved. These anatomical details supported its identification as Cyonosaurus sp. The second chapter employs paleohistology to assess the growth strategy and ontogenetic stage of NHCC LB1087. The results indicate that this specimen exhibits a growth pattern distinct from any other gorgonopsian sampled to date. These findings challenge current hypotheses about gorgonopsian biology and their extinction during the Permo-Triassic Mass Extinction.