Ben Creisler
Some recent non-dino papers:
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Satoshi UTSUNOMIYA (2019)
Oldest Elasmosauridae(Plesiosauria) in East Asia from the Upper Cretaceous Goshoura Group, Shishijima Island, Southwestern Japan.
Bulletin of the Osaka Museum of Natural History 73: 23-35 (in Japanese)
doi / 10.20643 / 00001333
Most fossils of the Plesiosauria from Japan are known from Hokkaido and Tohoku. In this report, the first plesiosaurian fossil from the Kyushu is described. The specimen was discovered from the Hegushi Formation of Goshoura Group (lower Cenomanian, Upper Cretaceous) of Shishijima Island, Kagoshima Prefecture, and consists of skull elements (frontal and basioccipital), most of the mandible (dentary, surangular, angular), a hyoid, cervical vertebrae including the atlas-axis complex. The pattern of striations on the tooth surface, elongated cervical vertebrae and single cervical rib heads indicate that this specimen belongs to the Elasmosauridae. Separation of the neural arch and centrum in most vertebrae indicate this individual is "juvenile" sensu Brown (1981). The Shishijima specimen is the oldest confirmed elasmosaurid in Japan and in East Asia. It is an important specimen showing that the existence of the family in the North western part of the Pacific Ocean by that time.Â
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Matthew R. McCurry, Alistair R. Evans, Erich M. G. Fitzgerald, Colin R. McHenry, Joseph Bevitt & Nicholas D. Pyenson (2019)
The repeated evolution of dental apicobasal ridges in aquatic-feeding mammals and reptiles.
Biological Journal of the Linnean Society, blz025,
Since the Permian, Earthâs aquatic ecosystems have been ecologically dominated by numerous lineages of predatory amniotes. Many of these groups evolved elevated ridges of enamel that run down the apicalâbasal axis of their teeth, referred to here as apicobasal ridges. This trait is commonly used as a taxonomic tool to identify fossil species and higher groupings, but the function of the ridges and their associated ecological significance are poorly understood. Here, we aim to clarify the phylogenetic distribution of apicobasal ridges among amniotes and to examine how the morphology of apicobasal ridges varies across species. We show that these ridges have evolved independently numerous times and are almost exclusively found in aquatic-feeding species. Ridge morphology varies, including tall, pronounced ridges, low, undulating ridges and interweaving ridges. Their internal structure also varies from tooth crowns with locally thickened enamel to undulating enamelâdentine interface. We assess the relative merits of different hypothetical functions of the ridges and propose that although apicobasal ridges might provide some strengthening of the tooth, their morphology and pattern of evolution do not indicate that this is their primary function. Instead, we suggest that apicobasal ridges serve to increase the efficiency of puncture, grip and/or removal.
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GÃbor Botfalvai, Orsolya GyÅriâ, EmÃlia Pozsgaiâ, Izabella M. Farkasâ, TamÃs SÃgiâ, MÃrton SzabÃ, Attila Åsiâ (2019)
Sedimentological characteristics and paleoenvironmental implication of Triassic vertebrate localities in VillÃny (VillÃny Hills, southern Hungary).
Geologica Carpathica 70 (2): 135--152
There are two Triassic vertebrate sites in VillÃny Hills (Southern Hungary), where productive and continuous excavations have been carried out in the last six years resulting in a rich and diversified assemblage of shallow marine to coastal animals. The studied formations belong to the VillÃnyâBihor Unit of the Tisza Megaunit, which was located at the passive margin of the European Plate during the Triassic. The relatively diverse vertebrate assemblage was collected from a Road-cut on Templom Hill and a newly discovered site at a construction zone located on the Somssich Hill. Four main lithofacies were identified and interpreted in the newly discovered Construction vertebrate site consisting of dolomite (deposited in a shallow, restricted lagoon environment), dolomarl (shallow marine sediments with enhanced terrigenous input), reddish silty claystone (paleosol) and sandstone (terrigenous provenance) indicating that the sediments of the Construction vertebrate site were formed in a subtidal to peritidal zone of the inner ramp environment, where the main controlling factor of the alternating sedimentation was the climate change. However, the recurring paleosol formation in the middle part of the section also indicates a rapid sea-level fall when the marine sediments were repeatedly exposed to subaerial conditions. In the Road-cut site the siliciclastic sediments of the MÃszhegy Sandstone Formation are exposed, representing a nearshore, shallow marine environment characterized by high siliciclastic input from the mainland.
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Adrian Currie (2019)
Mass extinctions as major transitions.
Biology & Philosophy 34(2):29
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Both paleobiology and investigations of 'major evolutionary transitions' are intimately concerned with the macroevolutionary shape of life. It is surprising, then, how little studies of major transitions are informed by paleontological perspectives and. I argue that this disconnect is partially justified because paleobiological investigation is typically 'phenomena-led', while investigations of major transitions (at least as commonly understood) are 'theory-led'. The distinction turns on evidential relevance: in the former case, evidence is relevant in virtue of its relationship to some phenomena or hypotheses concerning those phenomena; in the latter, evidence is relevant in virtue of providing insights into, or tests of, an abstract body of theory. Because paleobiological data is by-and-large irrelevant to the theory which underwrites the traditional conception of major transitions, it is of limited use to that research program. I suggest that although the traditional conception of major transitions is neither ad-hoc or problematically incomplete, its promise of providing unificatory explanations of the transitions is unlikely to be kept. Further, examining paleobiological investigations of mass extinctions and organogenesis, I further argue that (1) whether or not transitions in paleobiology count as 'major' turns on how we conceive of major transitions (that is, the notion is sensitive to investigative context); (2) although major transitions potentially have a unified theoretical basis, recent developments suggest that investigations are becoming increasingly phenomena-led; (3) adopting phenomena-led investigations maximizes the evidence available to paleobiologists.
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Also may be of interest:
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Richard Shine & Ruchira Somaweera (2019)
Last lizard standing: The enigmatic persistence of the Komodo dragon.
Global Ecology and Conservation e00624
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Highlights
Characteristics of megafauna that survived to the present day may clarify why so many other giant species went extinct.
Komodo Dragons evolved in Australia, but persist only on small islands in the Indonesian archipelago.
Flexibility conferred by ecological, behavioural and demographic features of Komodo Dragons may have allowed their survival through the Pleistocene.
Low densities of modern humans (due to landscape features) and the introduction of feral ungulates may have buffered human impacts in more recent years.
Abstract
To understand why much of the world's terrestrial megafauna went extinct within the last 50,000 years, we can look at the exceptions: large-bodied species that avoided that fate. The Komodo dragon (Varanus komodoensis) is tenfold heavier than almost any other surviving lizard species, is currently restricted to small islands, and relies on scavenging as well as predation â attributes that doomed other megafaunal taxa to extinction. How did these giant reptiles persist? We suggest that the Komodo dragons' survival reflects general attributes of ectotherms (low energy demands; an ability to reduce mean adult body sizes during resource shortages) coupled with features of varanid biology (behavioural and ecological flexibility that allowed utilization of marine subsidies; salt tolerance), the habitat (a fragmented arid landscape better-suited to reptiles than to humans; and with substantial spatial and temporal variation in rainfall patterns and thus productivity), and the history of hominid colonization (when modern humans arrived, they brought with them novel prey [pigs] that blunted the impacts of hunting and habitat degradation). In short, the surprising persistence of the Komodo dragon is not due to any single unique attribute, but instead reflects a fortunate combination of factors relating to the species, the habitat, and the timeframe and nature of human colonization.