A New Late Permian Burnetiamorph From Zambia Confirms Exceptional Levels of Endemism in Burnetiamorpha (Therapsida: Biarmosuchia) and an Updated Paleoenvironmental Interpretation of the Upper Madumabisa Mudstone Formation

A new burnetiamorph therapsid, Isengops luangwensis, gen. et sp. nov., is described on the basis of a partial skull from the upper Madumabisa Mudstone Formation of the Luangwa Basin of northeastern Zambia. Isengops is diagnosed by reduced palatal dentition, a ridge-like palatine-pterygoid boss, a palatal exposure of the jugal that extends far anteriorly, a tall trigonal pyramid-shaped supraorbital boss, and a recess along the dorsal margin of the lateral temporal fenestra. The upper Madumabisa Mudstone Formation was deposited in a rift basin with lithofacies characterized by unchannelized flow, periods of subaerial desiccation and non-deposition, and pedogenesis, and can be biostratigraphically tied to the upper Cistecephalus Assemblage Zone of South Africa, suggesting a Wuchiapingian age. Isengops is the second burnetiamorph recognized from Zambia and is part of a tetrapod assemblage remarkably similar to others across southern Pangea during the Wuchiapingian. A revised cladistic analysis of Biarmosuchia yielded over 500 most parsimonious trees that generally reaffirm the results of previous analyses for burnetiamorphs: Lemurosaurus is basal, Lobalopex and Isengops are proximate burnetiid outgroups, and Bullacephalus, Burnetia, Mobaceras, Niuksenitia, and Pachydectes are burnetiines. Furthermore, Russian biarmosuchians are scattered throughout the tree and do not form sister taxon relationships with each other. Burnetiamorphs display a wide disparity of cranial adornments and are relatively speciose (13 species), especially when compared to the number of specimens discovered to date (∼16 specimens). As has been suggested in some other tetrapod clades (e.g., ceratopsian dinosaurs), the burnetiamorph fossil record supports an inferred macroevolutionary relationship between cranial adornment and increased speciation rate.

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

Journal of Paleontology ◽

10.1017/jpa.2015.32 ◽

2015 ◽

Vol 89 (4) ◽

pp. 645-664 ◽

Cited By ~ 14

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.

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Systematics of the Rubidgeinae (Therapsida: Gorgonopsia)

PeerJ ◽

10.7717/peerj.1608 ◽

2016 ◽

Vol 4 ◽

pp. e1608 ◽

Cited By ~ 15

Author(s):

Christian F. Kammerer

Keyword(s):

South Africa ◽

Phylogenetic Analysis ◽

Body Size ◽

Endemic Species ◽

Large Body ◽

Strong Support ◽

Late Permian ◽

Large Body Size ◽

Karoo Basin ◽

Assemblage Zone

The subfamily Rubidgeinae, containing the largest known African gorgonopsians, is thoroughly revised. Rubidgeinae is diagnosed by the absence of a blade-like parasphenoid rostrum and reduction or absence of the preparietal. Seven rubidgeine species from the Karoo Basin of South Africa are recognized as valid:Aelurognathus tigriceps,Clelandina rubidgei,Dinogorgon rubidgei,Leontosaurus vanderhorsti,Rubidgea atrox,Smilesaurus ferox, andSycosaurus laticeps. Rubidgeines are also present in other African basins:A. tigricepsandS. laticepsoccur in the Upper Madumabisa Mudstone Formation of Zambia, andD. rubidgei,R. atrox, and the endemic speciesRuhuhucerberus haughtonicomb. nov. andSycosaurus nowakicomb. nov. occur in the Usili Formation of Tanzania.Aelurognathus nyasaensisfrom the Chiweta Beds of Malawi also represents a rubidgeine, but of uncertain generic referral pending further preparation. No rubidgeine material is known outside of Africa: the purported Russian rubidgeineLeogorgon klimovensisis not clearly referable to this group and may not be diagnosable. Phylogenetic analysis of rubidgeines reveals strong support for a clade (Rubidgeini) of advanced rubidgeines includingClelandina,Dinogorgon,Leontosaurus, andRubidgea. Support forSmilesaurusas a rubidgeine is weak; it may, as previous authors have suggested, represent an independent evolution of large body size from anArctops-like ancestor. Temporally, rubidgeines are restricted to the Late Permian, first appearing in theTropidostomaAssemblage Zone and reaching highest diversity in theCistecephalusandDaptocephalusassemblage zones of the Beaufort Group.

