scholarly journals Cranial morphology of the middle Permian pareiasaur Nochelesaurus alexanderi from the Karoo Basin of South Africa

2021 ◽  
pp. 1-21
Author(s):  
Marc J. VAN DEN BRANDT ◽  
Bruce S. RUBIDGE ◽  
Julien BENOIT ◽  
Fernando ABDALA
Keyword(s):  
South Africa ◽  
South African ◽  
Local Group ◽  
Cranial Morphology ◽  
Karoo Basin ◽  
Lower Jaw ◽  
Basal Group ◽  
Assemblage Zone ◽  
Globally Distributed ◽  
Distinct Taxon

ABSTRACT Pareiasaurs were globally distributed, abundant, herbivorous parareptiles with the basal-most members found only in the mid-Permian of South Africa. These basal forms form a monophyletic group and were locally abundant and became extinct at the top of the Tapinocephalus Assemblage Zone at the end of the Guadalupian. Four species of basal pareiasaurs are currently recognised: Bradysaurus baini, B. seeleyi, Embrithosaurus schwarzi and Nochelesaurus alexanderi, but they are all poorly understood and there remains historic uncertainty as to their validity. In this paper, our second contribution designed to improve understanding of the basal group, we present the first detailed cranial description and updated diagnosis for Nochelesaurus alexanderi and demonstrate that it is a distinct taxon based on one cranial autapomorphy, a large transversely wide postparietal, and a combination of cranial characters. Within the local group of mid-Permian pareiasaurs, we recognise new dental features of Nochelesaurus alexanderi: non-symmetrical marginal cusp arrangements on upper and lower teeth resulting from an extra basal mesial cusp; an incipient horizontal cingulum on lower jaw teeth, sometimes with one or two tiny medial cingular cusps; and up to ten marginal cusps. Our study demonstrates that tooth morphology and orientation, cranial ornamentation, morphology of the cheek bosses, shape of the postfrontal and postparietal, and morphology of the distal paroccipital process of the opisthotic are the most useful to identify South African mid-Permian pareiasaurs.

Cranial morphology and phylogenetic relationships of the Middle Permian pareiasaur Embrithosaurus schwarzi from the Karoo Basin of South Africa

2019 ◽  
Author(s):  
Marc Johan Van den Brandt ◽  
Fernando Abdala ◽  
Bruce Sidney Rubidge
Keyword(s):  
South Africa ◽  
South African ◽  
Middle Permian ◽  
Cranial Morphology ◽  
Karoo Basin ◽  
Assemblage Zone ◽  
Mandibular Teeth ◽  
First Time ◽  
Globally Distributed ◽  
Distinct Taxon

Abstract Pareiasaurs were globally distributed, abundant, herbivorous parareptiles of the Middle to Late Permian, with the basal-most members found in the Middle Permian of South Africa. These basal taxa were particularly abundant and went extinct at the end of the Gaudalupian (Capitanian) at the top of the Tapinocephalus Assemblage Zone. Currently four taxa are recognized in this group: Bradysaurus seeleyi, B. baini, Nochelesaurus alexanderi and Embrithosaurus schwarzi, but they are all poorly understood. We here present the first detailed cranial description and updated diagnosis for Embrithosaurus schwarzi. No cranial autapomorphies were identified. However, Embrithosaurus schwarzi is a distinct taxon in this group, based on its unique dentition and using a combination of cranial features. It has nine marginal cusps on all maxillary and mandibular teeth, and wider maxillary teeth than in the co-occurring taxa, due to the marginal cusps being arranged more regularly around the crown, and the apex of the crown lacking the long, central, three-cusped trident. Our updated phylogenetic analysis recovers the four Middle Permian South African taxa as a monophyletic group for the first time, which we call Bradysauria, comprising a clade including Embrithosaurus, Bradysaurus baini and a polytomy including Nochelesaurus and Bradysaurus seeleyi.

scholarly journals A new large cynodont from the Late Permian (Lopingian) of the South African Karoo Basin and its phylogenetic significance

2019 ◽  
Vol 186 (4) ◽  
pp. 983-1005 ◽  
Author(s):  
Fernando Abdala ◽  
Leandro C Gaetano ◽  
Roger M H Smith ◽  
Bruce S Rubidge
Keyword(s):  
South African ◽  
Posterior Margin ◽  
Cranial Morphology ◽  
Late Permian ◽  
Posterior Portion ◽  
Skull Length ◽  
Karoo Basin ◽  
Secondary Palate ◽  
Assemblage Zone

