Sedimentology and taphonomy of Late Permian vertebrate fossil localities in southwestern Madagascar

This is the first report of a project that tests the accuracy of the currently accepted palaeoposition of southern Madagascar during the late Permian in juxtaposition to the coast of Tanzania. This is done by comparing the sediments and fossils that accumulated in a series of rift valleys, each around 25 km wide, that formed in this part of Gondwana at the beginning of pull-apart some 250 million years ago. The study reported here on the Madagascan side of the rift system will be followed by a similar study of the Tanzanian portion. Field data on the sedimentology and vertebrate taphonomy of three separate fossil localities in the Late Permian, Lower Sakamena Formation of southwestern Madagascar are used to reconstruct the subenvironments of the Sakamena axial rift valley lake. 1. Ranohira: dominated by microlaminated mudrocks with three horizons of fossil bearing micrite nodules. The fossils are mostly complete articulated skeletons of an ?aquatic procolophonid reptile, Barasaurus, which inhabited the offshore epilimnion of a deep, thermally-stratified closed lake. 2. Zavoloa River: alternating cross-bedded conglomeratic sandstone and laminated siltstone are interpreted as braided delta deposits entering the linear margin of the lake from the passive side of the half graben. These deposits contain some fully articulated skeletons and numerous winnowed bonebeds of a supposedly semi-aquatic reptile, Claudiosaurus, that may be related to sauropterygians. 3. Mount Eliva: is dominated by the younginiform reptile, Hovasaurus, which occurs as articulated skeletons inside micritic siltstone nodules in the mudrocks of a sub-lacustrine deltaic sequence. Pebble masses in the abdomen of Hovasaurus are interpreted as ballast to facilitate swimming. The taphonomic style and sedimentary environment of the host strata confirm this interpretation. Thermal shock from periodic overturn and poisoning from algal blooms are the most likely causes of mass mortality among the aquatic fauna. Hydrogen sulphide released from anaerobic bacterial decay of soft tissue and girdle cartilage formed reduction halos around the newly buried reptile carcasses. At least 3 “micritization episodes” led to the precipitation of calcium cabonate in the reduction halos forming nodules around the vertebrate fossils. They are interpreted as periods of extended lowstand when thermal stratification could not be maintained and oxygenated waters came into contact with previously anoxic sediments. If such lowstand events were climatically controlled, they may be useful timelines to accurately correlate strata within and between these ancient rift valley lakes in both Madagascar and Tanzania.THE COUNCIL’S RESEARCH COMMITTEE, UNIVERSITY OF THE WITWATERSRAND; NATIONAL RESEARCH FOUNDATION (NRF); The Open Research Programme of the Foundation for Research Developmen

Fluvial facies, vertebrate taphonomy and palaeosols of the Teekloof formation (Permian) near Beaufort West, Cape Province, South Africa

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

An aggregation of juvenile Youngina from the Beaufort Group, Karoo Basin, South Africa

Main articleAn assemblage of five fully-articulated juvenile skeletons of Youngina has been recovered from the Late Permian strata of the south-western Karoo Basin. These 12-cm-long skeletons are not only the first articulated juveniles of this taxon, but also the oldest yet found in the Karoo Basin. They are preserved in overbank mudrocks of the Hoedemaker Member (Beaufort Group, Adelaide Subgroup) on the farm Leeukloof 43 in the Beaufort West district. Although they are estimated to be some three million years older than previously described Youngina, these specimens show no significant skeletal differences. The high degree of articulation and the spatial arrangement of these skeletons in a dish-shaped hollow is compelling evidence for them having huddled together within an underground burrow. Taphonomic analysis of associated fossils indicates that this was probably a mechanism to reduce water loss during drought on the ancient Karoo floodplains .Non

On the stratigraphic range of the dicynodont taxon Emydops (Therapsida: Anomodontia) in the Karoo Basin, South Africa

