Ben Creisler
Some recent non-dino papers:
Lorenzo Marchetti, Sebastian Voigt, Spencer G. Lucas, Heitor Francischini, Paula Dentzien-Dias, Roberto Sacchi, Marco Mangiacotti, Stefano Scali, Andrea Gazzola, Ausonio Ronchi & Amanda Millhouse (2018)
Tetrapod ichnotaxonomy in eolian paleoenvironments (Coconino and De Chelly formations, Arizona) and late Cisuralian (Permian) sauropsid radiation.
Earth-Science Reviews (advance online publication)
The tetrapod footprint record of Permian eolian environments has long been underestimated because of overall poor preservation and its apparent monospecifity. The best known and most abundant Cisuralian record of tetrapod footprints is from the Coconino and De Chelly formations of Arizona, which, however, thus far encompassed only the ichnogenera Chelichnus and Dromopus. We revised the locomotion and taphonomy of these footprints and propose a new model, basing it on: 1) trackways changing direction, 2) trackways heading in different directions on the same surface, 3) trackways in situ, and 4) laboratory experiments with common wall lizards, Podarcis muralis. In all cases, the Chelichnus-like appearance of footprints is due to digit tip sliding on inclined depositional surfaces, masking the original footprint shape and orientation. Also, the trackway pattern and body position are largely influenced by the angle of inclination (dip) of the substrate being walked on. Based on an anatomy-consistent ichnotaxonomy, Chelichnus and Laoporus are here considered nomina dubia, and the footprints from the Coconino and De Chelly formations are revised and assigned to: parareptiles/captorhinomorph eureptiles (Erpetopus, Varanopus curvidactylus), bolosaurid parareptiles/diapsid eureptiles (cf. Dromopus), varanopid synapsid (cf. Tambachichnium) and reptiliomorph amphibians (Amphisauropus, Ichniotherium sphaerodactylum). The ichnoassociation is dominated by parareptile/captorhinomorph tracks, similarly to all the late Cisuralian marginal marine, floodplain, alluvial fan and ephemeral lacustrine tetrapod ichnoassociations of North America, Europe and North Africa. A review of all the available data including the new results suggests a facies-crossing transition between an early-Cisuralian amphibian- and synapsid-dominated ichnofauna (Dromopus track biochron) and a late Cisuralian parareptile/captorhinomorph-dominated ichnofauna (Erpetopus track biochron) at low latitudes of Pangea.
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Juan P. Zurano, Felipe M. MagalhÃes, Ana E. Asato, Gabriel Silva, Claudio J. Bidau, Daniel O. Mesquita & Gabriel C. Costa (2018)
Cetartiodactyla: updating a time-calibrated molecular phylogeny.
Molecular Phylogenetics and Evolution (advance online publication)
Highlights
Time-calibrated molecular phylogeny of Cetartiodactyla covering more than 90% of extant species.
The origin of Cetartiodactyla dates back to ~67 Ma at the Cretaceous-Paleocene boundaries.
Relationship among major lineages and among families were recovered robustly.
Families divergence times are congruent with the available fossil records.
Missing-data has a limited effect on the estimation of the divergence times and in the support of the clades.
Abstract
Cetartiodactyla comprises one of the most diverse mammal radiations. Currently, 23 families, 131 genera and more than 330 species are recognized. Several studies have been trying to resolve its phylogenetic relationships. The most comprehensive dated phylogenetic hypothesis available includes only 55% of the extant species, precluding a clear understanding of ecological and evolutionary patterns in Cetartiodactyla. Here, we gathered all mitochondrial genetic data available in GenBank to build a robust Cetartiodactyla calibrated phylogenetic tree using 21 fossil calibration points. We found mitogenomic data for 225 species and included other 93 species from which there was at least one mitochondrial gene available. Using a Bayesian approach, we generated a dated tree comprising 90% of the extant Cetartiodactyla species (n= 318). The major lineages showed robust support and families divergence times are congruent with the available fossil evidence and with previously published phylogenetic hypotheses. By making available a dated phylogeny with extensively sampled clades, we expect to foster future studies on the origin, tempo and mode of Cetartiodactyla diversification.
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Kathleen K. Smith & Anna L. Keyte (2018)
Adaptations of the marsupial newborn: birth as an extreme environment.
The Anatomical Record (advance online publication)
At birth a mammalian neonate enters an extreme environment compared to the intrauterine environment in which it has grown. This transition may be particularly extreme in marsupials because they are born at an exceedingly altricial state, after an exceptionally short gestation. Their stage of development must be considered embryonic by almost any criteria. Yet at this very early stage of development marsupials must travel to the teat, attach and suckle, and have basic functioning of all major physiological systems. In this paper we review the adaptations of the marsupial neonate for survival at an embryonic state, showing that the neonate exhibits a mosaic of accelerations and delays of various tissues and organs as well as several special adaptations to produce the functioning newborn. We then discuss the development of the craniofacial region, the body axis and limbs in order to detail some of the major changes to development leading to this uniquely configured neonate. We show that marsupial development arises out of a variety of heterochronies (changes in relative timing of events) and heterotopies (changes in location of specific developmental events) at the genetic, cellular and organ level. We argue that these data support hypotheses that many of the specific patterns seen in marsupial development arise from the basic constraint of embryonic energetic and tissue resources. Finally ideas on the evolutionary context of the marsupial developmental strategy are briefly reviewed.
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Matteo Maron, Giovanni Muttoni, Manuel Rigo, Piero Gianolla & Dennis V.Kente (2018)
New magnetobiostratigraphic results from the Ladinian of the Dolomites and implications for the Triassic geomagnetic polarity timescale.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
Highlights
New U-Pb constrained Ladinian magnetostratigraphy improves Triassic chronology.
Using recent magnetostratigraphic data to update the Geomagnetic Polarity Timescale
Updated Geomagnetic Polarity Timescale led to a duration of 50.5âMyr for Triassic.
Abstract
We investigated for magnetostratigraphy the Rio Nigra and Rio Frommer stratigraphic sections from Alpe di Siusi/Seiser Alm (Dolomites, northern Italy) in order to improve the calibration of the Triassic time scale. Both sections are characterized by ammonoid and conodont associations typical of Longobardian (late Ladinian, Middle Triassic) age. Moreover, the Rio Nigra section is constrained by a U-Pb zircon date of 237.77âÂâ0.05âMa. Building on the recently verified Newark-Hartford astrochronological polarity timescale for the Late CarnianâRhaetian (plus the Hettangian) and through magnetostratigraphic correlations of an updated inventory of Tethyan marine stratigraphic sections from the literature, some of which are provided with U-Pb zircon age constraints, we propose a revised Geomagnetic Polarity Time Scale for the entire Triassic.