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Redescription of <i>Digalodon rubidgei</i>, an emydopoid dicynodont (Therapsida, Anomodontia) from the Late Permian of South Africa

Fossil Record ◽

10.5194/fr-18-43-2015 ◽

2015 ◽

Vol 18 (1) ◽

pp. 43-55 ◽

Cited By ~ 13

Author(s):

C. F. Kammerer ◽

K. D. Angielczyk ◽

J. Fröbisch

Keyword(s):

South Africa ◽

Time Span ◽

Central Portion ◽

Sister Taxon ◽

Recent Analysis ◽

Dorsal Margin ◽

Sexually Dimorphic ◽

Limited Time ◽

Late Permian ◽

Karoo Basin

Abstract. The Late Permian dicynodont Digalodon rubidgei Broom and Robinson, 1948, is redescribed based on reanalysis of the holotype and newly recognized referable specimens. Digalodon can be diagnosed by the presence of a long "beak" sharply demarcated from the caniniform process; an extremely tall zygomatic ramus of the squamosal, with a thickened, "folded-over" dorsal margin; raised parietal "lips" along the lateral edges of the pineal foramen; and a broad posterolateral expansion of the parietal, excluding the postorbital from the back of the skull roof. Inclusion of Digalodon in a recent analysis of anomodont phylogeny recovers it as a kistecephalian emydopoid, specifically as the sister taxon to the clade containing the remaining kistecephalians. Four definite specimens of Digalodon are known, but several additional specimens lacking tusks, the swollen pineal "lips", and a thickened zygoma may represent sexually dimorphic females or juveniles. Specimens of Digalodon are restricted to the central portion of the Karoo Basin, in the area around Graaff-Reinet, and are part of a characteristic fauna probably representing a limited time span.

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Calcic Vertisols in the upper Daptocephalus Assemblage Zone, Balfour Formation, Karoo Basin, South Africa: Implications for Late Permian Climate

Journal of Sedimentary Research ◽

10.2110/jsr.2020.32 ◽

2020 ◽

Vol 90 (6) ◽

pp. 609-628 ◽

Cited By ~ 2

Author(s):

Robert A. Gastaldo ◽

Kaci Kus ◽

Neil Tabor ◽

Johann Neveling

Keyword(s):

South Africa ◽

Geochemical Data ◽

Mean Annual Precipitation ◽

Mean Annual Temperature ◽

Paleoenvironmental Reconstruction ◽

Late Permian ◽

Karoo Basin ◽

Environmental Models ◽

Assemblage Zone

ABSTRACT The fully continental succession of the Beaufort Group, Karoo Basin, South Africa, has been used in the development of environmental models proposed for the interval that spans the contact between the Daptocephalus to Lystrosaurus Assemblage Zones, associated by some workers with the end-Permian extinction event. An aridification trend is widely accepted, yet geochemical data indicate that the majority of in situ paleosols encountered in this interval developed in waterlogged environments. To date, the presence of calcic paleosols in the latest Permian can be inferred only from the presence of calcite-cemented pedogenic nodules concentrated in fluvial channel-lag deposits. Here, we report on the first empirical evidence of in situ calcic Vertisols found in the upper Daptocephalus Assemblage Zone near Old Wapadsberg Pass, one of eight classic localities in which the vertebrate turnover is reported in the Karoo Basin. Seven discrete intervals of calcic Vertisols, exposed over a very limited lateral extent, occur in an ∼ 25 m stratigraphic interval. Estimates of mean annual temperature and mean annual precipitation are calculated from geochemical measurements of one paleosol, and these estimates indicate that the prevailing climate at the time of pedogenesis was seasonally cold and humid. Correlation with adjacent stratigraphic sections indicates that the late Permian landscape experienced poorly drained and better-drained phases, interpreted to reflect a climate that varied between episodically dry and episodically wet. In contrast to a paleoenvironmental reconstruction of unidirectional aridification from strata in the Wapadsberg Pass region, this study provides new evidence for a wetting trend towards the Daptocephalus–Lystrosaurus Assemblage-Zone boundary.

