Comparative morphology and functional interpretation of the sutures in the dermal skull roof of temnospondyl amphibians

Sutures in the dermal skull roof of several Palaeozoic temnospondyl amphibians were studied, including Archegosaurus decheni, Sclerocephalus haeuseri, Cheliderpeton latirostre (Archegosauridae), Acanthostomatops vorax (Zatrachydidae), Onchiodon labyrinthicus (Eryopidae), Micromelerpeton credneri and Branchierpeton amblystomum (Dissorophoidea). Lamellae, flat bevels, butt joints, steep walls, and grooves are the sutural types occurring. Morphological sutural differences cannot be used as taxonomically relevant characters, as they mainly differ in their functional manifestations. Similarities of sutural patterns in taxa not closely related are most probably based on convergence, therefore sutural morphology allows functional conclusions rather than revealing phylogenetic relationships. The basic sutural pattern is described in Micromelerpeton credneri. Different textures and obliquity patterns of the sutural surfaces are characteristic of each region of the skull roof. In all temnospondyls studied, the median plane and the margin of the skull roof show a nearly uniform sutural morphology; the circumorbital region is most complex. Although the skulls studied are akinetic, mesokinetic movements of dermal elements along their sutures must have been permitted to guarantee the dynamic stability of the skull construction.