Volume 56: 2023

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https://hdl.handle.net/10539/35651

Festschrift in Honour of Professor Bruce S Rubidge

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Anatomy and phylogenetic relationships of a possible lessemsaurid with associated plant fossils from the lower part of the Elliot Formation
(Evolutionary Studies Institute, 2023) Moopen, Atashni; Matiwane, Aviwe; Viglietti, Pia A; Choiniere, Jonah N
The Elliot Formation forms the middle layer of the Stormberg Group of South Africa and ranges in age from the Upper Triassic to the Lower Jurassic. This stratigraphic unit bears a rich and varied faunal assemblage, including a wide variety of vertebrate fossils, the most abundant of which are sauropodomorph dinosaurs. While Early Jurassic sauropodomorphs are increasingly well-known, our knowledge of Late Triassic sauropodomorphs from the lower Elliot Formation is still at a deficit. Specimens from this section of the Stormberg Group can provide key information on the early evolution of Sauropodomorpha. Here we report on a new specimen of a Late Triassic sauropodomorph from a locality a short distance above the Molteno – Elliot boundary making it among the stratigraphically lowest sauropodomorphs from South Africa. Phylogenetic analyses and body mass estimations indicate the specimen represents a medium-to-large-bodied possible lessemsaurid with a combination of plesiomorphic and derived characters. This specimen adds to the diversity of the lower Elliot Formation and provides stronger support for a biogeographical link between the Elliot Formation and the Los Colorados Formation of Argentina. This skeletally immature possible lessemsaurid also provides insight into body size evolution during the Norian, a critical time for the evolution of sauropodomorph gigantism. The fossil plant genera Taeniopteris and Cladophlebis were recovered from sediments containing the sauropodomorph specimen, documenting one of the first co-occurrences of dinosaurs and plant material in the Elliot Formation, as well as preserving direct evidence of plant-insect interactions.
Complete Volume
(The Evolutionary Studies Institute, 2023-12-21)
This file contains the complete downloadable volume including all papers, prefaces, and remembrances. Two versions are available: a larger version with embedded videos and a smaller version without.
New ‘rauisuchian’ fossil material from the lower Elliot Formation of South Africa
(Evolutionary Studies Institute, 2023) Tolchard, Frederick B; Bordy, Emese M; Choiniere, Jonah N
‘Rauisuchians’ are a grade of paracrocodylomorph archosaurs that evolved a diversity of body plans and played a key role in ecosystems worldwide throughout the Triassic. They are widely believed to have gone extinct during the end-Triassic mass extinction event though the fossil record of rauisuchians in the latest Triassic is still poorly known. In this study, we describe new rauisuchian fossil remains from the lower Elliot Formation of South Africa. Based on comparative anatomical evidence, we assign these specimens to the pseudosuchian clade Rauisuchidae. The addition of this material to the existing southern African fossil record allows us, along with some new insights into the taxonomic affinities of previously published material, to identify the presence of at least three distinct taxa of rauisuchian in the Norian of southern Africa: two of the clade Rauisuchidae; and one of the clade Poposauroidea. These likely filled the ecological role of apex predators in the Late Triassic of southern Africa. We also provide a revision of the stratigraphic record of ‘rauisuchians’ from the Elliot Formation and show that the existing record of rauisuchians in southern Africa, though among the youngest in the world, does not extend beyond the late Norian. Further exploration of the Elliot Formation and other terrestrial deposits at the Triassic–Jurassic boundary will be needed to assess whether rauisuchians survived until, or even beyond, the end-Triassic mass extinction event.
Re-identification and updated stratigraphic context of the holotypes of the late Permian tetrapods Dicynodon ingens and Scymnosaurus warreni from KwaZulu-Natal
(Evolutionary Studies Institute, 2023) Groenewald, David P; Kammerer, Christian F
Two historical therapsid holotypes held in the collections of the KwaZulu-Natal Museum (Dicynodon ingens Broom, 1907 and Scymnosaurus warreni Broom, 1907) are redescribed. The holotype of D. ingens is a snout tip of a large dicynodontoid that can be re-identified as a specimen of Daptocephalus leoniceps based on premaxillary proportions and palatal morphology. The holotype of S. warreni consists of a dorsoventrally crushed therocephalian snout, which is here re-identified as that of Moschorhinus kitchingi based on size, general proportions, tooth count, and septomaxillary morphology. The localities of both specimens are biostratigraphically assigned to the Lystrosaurus maccaigi-Moschorhinus Subzone of the Daptocephalus Assemblage Zone (latest Permian).
The first record of late Permian tetrapods from Namibia
(Evolutionary Studies Institute, 2023) Mocke, Helke B; Kammerer, Christian F; Smith, Roger M H; Marsicano, Claudia A
The entire Omingonde Formation in Namibia was previously assigned a Triassic age based on the fossil tetrapod fauna discovered southwest of theWaterberg Plateau. However, recently repatriated and newly collected material suggests that the lowermost part of the Omingonde Formation includes late Permian strata, equivalent in age to the upper Endothiodon Assemblage Zone of the South African Karoo Basin. In this study,we document the first record of late Permian tetrapod fossils from Namibia, and provide brief descriptions of a gorgonopsian skull collected at Mount Etjo in 1996 and the skull of a small dicynodont collected at the same site in 2019, referable to cf. Tropidostoma. This material confirms that there is need for better understanding of the stratigraphy of the Etjo Mountain area, in particular the position and nature of the unconformity between strata of the Permian Endothiodon and the Triassic Cynognathus assemblage zones.
The pre-eminence of the Karoo Basin in the knowledge of the Permo-Jurassic cynodonts: a historical synthesis and taxonomical quantification
(Evolutionary Studies Institute, 2023) Abdala, Fernando; Hendrickx, Christophe; Jasinoski, Sandra C; Gaetano, Leandro C; Liu, Jun
The search for the ancestors of mammals is historically connected with the extensive Karoo Basin of South Africa. This is because the Karoo features some of the largest exposures of Permo-Jurassic terrestrial deposits in the world and fossil discoveries were made here early in the history of palaeontology. Among the mammal-like lineages that are well-represented in Karoo fossil assemblages are the cynodonts. Originally conceived as a group exclusively containing fossil taxa, Cynodontia was subsequently redefined to include living mammals, and its Permian and early Mesozoic members are now referred to as non-mammaliaform cynodonts. Here we present a historical account of the research programme on non-mammaliaform cynodonts in the Karoo Basin, which represent the most important record of this group in the world. It covers a time spanning from the first named species in 1859 until the present day, which we arbitrarily divided into three periods: the Early Period extending from 1859 until 1932, the Second Period from 1933 to 1982, and the Current Period from 1983 until now. In the context of the global record of named species, we present quantitative analyses documenting the total number of nominal non-mammaliaform cynodont species from the Karoo (including junior synonyms and homonyms) as well as numerical comparison with taxa currently considered valid. Lastly, we compare the record of non-mammaliaform cynodont species from South Africa with other places in the world, such as Argentina and Brazil, which also have a diverse record of this group.

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