The dicynodont specimen SAM-PK-708 has been referred to the genera Pristerodon and Emydops by various authors, and was used to argue that the first appearance of Emydops was in the Tapinocephalus Assemblage Zone in the Karoo Basin of South Africa. However, the specimen never has been described in detail, and most discussions of its taxonomic affinities were based on limited data. Here we redescribe the specimen and compare it to several small dicynodont taxa from the Tapinocephalus and Pristerognathus assemblage zones. Although the specimen is poorly preserved, it possesses a unique combination of features that allows it to be assigned confidently to Emydops. The locality data associated with SAM-PK-708 are vague, but they allow the provenance of the specimen to be narrowed down to a relatively limited area southwest of the town of Beaufort West. Strata from the upper Tapinocephalus Assemblage Zone and the Pristerognathus Assemblage Zone crop out in this area, but we cannot state with certainty from which of these biostratigraphic divisions the specimen was collected. Nevertheless, SAM-PK-708 is an important datum because it demonstrates that the stratigraphic range of Emydops must be extended below its widely-accepted first appearance in the Tropidostoma Assemblage Zone. This range extension is significant because it implies that the divergence between the emydopid and dicynodontid lineages must have occurred no later than Pristerognathus Assemblage Zone times, and that most of the major lineages of Permian dicynodonts had emerged by a relatively early point in the history of the group.K.D.A. is supported by NSF DBI-0306158 and a Royal Society USA/Canada Research Fellowship. J.F. is supported by a full scholarship from the Government of Canada Awards

A temnospondyl trackway from the early mesozoic of Western gondwana and its implications for Basal tetrapod locomotion

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

The postcranial anatomy of Gorgonops torvus (Synapsida, Gorgonopsia) from the late Permian of South Africa

The article processing charge was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 491192747 and the Open Access Publication Fund of Humboldt-Universität zu Berlin.Gorgonopsians are among the most recognizable groups of synapsids from the Permian period and have an extensive but mostly cranial fossil record. By contrast, relatively little is known about their postcranial anatomy. Here, we describe a nearly complete, semi-articulated skeleton of a gorgonopsian (identified as Gorgonops torvus) from the late Permian Endothiodon Assemblage Zone of the South African Karoo Basin and discuss its paleobiological implications. Known gorgonopsian postcrania indicate morphological conservatism in the group, but the skeletal anatomy of Gorgonops does differ from that of other gorgonopsians in some respects, such as in the triangular radiale and short terminal phalanges in the manus, and a weakly developed distinction between pubis and ischium in ventral aspect of the pelvic girdle. Similarities between the specimen described herein and a historically problematic specimen originally referred to “Scymnognathus cf. whaitsi” confirm referral of the latter specimen to Gorgonops. Since descriptions of gorgonopsian postcrania are rare, new interpretations of the lifestyle and ecology of Gorgonopsia can be drawn from our contribution. We conclude that gorgonopsians were likely ambush predators, able to chase their prey over short distances and pin them down with strong forelimbs before using their canines for the kill. This is evidenced by their different fore- and hindlimb morphology; the former stouter and more robust in comparison to the longer, more gracile, back legs. Furthermore, the completeness of the study specimen facilitates calculation of an estimated body mass of approximately 98 kg, similar to that of a modern lioness.Peer Reviewe

Screening vaccine formulations for biological activity using fresh human whole blood.

Understanding the relevant biological activity of any pharmaceutical formulation destined for human use is crucial. For vaccine-based formulations, activity must reflect the expected immune response, while for non-vaccine therapeutic agents, such as monoclonal antibodies, a lack of immune response to the formulation is desired. During early formulation development, various biochemical and biophysical characteristics can be monitored in a high-throughput screening (HTS) format. However, it remains impractical and arguably unethical to screen samples in this way for immunological functionality in animal models. Furthermore, data for immunological functionality lag formulation design by months, making it cumbersome to relate back to formulations in real-time. It is also likely that animal testing may not accurately reflect the response in humans. For a more effective formulation screen, a human whole blood (hWB) approach can be used to assess immunological functionality. The functional activity relates directly to the human immune response to a complete formulation (adjuvant/antigen) and includes adjuvant response, antigen response, adjuvant-modulated antigen response, stability, and potentially safety. The following commentary discusses the hWB approach as a valuable new tool to de-risk manufacture, formulation design, and clinical progression

