A Jurassic pterosaur from Patagonia

Pterosaurs are an extinct group of highly modified flying reptiles that thrived during the Mesozoic. This group has unique and remarkable skeletal adaptations to powered flight, including pneumatic bones and an elongate digit IV supporting a wing-membrane. Two major body plans have traditionally been recognized: the primitive, primarily long-tailed paraphyletic “rhamphorhynchoids” (preferably currently recognized as non-pterodactyloids) and the derived short-tailed pterodactyloids. These two groups differ considerably in their general anatomy and also exhibit a remarkably different neuroanatomy and inferred head posture, which has been linked to different lifestyles and behaviours and improved flying capabilities in these reptiles. Pterosaur neuroanatomy, is known from just a few three-dimensionally preserved braincases of non-pterodactyloids (as Rhamphorhynchidae) and pterodactyloids, between which there is a large morphological gap. Here we report on a new Jurassic pterosaur from Argentina, Allkaruen koi gen. et sp. nov., remains of which include a superbly preserved, uncrushed braincase that sheds light on the origins of the highly derived neuroanatomy of pterodactyloids and their close relatives. A µCT ray-generated virtual endocast shows that the new pterosaur exhibits a mosaic of plesiomorphic and derived traits of the inner ear and neuroanatomy that fills an important gap between those of non-monofenestratan breviquartossans (Rhamphorhynchidae) and derived pterodactyloids. These results suggest that, while modularity may play an important role at one anatomical level, at a finer level the evolution of structures within a module may follow a mosaic pattern.
Codorniú L, Paulina Carabajal A, Pol D, Unwin D, Rauhut OWM. (2016) A Jurassic pterosaur from Patagonia and the origin of the pterodactyloid neurocranium. PeerJ 4:e2311

Nuevos hallazgos en La Invernada

El pasado fin de semana, el MAU, Museo Municipal Argentino Urquiza, Rincón de los Sauces, Neuquén, Argentina,  realizó la evaluación de una denuncia de hallazgo de restos fósiles en el área La Invernada. Después de transitar por un camino de muy dificil acceso, se pudo dar con el lugar exacto de donde provenian los restos recuperados. Los materiales entregados al Museo correspondían a tres de los cinco huesos metacarpianos de una pata delantera de un dinosaurio saurópodo. La evaluación realizada en el lugar permitió determinar que el resto de los huesos faltantes aún estaban in situ, los cuales se encontraban muy bien preservados y articulados con el resto de dicha pata. En futuras salidas, el resto de los huesos serán recuperados y se evaluará si puede que el resto del dinosaurio se encuentre bajo la roca.

Rodolfo A. Coria and Philip J. Currie

A skeleton discovered in the Upper Cretaceous Sierra Barrosa Formation (Turonian-Coniacian) of Neuquén Province, Argentina represents a new species of theropod dinosaur related to the long snouted, highly pneumatized Megaraptoridae. The holotype specimen of Murusraptor barrosaensis n.gen et n.sp. includes much of the skull, axial skeleton, pelvis and tibia. Murusraptor is unique in having several diagnostic features that include anterodorsal process of lacrimal longer than height of preorbital process, and a thick, shelf-like thickening on the lateral surface of surangular ventral to the groove between the anterior surangular foramen and the insert for the uppermost intramandibular process of the dentary. Other characteristic features of Murusraptor barrosaensis n.gen. et n. sp. include a large mandibular fenestra, distal ends of caudal neural spines laterally thickened into lateral knob-like processes, short ischia distally flattened and slightly expanded dorsoventrally. Murusraptor belongs to a Patagonian radiation of megaraptorids together with Aerosteon, Megaraptor and Orkoraptor. In spite being immature, it is a larger but more gracile animal than existing specimens of Megaraptor, and is comparable in size with Aerosteon and Orkoraptor. The controversial phylogeny of the Megaraptoridae as members of the Allosauroidea or a clade of Coelurosauria is considered analyzing two alternative data sets.

Coria RA, Currie PJ (2016) A New Megaraptoran Dinosaur (Dinosauria, Theropoda, Megaraptoridae) from the Late Cretaceous of Patagonia. PLoS ONE 11(7): e0157973. doi:10.1371/ journal.pone.0157973

Sebastián Apesteguía, Nathan D. Smith, Rubén Juárez Valieri, Peter J. Makovicky

Late Cretaceous terrestrial strata of the Neuquén Basin, northern Patagonia, Argentina have yielded a rich fauna of dinosaurs and other vertebrates. The diversity of saurischian dinosaurs is particularly high, especially in the late Cenomanian-early Turonian Huincul Formation, which has yielded specimens of rebacchisaurid and titanosaurian sauropods, and abelisaurid and carcharodontosaurid theropods. Continued sampling is adding to the known vertebrate diversity of this unit.