Abstract The Karoo Basin of South Africa has the best global record of Lopingian (Late Permian) non-mammaliaform cynodonts, currently represented by five species. We describe Vetusodon elikhulu gen. et sp. nov., documented by four specimens from the Daptocephalus Assemblage Zone. With a basal skull length of ~18 cm, it is the largest Lopingian cynodont and is also larger than Induan representatives of the group. Vetusodon elikhulu has a cranial morphology that departs notably from that previously documented for Permo-Triassic cynodonts. It features a short and extremely wide snout, resembling that of the contemporaneous therocephalian Moschorhinus, and has large incisors and canines that contrast with the small unicusped postcanines, suggesting a more important role of the anterior dentition for feeding. The dentary is extremely long and robust, with the posterior margin located closer to the craniomandibular joint than in other Lopingian and Induan cynodonts (e.g. Thrinaxodon). The secondary palate morphology of V. elikhulu is unique, being short and incomplete and with the posterior portion of the maxilla partly covering the vomer. A phylogenetic analysis suggests that V. elikhulu is the sister taxon of Eucynodontia and thus the most derived of the Lopingian to Induan cynodonts yet discovered.

The South African stereospondyl Lydekkerina huxleyi (Tetrapoda, Temnospondyli) from the Lower Triassic of Australia

2006 ◽  
Vol 143 (6) ◽  
pp. 877-886 ◽  
Author(s):  
A. A. WARREN ◽  
R. DAMIANI ◽  
A. M. YATES
Keyword(s):  
South Africa ◽  
South African ◽  
Posterior Margin ◽  
Lower Triassic ◽  
Ventral Surface ◽  
The South ◽  
Karoo Basin ◽  
Skull Roof ◽  
Assemblage Zone

The first tetrapod fossil from the Rewan Formation of the Galilee Basin, central Queensland, Australia, is identified as Lydekkerina huxleyi, a stereospondyl found elsewhere only in the Lystrosaurus Assemblage Zone of South Africa. Apomorphies shared with L. huxleyi are: anterior palatal vacuity with anterodorsal projections from its posterior margin; ventral surface of skull roof with series of thickened ridges (condition unknown in other lydekkerinids); and vomerine shagreen present (possible autapomorphic reversal). Restudy of the only other Australian lydekkerinid, Chomatobatrachus halei, shows it to be distinct from L. huxleyi. The Rewan Formation, undifferentiated in the Galilee Basin, can be correlated with the Rewan Group of the Bowen Basin, and to the early part of the Lystrosaurus Assemblage Zone of the Karoo Basin, South Africa, which are of Griesbachian age. Varying palaeoenvironments may contribute to the contrasting nature of the Australian and South African faunas.

scholarly journals New Specimen of the Enigmatic Dicynodont Lanthanostegus mohoii (Therapsida, Anomodontia) from the Southwestern Karoo Basin of South Africa, and its Implications for Middle Permian Biostratigraphy

2021 ◽  
Vol 9 ◽  
Author(s):  
Bruce S. Rubidge ◽  
Michael O. Day ◽  
Julien Benoit
Keyword(s):  
South Africa ◽  
Depositional Environment ◽  
Middle Permian ◽  
Western Cape ◽  
Eastern Cape ◽  
Karoo Basin ◽  
Lower Jaw ◽  
Assemblage Zone ◽  
Western Side ◽  
Single Locality

Lanthanostegus is an unusual dicynodont known from only two partial skulls from a single locality near Jansenville in the Eastern Cape Province of South Africa. Although these specimens can be constrained to near the base of the late middle Permian (Guadalupian) Abrahamskraal Formation, their precise age is uncertain as a result of diachroneity of the base of the Formation and the absence, in the Jansenville area, of index taxa to correlate this horizon with the biostratigraphy established in the Western Cape Province. Here, we describe a third skull that we identify as Lanthanostegus, which we recently discovered from a locality north of Laingsburg, on the western side of the main Karoo Basin. This skull reveals morphological details of the palate, occiput, and lower jaw that are not preserved in the described specimens of Lanthanostegus mohoii and will advance understanding of this poorly known dicynodont. This discovery provides the first direct correlation between the lower Abrahamskraal Formation at Jansenville on the eastern side of the basin and the southwestern part of the basin, and suggests that Lanthanostegus occurs in the lowest Tapinocephalus Assemblage Zone (AZ), or possibly to a new assemblage transitional between the Eodicynodon and Tapinocephalus AZs. This supports earlier work proposing that the Eodicynodon AZ is present only on the western side of the Karoo Basin and that the transition from a marine to continental depositional environment occurred later toward the East.

