F. Barroso-Barcenilla, M. Berrocal-Casero, H.A. Blain, P.M. Callapez, O. Cambra-Moo, F. Escaso, C. Martín-Closas, F. Ortega, A. Pérez-García, I. Prieto, J. Rodríguez-Lázaro, A. Ruiz-Galván, J.L. Sanz, M. Segura & P. Sevilla (2017)
Geological and Palaeontological context of three new Barremian (Lower Cretaceous) vertebrate sites in the Iberian Peninsula (Cuenca Province, Central Spain).
Proceedings of the Geologists' Association (advance online publication)
Three new Lower Cretaceous vertebrate sites (Vadillos-1, Vadillos-2, El Tobar) have been recently discovered and studied in the Cuenca Province (Central Spain). They are located in deposits of “Wealden” facies belonging to the El Collado Sandstone and Clay Formation. In these outcrops, micro and macroremains corresponding to plants, invertebrates and vertebrates have been collected and subsequently assigned to macrophytes, charophytes (e.g., Atopochara trivolvis triquetra, Globator maillardii trochiliscoides, Clavator harrisii harrisii), ostracods (e.g., Cypridea gr. modesta, Cypridea cf. C. isasae, Cypridea sp. aff. C. moneta, Cypridea sp. 1, Cypridea sp. 2), molluscs (Unionoida, Viviparus sp.), fishes, amphibians, turtles (cf. Eucryptodira), crocodyliforms (Neosuchia) and dinosaurs (ankylosaurs, ornithopods, theropods). Among the vertebrate remains, scales, teeth, plates, osteoderms, phalanges, ribs, vertebrae and other incomplete bones, as well as eggshell fragments have been identified. This rich and diverse assemblage was deposited in an upper Barremian alluvial-palustrine muddy floodplain crossed by braided sandy channels.
A. W. Crompton, T. Owerkowicz, B.-A. S. Bhullar & C. Musinsky (2017)
Structure of the nasal region of non-mammalian cynodonts and mammaliaforms: Speculations on the evolution of mammalian endothermy.
Journal of Vertebrate Paleontology Article: e1269116 (advance online publication)
Nasal regions of the non-mammalian cynodonts Massetognathus, Probainognathus, and Elliotherium were reconstructed from micro-computed tomography scans and compared with scans and published accounts of more derived forms, including Brasilitherium, Morganucodon, Haldanodon, and extant mammals. The basic structure of the modern mammalian nose, already present in non-mammalian cynodonts of the Early Triassic, underwent little modification during the Triassic. A respiratory chamber opened into a nasopharyngeal passage through an enlarged primary choana bordered posteriorly by a transverse lamina that formed the floor to a more posterior olfactory chamber. Cartilaginous respiratory turbinals initially provided a surface for evaporative cooling during periods of increased activity in the exceptionally high ambient temperatures of the Triassic. A similar mechanism for heat loss is present in extant crocodilians, squamates, and mammals. In the Late Triassic and Early Jurassic non-mammaliaform cynodonts (Elliotherium) and mammaliaforms (Morganucodon), the pterygopalatine ridges behind the hard secondary palate extended ventrally and formed the lateral walls to a narrow nasopharynx, as pterygoid hamuli do in extant mammals. Ridges in this position suggest the presence of a palatopharyngeus muscle in late non-mammaliaform cynodonts that could hold the larynx in an intranarial position during rest or low activity levels to prevent inhaled air from entering the oral cavity, thus allowing cartilaginous respiratory turbinals to assume an additional role as temporal countercurrent exchange sites for heat and water conservation. Ossification of respiratory turbinals in mammals enhanced their efficiency for conserving heat and water at rest, as well as their ability to dissipate heat during thermal stress.
Dawid Surmik, Bruce M. Rothschild & Roman Pawlicki (March 2017)
Unusual intraosseous fossilized soft tissues from the Middle Triassic Nothosaurus bone.
The Science of Nature 104:25
Fossilized soft tissues, occasionally found together with skeletal remains, provide insights to the physiology and functional morphology of extinct organisms. Herein, we present unusual fossilized structures from the cortical region of bone identified in isolated skeletal remains of Middle Triassic nothosaurs from Upper Silesia, Poland. The ribbed or annuli-shaped structures have been found in a sample of partially demineralized coracoid and are interpreted as either giant red blood cells or as blood vessel walls. The most probable function is reinforcing the blood vessels from changes of nitrogen pressure in air-breathing diving reptiles. These structures seem to have been built of extensible muscle layers which prevent the vessel damage during rapid ascent. Such suspected function presented here is parsimonious with results of previous studies, which indicate rarity of the pathological modification of bones associated with decompression syndrome in Middle Triassic nothosaurs.
Jorge I. Noriega, Emilio A. Jordan, Raúl I. Vezzosi & Juan I. Areta (2017)
A new species of Opisthodactylus Ameghino, 1891 (Aves, Rheidae), from the late Miocene of northwestern Argentina, with implications for the paleobiogeography and phylogeny of rheas.
Journal of Vertebrate Paleontology Article: e1278005 (advance online publication)
A new species of rheid, Opisthodactylus kirchneri, sp. nov., is erected on the basis of associated elements of both hind limbs from the late Miocene in northwestern Argentina. The new species extends the biochron of Opisthodactylus from early Miocene to late Miocene and its distribution from Patagonia to northwest Argentina. Cladistic analysis recovered an Opisthodactylus-Pterocnemia clade as sister to a Rhea americana clade. The Opisthodactylus-Pterocnemia clade would have inhabited the most southern, central, and western regions of southern South America throughout the early-middle Neogene, whereas the Rhea stock would have had a north-northeastern or Brazilian ancestral distribution in the lowlands of the continent. The similar biogeographic patterns of living and fossil rheids, cariamids, and tinamids seem to roughly reflect the environmental shift from closed to open habitats that took place at the southern end of South America during the Neogene and Pleistocene, and at least in the former two families the effects of isolation produced by the ‘Paranaense’ sea. Closed-habitat taxa of these three families are recorded at early Miocene localities in Patagonia (O. horacioperezi, O. patagonicus, Noriegavis santacrucensis, and Crypturellus reai), whereas open-habitat taxa come from late Miocene–early Pliocene sites at central (Pterocnemia sp. and Eudromia sp.), northwestern (O. kirchneri and Pterocnemia cf. mesopotamica), and northeastern (Pterocnemia mesopotamica) regions in Argentina.