Article: A relict rhinesuchid (Amphibia: Temnospondyli) from the Lower Triassic of South Africa
Publication: Palaeontology
Volume:
43
Part:
4
Publication Date:
October
2000
Page(s):
653
–
670
Author(s):
Michael A. Shishkin and Bruce S. Rubidge
Abstract
'Lydekkerina' putterilli Broom from the Lystrosaurus Assemblage Zone (Middle Beaufort Group, South Africa) is shown to be a paedomorphic rhinesuchid (Broomistega putterilli gen. nov.) rather than a lydekkerinid or juvenile stage of the rhinesuchid Uranocentrodon, as previously presumed. The most conspicuous characters, not related to its paedomorphic condition, include the shape of the parietals and the structure of the parasphenoid body and exoccipitals. The pattern of cranial growth changes in Broomistega has been investigated by comparison of the holotype with two hitherto undescribed immature specimens. For several characters referring to the size and position of the orbits, and re-modelling of the jugal proportions, retarded timing of growth transformations, compared to ontogenetic patterns in Permian rhinesuchids (typified by Muchocephalus) is demonstrated. Some features of the evolution of the basicranial region of the skull, in the transition from rhinesuchids to more advanced capitosauroids, are re-evaluated.