Wits Evolutionary Studies Institute (ESI)

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Author: search.filters.author.Abdala, FernandoStart date: 2020

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    Cranial morphology of Jonkeria truculenta (Therapsida, Dinocephalia) and a taxonomic reassessment of the family Titanosuchidae
    (The Evolutionary Studies Institute, 2024-06) Jirah, Sifelani; Rubide, Bruce S; Abdala, Fernando
    Titanosuchidae are a group of herbivorous, long-snouted dinocephalians with definitive records known only from the middle Permian Tapinocephalus Assemblage Zone of the Beaufort Group (Karoo Supergroup) of South Africa. Here, the taxonomy of this family is revised; of the nine species currently recognized, only two are found to be valid: Titanosuchus ferox and Jonkeria truculenta, which can be distinguished on the basis of appendicular proportions. Jonkeria boonstrai, J. haughtoni, J. ingens, J. parva, J. rossouwi, and J. vanderbyli are synonymized with Jonkeria truculenta, and J. koupensis is considered a nomen dubium (Titanosuchidae indet.). Several new cranial features are described for J. truculenta, such as pachyostosis of the prefrontals, postorbitals and parietals, and an ontogenetic series for the species is presented.
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    Cranial morphology of Jonkeria truculenta (Titanosuchidae, Therapsida, Dinocephalia) and a taxonomic reassessment of the family
    (Evolutionary Studies Institute, 2023) Jirah, Sifelani; Rubidge, Bruce S; Abdala, Fernando
    Titanosuchidae are a group of derived herbivorous long snouted dinocephalians currently only known from the South African Karoo. Taxonomic revision of the Titanosuchids, for the first time accompanied by detailed anatomical descriptions and illustrations of representative cranial material, enabled recognition of only two species out of the nine previously recognized. These are Titanosuchus ferox and Jonkeria truculenta. Jonkeria vanderbyli, Jonkeria ingens, Jonkeria haughtoni, Jonkeria parva, Jonkeria rossouwi and Jonkeria boonstrai are here, synonymized with Jonkeria truculenta. The species Jonkeria koupensis is a nomen dubium only identified as Titanosuchid indet. Cranial characters, which modify during ontogenetic development, were, recognized for Jonkeria truculenta, and for the first time an ontogenetic growth series is, presented for this species.
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    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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    Late Permian terrestrial faunal connections invigorated: the first whaitsioid therocephalian from China
    (2023-07) Liu, Jun; Abdala, Fernando
    The record of therocephalian therapsids from the late Permian of China has recently been greatly expanded by the discovery of several new taxa of Akidnognathidae, a group previously known principally from South Africa and Russia. Continuing this string of discoveries, we present here the first Chinese record of a whaitsiid therocephalian. This is also the first record published of a tetrapod from Jingtai, Gansu, a late Permian locality that also yields remains of other groups such as dicynodonts, captorhinids, and chroniosuchians. This is the third taxon of whaitsiid therocephalian recognized in North Pangea. The new therocephalian is similar to the Russian Moschowhaitsia vjuschkovi in overall appearance, and although they are only recovered as sister-taxa in 6 out of 30 most parsimonious trees in our phylogenetic analysis, it is tentatively referred to Moschowhaitsia as a new species,M. lidaqingi. The phylogeny obtained is largely similar to previous hypotheses, recovering three main lineages of Eutherocephalia: Akidnognathidae, Whaitsioidea and Baurioidea. However, it differs from previous analyses in finding Chthonosauridae (comprising the Russian Chthonosaurus and Zambian Ichibengops) to be deeply nested within Whaitsioidea. Therocephalians were among the largest carnivores in the late Permian of North China, and may have represented the top predators in some faunas.
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    Postcranial morphology of the South African middle Permian pareiasaurs from the Karoo Basin of South Africa
    (Evolutionary Studies Institute, 2021-05-28) van den Brandt, Marc J.; Benoit, Julien; Abdala, Fernando; Rubidge, Bruce S.
    Pareiasaurs were relatively abundant and globally distributed herbivorous parareptiles of the middle to late Permian. The basal-most pareiasaurs, the Bradysauria, are restricted to the middle Permian of South Africa and went extinct at the end of the Guadalupian (Capitanian) at the top of the Tapinocephalus Assemblage Zone. Currently, three genera are recognized in this group: Bradysaurus, Embrithosaurus and Nochelesaurus, but their postcrania are poorly known, and consequently poorly understood. In this paper, our third contribution designed to improve understanding of the Bradysauria, we present a detailed comparative postcranial description and updated diagnoses for Bradysaurus baini, Embrithosaurus schwarzi and Nochelesaurus alexanderi. Bradysaurus baini has one postcranial autapomorphy: anterior dorsal osteoderms smooth and strongly convex, with an incipient central boss, and very light ornamentation. Three pelvic autopomorphies of Embrithosaurus schwarzi are confirmed: anterior portion of the iliac blades flat and vertical (not everted or upturned); iIiac blades diverge anteriorly, oriented at 45–60° off the sagittal plane; and a very thick pelvic symphysis. For Nochelesaurus alexanderi we remove all three of the postcranial autapomorphies previously proposed. To the diagnoses of each species, we have added several new distinguishing postcranial features, within the local group of middle Permian pareiasaurs. The results reinforce our previous cranial studies concluding that three valid species of pareiasaurs are represented in the South African middle Permian.