E. Martín Hechenleitner,
Gerald Grellet-Tinner and Lucas E. Fiorelli
Titanosauria is a
globally distributed clade of sometimes extremely large Mesozoic herbivorous
sauropod dinosaurs. On the basis of current evidence these giant dinosaurs seem
to have reproduced in specific and localized nesting sites. However, no
investigations have been performed to understand the possible ecological and geological
biases that acted for the selection of these nesting sites worldwide. In this study,
observations were performed on the best-known Cretaceous nesting sites around
the world. Our observations strongly suggest their eggs were incubated with environmental
sources of heat, in burial conditions. Taking into account the clutch composition
and geometry, the nature and properties of the sediments, the eggshells’ structures
and conductance, it would appear that titanosaurs adopted nesting behaviors
comparable to the modern Australasian megapodes, using burrow-nesting in
diverse media and mound-building strategies.
Hechenleitner et al.
(2015),What do giant titanosaur dinosaurs and modern Australasian megapodes
have in common? PeerJ 3:e1341; DOI 10.7717/peerj.1341
Una nueva vitrina en el MAU
Se han realizado cambios en una de las vitrinas del Museo Municipal Argentino Urquiza, como continuación de un plan de reestructuración de la exhibición. En este caso se ha incorporado la réplica del brazo de Megaraptor, proyecto que se estaba desarrollando desde hace unos meses. Los resultados han superado las expectativas, por lo que se planean llevar adelante nuevas réplicas para mejorar la actual exhibición.
Se han realizado cambios en una de las vitrinas del Museo Municipal Argentino Urquiza, como continuación de un plan de reestructuración de la exhibición. En este caso se ha incorporado la réplica del brazo de Megaraptor, proyecto que se estaba desarrollando desde hace unos meses. Los resultados han superado las expectativas, por lo que se planean llevar adelante nuevas réplicas para mejorar la actual exhibición.
Pablo Ariel Gallina and Alejandro Otero
The original material
assigned to Laplatasaurus araukanicus Huene come from five different localities
in northern Patagonia (Argentina) where the Upper Cretaceous (Campanian) lies
exposed. This material includes several postcranial bones from multiple
specimens and showing different conditions of preservation, often lacking
anatomical overlap. The taxonomic status of the taxon is further obscured by
the absence of quarry maps of the multiple localities (lacking the recognition
of associated materials), and a proper designation of type material in its
original description. After Huene, new material was assigned to this taxon,
although none of it resolved the existing taxonomic issues. In 1979, the
designation of a lectotype (one tibia and one fibula) was the first stage in
the nomenclatural stabilization of the species. However, the assignment of the
remaining material to L. araukanicus remained uncertain. Here we review all the
material hitherto assigned to this taxon in order to clarify its taxonomic
status. We also provide a re-description of the lectotype and discuss the taxonomic
identification of material previously referred to this taxon. Lastly we include
it for the first time in an updated phylogenetic data matrix. Laplatasaurus
araukanicus is retained only for the lectotype. The material from Rancho de
Ávila is referred to cf. Bonitasaura sp. because they share diagnostic features
and are stratigraphically congruent. The remaining material is referred as
Lithostrotia indet. A phylogenetic analysis nests Laplatasaurus within Titanosauria
in a clade formed by ((Laplatasaurus + Uberabatitan) + (Bonitasaura +
(Futalognkosaurus + Mendozasaurus))).
Gallina, P. A. and
Otero, A. 2015. Reassessment of Laplatasaurus
araukanicus (Sauropoda: Titanosauria) from the Upper Cretaceous of
Patagonia, Argentina. Ameghiniana 52(5): 487-501.
Sebastián Rozadilla, Federico L. Agnolin, Fernando E. Novas, Alexis
M. Aranciaga Rolando, Matías J. Motta, Juan M. Lirio, Marcelo P. Isasi
A new ornithopod
dinosaur from the Upper Cretaceous (Maastrichtian) Snow Hill Island Formation,
at James Ross Island, Antarctica is here described. This new taxon, named as Morrosaurus antarcticus gen. et sp. nov.,
is represented by a fragmentary right hind limb belonging to a medium-sized
individual. Our phylogenetic analysis nests the new taxon in a monophyletic
clade of Southern Hemisphere ornithopods that includes most Patagonian and
Antarctic ornithopods. Several members of this group share a slender and
bunched foot with narrow metatarsal IV, expanded chevrons, and bowed humerus
without deltopectoral crest. Several features indicate that these ornithopods
exhibit adaptations for a specialized cursorial mode of life. The recognition
of Patagonian and Antarctic Ornithopoda belonging to a monophyletic clade
reinforces palaeobiogeographical signals indicating that Patagonia, Antarctica
and Australia shared a common Late Cretaceous terrestrial fauna.
