New contributions to the presacral osteology of Saltasaurus loricatus
2 comentarios Publicado por Leonardo Filippi en 7:11
Virginia Zurriaguz and Jaime Powell
Saltasaurus
loricatus is a derived form of sauropod dinosaur from the
Upper Cretaceous of northern Argentina. In this work, we expand the information
of the presacral vertebral column of Saltasaurus
loricatus, including a detailed description of neural laminae, fossae and
pneumatic foramina of the neural arch, and establish a comparative analysis
with closely related taxa (Neuquensaurus
australis and Rocasaurus muniozi).
Our data does not support previous phylogenetic hypothesis in which S.
loricatus is more closely related to R.
muniozi than N. australis. A
conservative pattern of distribution of pneumatic foramina in the neural arch
of cervical vertebrae cannot be recognized. Although variation in the pneumatic
foramina distribution is also present in dorsal vertebrae, these structures are
more commonly observed in certain regions (within the postzygapophyseal
spinodiapophyseal fossa and spinoprezygapophyseal fossa + prezygapophyseal
spinodiapophyseal fossa and in the dorsal border of the spinodiapophyseal lamina).
Our data reveal that, despite its value in paleobiological and systematic
studies, the presence and distribution pattern of pneumatic foramina in neural
arches of presacral vertebrae appears to be underestimated in previous
anatomical studies.
Zurriaguz, V.
and Powell, J. 2015. New contributions to the presacral osteology of Saltasaurus loricatus (Sauropoda,
Titanosauria) from the Upper Cretaceous of northern Argentina. Cretaceous Research 50: 283-300.
En el MAU se lleva adelante la lenta preparación del cráneo del nuevo Titanosaurio
0 comentarios Publicado por Leonardo Filippi en 7:03
Desde hace unos días, en el laboratorio del MAU, se dio comienzo a la preparación del cráneo completo de un dinosaurio saurópodo titanosaurio. Este dinosaurio fue hallado casi al finalizar la última campaña realizada en la localidad de La Invernada en noviembre del 2014. Por tal motivo, sólo pudo ser retirado solamente su cráneo. El mismo fue hallado completo y articulado en posición natural al cuello del animal. Cuando se realizó su rescate, se pudo comprobar que se encontraba articulado al cuello, del que se llegó a contabilizar unas seis vértebras cervicales articuladas. No obstante, las vértebras continuaban dentro de la roca por lo que se estima que el resto del ejemplar también se ha preservado. Durante el presente año, se espera poder continuar con las excavaciones en La Invernada, teniendo como prioridad este magnífico ejemplar.
Hasta el momento, se sospechaba que los huesos de varios de los ejemplares de saurópodos titanosaurios hallados en la excavación principal en La Invernada, correspondían a una especie ya conocida para la zona, Overosaurus paradasorum. Este hecho revestía relevancia ya que se podría conocer aún mejor a dic...ha especie. No obstante, los nuevos materiales de estos ejemplares que se encuentran bajo preparación en el laboratorio del Museo, están contando una historia diferente. Los huesos están mostrando una serie de características no esperadas, que lo diferencian claramente por lo que finalmente, estos dinosaurios pertenecerían a una nueva especie de titanosaurio, la cual habría convivido con Overosaurus en los mismos niveles de la Formación Bajo de la Carpa, de la cual provienen los materiales recuperados.
Redescription and reevaluation of the taxonomical status of Microsuchus schilleri
0 comentarios Publicado por Leonardo Filippi en 14:37
Juan
Martín Leardi, Lucas E. Fiorelli, and Zulma Gasparini
Fragmentary remains of Microsuchus schilleri (Crocodyliformes:
Mesoeucrocodylia) from the Bajo de La Carpa Formation (Santonian, Late
Creteceous) of northern Patagonia, Argentina, are decribed and reevaluated
taxonomically. The type specimen is an articulated individual with hindlimb and
axial remains. Microsuchus has several traits that allow to recognize it as a
valid taxon (the presence of bulge lateral to the prezygapophyses of the second
sacral vertebra; elongated posterior zeugopodia; proximal caudal centra with
triangular cross section). Microsuchus
was originally assigned as a goniopholidid based on the platycely of its
vertebral centra, a character that is widely distributed among fossil crocodyliforms.
