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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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.
Craniomandibular anatomy of the akidnognathid therocephalian Olivierosuchus parringtoni from the Early Triassic of South Africa
(Evolutionary Studies Institute, 2023) Gigliotti, Alessandro; Pusch, Luisa C; Kammerer, Christian F; Benoit, Julien; Fröbisch, Jörg
Therocephalians were an ecomorphologically varied and diverse-sized group of therapsids with widespread distribution during the late Permian and earliest Triassic periods. Here, we redescribe the holotype of the therocephalian Olivierosuchus parringtoni (BP/1/3849) from the Early Triassic Lystrosaurus declivis Assemblage Zone in the main Karoo Basin of South Africa. The specimen includes a complete skull, mandible, and the anterior portion of the skeleton. Previously unknown endocranial features are described using high-resolution computed tomography (CT), including internal surfaces of braincase and palatal bones, as well as soft tissue structures such as the brain and inner ear endocasts. Comparisons with closely related therapsids permit a detailed comparative analysis of the brain and inner ear morphology of Olivierosuchus.
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.
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.
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.
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.
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.
Early release volume (more papers coming in September!)
(2023)
Imprint page
(2023-07)
Inside the front cover
(2023-07)
Table of Contents
(2023-07)
Front Cover
(2023-07)
Preface
(2023-07) Choiniere, Jonah N; Chapelle, Kimberley E.J.; Kammerer, Christian F.
A preface to the Bruce Sidney Rubidge Festschrift volume with anecdotes about his early years.
Re-discovery of the Euparkeria bonebed locality (Mid-Triassic) in Aliwal North, South Africa, with an update of the taphonomy and depositional environment
(2023-07) Wolvaardt, Frederik P.; Smith, Roger M. H.; Arcucci, Andrea
Euparkeria capensis is an Early to Middle Triassic archosauriform reptile widely regarded as phylogenetically close to the base of the Archosauria. Fossils of this species are only known from a single locality in the townlands of Aliwal North, South Africa. The exact location was, until now, uncertain due to mis-reading of the field notes of the collector Mr Alfred ‘Gogga’ Brown and conflicting anecdotal information gleaned from local townsfolk. Careful transcription of the voluminous handwritten field notes, followed by archival research in the town museum, and ground-truthing of the targeted area, has led to the re-discovery of the Euparkeria type locality. Sedimentological facies analysis of the locality combined with taphonomic observations of the 38 fossil-bearing rock slabs collected by Brown, now housed in the Iziko South African Museum reveal the following scenario for the origin of the Euparkeria/ Mesosuchus bonebed: the bones are preserved within the base of two tabular massive sandstone beds in upper point-bar facies of a high sinuosity channel-fill. The stratigraphic position, sedimentology, and geometry of the sandstone beds with their interdigitation with overlying floodplain mudrocks is interpreted as part of an infilled chute-channel cutting across a point-bar of a meandering river. The taphonomic analysis of the main bonebed suggests that the initial concentration of tetrapod remains was controlled by a combination of a mass mortality event of a pack of Euparkeria, and a few Mesosuchus becoming overwhelmed by a flash flood, and the hydrodynamics of the small floating carcasses getting trapped within the confines of a downstream chute-channel. The re-discovered Euparkeria locality is stratigraphically positioned at the top of a locally significant sandstone marker bed informally named the Eldorado marker. This unit is generally accepted as the contact between the lower and middle Burgersdorp Fm. Biostratigraphically, the locality is positioned within the transition between the lower and middle subzones of the Cynognathus AZ, namely Langbergia-Garjainia below and Trirachodon- Kannemeyeria above. This is some 23mlower in the stratigraphy than previously thought, and the possible association with Langbergiatype burrow casts leads us to tentatively place it within the lower subzone.
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.
Synchrotron scanning reveals the deep evolutionary root of the mammalian brain: the surprisingly advanced endocast morphology of Lumkuia fuzzi (Cynodontia: Probainognathia)
(2023-07) Benoit, Julien
The mammalian brain is very distinctive for its large relative size, enlarged olfactory bulbs, and layered isocortex. These defining traits likely evolved in the non-mammalian probainognathian cynodonts, although the timing and exact phylogenetic sequence in which these characters evolved is not well understood. The endocast of the brain cavity provides a unique window into the evolution of the central nervous system of extinct species. The endocast of the basal-most probainognathian, Lumkuia fuzzi, is here described for the first time. Its olfactory bulbs are relatively large despite that its encephalization quotient is lower than in Mammaliaformes. This contradicts the consensually established hypothesis that encephalization and olfaction evolved in concert. Moreover, the data presented here do not indisputably distinguish between the encephalization quotients of Mesozoic mammals, non-mammalian mammaliaforms, and non-mammaliaform cynodonts, which suggests that brain enlargement was gradual in this lineage. Lumkuia also possesses marked cerebral hemispheres, which is traditionally interpreted as the sign of the presence of an isocortex and hair. The enlarged olfactory bulbs and cerebral hemisphere in Lumkuia strongly support that the defining features of the mammalian brain began evolving in the last common ancestor of the Probainognathia clade, as early as the early Anisian.