Contrasting geochemical signatures on land from the Middle and Late Permian extinction events

The end of the Palaeozoic is marked by two mass‐extinction events during the Middle Permian (Capitanian) and the Late Permian (Changhsingian). Given similarities between the two events in geochemical signatures, such as large magnitude negative δ 13 C anomalies, sedimentological signatures such as claystone breccias, and the approximate contemporaneous emplacement of large igneous provinces, many authors have sought a common causal mechanism. Here, a new high‐resolution continental record of the Capitanian event from Portal Mountain, Antarctica, is compared with previously published Changhsingian records of geochemical signatures of weathering intensity and palaeoclimatic change. Geochemical means of discriminating sedimentary provenance (Ti/Al, U/Th and La/Ce ratios) all indicate a common provenance for the Portal Mountain sediments and associated palaeosols, so changes spanning the Capitanian extinction represent changes in weathering intensity rather than sediment source. Proxies for weathering intensity chemical index of alteration, ∆ W and rare earth element accumulation all decline across the Capitanian extinction event at Portal Mountain, which is in contrast to the increased weathering recorded globally at the Late Permian extinction. Furthermore, palaeoclimatic proxies are consistent with unchanging or cooler climatic conditions throughout the Capitanian event, which contrasts with Changhsingian records that all indicate a significant syn‐extinction and post‐extinction series of greenhouse warming events. Although both the Capitanian and Changhsingian event records indicate significant redox shifts, palaeosol geochemistry of the Changhsingian event indicates more reducing conditions, whereas the new Capitanian record of reduced trace metal abundances (Cr, Cu, Ni and Ce) indicates more oxidizing conditions. Taken together, the differences in weathering intensity, redox and the lack of evidence for significant climatic change in the new record suggest that the Capitanian mass extinction was not triggered by dyke injection of coal‐beds, as in the Changhsingian extinction, and may instead have been triggered directly by the Emeishan large igneous province or by the interaction of Emeishan basalts with platform carbonates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108696/1/sed12117.pd

A new large cynodont from the Late Permian (Lopingian) of the South African Karoo Basin and its phylogenetic significance

The Karoo Basin of South Africa has the best global record of Lopingian (Late Permian) non-mammaliaform cynodonts, currently represented by five species. We describe Vetusodon elikhulu gen. et sp. nov., documented by four specimens from the Daptocephalus Assemblage Zone. With a basal skull length of ~18 cm, it is the largest Lopingian cynodont and is also larger than Induan representatives of the group. Vetusodon elikhulu has a cranial morphology that departs notably from that previously documented for Permo-Triassic cynodonts. It features a short and extremely wide snout, resembling that of the contemporaneous therocephalian Moschorhinus, and has large incisors and canines that contrast with the small unicusped postcanines, suggesting a more important role of the anterior dentition for feeding. The dentary is extremely long and robust, with the posterior margin located closer to the craniomandibular joint than in other Lopingian and Induan cynodonts (e.g. Thrinaxodon). The secondary palate morphology of V. elikhulu is unique, being short and incomplete and with the posterior portion of the maxilla partly covering the vomer. A phylogenetic analysis suggests that V. elikhulu is the sister taxon of Eucynodontia and thus the most derived of the Lopingian to Induan cynodonts yet discovered.Fil: Abdala, Nestor Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Gaetano, Leandro Carlos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; ArgentinaFil: Smith, Roger M. H.. Evolutionary Studies Institute; SudáfricaFil: Rubidge, Bruce. Evolutionary Studies Institute; Sudáfric

Information Privacy in a Globally Networked Society: Implications for IS Research

This paper presents an extended discussion of issues associated with the role of information privacy in IS research. This discussion was initiated in conjunction with a panel session at ICIS 2002. Following the conference, each of the panelists reworked and extended their position statements, and provided a commentary on the position statements of the other panelists. The paper is framed with head and tail pieces written by the panel chair. The result is a (unique and provocative) blend of opinion and commentary on a topic that is of importance to IS research in the globally networked society in which we all live. IS researchers will find research questions, research conundrums, and research advice in equal measure