Ben Creisler
Some recent non-dino papers:
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Dylan Bastiaans, Jeroen J. F. Kroll, Dirk Cornelissen, Anne S. Schulp & John W. M. Jagt (2020)
Cranial palaeopathologies in a Late Cretaceous mosasaur from the Netherlands.
Cretaceous Research Article 104425 (advance online publication)
doi:
https://doi.org/10.1016/j.cretres.2020.104425https://www.sciencedirect.com/science/article/pii/S0195667119304082Here we describe multiple pathological skeletal elements in a specimen assigned to a globidensine mosasaur as Prognathodon cf. sectorius. This individual, NHMM 2012 072, was recovered from the upper Lixhe 3 Member (Gulpen Formation, upper Maastrichtian) near Maastricht, the Netherlands. In all likelihood, it was bitten in the snout by a large, possibly conspecific mosasaur â and survived this attack. The specimen described here is among the very few with clear and unambiguous evidence of (very likely intraspecific) agonistic interactions amongst mosasaurs. Despite significant injuries, including partial amputation of the premaxilla, this animal initially recuperated from the encounter, but the subsequent infectious processes as a result of this attack was still ongoing at the time of death. Radiological and morphological features suggest chronic osteomyelitis which led to loss of bone within the left maxilla, which probably hampered the ability to feed, potentially contributing to its demise. This case study illustrates the potential of integrative three-dimensional approaches in palaeopathological studies to provide a much more comprehensive and detailed description of alterations and underlying physiological processes.
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A new bird coracoid from the Uinta Formation in the Uinta Basin in Utah (USA) records the presence of the only known pangalliform from the middle Eocene of North America, occurring in a >15 million year gap in their history. This fossil represents a new taxon, informally termed the Uintan paraortygid, which is also currently the best-supported record of the extinct Paraortygidae in North America (and among the oldest records of the group in the world). The specimen exhibits a derived enlarged procoracoid prominence with a small procoracoid process, and concave elliptical scapular cotyle that are shared with the middle Eocene paraortygids, Xorazmortyx and Scopelortyx; however, the Uintan paraortygid also has a possibly autapomorphic (pneumatic) fossa adjacent to the scapular cotyle. The similarity in body size and morphology among these widely distributed early paraortygids suggests phylogenetic affinity among them. Given their occurrence in the United States, Uzbekistan, and Namibia during the middle Eocene, these birds likely were good fliers with an increased ability to disperse; and probably had a flexible biology or diet allowing them to occupy a diversity of habitats from coasts and forests to semi-arid savannah-like habitats. The problematic early records of Odontophoridae need to be reexamined as potential members of Paraortygidae and associates of these small-bodied taxa.
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Rafael Nascimento & LuÃs FÃbio Silveira
The Fossil Birds of Peter Lund.
Zootaxa 4743 (4): 480-510
doi:
https://doi.org/10.11646/zootaxa.4743.4.2https://www.biotaxa.org/Zootaxa/article/view/zootaxa.4743.4.2
The Danish naturalist Peter Wilhelm Lund (1801â1880), regarded as the father of Brazilian palaeontology and archaeology, is known mainly for his work with fossil mammals of Quaternary age from the limestone caves of the Lagoa Santa region in the state of Minas Gerais, southeastern Brazil. However, during one decade of fieldwork (1835â1844), he also collected a large number of remains of other animal groups from these caves. Birds were well represented and, following assessment by the Danish ornithologist Oluf Winge (1855â1889), most of the specimens collected by Lund belong to species still living in the area. Here we present an overview of the bird remains (fossil and recent), found by Lund and others in the region, we update their taxonomic attributions, and comment on the history of the material, making information previously published only in Danish available in English.
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We are beginning to appreciate that the huge radiations of both marine and terrestrial taxa in the aftermath of the K/Pg mass extinction event were concentrated largely, but not exclusively, in the low-latitude and tropical regions. This in turn means that significant latitudinal diversity gradients were developed well before the onset of global cooling at the Eocene/Oligocene boundary. Net rates of evolutionary radiations were significantly higher through the Early Paleocene - Middle Eocene interval (i.e. ~62-42 Ma) in the tropics than at the poles but this may be due as much to their retardation in the latter regions as to their acceleration in the former. At least in the marine realm, polar assemblages are characterised by the phenomenon of high dominance/low evenness, and it is thought likely that this is due to the extreme seasonality of primary production at the base of the food chain. Many modern polar marine organisms are de facto trophic generalists and occupy significantly broader ecological niches than their tropical counterparts. Although we cannot dismiss the roles of both temperature and area in promoting tropical diversity, it could well be that LDGs are just as much the product of a latitudinal gradient in the seasonality of primary productivity. Such a gradient would have operated in both greenhouse and icehouse worlds.
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Parallel records are required for cyclostratigraphic analyses of fluvial strata.
We present the highest-resolution terrestrial C record of the PETM up to date.
The body of the PETM CIE encompasses 101 Â 9 kyr.
