A review of fighting adaptations in dinocephalians (Reptilia, Therapsida)

Abstract

The cranial structure of anteosaurid and many tapinocephalid dinocephalians became modified in a manner consistent with Geist's hypothesis that they used their heads for pushing and ramming during intraspecific combat. These modifications are most pronounced in certain tapinocephalids by the evolution of a strong dorsal head shield supported by a massive arch network suitable for receiving and supporting blows delivered to the dorsal surface of the head. The position of the occipital condyle reduced the torque created by such blows at the craniocervical joint. Evidence also indicates that the head was reoriented into a position suitable for butting. The cranial architecture displayed by dinocephalians suspected of headbutting differs from that of living mammalian rammers. The differences can be directly attributed to the modification, in the former, of a reptilian skull with its relatively unexpanded braincase into a ramming instrument.