The earliest gorgonopsians from the Karoo Basin of South Africa
Abstract
Therapsids underwent an explosive radiation in the middle Permian, with all but one of the major therapsid subclades appearing in the fossil record at this time. However, the therapsid subclade Gorgonopsia is rare in the middle Permian (in strong contrast to their late Permian record, where they are the dominant terrestrial vertebrate predators), and known mainly from Capitanian (latest middle Permian) strata in the Karoo Basin of South Africa. Here we present three previously undescribed middle Permian gorgonopsian specimens from earlier South African deposits, which constitute the earliest well-supported records of this group worldwide. The oldest known gorgonopsian specimen is a partial snout from the Eodicynodon Assemblage Zone (Wordian), nondiagnostic to species but identifiable as gorgonopsian based on septomaxillary morphology. Two partial skulls from the lowermost Tapinocephalus Assemblage Zone (late Wordian/early Capitanian) in the eastern Karoo represent a new taxon of gorgonopsian (Phorcys dubei gen. et sp. nov.) diagnosed by the autapomorphic presence of knob-like protuberances on the basioccipital between the basal tubera and occipital condyle. Inclusion of Phorcys in a phylogenetic analysis of Gorgonopsia recovers it in a weakly-supported basal position within the clade of African gorgonopsians. All three of the specimens described herein are substantially larger than previously known middle Permian gorgonopsians, suggesting that patterns of competition and replacement between gorgonopsians and coeval therocephalians were more complicated than previously thought.
- Publication:
-
Journal of African Earth Sciences
- Pub Date:
- October 2022
- DOI:
- 10.1016/j.jafrearsci.2022.104631
- Bibcode:
- 2022JAfES.19404631K
- Keywords:
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- Synapsida;
- Permian;
- South Africa;
- Biostratigraphy;
- Phylogeny