Cranial kinesis in the amphibia: a review.

All extant orders of amphibians are characterized by kinetic skulls. Main type of intracranial movability in amphibians is pleurokinetism, that is supplemented in different amphibian groups by various types of rhyncho- and prokinetism. The most primitive pattern of cranial kinesis is revealed in the stegocrotaphic gymnophions. More paedomorphic species retain general cranial flexibility that is characteristic of larval skull. That is unfavourable for evolution of well-regulated (adult) cranial kinesis and related feeding adaptations. Kinetism is also reduced in the species with heavily ossified skulls. Adaptive role and evolution of cranial kinesis in amphibians are discussed.