75 research outputs found

    The first biarmosuchian from the upper Madumabisa Mudstone Formation (Luangwa Basin) of Zambia

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    This contribution reports the first occurrence of a biarmosuchian therapsid from the upper Madumabisa Mudstone Formation of the Luangwa Basin of northeastern Zambia. Although incomplete, the fossil preserves diagnostic features of post-Biarmosuchus biarmosuchians, such as the presence of a preparietal bone and parasagittal ridges on the basicranial rami of the pterygoids, that allow its unambiguous referral to this group. Based primarily on the record of dicynodonts, the upper Madumabisa Mudstone assemblage can be correlated with the Cistecephalus Assemblage Zone of South Africa. During this interval, the tetrapod faunas of the Karoo and Luangwa basins were remarkably similar and likely characterized by frequent biotic interchange.National Geographic Society grant 8571-08 and 8962-11 The Grainger Foundation and Field Museum/IDP Foundation, Inc. African Partners Program National Science Foundation (EAR-1337569, EAR-1337291, EAR-1336986

    Replacement names for the therapsid genera Criocephalus Broom 1928 and Olivieria Brink 1965.

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    Main articleOur knowledge of premammalian synapsid evolutionary history has benefited from over a hundred years of fossil collecting, especially within the Permo-Triassic sediments of South Africa's Beaufort Group (Rubidge 1995) and the Cis-Ural region of Eastern Europe (Ivachnenko et al. 1997). In the course of our research and discussions we have discovered several errors in the present state of non-mammalian synapsid taxonomy. Here we propose emendations concerning the genera Criocephalus Broom 1928 and Olivieria Brink 1965.Palaeo-Anthropology Scientific Trust; French Embassy in South Africa; Co-operation and Cultural Service

    The vertebrate fauna of the Upper Permian of Niger — II, Preliminary description of a new pareiasaur

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    Main articleThe skull of a new pareiasaur, Bunostegos akokanensis gen. et sp. nov., is described on the basis of a partial skull from the Upper Permian Moradi Formation of north-central Niger. Autapomorphies of the genus include the presence of three hemispherical bosses at the tip of the snout, an enlarged laterally projecting supraorbital boss positioned on each postfrontal, and additional, smaller bosses on the squamosal and supratemporal bones. Bunostegos is further characterized by a tab-like process of the nasal that articulates with the frontal, a pineal foramen located equidistant between the parietal-frontal and parietal-postparietal sutural contacts, a postparietal that is excluded from the caudal margin of the dorsal skull roof, and a blunt interpterygoid vacuity. The discovery of Bunostegos suggests an unsuspected degree of biogeographic endemism for central West Africa during the Late Permian.Non

    Histological evidence of trauma in tusks of southern African dicynodonts

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    Dicynodonts were a clade of globally-distributed therapsids known for their abundance in the fossil record and for surviving the Permo-Triassic mass extinction. The group had distinctive dental adaptations including a beak and, in many species, paired maxillary tusks. The function of these tusks has long been of interest, yet remains poorly understood.We report here on two instances of unusual morphology in tusk dentine from specimens of: 1) Lystrosaurus from the Karoo Basin of South Africa and, 2) an unidentified dicynodontoid from the Luangwa Basin of Zambia. In both, the cross-sectional shape of the tusk root is lobed and infolded, which histological features suggest is a result of abnormal dentine deposition. We infer that this abnormal morphology is likely the consequence of trauma given its reparative nature and structural similarities to trauma-related morphologies reported in the tusks of modern elephants. This study demonstrates that histological sampling of dicynodont tusks can shed light on the biology of this important clade of therapsids.National Geographic Exploration Grant NGS-158R-18 National Science Foundation PLR-1341304 National Science Foundation DEB-1701383 Palaeontological Scientific TrustJNC201

    A new record of \u3ci\u3eProcynosuchus delaharpeae\u3c/i\u3e (Therapsida: Cynodontia) from the Upper Permian Usili Formation, Tanzania

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    Procynosuchus, the best-known Permian cynodont, has a remarkably broad geographic range, with records stretching from southern Africa to Europe. Fossils\u27 of Procynosuchus are most common in the Upper Permian Dicynodon Assemblage Zone of South Africa, but also occur in coeval East African rocks. Currently, there is one documented occurrence from the Madumabisa Mudstone Formation of Zambia, and two specimens from the Usili (=Kawinga) Formation of Tanzania. The Tanzanian specimens include a poorly preserved, incomplete skull and a partial cranium originally attributed to Parathrinaxodon proops. The latter is now considered a subjective junior synonym of Procynosuchus delaharpeae. Here we report on a new specimen collected in 2007 near the base of Kingori Mountain in Tanzania. It preserves the postorbital region of the skull and the posterior portions of both lower jaws, each containing several intact teeth. A well-preserved postcanine tooth exhibits the dental hallmarks of Procynosuchus and permits unambiguous referral to this taxon. Recent fieldwork corroborates previous suggestions that the Usili tetrapod fauna includes representatives of the Tropidostoma, Cistecephalus and Dicynodon assemblage zones of South Africa. Moreover, the presence of several endemic Usili taxa (e.g. Katumbia, Kawingasaurus, Peitobatrachus), suggests that a straightforward correlation between the Usili tetrapod fauna and a particular assemblage zone from the Beaufort Group may not be possible