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

South African Journal of Geology ◽

10.25131/sajg.123.0013 ◽

2020 ◽

Vol 123 (2) ◽

pp. 181-190

Author(s):

R.M.H. Smith

Keyword(s):

South Africa ◽

Mass Extinction ◽

Large Carnivores ◽

Late Permian ◽

Maximum Thickness ◽

Assemblage Zone ◽

The Town

Abstract The late Permian (Lopingian) Cistecephalus Assemblage Zone (CiAZ) of the Karoo Supergroup in South Africa has recently been radiometrically-dated to range from 256 to 255 My. It encompasses approximately one million years of the late Wuchiapingian epoch, at a time when the ancient intra-continental lowlands of southern Gondwana had fully recovered from the end-Guadalupian mass extinction. The diverse Cistecephalus Assemblage Zone fauna is dominated by the small herbivorous dicynodonts Diictodon, Pristerodon and the molelike Cistecephalus, along with a range of larger dicynodont herbivores including Oudenodon, Aulacephalodon, Rhachiocephalus, Dinanomodon and rare Endothiodon. The attendant large carnivores include the gorgonopsians Aelurognathus, Rubidgea, and Smilesaurus, while smaller carnivores are represented by eutherocephalians (e.g., Ictidosuchoides, Ictidosuchops) and small gorgonopsians (e.g., Aloposaurus, Scylacocephalus). Of the parareptiles, the large-bodied taxon Pareiasaurus is most common, with the diminutive pareiasaurs Anthodon, Nanoparia, and Pumiliopareia making their first appearance. Lithostratigraphically, the biozone for the most part coincides with the arenaceous Oukloof and lower Steenkampsvlakte members in the western sub-basin and the equivalent Oudeberg and lower Daggaboersnek members in the east, where it reaches its maximum thickness of 300 m. The Cistecephalus Assemblage Zone thins westwards to 120 m at Teekloof Pass, and eastwards to approximately 100 m near the town of Fort Beaufort.

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An early geikiid dicynodont from theTropidostomaAssemblage Zone (late Permian) of South Africa

PeerJ ◽

10.7717/peerj.2913 ◽

2017 ◽

Vol 5 ◽

pp. e2913 ◽

Cited By ~ 5

Author(s):

Christian F. Kammerer ◽

Roger M.H. Smith

Keyword(s):

South Africa ◽

Phylogenetic Analysis ◽

New Taxon ◽

Late Permian ◽

Skull Length ◽

Karoo Basin ◽

Skull Size ◽

Assemblage Zone

Based on specimens previously identified asTropidostoma, a new taxon of dicynodont (Bulbasaurus phylloxyrongen. et sp. nov.) from the Karoo Basin of South Africa is described.Bulbasaurusis a medium-sized dicynodont (maximum dorsal skull length 16.0 cm) restricted to theTropidostomaAssemblage Zone (early Lopingian) of the Beaufort Group.Bulbasauruscan be distinguished fromTropidostomaby an array of characters including the presence of a tall, sharp premaxillary ridge, large, rugose, nearly-confluent nasal bosses, a nasofrontal ridge, massive tusks, robust pterygoids, prominently twisted subtemporal bar, and absence of a distinct postfrontal. Inclusion ofBulbasaurusin a phylogenetic analysis of anomodont therapsids recovers it as a member of Geikiidae, a clade of otherwise later Permian dicynodonts such asAulacephalodonandPelanomodon.Bulbasaurusexhibits many of the characters typical of adultAulacephalodon, but at substantially smaller skull size (these characters are absent in comparably-sizedAulacephalodonjuveniles), suggesting that the evolution of typical geikiid morphology preceded gigantism in the clade.Bulbasaurusis the earliest known geikiid and the only member of the group known from theTropidostomaAssemblage Zone; discovery of this taxon shortens a perplexing ghost lineage and indicates that abundant clades from the later Permian of South Africa (e.g., Geikiidae, Dicynodontoidea) may have originated as rare components of earlier Karoo assemblage zones.

