Ben Creisler
More new non-dino papers:
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Flavio Bellardini & Laura Codornià (2019)
First pterosaur post-cranial remains from the Lower Cretaceous Lohan Cura Formation (Albian) of Patagonia, Argentina.
Ameghiniana (advance online publication)
doi:10.5710/AMGH.13.03.2019.3225
In this contribution, we present the first pterosaur post-cranial bone from the Lohan Cura Formation (Albian) of the Cerro de los Leones locality (PicÃn LeufÃ, NeuquÃn Province). The bone (MCF-PVPH-881) is an incomplete left ulna, preserved in three dimensions, and composed of the proximal epiphysis and part of the diaphysis. The element shares several affinities with derived pterodactyloid pterosaurs, such as a diaphysis with a sub-oval cross-section, thin bone walls, pneumatic foramina in the dorsal surface of the proximal epiphysis and between the cotyles, and wingspan reconstruction indicating a medium-size specimen. An analysis of the microstructure allowed us to evaluate the ontogenetic stage of the specimen. The thin-section from the mid-shaft shows a wide and sub-circular medullary cavity, encircled by a thin cortical bone ring. In the innermost cortex, secondary lamellar bone forms a distinct and avascular endosteal layer, while the cortical layer is dominated by a well-vascularized primary bone with coarse parallel fibers, as in other pterodactyloids. The presence of an avascular endosteal lamellar layer, an unremodeled cortical layer dominated by parallel-fibered bone, and a well ossified proximal epiphysis suggest that the specimen was an advanced juvenile or sub-adult with active-growth at the time of death. Considering the limited pterosaurian fossil record of Argentina, the new pterosaur specimen not only contributes to the reconstruction of the paleoecosystem of the Lohan Cura Formation in the central NeuquÃn Basin, but also improves our knowledge on the pterosaur taxonomic diversity during the Early Cretaceous of Patagonia.
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Irena Jadwiga Burek - Raselli & JÃrÃmy Anquetin (2019)
Novel insights into the morphology of Plesiochelys bigleri from the early Kimmeridgian of Northwestern Switzerland.
bioRxiv 582700;
Plesiochelyidae were relatively large coastal marine turtles, which inhabited the epicontinental seas of Western Europe during the Late Jurassic. Their fossil record can be tracked in Germany, Switzerland, the United Kingdom, France, Spain and Portugal. The Jura Mountains, in northwestern Switzerland, have been the main source for the study of this group, mostly thanks to the rich and famous historical locality of Solothurn. In the last two decades, numerous plesiochelyid remains have been collected from Kimmeridgian deposits (Lower Virgula Marls and Bannà Marls) in the area of Porrentruy (Canton of Jura, Switzerland). This material was revealed by construction works of the A16 Transjurane highway between 2000 and 2011, and led to the recent description of the new species Plesiochelys bigleri. In the years 2014 and 2016, new fragmentary turtle material was collected from the Bannà Marls (Reuchenette Formation, lower Kimmeridgian) near the village of Glovelier, Canton of Jura, Switzerland. The new material consists of a complete shell, additional shell elements, a few bones from the appendicular and vertebral skeleton, and a fragmentary basicranium. This material can be confidently assigned to the species P. bigleri. It supports the presence of this species in the Bannà Marls, slightly extends its spatial distribution and confirms the differences with the closely related species P. etalloni. The new material reveals that the split between the cerebral and palatine branches of the internal carotid artery occurs in a vertical plane in P. bigleri. This condition could not be observed in the type material due to poor preservation. This new character clearly distinguishes P. bigleri from P. etalloni and seems to be unique among thalassochelydians.
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Now out in full form (previously abstract only):
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Ingmar Werneburg (2019)
Morphofunctional Categories and Ontogenetic Origin of Temporal Skull Openings in Amniotes.
Frontiers in Earth Science 7:13
The rise of phylogenetic systematics (Hennig, 1950) uncovered many natural groups of amniotes with Synapsida-characterized by one temporal opening, and Reptilia (Modesto and Anderson, 2004)-which contains ancestral, typically anapsid groups, without temporal openings, and Diapsida, with two temporal openings and diverse secondary modifications. The ancestrally anapsid parareptiles partly show, with certain ontogenetic, inter-, and intra-specific variation, one opening or marginal excavation in their temporal region (Cisneros et al., 2004; Tsuji and MÃller, 2009; MacDougall and Reisz, 2014), although evidence from other characters clearly separates them from Synapsida (MÃller, 2004; Tsuji et al., 2012; Brocklehurst et al., 2018). Furthermore, the phylogenetic position of one early "classical" synapsid group (i.e., varanopsids) has become controversial, as it has appeared within Reptilia in some phylogenetic analyses (Ford and Benson, 2018; Laurin and PiÃeiro, 2018). Compared to historical classifications (Osborn, 1903; Williston, 1917; Goodrich, 1930), there is a common consensus that temporal openings are only a weak indication for higher taxon interrelationship, although it can be informative on lower taxonomic level (MÃller, 2003; Laurin and PiÃeiro, 2018; MacDougall et al., 2018). Here, I present a rather morphofunctional categorization of temporal openings, introduce a refined terminology, and provide an ontogenetic explanation on their evolutionary origins.