Rozadilla, S., Agnolin, F.L., Novas, F.E., Aranciaga Rolando, A.M., Motta,
M. J.,Lirio, J. M. and Isasi, M.P. 2016. A new ornithopod
(Dinosauria, Ornithischia) from the Upper Cretaceous of Antarctica and its
palaeobiogeographical implications. Cretaceous Research 57: 311-324
Histology of teeth and tooth attachment in titanosaurs
0 comentarios Publicado por Leonardo Filippi en 8:31
Rodolfo A. García
and Virginia Zurriaguz
Dental histology of periodontal
tissues (cementum, periodontal ligament and alveolar bone) has been studied in
mammals, crocodylians and some basal tetrapods, but these structures have never
been studied in titanosaur sauropods. The goal of this work was to study the
structures of dental insertion in Titanosaurs. Like many physiological processes,
histological analysis of titanosaur teeth shows hard tissue formation,
characterized by a circadian rhythm. From thin sections it was possible to
observe microstructures such as incremental lines of von Ebner, dentinal
tubules and cross striations, all key to the understanding of developmental
tooth dynamics. The structural and histological analyses carried out here on
teeth of Late Cretaceous titanosaurs reveals the presence of acellular and
cellular cementum, periodontal ligament, and alveolar bone, all structures
necessary for a truly thecodont dentition. This is the first time documented
for a dinosaur via histological tissue, and is an important finding that will
help elucidate aspects of dinosaurian dentition, tooth replacement rate,
feeding strategy, metabolism, and general biology.
García, R. A. and Zurriaguz, V.
2016. Histology of teeth and tooth attachment in titanosaurs (Dinosauria; Sauropoda)
Cretaceous Research 57: 248-256. http://dx.doi.org/10.1016/j.cretres.2015.09.006
Morphological diversity of Neuquensaurus Powell, 1992
0 comentarios Publicado por Leonardo Filippi en 8:20
V. Zurriaguz
Neuquensaurus is a small-sized titanosaur from the Upper
Cretaceous of Patagonia, Argentina, for which two species were recognised in
the past (Neuquensaurus australis and Neuquensaurus robustus). Given that such
division was only based on the relative robustness of the limb bones, the
validity of the species N. robustus has been questioned. In this work, we
studied the morphological variation of the vertebrae of this genus through
geometric morphometric techniques and the description of relevant anatomical features
in order to assess if there are one or more morphotypes within Neuquensaurus.
We found two distinguishable morphotypes, one belonging to N. australis and
other that includes specimens assigned to both N. australis and N. robustus.
The occurrence of a posterior cervical vertebra with a particular anatomical feature
(i.e. four sprl) could indicate the presence of another taxon than N. australis
in the studied sample. Although the validity of the species N. robustus cannot
be discussed on the basis of the current data, our study supports the
hypothesis of at least two different morphotypes of Neuquensaurus (which could
be related to different taxa).
V. Zurriaguz (2015):
Morphological diversity of Neuquensaurus Powell, 1992 (Sauropoda;
Titanosauria): insights from geometric morphometrics applied to the vertebral
centrum shape, Historical Biology: An International Journal of Paleobiology,
DOI: 10.1080/08912963.2015.1079630
Megarraptóridos y un ambicioso proyecto para hacer réplicas
0 comentarios Publicado por Leonardo Filippi en 5:22
La posibilidad futura de contar con un nuevo edificio para el MAU, ha generado el desarrollo de un proyecto que tiene como objetivo la confección de réplicas parciales de algunos ejemplares de la colección, para la actual exhibición, las cuales a su vez, servirán como prueba piloto para la construcción de réplicas completas. Luego de haber experimentado y llevado a delante exitosamente la primer réplica en el MAU durante el 2012, de la pata delantera de uno de los dinosaurios titanosaurios, se ha encarado el primero de los proyectos, la realización a escala del brazo derecho de Megarraptor, un particular dinosaurio carnívoro que poseía brazos con enormes garras afiladas. Si bien este dinosaurio no pertenece a la colección del MAU, en las últimas salidas de campo se ha registrado el hallazgo de restos aislados de algunos ejemplares de este grupo en la zona de La Invernada. Algunas de las pruebas realizadas, utilizando las nuevas técnicas para la realización de réplicas, han arrojado resultados muy satisfactorios, por lo que la posibilidad de poder replicar los ejemplares para una exhibición futura, es muy probable. A pesar de que este ambicioso proyecto signifique un gran reto, el personal del MAU se encuentra trabajando en la búsqueda de nuevos materiales y la utilización de diferentes técnicas que resulten alternativas viables para poder desarrollarlo.
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