Cesar Leandro Schultz, Max Cardoso Langer and Felipe Chinaglia Montefeltro (2016)
A new rhynchosaur from south Brazil (Santa Maria Formation) and rhynchosaur diversity patterns across the Middle-Late Triassic boundary.
Paläontologische Zeitschrift (advance online publication)
The rhynchosaur previously referred to as the “Mariante Rhynchosaur” is here formally described as a new genus and species based on two specimens: a complete skull (without the lower jaw) articulated with the three first cervical vertebrae and a set of right maxilla and dentary. Both specimens were collected at the same site in Rio Grande do Sul, Brazil, from deposits of the Santa Maria Formation considered of Ladinian (Middle Triassic) age. Diagnostic characters include the contact between prefrontal and postfrontal, a pair of deep frontal grooves, and a very deep skull. A new phylogenetic analysis recovered the new taxon as a member of the Stenaulorhynchinae, a relatively diverse clade of Middle Triassic rhynchosaurs, with records in India, east Africa, and the Americas. Evidence suggests that the extinction of that clade took place in the context of a faunal turnover across the Ladinian-Carnian boundary, when it was replaced by the much more abundant Late Triassic hyperodapedontine rhynchosaurs.
Zoltan Csiki-Sava, Artur Kedzior, Grzegorz Pienkowski & Mihai Emilian Popa (2016)
Hettangian tetrapod burrows from the continental Steierdorf Formation at Anina, western Romania.
Geological Quarterly (advance online publication)
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Very large, sparsely distributed, sinuous, gently dipping and occasionally branching tunnels with subordinate swells, chambers and scratches, are described from the Hettangian Dealul Budinic Member of the Lower Jurassic continental Steierdorf Formation at Anina in the South Carpathians, Romania, and are interpreted as tetrapod burrows. No bone remains have been found in association with these structures. The morphology and large dimensions of the burrows suggest that the trace-makers were sauropsid amniotes, most probably either crocodyliforms or small-sized basal euornithopod dinosaurs, but their therapsid affinities, although less likely, cannot be discarded either. The age, large size and probable origin of these burrows add important information to a poorly documented period of the evolution of tetrapod fossoriality. It may be suggested that within a relatively short interval following the Triassic⁄Jurassic extinction event, when environmental conditions were still marked by strongly seasonal climate with prolonged droughts as well as extreme moisture and temperature fluctuations, fossorial habit probably became yet again an endurance strategy for the burrow makers.
Nicole Klein , Robert Bussert, David Evans, Khalaf Allah O. Salih, Ali A. M. Eisawi, Mutwakil Nafi & Johannes Müller (2016)
Turtle remains from the Wadi Milk Formation (Upper Cretaceous) of Northern Sudan.
Palaeobiodiversity and Palaeoenvironments (advance online publication)
We describe here turtle remains from lag-type concentrations in channels and scours in the Wadi Milk Formation (Upper Cretaceous) of the Wadi Abu Hashim region in northern Sudan. Due to the isolated nature of the finds and the lack of any diagnostic material, such as skulls or more complete shell fragments, low-level taxonomic assignment was not possible. However, the morphology as well as the superficial ornamentation of most plates indicates pelomedusoid (Pleurodira) affinities, which is consistent with the geographically isolated nature of continental Africa during much of the Upper Cretaceous. The fauna contains one or two smaller sized pelomedusoid taxa as well as at least two large forms that are identified as members of Bothremydidae. A few plates may indicate the presence of other turtle lineages. Bothremydidae are known to have inhabited a variety of fluviatile and marine–littoral/near-coastal environments and thus are poor palaeoenvironmental indicators. However, bone compactness of one of the four peripheral morphotypes indicates the presence of a taxon that was more aquatic than typical Bothremydidae. Many plates show bioerosional traces that are interpreted as bore holes of clionid sponges, indicating a connection to a coastal environment exposed to marine influences. A marine or tidal influence is additionally suggested by sedimentological indicators, such as inclined heterolithic stratification, very variable palaeocurrent directions and partly intense bioturbation.
Verónica Krapovickas, M. Gabriela Mángano, Luis A. Buatois & Claudia A. Marsicano (2016)
Integrated Ichnofacies models for deserts: Recurrent patterns and megatrends.
Although it is commonly assumed that the trace-fossil record of eolian dunes and associated environments is invariably poor, a systematic review of the available information indicates that this is not necessarily the case. A model involving five main phases of colonization of desert environments through the Phanerozoic is proposed in this paper. The first phase (Cambrian–Silurian) involved animal incursions into coastal dune fields directly from the sea, although it is unlikely that these animals would have remained for long periods of time in coastal deserts. The second phase (Devonian) reflects the activities of dune pioneers that left their fluvial habitat to enter temporary or permanently into inland deserts. The third phase (Carboniferous–Permian) involved the colonization of deserts by tetrapods. The fourth phase (Triassic–Cretaceous) involved a major exploitation of the infaunal ecospace as reflected by the appearance of more varied behavioral patterns in sub-superficial structures. The fifth phase (Paleogene–Recent) reflects the appearance of the ecological dynamic that characterizes modern desert communities. The invertebrate ichnofacies for eolian dunes is re-named herein as the “Octopodichnus–Entradichnus Ichnofacies” honoring the seminal work of previous workers who simultaneously tackled the issue of eolian dune ichnofacies. The Chelichnus ichnofacies is retained for vertebrate trace-fossil assemblages in eolian settings. Both ichnofacies occur in mobile and temporary stabilized sandy substrates, subject to frequent erosion and deposition, and to strong seasonality. Desert settings consist of complex mosaics of habitats or physical units associated with organism activity. Trace-fossil distribution can be understood as reflecting the partitioning of desert settings in a mosaic of landscape units, characterized by water content and its temporal fluctuations, nutrient availability, nature of the substrate, and the dominant organisms present. In turn, desert systems are dynamic entities that change as a response to regional climate. Landscape units, such as eolian sand seas, salt flat and playa lake systems, ephemeral rivers and alluvial fans, interact in response to regional-scale climate variations in hyper-arid, arid, and semiarid climatic settings. Ancient deserts completely developed under hyper-arid climatic conditions rarely preserve trace fossils due to the absence of moisture near the surface. However, the alternation of wet periods may represent windows for life development and thus, preservation of biogenic structures. Arid deserts display complex patterns of dunes combined with dry, wet, and flooded interdunes. Dry desert elements (e.g. dunes, interdunes, sand sheets) typically record the Entradichnus–Octopodichnus and Chelichnus Ichnofacies. Slight rises in regional precipitation produce elevation of the water table and increase of fluvial discharges that provide water and sediment to the system. These processes may result in the local concentration of trace fossils in wet interdunes and ephemeral fluvial systems, illustrating the Scoyenia and Chelichnus Ichnofacies. In semiarid systems playa lakes expand by the addition of freshwater, evolving into freshwater lakes, and fluvial systems may become more common; lake margins and fluvial overbanks typically contain trace-fossil assemblages that may be ascribed to the Scoyenia Ichnofacies.