Browsing by Author "Smith, Roger M H"

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    Comprehensive description of a skeleton of Endothiodon Bathystoma (Anomodontia, Therapsida), a dicynodont from the Late Permian of the Karoo Basin of South Africa
    (2018) Maharaj, Iyra Esmen Maeve; Chinsamy-Turan, Anusuya; Smith, Roger M H
    The dicynodonts are an extinct group of herbivorous non-mammalian synapsids that were fairly abundant in Gondwanan deposits of the middle Permian to the Early Triassic periods. The extinct genus Endothiodon was first described by Sir Richard Owen in 1876, and is well known from the late Permian deposits of the Karoo Basin of South Africa. It is characterized by rows of internal teeth on the premaxilla and dentary arranged in replacement waves called Zahnreihen; longitudinal ridges running from the premaxilla to the pineal crest; and a prominent pineal boss with a pineal foramen. Endothiodon is well-represented by cranial and postcranial material in the Karoo vertebrate collections at various museums in South Africa. The repeated taxonomic revision of this genus over the years has led to much confusion about what constitutes the type species, E. bathystoma. Recently, an almost complete skeleton of Endothiodon (SAM-PK-K011271) was recovered from the uppermost Pristerognathus Assemblage Zone of the Karoo Supergroup. The fossil comprises the skull and most of its postcranial elements preserved in articulation. The current study provides a comprehensive description of the anatomy of this specimen, which permitted its identification as E. bathystoma. Furthermore, by comparison with other South African Endothiodon specimens this study determined that this specimen is the second largest E. bathystoma specimen known to date. The well-preserved skull and postcranial skeleton of SAM-PK-K011271 makes it an ideal reference specimen for E. bathystoma and has permitted a good assessment of its overall anatomy. The findings of this study provide a perfect stepping-stone for future studies to further address E. bathystoma’s skeletal reconstruction and biomechanical functions, as well as other aspects of the palaeobiology of this animal.
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    Fluvial facies, vertebrate taphonomy and palaeosols of the Teekloof formation (Permian) near Beaufort West, Cape Province, South Africa
    (1989) Smith, Roger M H; Minter, Laurie; Cluver, Mike
    The main Karoo Basin of South Africa contains a relatively continuous sequence of continental deposits that accumulated over a 100 million year period from Permo-Carboniferous (280 Ma) to early Jurassic (180 Ma). In the southwestern region of the basin the Karoo succession is approximately 4 000 m thick, the upper half of which consists of vertebrate fossil-bearing fluvial rocks of the Beaufort Group. This study deals with Lower Beaufort (Adelaide Subgroup) strata belonging to the Teekloof Formation which are exposed in the cast-west trending erosional escarpment between the towns of Beaufort West and Fraserburg in the central Cape Province. The 450-mctre succession consists mainly of vertically accreted floodplain mudrocks with interbedded continuous sheets of fine-grained sandstone that bear evidence of having accumulated by lateral accretion on the inner banks of meandering channels. The mudrocks contain numerous fossilized skeletons of therapsid "mammal-like" reptiles as well as more primitive cotylosaurs and a few amphibians. Rarely, impressions of Glossopteris leaves and equisetalcan stems are found although root moulds are relatively abundant. Several types of calcareous nodules and sheets occur in the mudrocks and arc interpreted as evidence of calcic palaeosols that formed under semi-arid climatic conditions. This is an interdisciplinary study that integrates a conventional sedimentary facies analysis with investigations of the taphonomy of in situ therapsid fossils and the nature and distribution of palaeosols. Such an approach has not previously been applied to any of the Karoo strata. The results contain descriptive and quantitative information on sedimentary processes, palaeohydrology, absolute time represented in the stratigraphic record and the topography, soils and habitats of the ancient landscape. These are summarized into a palaeoenvironmental synthesis of the Teckloof Formation.
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    A temnospondyl trackway from the early mesozoic of Western gondwana and its implications for Basal tetrapod locomotion
    (Public Library of Science, 2014) Marsicano, Claudia A; Wilson, Jeffrey A; Smith, Roger M H
    BACKGROUND: Temnospondyls are one of the earliest radiations of limbed vertebrates. Skeletal remains of more than 190 genera have been identified from late Paleozoic and early Mesozoic rocks. Paleozoic temnospondyls comprise mainly small to medium sized forms of diverse habits ranging from fully aquatic to fully terrestrial. Accordingly, their ichnological record includes tracks described from many Laurasian localities. Mesozoic temnospondyls, in contrast, include mostly medium to large aquatic or semi-aquatic forms. Exceedingly few fossil tracks or trackways have been attributed to Mesozoic temnospondyls, and as a consequence very little is known of their locomotor capabilities on land. METHODOLOGY/PRINCIPAL FINDINGS: We report a ca. 200 Ma trackway, Episcopopus ventrosus , from Lesotho, southern Africa that was made by a 3.5 m-long animal. This relatively long trackway records the trackmaker dragging its body along a wet substrate using only the tips of its digits, which in the manus left characteristic drag marks. Based on detailed mapping, casting, and laser scanning of the best-preserved part of the trackway, we identified synapomorphies (e.g., tetradactyl manus, pentadactyl pes) and symplesiomorphies (e.g., absence of claws) in the Episcopopus trackway that indicate a temnospondyl trackmaker. Conclusions/Significance Our analysis shows that the Episcopopus trackmaker progressed with a sprawling posture, using a lateral-sequence walk. Its forelimbs were the major propulsive elements and there was little lateral bending of the trunk. We suggest this locomotor style, which differs dramatically from the hindlimb-driven locomotion of salamanders and other extant terrestrial tetrapods can be explained by the forwardly shifted center of mass resulting from the relatively large heads and heavily pectoral girdles of temnospondyls.