The water vapor conductance (GH2O) of the neosauropod eggs from the Lower Cretaceous Sanagasta nesting site in La Rioja Province, Argentina, was examined and compared with other Cretaceous Argentinean oological material. The 2900 mgH2O/day?Torr GH2O of the Sanagasta eggshells confirms an extremely moist nesting environment and supports field observations of dug-out nests in a geothermal setting. The observed thinning of the outer eggshell surface during incubation increases gas conductance and concomitantly decreases eggshell mechanical resistance during the late ontogenetic stages, thus facilitating embryonic development and hatching. The Sanagasta and Entre Ríos Province faveoloolithid eggs display the highest and comparable GH2O values and share several morphological and diagenetic characters, indicating comparable nesting strategy in geothermal settings. However, the faveoloolithid Yaminue´ and La Pampa Province specimens cluster together with lower GH2O values closer to the megaloolithid eggs. The GH2O of the megaloolithid egg Megaloolithus patagonicus was reconsidered and new results are now congruent with other reported megaloolithid GH2O values. Additionally, we hypothesize that Y-shaped pore canals of M. patagonicus, which upper sections reach only the top third or half eggshell thickness and, a wider section in the middle would not compromise the overall egg mechanical resistance like vertical pores connecting directly the outer to the inner eggshell surfaces. Such pore spatial arrangement and geometry would enhance, as the eggshell thins during incubation, a greater GH2O, GO2 and GCO2 and facilitate embryonic development in high moisture nesting contents. Overall, data suggests that neosauropod nesting and brooding behaviors were dependent on elevated moisture nesting environments.

Alejandro Otero, Juan I. Canale, Alejandro Haluza y Jorge O. Calvo.


 

The Neuquén Basin has yielded a highly diverse fauna of sauropod dinosaurs. This group includes diplodocoids and titanosaurs. The plentiful record of titanosaur sauropods in the Upper Cretaceous of northern Patagonia is mostly restricted to derived titanosaurs included in the Titanosauridae (=Lithostrotia sensu Upchurch et al., 2004). Derived titanosaurs were traditionally characterized by the possession of strongly procoelous anterior-middle caudal vertebrae. This feature was used as a diagnostic trait to differentiate them from basal forms of titanosaurs with amphiplatyan or amphicoelous caudal vertebrae However recent discoveries have demonstrated that a great variation exists throughout the titanosaurian caudal series. In this sense, procoely appears to be non-continuous along the tail, implying a very different morphological scenario. In this paper we report a series of sauropod caudal vertebrae collected from the upper levels of the Candeleros Formation (Neuquén Group) near Villa El Chocón, Neuquén Province, Argentina. The materials, previously referred tentatively to Andesaurus, include a discontinuous series of mid- and mid-posterior caudal vertebrae,most of them including their haemal arches. The latter elements present an unusual morphology hitherto not reported in other sauropod dinosaurs.

Otero, A., Canale, J. I., Haluza, A. y Calvo, J. O. 2011 New Titanosaur with unusual haemal arches from the Upper Cretaceous of Neuquén Province, Argentina. Ameghiniana 48 (4): 655 – 661.

A new basal mesoeucrocodylian, Lorosuchus nodosus gen. et sp. nov., from the Palaeocene of north-western Argentina is presented here. The new taxon is diagnosed by the presence of external nares facing dorsally, completely septated, and retracted posteriorly, elevated narial rim, sagittal crest on the anteromedial margins of both premaxillae, dorsal crests and protuberances on the anterior half of the rostrum, and anterior-most three maxillary teeth with emarginated alveolar margins. This taxon is most parsimoniously interpreted as a bizarr and highly autapomorphic basal member of Sebecidae, a position supported (amongst other characters) by the elongated bar-like pterygoid flanges, a laterally opened notch and fossa in the pterygoids located posterolaterally to the choanal opening (parachoanal fossa), base of postorbital process of jugal directed dorsally, and palatal parts of the premaxillae meeting posteriorly to the incisive foramen. Lorosuchus nodosus also shares with basal neosuchians a suite of derived characters that are interpreted as convergently acquired and possibly related to their semiaquatic lifestyle. The phylogenetic analysis used for testing the phylogenetic affinities of L. nodosus depicts Sebecidae as the sister group of Baurusuchidae, forming a monophyletic Sebecosuchia that is deeply nested within Notosuchia. Alternative phylogenetic placements of Sebecidae, such as the recently proposed affinities with peirosaurids, were also evaluated within the context of the present data matrix and found to be only marginally suboptimal.

Pol, D. y Powell, J. 2011. A new sebecid mesoeucrocodylian from the Rio Loro Formation (Palaeocene) of north-western Argentina. Zoological Journal of the Linnean Society, 2011, 163, S7–S36.

The fossil record of rebbachisaurid sauropods has greatly increased recently (Calvo and Salgado, 1995; Bonaparte, 1996; Dalla Vecchia, 1998; Sereno et al., 1999, 2007; Medeiros and Schultz, 2001; Pereda-Suberbiola et al., 2001, 2003; Salgado et al., 2004, 2006; Gallina and Apesteguía, 2005; Apesteguía, 2007; Mannion, 2009). The first fossil remains belonging to this group were described by Nopcsa (1902) but only recently recognized as a rebbachisaurid (Calvo and Salgado, 1995; Apestegu´ıa, 2007). Lavocat (1954) erected Rebbachisaurus garasbae, which has a scapula with broad, ‘racquet’-shaped blade, and a mid-dorsal vertebra with a very tall neural spine. This family is mostly known from rather fragmentary remains, and many specimens are unpublished or only partially described (Gallina and Apestegu´ıa, 2005). In this contribution, we present new materials assignable to Rebbachisauridae, recovered from the Huincul Formation, Neuquén Group, near Villa El Chocón, Neuquén Province. The lowermost section of this geological unit has yielded other dinosaur taxa, such as Skorpiovenator bustingorryi (Canale et al., 2009). The rebbachisaurid remains correspond to a single, partially articulated, and exceptionally preserved skeleton, which includes cervical and dorsal vertebrae, thoracic ribs, scapula, and a humerus. The importance of studying complete serial elements of the skeleton (e.g., vertebral series) lies on the ability to track specific elements (i.e., landmarks), which are useful to unambiguously recognize homologous structures (Wilson, 1999; Otero et al., In press; Wilson et al., 2011). In this regard, the preserved cervicodorsal series described herein gives remarkable anatomical and systematic information, allowing the recognition of the transitional morphology, topology, and extent of the vertebral laminae

Haluza, A., Canale, J. I., Otero, A.,  Pérez, L. M., and Scanferla, C., 2012.Changes in vertebral laminae across the cervicodorsal transition of a well-preserved rebbachisaurid (Dinosauria, Sauropoda) from the Cenomanian of Patagonia, Argentina, Journal of Vertebrate Paleontology, 32:1, 219-224.

Desde el 10 de diciembre del corriente, el Museo Municipal Argentino Urquiza de la localidad de Rincón de los Sauces, Provincia de Neuquén, vuelve a tener un profesional a cargo, el Prof. Leonardo S. Filippi, paleontólogo de vertebrados que ya se había hecho cargo de la institución entre los años 2002 y 2007. A partir de esta nueva etapa, se pretende retomar una serie de proyectos postergados, además de generar otros nuevos, que permitan crear instancias para el crecimiento y desarrollo del museo, y a su vez, el de la localidad en la cual se encuentra inmerso.