Refined stratigraphy of the Middle Permian Abrahamskraal Formation (Beaufort Group) in the southern Karoo Basin

Jirah, Sifelani; Rubidge, Bruce S.

doi:10.1016/j.jafrearsci.2014.06.014

Cited by 22 publications

(7 citation statements)

References 19 publications

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“…Unfortunately, neither were collected with precise locality data, and the farm Abrahamskraal exposes a wide stratigraphic interval encompassing the lower Moordenaars Member, Swaerskraal Member and upper Koornplaats Member of the Abrahamskraal Formation (Marpmann et al . ; Day and Rubidge ; Jirah and Rubidge ). Another specimen, SAM‐PK‐12220, which comes from the farm Skoppelmaaikraal in the Laingsburg district, can be constrained to the lower part of the Moordenaars Member or the Swaerskraal Member (Cole and Vorster ; Day and Rubidge ).…”

Section: Discussionmentioning

confidence: 99%

New information on the morphology and stratigraphic range of the mid‐Permian gorgonopsian Eriphostoma microdon Broom, 1911

Kammerer

Smith

Day

et al. 2015

Papers in Palaeontology

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New specimens of the oldest gorgonopsian taxon Eriphostoma microdon from the Pristerognathus Assemblage Zone (AZ) of South Africa significantly improve our understanding of the anatomy of this taxon. The new specimens consist of nearly complete skulls and lower jaws and allow for a more complete diagnosis of Eriphostoma than was possible based on the poorly preserved holotype. In addition to the characteristic palatal dentition and delta‐shaped palatine bosses previously recognized for Eriphostoma, this taxon can be diagnosed by the presence of three close‐packed upper postcanines occupying an indented margin of the maxilla, a large, tetragonal‐to‐rounded preparietal bone, and large, paired interorbital depressions expanding outwards in front of the pineal boss. The revised diagnosis permits Eoarctops vanderbyli, Galesuchus gracilis, and Scylacognathus parvus to be synonymized with Eriphostoma microdon, as previously suspected. Among gorgonopsians, Eriphostoma is most similar to Aelurosaurus and Gorgonops, although these similarities are likely plesiomorphic for Gorgonopsia. Eriphostoma ranges from the Tapinocephalus AZ (where it is the only valid gorgonopsian known from the Karoo Basin) through the Pristerognathus AZ (where it co‐occurs with Gorgonops).

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Section: Discussionmentioning

confidence: 99%

New information on the morphology and stratigraphic range of the mid‐Permian gorgonopsian Eriphostoma microdon Broom, 1911

Kammerer

Smith

Day

et al. 2015

Papers in Palaeontology

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“…As a result, I have only been able to properly examine a relatively small portion of this material ». This problem has subsequently been raised again in the literature (Jirah and Rubidge, 2014;Day et al, 2015). Moreover, a recent study described a probable new species of Middle Permian pareiasaur; suggesting that the diversity of this group in the Tapinocephalus AZ is likely to have been underestimated (Cisneros and Rubidge, 2012).…”

Section: Bone Microstructural Variabilitymentioning

confidence: 99%

Bone Microstructure of Pareiasaurs (Parareptilia) from the Karoo Basin, South Africa: Implications for Growth Strategies and Lifestyle Habits