    The vertebrate fauna of the Upper Permian of Niger—III, morphology and ontogeny of the hindlimb of Moradisaurus grandis (Reptilia, Captorhinidae)

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    We describe hindlimb elements of the large captorhinid Moradisaurus grandis (Reptilia: Captorhinidae) recently collected from the Upper Permian Moradi Formation of north-central Niger. This description is based primarily on an associated partial skeleton comprising a hemimandible, vertebral column, and partial left and nearly complete right hindlimb. Additionally, we report on a well-preserved, articulated, and essentially complete juvenile pes that provides important information on the ontogeny of the captorhinid tarsus. The hindlimb of Moradisaurus is stout and more massively built than in any other known captorhinid. The femur displays several features interpreted as adaptations to the demands of large body size, and the tibia and fibula have short, wide shafts and hypertrophied condyles and epicondyles. The astragalus is very derived, possessing two accessory ossifications and a relatively horizontal tibial articulation, indicating that the tibia was held more vertically than in other captorhinids. The calcaneum is co-ossified with distal tarsal five. The juvenile pes indicates that the captorhinid centrale arose from the fusion of two ossification centers, and that the captorhinid astragalus arose from the fusion of at least three ossification centers

    The vertebrate fauna of the Upper Permian of Niger. IV. Nigerpeton ricqlesi (Temnospondyli: Cochleosauridae), and the Edopoid Colonization of Gondwana

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    We describe the edopoid temnospondyl Nigerpeton ricqlesi from the Upper Permian Moradi Formation of northern Niger on the basis of two partial skulls and tentatively associated postcranial material. This crocodile-like taxon displays several edopoid characters states such as a long prenarial region with enlarged premaxillae, elongated vomers, large, posteriorly tapering choanae, and a jugal that broadens anteriorly. Nigerpeton possesses a unique carnivorous dentition. It is autapomorphic in its possession of an extremely elongate snout bearing a maxillary bulge that accommodates three hypertrophied caniniform teeth, inner premaxillary tusks, and anterior paired fenestrae, which pierce the skull roof. In addition, both the maxilla and dentary tooth rows show the sporadic appearance of ‘doubled’ tooth positions. The lateral-line system is present at the adult stage, which suggests an aquatic habitat for this taxon. A phylogenetic analysis of Edopoidea and its relatives places Nigerpeton as the sister taxon to the Permo-Carboniferous genus Chenoprosopus from the U.S.A. As with other members of the Moradi tetrapod fauna, the discovery of Nigerpeton strengthens support for the hypothesis that West Africa hosted an endemic fauna at the close of the Paleozoic Era. Biogeographically, we propose that Late Carboniferous and Permian edopoids were geographically widespread and that they twice crossed the Central Pangean mountain chain (between Laurussia and Gondwana) during their evolution. This distribution was later fragmented with the onset of Late Permian climatic warming

    Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

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    Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≄ II, EF ≀35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

    Nouvelles données sur les temnospondyles triasiques des bassins du rift tanzanien et zambien

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    Des restes de temnospondyles dĂ©couverts rĂ©cemment dans le Trias Moyen- ?SupĂ©rieur des bassins de Ruhuhu (Tanzanie) et Luangwa (Zambie) sont dĂ©crits et figurĂ©s ici. Ils sont attribuĂ©s Ă  cf. Cherninia megarhina (Chernin &amp; Cosgriff, 1975), Stereospondyli indet., et cf. Stereospondyli, et regroupent notamment de petits intercentres d’individu(s) adulte(s) qui pourraient correspondre Ă  un nouveau taxon. Ces dĂ©couvertes, bien que fragmentaires, permettent de mettre Ă  jour les assemblages des temnospondyles de Tanzanie et Zambie et montrent une intĂ©ressante diversitĂ© aussi bien phylogĂ©nĂ©tique qu’écologique : par exemple, concernant les mastodonsauroĂŻdes du Trias de Zambie, Cherninia megarhina a co-existĂ© avec Stanocephalosaurus pronus (Howie, 1970) dans les environnements non-marins. Comparable Ă  celui du Bassin du Karoo d’Afrique du Sud, ces assemblages illustrent la reconquĂȘte du groupe aprĂšs l’extinction en masse du Permien-Trias et permettent une meilleure comprĂ©hension de l’impact de cette crise sur les faunes de tĂ©trapodes du sud de la PangĂ©e.Temnospondyl specimens collected recently in the Middle-?Late Triassic of the Ruhuhu (Tanzania) and Luangwa (Zambia) rift basins are described and figured. They are attributed to cf. Cherninia megarhina (Chernin &amp; Cosgriff, 1975), Mastodonsauroidea indet., Stereospondyli indet., and cf. Stereo­spondyli, as well as intercentra of small adult individual(s) which may belong to a new taxon. Although fragmentary, this new material allows taxonomic updates to the Triassic temnospondyl assemblages of Tanzania and Zambia and documents an interesting phylogenetic and ecological diversity. For example, among the Triassic mastodonsauroids of Zambia, Cherninia megarhina coexisted with Stanocephalosaurus pronus (Howie, 1970) in nonmarine environments. Similar to that of the South African Karoo Basin, these temnospondyl assemblages also illustrate the rapid recovery of the group after the Permian-Triassic mass extinction and contribute to a better understanding of the impact of this extinction on the tetrapod faunas of southern Pangea.</p
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