The mandible of Compsodon helmoedi (Therapsida: Anomodontia), with new records from the Ruhuhu Basin, Tanzania
(2023-07) Angielczyk, Kenneth D.; Peecook, Brandon R.; Smith, Roger M. H.
The emydopoid dicynodont Compsodon helmoedi originally was named from a single skull collected in Daptocephalus Assemblage Zone strata in the South African Karoo Basin. Recently described specimens from the Luangwa Basin, Zambia, have elucidated the species’ cranial morphology and facilitated identification of other historical Karoo specimens. Neither the holotype nor any of the described Zambian specimens preserve a mandible; a referred Karoo specimen preserves a highly damaged mandible, but poor preservation obscures most details.We present an additional Zambian Compsodon specimen that includes an articulated cranium and mandible, and use μCT data to describe the mandible of this taxon for the first time. The mandible has an upturned dentary symphysis; ‘postcanine’ teeth with coarse distal denticles; a shallow, elongate posterior dentary sulcus with medial expansion anterior to the tooth row, and a prominent lateral dentary shelf. Although the mandible is similar to those of Emydops and Pristerodon, it can be differentiated from Emydops by the latter’s more triangular posterior dentary sulcus, and the absence of a rugose muscle scar on the lateral edge of the lateral dentary shelf. It differs from Pristerodon in the absence of a dentary table rostral to the tooth row, the presence of a transverse ridge dividing the lateral dentary shelf into posterior and anterior sections, and the anterodorsal angulation of the lateral dentary shelf. Three fragmentary specimens from the Usili Formation (Ruhuhu Basin) display the same morphotype and represent the first record of Compsodon from Tanzania. The expanding geographic range of Compsodon underscores its potential as a biostratigraphic index fossil, but more information on its stratigraphic and temporal ranges is needed to realize that potential.
Revision of the Scylacosauridae (Therapsida: Therocephalia)
(2023-07) Kammerer, Christian E.
The abundant, primarily middle Permian therocephalian family Scylacosauridae is comprehensively reviewed and revised. The 33 nominal scylacosaurid species from the Tapinocephalus Assemblage Zone of the Karoo Basin of South Africa are reduced to seven: Alopecodon priscus, Alopecognathus angusticeps, Glanosuchus macrops, Maraisaurus parvus, Pardosuchus whaitsi, Pristerognathus polyodon, and Scylacosaurus sclateri. The scylacosaurid records from the earlier Eodicynodon Assemblage Zone (previously referred to Glanosuchus and Ictidosaurus) are recognized as a new taxon, Eutheriodon vandenheeveri. Scylacosaurid records from the later Endothiodon Assemblage Zone consist of two long-snouted taxa (the long-ranging species A. angusticeps and P. polyodon) and a short-snouted taxon (Hyorhynchus platyceps) possibly restricted to this zone. The revised identifications presented herein demonstrate that there was substantial scylacosaurid turnover between the Tapinocephalus and Endothiodon AZs, corresponding to the end-Guadalupian extinction.
Reappraisal of supposed ‘dinocephalian’ specimens expands burnetiamorph diversity in the Guadalupian Tapinocephalus Assemblage Zone of South Africa
(2023-07) Day, Michael O.; Kammerer, Christian E.
Burnetiids are a rare, yet seemingly species-rich family of therapsids in the rocks of the Karoo Basin of South Africa. Discoveries over the past 20 years have provided a greater understanding of the morphological variation within the group and have led to differing hypotheses of burnetiid phylogeny and that of their parent clade, Burnetiamorpha. One posits the existence within Burnetiidae of two subclades, Burnetiinae and Proburnetiinae, but this hypothesis invokes lengthy and thus problematic ghost lineages, particularly for proburnetiines. Herewereview and describe cranial material from the Capitanian Tapinocephalus Assemblage Zone that was previously referred to the dinocephalian therapsid Styracocephalus platyrhynchus, showing that it instead represents two new morphotypes of proburnetiine burnetiids. One of these, Nierkoppia brucei gen. et sp. nov., is diagnosed by the autapomorphic presence of a supraorbital boss ‘folded over’ the dorsal margin of the orbit, giving this structure a roughly ‘ear’ or ‘kidney’-shaped appearance; flattened, posteriorly directed squamosal horns; a median frontal boss taller than the supraorbital bosses, reaching itsmaximumheight anterior to them; and massive, rounded nuchal bosses borne on the postparietal and supraoccipital. The other specimen is left in open nomenclature due to incompleteness, but represents a heavily pachyostosed proburnetiine similar to Lende and Leucocephalus. The recovery of proburnetiines within theTapinocephalus Assemblage Zone shortens the ghost lineage of this clade and indicates that a diverse burnetiid fauna was present in the Guadalupian Karoo, comparable to that now known from Tanzania and Zambia.

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