Recovery from the CIE starts with an initial recovery step (IRS) of +2.7 Â 1.0â.
A transitional Wa-0 to Wa-1 fauna, named Wa-R, precedes the C recovery step.
Abstract
Massive addition of isotopically-depleted carbon to the ocean and atmosphere caused a carbon isotope excursion (CIE) and global greenhouse warming during the PaleoceneâEocene Thermal Maximum (PETM) circa 56 million years ago. The body of the CIE is followed by a recovery interval that is key to understanding Earth's capacity for carbon uptake, mechanisms of carbon uptake, and biotic responses following an extreme greenhouse warming event. Expanded terrestrial stratigraphic sections in the Bighorn Basin of Wyoming provide exceptionally high-resolution records of the CIE and can be linked directly to the mammalian fossil record.
Here, we provide carbon isotope records of unprecedented resolution measured on in-situ pedogenic carbonate nodules in two parallel 8-km-spaced sections of upper Paleocene and lower Eocene fluvial sediments in the northern Bighorn Basin. We find consistent precession-driven sedimentary cycles in the two sections. Cycle thicknesses show significant lateral, and thus vertical, variation, demonstrating that astronomical age models constructed for fluvial successions require detailed sedimentary facies analysis of parallel sites.
Plotting the high-resolution carbon isotope records in time using our astronomical age model for the correlated sections indicates a CIE body duration of 101 Â 9 kyr. The CIE shows an initial recovery step of +2.7 Â 1.0â. This step occurs across the single, well-developed paleosol marker bed known as Purple-4, which represents a time interval of up to 15 kyr. The rapidity of recovery at the end of the CIE body is remarkable in light of existing hypotheses for carbon removal from the oceanâatmosphere system. Concurrent mammal finds show that the transition from faunal zone Wa-0 to faunal zone Wa-1 occurred in two steps, with a transitional Wa-R fauna preceding the CIE initial recovery step and Wa-1 fauna following the step.
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Highlights
Macrauchenia patachonica and Xenorhinotherium bahiense had the same eating habits.
Occurrence areas of macraucheniids decreased in Pleistocene/Holocene transition.
Macrauchenia preferred drier/colder areas and Xenorhinotherium drier/warmer areas.
Climatic conditions could be crucial to South American macraucheniids occurrences.
The extinction may have been caused by the Pleistocene/Holocene climatic changes.
Abstract
The extinction of the Quaternary megafauna stands out among the evolutionary history of Cenozoic mammals. In South America, nearly 80% of the megamammals went extinct, including the native ungulates Macrauchenia patachonica and Xenorhinotherium bahiense. Little is known about the causes of the macraucheniidsâ extinction and their paleobiology. Here, we have reconstructed the dietary habits of M. patachonica and X. bahiense using enamel microwear and occlusal enamel index analyses, and also inferred their niches using species distribution modeling and stable isotope paleoecology, in addition to enamel microwear and occlusal enamel index data. We found that both macraucheniids had grazer-feeding habits, although their environmental requirements were different. M. patachonica could live in colder temperatures and arid, subtropical/temperate ecosystems, while X. bahiense was adapted to warmer temperatures and more humid, semi-arid tropical environments. Thus, despite similar feeding habits, these macraucheniids had distinct environmental requirements and ecological niches, which might explain the disjunction in the South American records.
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Lekaneleo roskellyae, comb. nov.Â
Anna K. Gillespie, Michael Archer & Suzanne J. Hand (2020)
Lekaneleo, a new genus of marsupial lion (Marsupialia, Thylacoleonidae) from the OligoceneâMiocene of Australia, and the craniodental morphology of L. roskellyae, comb. nov.
Journal of Vertebrate Paleontology Article: e1703722
doi:
https://doi.org/10.1080/02724634.2019.1703722 https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1703722The domestic cat-sized marsupial lion Priscileo roskellyae (Thylacoleonidae) from the Oligocene-Miocene of Australia was originally allocated to the genus Priscileo Rauscher, 1987, on the basis of its plesiomorphic upper dental formula of three premolars and four molars and its relatively small size. Recent reassignment of the Priscileo type species P. pitikantensis to the genus Wakaleo has now necessitated establishment of a new generic name for the species roskellyae Gillespie, 1997. In contrast to W. pitikantensis, which is only known from a fragmented palate and associated postcranial elements, the skull and lower dentition of P. roskellyae, described here, exhibit features that support its generic distinction within Thylacoleonidae. It is renamed here Lekaneleo roskellyae, comb. nov. Distinctive craniodental features include small sagittal and nuchal crests, lack of a prominent rostral tympanic process on the periotic, lack of alisphenopalatine pterygoid processes, a stylomastoid sulcus that courses through the mastoid, three teeth between i1 and p3, and very broad talonid basins on the lower molars. In contrast to species of Wakaleo, which appear to form a morphocline during the late Oligocene and early Miocene, L. roskellyae is a relatively conservative taxon, exhibiting no discernible change over the same interval of time.