Biostratigraphy of the Daptocephalus Assemblage Zone (Beaufort Group, Karoo Supergroup), South Africa

2020 ◽  
Vol 123 (2) ◽  
pp. 191-206 ◽  
Author(s):  
P.A. Viglietti
Keyword(s):  
South Africa ◽  
South African ◽  
Taxonomic Revision ◽  
Species Level ◽  
Karoo Basin ◽  
Assemblage Zone ◽  
Stratigraphic Ranges

Abstract The name Daptocephalus Assemblage Zone (DaAZ) is re-instated for vertebrate assemblages of the uppermost Permian strata (Balfour, upper Teekloof, and Normandien formations) of South Africa’s main Karoo Basin (MKB). This involved taxonomic revision of the dicynodontoid “Dicynodon” sensu lato, reviving Daptocephalus leoniceps, and revising the stratigraphic ranges of co-occurring index taxa (Theriognathus microps, Procynosuchus delaharpeae) of the Dicynodon Assemblage Zone (DiAZ) as it was known. This work has demonstrated the appearance of index taxa below the stratigraphically defined DiAZ. Moreover, the first appearance of Lystrosaurus maccaigi and Moschorhinus kitchingi in the upper reaches of the biozone calls for the establishment of a two-fold subdivision of the current DaAZ into lower (Dicynodon-Theriognathus) and upper (Lystrosaurus maccaigi-Moschorhinus) subzones. The biostratigraphic utility of Daptocephalus and other South African dicynodontoids outside of the MKB is limited due to basinal endemism at the species level and varying temporal ranges of dicynodontoids globally. Accordingly, their use is recommended only for correlation within the Karoo Basin at this stage.

Biostratigraphy of the Scalenodontoides Assemblage Zone (Stormberg Group, Karoo Supergroup), South Africa

2020 ◽  
Vol 123 (2) ◽  
pp. 239-248 ◽  
Author(s):  
P.A. Viglietti ◽  
B.W. McPhee ◽  
E.M. Bordy ◽  
L. Sciscio ◽  
P.M. Barrett ◽  
...  
Keyword(s):  
South Africa ◽  
Qualitative And Quantitative ◽  
Karoo Basin ◽  
Maximum Thickness ◽  
Nomen Dubium ◽  
Assemblage Zone

Abstract The Scalenodontoides Assemblage Zone (SAZ) is the oldest fossil tetrapod biozone of the Stormberg Group (Karoo Supergroup) and preserves the oldest dinosaur bearing deposits in the Karoo Basin. The SAZ represents a revision of the ‘Euskelosaurus’ Range Zone, whose taxonomic basis has been undermined because ‘Euskelosaurus’ is well demonstrated to be a nomen dubium. Recent qualitative and quantitative investigations into the biostratigraphy of the Elliot and Clarens formations have resulted in the first biostratigraphic review of all lower Elliot Formation (lEF) taxa in nearly 40 years. Thus, we replace the ‘Euskelosaurus’ Range Zone with a new biostratigraphic assemblage zone, the Scalenodontoides Assemblage Zone (SAZ). Named after the traversodontid cynodont Scalenodontoides macrodontes, which co-occurs with the sauropodomorphs Blikanasaurus cromptoni and Melanorosaurus readi. The SAZ is currently accepted to range in age between the upper Norian and Rhaetian. Our new biozone, which reaches a maximum thickness of ~200 m, is wholly contained within the lower Elliot Formation (Stormberg Group, Karoo Supergroup).

