Endothiodon

Abstract: The Endothiodon Assemblage Zone is the third oldest tetrapod biozone of the Beaufort Group (Adelaide Subgroup, Karoo Supergroup). It is situated between the underlying Tapinocephalus and overlying Cistecephalus assemblage zones and in the southwestern part of the basin corresponds to the majority of the Poortjie and Hoedemaker members of the Teekloof Formation. It is characterised by the dicynodont genus Endothiodon, especially in the lower part of assemblage zone, and records early ecosystem recovery from the Capitanian mass extinction. It also contains the lowest occurrence in the Karoo Basin of cynodont therapsids, eutherocephalians, bidentalian dicynodonts, and diapsids. The biozone reaches a maximum thickness of around 250 m in the southwestern part of the basin. We propose a two-fold subdivision into a lower Lycosuchus - Eunotosaurus Subzone (equivalent to the upper two-thirds of the former Pristerognathus Assemblage Zone) and an upper Tropidostoma - Gorgonops Subzone (equivalent to the former Tropidostoma Assemblage Zone), with the contact defined by the first appearance of Tropidostoma dubium. The Endothiodon Assemblage Zone is terminated by the first appearance of Aulacephalodon bainii.

Abstract: The first dicynodont reported for the Permian of South America is described in detail here. The specimen consists of a partial skull and associated lower jaws, collected from the Serra do Cadeado locality, Rio do Rasto Formation, Brazil. The specimen was assigned to the genus Endothiodon Owen in a preliminarily description published in the 1970s. This identification implied a direct correlation with some of the well-established biozones of the Beaufort Group, South Africa, where this taxon is known to occur. Although badly weathered, the Brazilian material preserves several features that allow us to confirm its assignment to Endothiodon, such as the pineal foramen situated on a boss, the bulbous swellings of the dentaries, a boss situated on the ventral margin of the jugal, the extensive number of dentary teeth and the upturned pointed beak of the lower jaw. However, this set of characters is not enough to establish a specific taxonomic assignment for the specimen, although it seems to be more closely related to E. bathystoma, E. uniseries and E. whaitsi than to E. mahalanobisi. The biostratigraphical correlations proposed for the tetrapod faunas of the Rio do Rasto Formation highlight the similarities between these associations and others from the Mid and Late Permian of South Africa and Eastern Europe. However, until now, these correlations are tentative because only a few faunal elements have been recovered from Brazil, and most of them lack stratigraphic data on the levels from where they were collected. Due to the presence of Endothiodon, at least part of the Rio do Rasto Formation can be correlated with deposits in India, Malawi, Mozambique, South Africa, Tanzania, Zambia and Zimbabwe.

Abstract: The cranial morphology and extensive dentition of the dicynodont therapsid Endothiodon are different from those of any other dicynodont and it clearly had a different feeding niche. Recently prepared material from Mozambique which has relatively well preserved dentition has revealed that the mode of tooth replacement of Endothiodon differs in the upper and lower jaws. The very high and narrow vaulted palate with a close fitting, pointed lower jaw indicates that Endothiodon had a small mouth with muscular cheeks and extensive cheek pouches, suggesting a browsing feeding niche.

Abstract: Two fragmentary skulls from the Upper Permian Tapinocephalus Assemblage Zone (Abrahamskraal Formation, Beaufort Group) in Eastern Cape Province, South Africa, represent a new dicynodont taxon. Lanthanocephalus mohoii gen. et sp. nov. is distinguished from other dicynodonts by the presence of a conspicuous laterally facing excavation on the dorsal surface of the postfrontal, by dorsal expansions of the supraoccipital that contact the parietals, and by extensive ossification of the lateral wall of the braincase. Lanthanocephalus features several characters that are suggestive of a close relationship with Endothiodon. These include a transversely narrow intertemporal region, the presence of a pineal boss, and the presence of a distinct boss on the ventral margin of the jugal. Cladistic analysis of a modified data matrix from the literature supports the hypothesis of a sister-group relationship between Lanthanocephalus and Endothiodon. However, this grouping and most others found in the analysis collapse with...