Palaeontologia africana
Permanent URI for this communityhttps://wiredspace.wits.ac.za/handle/10539/13253
ISSN (print): 0078-8554
ISSN (electronic): 2410-4418
For queries regarding content of Palaeontologia africana collections please contact Jonah Choiniere by email : jonah.choiniere@wits.ac.za or Tel : 011 717 6684
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Item The bony labyrinth of late Permian Biarmosuchia: palaeobiology and diversity in non-mammalian Therapsida(2017-07) Benoit, Julien; Manger, Paul R; Fernandez, Vincent; Rubidge, Bruce SBiarmosuchia, as the basalmost group of Therapsida (the stem group of mammals), are important for understanding mammalian origins and evolution. Unlike other therapsid groups, the bony labyrinth of biarmosuchians has not yet been studied, despite insightful clues that bony labyrinth morphology can provide to address palaeobiology and phylogeny of extinct animals. Here, using CT scanning, surface reconstruction and a 3D geometric-morphometric protocol of 60 semi-landmarks on the bony labyrinth of 30 therapsids (including three Mammaliaformes), it is demonstrated that bony labyrinth morphology of biarmosuchians is very distinctive compared to that of other therapsids. Despite the primitive nature of their cranial morphology, biarmosuchians display highly derived traits in the structure of the bony labyrinth. The most noticeable are the presence of a long and slender canal linking the vestibule to the fenestra vestibuli, an enlarged and dorsally expanded anterior canal, and the absence of a secondary common crus (except for one specimen), which sets them apart from other non-mammalian therapsids. These characters provide additional support for the monophyly of Biarmosuchia, the most recently recognized major therapsid subclade. Although implications of the derived morphology of the biarmosuchian bony labyrinth are discussed, definitive interpretations are dependent on the discovery of well-preserved postcranial material. It nevertheless sheds light on a previously overlooked diversity of bony labyrinth morphology in non-mammalian therapsids.Item The first biarmosuchian from the upper Madumabisa Mudstone Formation (Luangwa Basin) of Zambia(2015-04-01) Sidor, Christian A;This contribution reports the first occurrence of a biarmosuchian therapsid from the upper Madumabisa Mudstone Formation of the Luangwa Basin of northeastern Zambia. Although incomplete, the fossil preserves diagnostic features of post-Biarmosuchus biarmosuchians, such as the presence of a preparietal bone and parasagittal ridges on the basicranial rami of the pterygoids, that allow its unambiguous referral to this group. Based primarily on the record of dicynodonts, the upper Madumabisa Mudstone assemblage can be correlated with the Cistecephalus Assemblage Zone of South Africa. During this interval, the tetrapod faunas of the Karoo and Luangwa basins were remarkably similar and likely characterized by frequent biotic interchange.