Revision of the first therocephalian,TheriognathusOwen (Therapsida: Whaitsiidae), and implications for cranial ontogeny and allometry in nonmammaliaform eutheriodonts

2015 ◽  
Vol 89 (4) ◽  
pp. 645-664 ◽  
Author(s):  
Adam K. Huttenlocker ◽  
Fernando Abdala
Keyword(s):  
South Africa ◽  
Southern Africa ◽  
Single Species ◽  
Late Permian ◽  
Triassic Boundary ◽  
Karoo Basin ◽  
Wide Range ◽  
The Status ◽  
Assemblage Zone ◽  
Jaw Function

AbstractHistorically, the whaitsiid therocephalianTheriognathusOwen was one of the earliest described nonmammalian therapsids, its morphology helping to link phylogenetically the Paleozoic synapsids of North America and southern Africa to their mammalian successors. However, decades of taxonomic over-splitting and superficial descriptions obscured the morphologic diversity of the genus, hindering its utility as a study system for the evolution of synapsid cranial function as well as its biostratigraphic significance in the Late Permian of southern Africa. Here, we revise the status and provenance of all the known specimens ofTheriognathusfrom South Africa, Tanzania, and Zambia. We present both qualitative and quantitative support for the presence of a single morphospecies as proposed by some authors. Proportional differences in skulls that were previously ascribed to different morphotypes (‘Aneugomphius,’ ‘Notosollasia,’ ‘Moschorhynchus,’ and ‘Whaitsia’) are largely size-related and allometric trends are considered here in the context of jaw function and prey prehension. Our results suggest that the single species,Theriognathus microps, represented one of the most abundant Late Permian therocephalians in southern Africa and is consequently a potentially useful biostratigraphic marker for the upperCistecephalus-lowerDicynodonAssemblage Zone transition (i.e., late Wuchiapingian). The wide range of preserved sizes in conjunction with recent paleohistological evidence supports that individuals spent much of their lives in an actively-growing, subadult phase. LaterDicynodonAssemblage Zone records (e.g., upper Balfour Formation) are unconfirmed as the genus was likely replaced by other theriodont predators (e.g.,Moschorhinus) leading up to the Permo-Triassic boundary in the Karoo Basin of South Africa.

Biostratigraphy of the Massospondylus Assemblage Zone (Stormberg Group, Karoo Supergroup), South Africa

2020 ◽  
Vol 123 (2) ◽  
pp. 249-262 ◽  
Author(s):  
P.A. Viglietti ◽  
B.W. McPhee ◽  
E.M. Bordy ◽  
L. Sciscio ◽  
P.M. Barrett ◽  
...  
Keyword(s):  
South Africa ◽  
Faunal Turnover ◽  
Qualitative And Quantitative ◽  
Karoo Basin ◽  
Maximum Thickness ◽  
Extinction Event ◽  
Assemblage Zone ◽  
Main Index ◽  
Stratigraphic Interval

Abstract The Massospondylus Assemblage Zone is the youngest tetrapod biozone in the Karoo Basin (upper Stormberg Group, Karoo Supergroup) and records one of the oldest dinosaur dominated ecosystems in southern Gondwana. Recent qualitative and quantitative investigations into the biostratigraphy of the lower and upper Elliot formations (lEF, uEF) and Clarens Formation in the main Karoo Basin resulted in the first biostratigraphic review of this stratigraphic interval in nearly four decades, allowing us to introduce a new biostratigraphic scheme, the Massospondylus Assemblage Zone (MAZ). The MAZ expands upon the Massospondylus Range Zone by including the crocodylomorph Protosuchus haughtoni and the ornithischian Lesothosaurus diagnosticus as two co-occurring index taxa alongside the main index taxon, the sauropodomorph Massospondylus carinatus. With a maximum thickness of ~320 m in the southeastern portion of the basin, our new biozone is contained within the uEF and Clarens formations (upper Stormberg Group), however, based on vertebrate ichnofossils evidence, it may potentially extend into the sedimentary units of the lowermost Drakensberg Group. We do not propose any further subdivisions, and do not consider the Tritylodon Acme Zone (TAZ) as a temporal biostratigraphic marker within the MAZ. The MAZ is currently accepted to range in age between the Hettangian and Pliensbachian, however a faunal turnover, which observes an increase in the diversity of dinosaur clades, crocodylomorph, and mammaliaform taxa in the lower uEF, could reflect effects of the end-Triassic extinction event (ETE).

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