A phylogenetical analysis using an expanded data matrix focusing on postcranial
data was performed in which Microsuchus and
another long-limbed crocodyliform from the same location, Neuquensuchus, were included. Microsuchus
is depicted in a politomy as a basal mesoeucrocodylian, with its position as a
neosuchian or notosuchian supported by a single synapomorphy on the different
most parsimonious trees. Additionaly, Neuquensuchus is well nested among
notosuchians, in contrast to previous hypothesis. These findings further
increase the crocodyliform diversity of the Bajo de la Carpa Formation and
emphasize the relevance of its fauna in studies of the diversification of
mesoeucrocodylians and notosuchians. Furthermore, the occurrence of both Microsuchus and Neuquensuchus gives evidence of a basal stock of mesoeucrocodylians
with elongated limbs that was not previously reported for northern Patagonia.
Leardi, J.M, Fiorelli,
L.E. and Gasparini, Z. 2015.Redescription
and reevaluation of the taxonomical status of Microsuchus schilleri (Crocodyliformes: Mesoeucrocodylia) from the Upper
Cretaceous of Neuquen, Argentina. Cretaceous
Research 52 (2015) 153e166
Durante los días 11 y 12 de noviembre, el equipo del MAU (Museo Argentino Urquiza) conjuntamente con personal de la empresa ExxonMobil y un equipo cinematográfico especializado proveniente de Estados Unidos, llevaron adelante escenas de campo y en las instalaciones del museo, para una documental solicitada por dicha empresa. Este documental resume las dos campañas realizadas en el área La Invernada, la cual se ubica a pocos kilómetros al sur de la localidad de Rincón de los Sauces, en el norte de la Provincia de Neuquén, Argentina.
Redescription of the Skull of Coloradisaurus brevis, (Dinosauria, Sauropodomorpha) from the Late Triassic of Argentina
0 comentarios Publicado por Leonardo Filippi en 6:51
Cecilia
Apaldetti, Ricardo N. Martinez, Diego Pol and Thibaud Souter
The cranial anatomy of
the basal sauropodomorph Coloradisaurus brevis from the upper
levels of the Norian Los Colorados
Formation is here redescribed and comparisons made based on the holotype
skull and mandible. Coloradisaurus brevis is diagnosed by most of the features
proposed in the original description and an additional set of autapomorphies,
such as presence of circular upper temporal fenestrae, laminae on the
ventrolateral margins of a ventral fossa of the basisphenoid and on the ventral
region of the parasphenoid, and tab-like medial process at the posteromedial
end of the mandible. Coloradisaurus is placed within Massospondylidae, as in recent analyses.
This position is supported primarily by postcranial characters, but some
cranial features identified in this study provide additional evidence
supporting this position (e.g., jugal contribution to the antorbital fenestra,
frontal proportionately longer than nasals). However, the cranial anatomy of
Coloradisaurus also bears several characters that are shared with plateosaurids
(e.g., low mandibular articulation, broad maxillary wall on the anterior margin
of antorbital fossa, broad prefrontals, projection of infratemporal fenestra behind
the orbit, stepped braincase, robust septum between basipterygoid processes).
Thus, Coloradisaurus is interpreted as a massospondylid that has
convergently acquired characters that are otherwise only known in
plateosaurids, highlighting the conflicting pattern of character distribution
among basal sauropodomorphs.
Cecilia Apaldetti,
Ricardo N. Martinez, Diego Pol & Thibaud Souter (2014) Redescription of the
Skull of Coloradisaurus brevis
(Dinosauria, Sauropodomorpha) from the Late Triassic Los Colorados Formation of
the Ischigualasto-Villa Union Basin, northwestern Argentina, Journal of
Vertebrate Paleontology, 34:5, 1113-1132.
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