Cranial Bosses of Choerosaurus dejageri (Therapsida, Therocephalia): Earliest Evidence of Cranial Display Structures in Eutheriodonts.

Abstract in brief

• Choerosaurus dejageri, a late Permian therapsid from South Africa, had unique cranial bosses on its maxilla and mandible, representing the earliest evidence of such display structures in eutheriodonts.
• These cranial features are believed to be used for low-energy display or intraspecific competition rather than aggressive head-butting, indicating their role in sexual selection and social behaviors.
• The presence of similar display features in other basal therapsids suggests that sexual selection was an important factor in the early evolution of mammals, influencing the development of cranial outgrowths across different lineages.