The Bivalve Megadesmus from the Permian Volksrust Shale Formation (Karoo Supergroup), northeastern Karoo Basin, South Africa: implications for late Permian Basin development

2005 ◽  
Vol 108 (4) ◽  
pp. 547-556 ◽  
Author(s):  
B. Cairncross
2012 ◽  
Vol 108 (11/12) ◽  
Author(s):  
Nicholas Fordyce ◽  
Roger Smith ◽  
Anusuya Chinsamy

2015 ◽  
Vol 89 (4) ◽  
pp. 645-664 ◽  
Author(s):  
Adam K. Huttenlocker ◽  
Fernando Abdala

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.


2016 ◽  
Author(s):  
Robert A. Gastaldo ◽  
◽  
Johann Neveling ◽  
J.W. Geissman ◽  
Sandra L. Kamo ◽  
...  

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1608 ◽  
Author(s):  
Christian F. Kammerer

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.


Sign in / Sign up

Export Citation Format

Share Document