A new, partially articulated mid-sized theropod was found in rocks from the Huincul Formation. It exhibits a unique combination of traits that distinguish it from other known theropods justifying erection of a new taxon, Gualicho shinyae gen. et sp. nov. Gualicho possesses a didactyl manus with the third digit reduced to a metacarpal splint reminiscent of tyrannosaurids, but both phylogenetic and multivariate analyses indicate that didactyly is convergent in these groups. Derived characters of the scapula, femur, and fibula supports the new theropod as the sister taxon of the nearly coeval African theropod Deltadromeus and as a neovenatorid carcharodontosaurian. A number of these features are independently present in ceratosaurs, and Gualicho exhibits an unusual mosaic of ceratosaurian and tetanuran synapomorphies distributed throughout the skeleton.

Apesteguía S, Smith ND, Juárez Valieri R, Makovicky PJ (2016) An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina. PLoS ONE 11(7): e0157793. doi:10.1371/journal.pone.0157793

Durante la semana pasada el equipo del MAU, Museo Municipal Argentino Urquiza de Rincón de los Sauces, Neuquén, realizó el inesperado hallazgo de los restos de un ejemplar de dinosaurio ornitópodo, el cual se encuentra en muy buen estado de preservación. Las tareas de campo permitieron recuperar los restos integrados por la porción anterior del cuerpo del animal, integrada por las últimas cervicales y las primeras siete dorsales, articuladas con sus correspondientes costillas y ambas escapulo-coracoides. Además, excepcionalmente se halló el miembro anterior derecho completo y articulado al cuerpo. Si bien se habían hallado restos en la zona de este grupo de dinosaurios ornitisquios, este es el primer ejemplar de relevancia hallado en la zona norte de la Provincia de Neuquén, por lo que permite engrosar el conocimiento de la fauna de dinosaurios de esta región. Actualmente el material esta siendo preparado en el laboratorio del Museo.

Penélope Cruzado-Caballeroa, Leonardo S. Filippi, Ariel H. Méndez, Alberto C. Garrido and Rubén D. Juárez Valieri

Ornithopods are the least known dinosaurs within the Upper Cretaceous record of Argentina. For this rea-son every new record is very important to know their evolution in South America. Here, we describe a new remain of an indeterminate ornithopod recovered in the Petrobrasaurus quarry of the Puesto Hernández area, northeastern Neuquén province (Argentina), late Coniacian–early Santonian in age. MAU-Pv-PH-458 is the northernmost bone record of an ornithopod in Argentina. This is a fragmentary neural arch fromthe middle section of the dorsal series of similar size to Macrogryphosaurus gondwanicus. MAU-Pv-PH-458 has typical ornithopod characters such as a lateromedial narrow neural spine and transverse processes dorsoposteriorly to posteriorly oriented. It shares with Macrogryphosaurus the presence of a deep cannel between the bases of the postzygapophysis, which is a continuation of the channel that separates the postzygapophyses in posterior view. MAU-Pv-PH-458 increases the ornithopod record from the Plottier Formation.

Cruzado-Caballero, P., et al., New record of ornithopod dinosaur from the Plottier Formation (Upper Cretaceous), Patagonia, Argentina. Annales de Paléontologie (2016), http://dx.doi.org/10.1016/j.annpal.2016.02.003

Ariana Paulina Carabajal, Juan I. Canale, and Alejandro Haluza

Report a new rebbachisaurid material recovered from the Candeleros Formation (Cenomanian) of northwest Patagonia, Argentina. The cranial remains consist of a partial braincase and a right quadrate. Fractures in the braincase exposed the endocranial cavity, allowing the first study of the brain and inner ear morphologies of a South American rebbachisaurid. The braincase and cranial endocast both exhibit traits similar to those observed in the Cretaceous rebbachisaurs Nigersaurus from Africa and Limaysaurus from Argentina, although in terms of osteology, the South American taxa are highly similar. The endocast is more similar to that of Nigersaurus than to those of Diplodocus and Camarasaurus, suggesting some probable rebbachisaurid features such as the noteworthy presence of the flocculus. The overall morphology of the quadrate shows similarities with Limaysaurus and Nigersaurus. However, differences such as the broader posterior fossa and the shape and orientation of the head and the pterygoid process indicate that the new specimen could represent a distinct taxon.

Ariana Paulina Carabajal, Juan I. Canale & Alejandro Haluza (2016): New rebbachisaurid cranial remains (Sauropoda, Diplodocoidea) from the Cretaceous of Patagonia, Argentina, and the first endocranial description for a South American representative of the clade, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2016.1167067