Systematics of the Rubidgeinae (Therapsida: Gorgonopsia)

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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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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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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Evolutionary rates of mid-Permian tetrapods from South Africa and the role of temporal resolution in turnover reconstruction

Paleobiology ◽

10.1017/pab.2018.17 ◽

2018 ◽

Vol 44 (3) ◽

pp. 347-367 ◽

Cited By ~ 9

Author(s):

Michael O. Day ◽

Roger B. J. Benson ◽

Christian F. Kammerer ◽

Bruce S. Rubidge

Keyword(s):

South Africa ◽

Species Richness ◽

High Resolution ◽

Strong Support ◽

Data Set ◽

Terrestrial Vertebrates ◽

Karoo Basin ◽

Extinction Rates ◽

Assemblage Zone ◽

Important Time

AbstractThe Main Karoo Basin of South Africa contains a near-continuous sequence of continental deposition spanning ~80 Myr from the mid-Permian to the Early Jurassic. The terrestrial vertebrates of this sequence provide a high-resolution stratigraphic record of regional origination and extinction, especially for the mid–late Permian. Until now, data have only been surveyed at coarse stratigraphic resolution using methods that are biased by nonuniform sampling rates, limiting our understanding of the dynamics of diversification through this important time period. Here, we apply robust methods (gap-filler and modified gap-filler rates) for the inference of patterns of species richness, origination rates, and extinction rates to a subset of 1321 reliably-identified fossil occurrences resolved to approximately 50 m stratigraphic intervals. This data set provides an approximate time resolution of 0.3–0.6 Myr and shows that extinction rates increased considerably in the upper 100 m of the mid-Permian Abrahamskraal Formation, corresponding to the latest part of theTapinocephalusAssemblage Zone (AZ). Origination rates were only weakly elevated in the same interval and were not sufficient to compensate for these extinctions. Subsampled species richness estimates for the lower part of the overlying Teekloof Formation (corresponding to thePristerognathusandTropidostomaAZs) are low, showing that species richness remained low for at least 1.5–3 million years after the main extinction pulse. A high unevenness of the taxon abundance–frequency distribution, which is classically associated with trophically unstable postextinction faunas, in fact developed shortly before the acme of elevated extinction rates due to the appearance and proliferation of the dicynodontDiictodon. Our findings provide strong support for a Capitanian (“end-Guadalupian”) extinction event among terrestrial vertebrates and suggest that further high-resolution quantitative studies may help resolve the lack of consensus among paleobiologists regarding this event.

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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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A gigantic bird from the Upper Cretaceous of Central Asia

Biology Letters ◽

10.1098/rsbl.2011.0683 ◽

2011 ◽

Vol 8 (1) ◽

pp. 97-100 ◽

Cited By ~ 12

Author(s):

Darren Naish ◽

Gareth Dyke ◽

Andrea Cau ◽

François Escuillié ◽

Pascal Godefroit

Keyword(s):

Phylogenetic Analysis ◽

Body Size ◽

Central Asia ◽

Late Cretaceous ◽

Upper Cretaceous ◽

Large Body ◽

New Taxon ◽

Ecological Diversity ◽

Large Body Size ◽

Fossil Bird

We describe an enormous Late Cretaceous fossil bird from Kazakhstan, known from a pair of edentulous mandibular rami (greater than 275 mm long), which adds significantly to our knowledge of Mesozoic avian morphological and ecological diversity. A suite of autapomorphies lead us to recognize the specimen as a new taxon. Phylogenetic analysis resolves this giant bird deep within Aves as a basal member of Ornithuromorpha. This Kazakh fossil demonstrates that large body size evolved at least once outside modern birds (Neornithes) and reveals hitherto unexpected trophic diversity within Cretaceous Aves.

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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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A new species of the subgenus Scheloribates (Topobates) (Acari: Oribatida: Scheloribatidae) from Panama

Zoosystematica Rossica ◽

10.31610/zsr/2020.29.2.278 ◽

2020 ◽

Vol 29 (2) ◽

pp. 278-283

Author(s):

S.G. Ermilov

Keyword(s):

New Species ◽

Body Size ◽

Leaf Litter ◽

Related Species ◽

Large Body ◽

Oribatid Mite ◽

Neotropical Region ◽

Large Body Size ◽

First Time ◽

A New Species

The oribatid mite subgenus Scheloribates (Topobates) Grandjean, 1958, is recorded from the Neotropical region for the first time. A new species of this subgenus is described from the leaf litter collected in Cayo Agua Island, Panama. Scheloribates (Topobates) panamaensis sp. nov. differs from its related species by the very large body size and presence of a strong ventrodistal process on the leg femora II–IV.

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