Canoville

Chinsamy

2017

The Anatomical Record

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Numerous morphological studies have been carried out on pareiasaurs; yet their taxonomy and biology remain incompletely understood. Earlier works have suggested that these herbivorous parareptiles had a short juvenile period as compared to the duration of adulthood. Several studies further suggested an (semi-) aquatic lifestyle for these animals, but more recent investigations have proposed a rather terrestrial habitat. Bone paleohistology is regarded as a powerful tool to assess aspects of tetrapod paleobiology, but few studies have been conducted on pareiasaurs. The present study assesses intra and inter-specific histovariability of pareiasaurs and provides fresh insights into their paleobiology, thereby permitting a re-evaluation of earlier hypotheses. Our sample comprises various skeletal elements and several specimens covering most of the taxonomic and stratigraphic spectrum of South African pareiasaurs, including large and basal forms from the Middle Permian, as well as smaller and more derived forms from the Late Permian. Our results concerning size of elements and histological tissues show that for pareiasaurs, element size is not a good indicator of ontogenetic age, and furthermore, suggest that the specific diversity of the Middle Permian pareiasaurs may have been underestimated. The bone histology of these animals shows that they experienced a relatively rapid growth early in ontogeny. Periosteal growth later slowed down, but seems to have been protracted for several years during adulthood. Pareiasaur bone microanatomy is unusual for continental tetrapods, in having spongious stylopod diaphyses and thin compact cortices. Rigorous paleoecological interpretations are thus limited since no modern analogue exists for these animals. Anat Rec, 300:1039-1066, 2017. © 2016 Wiley Periodicals, Inc.

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“…The contact between the Ecca Group and the Beaufort Group is defined as the boundary between the Eodicynodon and Tapinocephalus assemblage zones [ Rubidge et al ., ]. The Abrahamskraal Formation lies within the Tapinocephalus zone [ van der Walt et al ., ; Day and Rubidge , ; Jirah and Rubidge , ]. The upper Beaufort Group is interpreted to preserve a record of the Permian‐Triassic mass extinction, which is represented by the boundary between Dyconodon and Lystrosaurus zones [e.g., Maxwell , ; Botha and Smith , ; cf.…”

Section: Regional Geologymentioning

confidence: 99%

Magnetostratigraphic constraints on the age of the lower Beaufort Group, western Karoo basin, South Africa, and a critical analysis of existing U‐Pb geochronological data

Tohver

Lanci

Wilson

et al. 2015

Geochem Geophys Geosyst

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We studied three partially overlapping sections with a composite thickness of ∼600 m in the upper Permian fluvial siltstones and fine‐grained sandstones of the Abrahamskraal Formation, the basal unit of the Beaufort Group, in the Karoo Basin of Western Cape Province, South Africa. Paleomagnetic analysis reveals three components of Natural Remanent Magnetization (NRM). Heating to ∼180°C removes a remanent magnetization parallel to the present‐day field, which is interpreted as a viscous overprint. An intermediate unblocking temperature component is removed by heating to 450°C; this direction is always of normal polarity and is identical to a regional overprint imparted during the Early Jurassic emplacement of the Karoo Large Igneous Province. A high‐temperature component isolated above 450°C is of dual polarity and is interpreted as primary on the basis of a positive reversals test. The virtual geomagnetic pole position for the Abrahamskraal Formation computed from the average high‐temperature characteristic remanent magnetization direction is in agreement with the late Permian directions for stable Gondwana and with previous results from the lowermost Abrahamskraal Formation and Waterford Formation at the Ouberg Pass section. The predominantly normal polarity of this magnetization is in agreement with either a middle‐late Lopingian age (ca. 254–256 Ma) or a late Guadalupian age (ca. 262 Ma) according to the global geomagnetic polarity time scale. We integrate these new results with existing magnetostratigraphic, biostratigraphic, and geochronological results from the Karoo Basin, with particular emphasis on the controversy over zircon age data reported from the underlying Ecca Group.

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Refined stratigraphy of the Middle Permian Abrahamskraal Formation (Beaufort Group) in the southern Karoo Basin

Cited by 22 publications

References 19 publications

New information on the morphology and stratigraphic range of the mid‐Permian gorgonopsian Eriphostoma microdon Broom, 1911

New information on the morphology and stratigraphic range of the mid‐Permian gorgonopsian Eriphostoma microdon Broom, 1911

Bone Microstructure of Pareiasaurs (Parareptilia) from the Karoo Basin, South Africa: Implications for Growth Strategies and Lifestyle Habits

Magnetostratigraphic constraints on the age of the lower Beaufort Group, western Karoo basin, South Africa, and a critical analysis of existing U‐Pb geochronological data

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