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

South African Journal of Geology ◽

10.25131/sajg.123.0016 ◽

2020 ◽

Vol 123 (2) ◽

pp. 217-238 ◽

Cited By ~ 3

Author(s):

P.J. Hancox ◽

J. Neveling ◽

B.S. Rubidge

Keyword(s):

South Africa ◽

Fossil Record ◽

Maximum Thickness ◽

Terrestrial Vertebrate ◽

The North ◽

Upper Limit ◽

Assemblage Zone

Abstract The Cynognathus Assemblage Zone is the youngest tetrapod biozone of the Beaufort Group (Tarkastad Subgroup, Karoo Supergroup). It is situated between the underlying Lystrosaurus declivis Assemblage Zone and the base of the overlying Molteno Formation (Stormberg Group) and corresponds to the entire Burgersdorp Formation. It is characterised by the presence throughout of the cynodont genus Cynognathus. The biozone reaches a maximum thickness of around 650 m in the southeast part of the basin and thins dramatically to the north, where it is only a maximum of 50 m thick. We here propose a three-fold subdivision into a lower Langbergia-Garjainia Subzone, a middle Trirachodon-Kannemeyeria Subzone and an upper Cricodon-Ufudocyclops Subzone. The basal contact is deﬁned biostratigraphically by the ﬁrst appearance of Cynognathus crateronotus and Langbergia modisei. The Cynognathus Assemblage Zone lacks a deﬁned biostratigraphic upper limit, being unconformably terminated by the base of the overlying Molteno Formation, which lacks a terrestrial vertebrate fossil record other than trackways.

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New whaitsioids (Therapsida: Therocephalia) from the Teekloof Formation of South Africa and therocephalian diversity during the end-Guadalupian extinction

PeerJ ◽

10.7717/peerj.3868 ◽

2017 ◽

Vol 5 ◽

pp. e3868 ◽

Cited By ~ 10

Author(s):

Adam K. Huttenlocker ◽

Roger M.H. Smith

Keyword(s):

South Africa ◽

New Records ◽

Critical Time ◽

Sister Group ◽

Upper Permian ◽

Late Permian ◽

Faunal Turnover ◽

Karoo Basin ◽

Evolutionary Diversification ◽

Assemblage Zone

Two new species of therocephalian therapsids are described from the upper Permian Teekloof Formation of the Karoo Basin, South Africa. They include two specimens of a whaitsiid, Microwhaitsia mendrezi gen. et sp. nov., and a single, small whaitsioid Ophidostoma tatarinovi gen. et sp. nov., which preserves a combination of primitive and apomorphic features. A phylogenetic analysis of 56 therapsid taxa and 136 craniodental and postcranial characters places the new taxa within the monophyletic sister group of baurioids—Whaitsioidea—with Microwhaitsia as a basal whaitsiid and Ophidostoma as an aberrant whaitsioid just outside the hofmeyriid+whaitsiid subclade. The new records support that whaitsioids were diverse during the early-late Permian (Wuchiapingian) and that the dichotomy between whaitsiid-line and baurioid-line eutherocephalians was established early on. The oldest Gondwanan whaitsiid Microwhaitsia and additional records from the lower strata of the Teekloof Formation suggest that whaitsioids had diversified by the early Wuchiapingian and no later than Pristerognathus Assemblage Zone times. Prior extinction estimates based on species counts are reflected in an analysis of origination/extinction rates, which imply increasing faunal turnover from Guadalupian to Lopingian (late Permian) times. The new records support a growing body of evidence that some key Lopingian synapsid clades originated near or prior to the Guadalupian-Lopingian boundary ca. 260–259 million years ago, but only radiated following the end-Guadalupian extinction of dinocephalians and basal therocephalian predators (long-fuse model). Ongoing collecting in older portions of the Teekloof Formation (e.g., Pristerognathus Assemblage Zone) will shed further light on early eutherocephalians during this murky but critical time in their evolutionary diversification.

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