Wits Evolutionary Studies Institute (ESI)

Permanent URI for this community

https://wiredspace.wits.ac.za/handle/10539/13252

Browse

Now showing 1 - 8 of 8

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.
Molteno Kannaskoppia: Mid-Triassic gymnosperm case study for whole-plant taxonomy
(Evolutionary Studies Institute, 2023-12) Anderson, John M; Anderson, Heidi M
The flora from the Upper Triassic Molteno Formation, southern Africa, is the most extensively collected and documented macro-flora in the Gondwana Triassic. The collection includes c. 30 000 catalogue slabs from 100 assemblages in 43 super-localities. Some 61 genera and 211 species have been described in a series of publications from the early 1980s covering most of the plant groups. In this volume, the genus Kannaskoppia and affiliates, in the order Petriellales, are described in greater detail than previously in 2003, and offer the opportunity to explore the question of whole-plant genera and species. The ovulate strobilus, Kannaskoppia, with the single species K. vincularis, occurs in only one assemblage – where it is common with c. 50 specimens, including five with both the foliage and strobili found attached to shoots. This find remains unique for the Gondwana Triassic. The male strobilus, Kannaskoppianthus, with eight species recognized (four described as new), occurs in 12 assemblages; at two of these, both distinct species, it is found attached to shoots. The foliage Rochipteris, with 12 Molteno species recognized (seven described as new), is known from 26 of the 100 Molteno assemblages; at four of these, in three distinct species, the foliage has been found attached to shoots. For each of the these 26 assemblages, geographic and stratigraphic information is provided, plus the associated fl ora and plant/insect records. As in previous Molteno publications, the Palaeodeme approach is followed in the circumscription of species. All the Reference Palaeodemes are illustrated by line drawings and extensive photographs as are the more important Sister Palaeodemes. A comprehensive revision of the Gondwana Triassic records of Rochipteris has resulted in 24 accepted species, of which seven occur only in the Molteno Flora. All previously illustrated material is listed in the hypodigm table and used for comparison and nomenclatural considerations with the Molteno specimens. Whole-plant species from the Molteno have been recognized, based on considerations of affiliation and taphonomy. For each of these the habit and habitat are reconstructed in colour. Each is placed in its most-likely habitat within the Molteno Biome, with the seven primary habitats (ecozones) as recognized previously for the Formation. These plants are typically considered perennials to about one metre high that grew in a variety of habitats and were often associated with Dicroidium/Umkomasia or with Heidiphyllum/Telemachus trees. The current study of Kannaskoppia, and affiliates, supports previous phylogenetic, anatomical and ecological studies that amongst the gymnosperms the order Petriellales constitutes a likely sister group of the angiosperms.
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).
Taxonomic and taphonomic interpretations of newly excavated in situ GD 2 faunal remains at Gondolin
(The Evolutionary Studies Institute, 2024-01) Engelbrecht, Micke; Val, Aurore; Kibii, Job M.; Steininger, Christine
Gondolin is one of the fossil-bearing karstic localities in the Cradle of Humankind, South Africa. Periodic excavations of calcified and decalcified sediments at several loci (GD 1,GD2 andGDA) over the last few decades have yielded a sizeable sample of Plio-Pleistocene fauna, including two hominin teeth from ex situ deposits. In 2015, renewed excavations were conducted at the GD 2 locality, which consists of decalcified in situ deposits, in order to shed more light on the site’s complex formation processes as well as to try finding new hominin material from a stratigraphically secured context. While these excavations did not yield any hominin material, abundant macrovertebrate remains were recovered. This paper presents the taxonomic composition and taphonomic characteristics of this new faunal assemblage. The occurrence of Equus sp. as well as the extinct species Metridiochoerus andrewsi and Hystrix makapanensis places the assemblage in a depositional age bracket of 2.33–1.78 Ma, which is consistent with ages already proposed forGD2. No primate material was recovered. The assemblage displays a taxonomic and bodyweight bias towards small-bodied (size classes I and II) bovids. The taphonomic characteristics of the bovid remains suggest the selective action of a leopard-like carnivore and while there is no direct evidence that the locality was used as a hyaena den, secondary scavenging by hyaenids cannot be excluded. Porcupines played an ancillary role in the bone accumulation. We performed intra- and inter-site taxonomic and taphonomic comparisons between this faunal sample and fossil assemblages from previously excavated localities at Gondolin (GD 1, GD 2 and GD A), as well as from other Paranthropus robustus-bearing sites in the Cradle of Humankind. These comparisons indicate that this new sample closely resembles the faunal assemblage previously collected from in situ calcified sediments at the GD 2 locality, in terms of species composition, bovid size class distribution, carnivore to ungulate ratio, and general taphonomic characterization.
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.

Browse

Browsing Wits Evolutionary Studies Institute (ESI) by School "Library"

Results Per Page

Sort Options