Cranial morphology and phylogenetic analysis of Cynosaurus suppostus (Therapsida, Cynodontia) from the upper Permian of the Karoo Basin, South Africa

Show simple item record van den Brandt, Marc Abdala, Fernando 2018-03-26T14:52:23Z 2018-03-26T14:52:23Z 2018-03
dc.identifier.issn 2410-4418
dc.description.abstract Non-mammaliaform cynodonts are an important fossil lineage which include the ancestors of mammals and which illustrate the gradual evolution of mammalian characteristics. The earliest cynodonts (‘basal cynodonts’) are known from the late Permian. Cynosaurus suppostus is the second most abundant basal cynodont from the late Permian of the Karoo Basin of SouthAfrica, but is poorly studied, with the most recent description of this taxon being 50 years old. Since then, several important new specimens of this species have been collected, meriting a thorough description of its cranial anatomy and exploration of its interspecific variation. Here we present a comprehensive description of the cranial morphology of Cynosaurus suppostus, producing an updated diagnosis for the species and comparisons amongst basal cynodonts. Cynosaurus is identified by three autapomorphies amongst basal cynodonts: a subvertical mentum on the anterior lower jaw; a robust mandible with a relatively high horizontal ramus; and the broadest snout across the canine region, representing up to 31.74% of basal skull length. One of the new specimens described here preserves orbital scleral ossicles, structures rarely preserved in non-mammaliaform cynodonts. Cynosaurus is now only the third cynodont in which scleral ossicles have been reported.Anupdated phylogenetic analysis of basal cynodont interrelationships recovered Cynosaurus suppostus as a member of the Galesauridae in only two of 16 most parsimonious trees, providing poor support for its inclusion in that family. The majority of known Cynosaurus specimens were collected in a geographically restricted area approximately 150 kilometres in diameter. Most specimens have been recovered from the latest Permian Daptocephalus Assemblage Zone, with only two specimens known from the older Cistecephalus Assemblage Zone. en_ZA
dc.description.sponsorship National Research Foundation (NRF) student assistant researcher grant under the African Origins Programme of Bruce Rubidge en_ZA
dc.language.iso en en_ZA
dc.publisher Evolutionary Studies Institute en_ZA
dc.rights Co en_ZA
dc.subject Cynodontia en_ZA
dc.subject late Permian en_ZA
dc.subject Karoo Basin en_ZA
dc.subject South Africa en_ZA
dc.title Cranial morphology and phylogenetic analysis of Cynosaurus suppostus (Therapsida, Cynodontia) from the upper Permian of the Karoo Basin, South Africa en_ZA
dc.type Article en_ZA
dc.journal.volume 52 en_ZA
dc.journal.title Palaeontologia africana en_ZA
dc.description.librarian JNC en_ZA
dc.funder Palaeontological Scientific Trust; DST/NRF Centre of Excellence for Palaeosciences en_ZA

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