Merry Christmas and happy New Year

0 comentarios Publicado por Leonardo Filippi en 4:09


Feliz Navidad y prospero Año Nuevo
Merry Christmas and happy New Year

Best wishes
PaleoSur

 

New remains of Astraponotus

0 comentarios Publicado por Leonardo Filippi en 15:22


New remains of Astraponotus (Mammalia, Astrapotheria) and considerations on Astrapothere cranial evolution


Alejandro G. Kramarz, Mariano Bond and Analia M. Forasiepi

Astraponotus Ameghino, 1901, the only valid Mustersan (late Eocene) astrapothere, typifies the Ameghino’s ‘‘Capas Astraponotenses’’. This taxon is traditionally interpreted as structurally ancestral to all the Oligocene– Miocene astrapotheriids. However, it was imperfectly known: only isolated teeth and very partial mandibles have hitherto been described. In this contribution we provide the first description of the skull, mandible, and complete dentition of Astraponotus based on new materials from the Gran Hondonada and other Mustersan localities in central Patagonia, Argentina. The features observed in the dentition of Astraponotus are intermediate between the Casamayoran (middle Eocene) and the Oligocene–Miocene astrapotheres in the degree of hypsodonty, reduction of the dental formula, and development of accessory occlusal elements. Concordantly, the skull retains some plesiomorphies, also observed in Trigonostylops, whereas the auditory region and the basicranium are much closer to those of Parastrapotherium, Astrapotherium, and Granastrapotherium. On the other hand, the skull of Astraponotus differs from all known astrapotheres by the disproportioned height and narrowness of the braincase, the extreme reduction of the nasals and the premaxillaries, the absence of anteorbital rim, and the reduction of the frontal region. Some of these features represent cranial specializations exactly opposite to that of Astrapotherium. These characters look astonishingly derived for an Eocene astrapothere, suggesting that extreme cranial specializations occurred independently during the evolution of the order, and that Astraponotus represents a distinctive lineage from that of Astrapotherium and other Miocene forms.

Kramarz, A. G., Bond M. and Forasiepi, A. M., 2010. New remains of Astraponotus (Mammalia, Astrapotheria) and considerations on Astrapothere cranial evolution. Paläontol Z. DOI 10.1007/s12542-010-0087-4.

 

A glimpse at the ontogeny of the Calyptocephalella canqueli

0 comentarios Publicado por Leonardo Filippi en 6:25


A glimpse at the ontogeny of the fossil neobatrachian frog Calyptocephalella canqueli from the Deseadan (Oligocene) of Patagonia, Argentina


Paula Muzzopappa and Laura Nicoli

Two fossil tadpoles collected in the Deseadan levels (Oligocene) at the Scarritt Pocket locality of central Patagonia are studied herein. These specimens, which show different degrees of skeletal development, have been assigned to the neobatrachian Calyptocephalella canqueli based on the morphology of the frontoparietals and the presence of adult spec− imens of this fossil species at the same locality. The concurrent analysis of three developmental stages (Gosner Stages 35/36 and 38/39, and adult) has provided significant data about the ontogeny of this species, including the change of the pattern of exostosis of the frontoparietals, from a pitted to a tuberculated pattern, and the corroboration of the inclusion of two neural arches in the formation of the urostyle. This evidence will shed light on developmental mechanisms that might be involved in the evolution of the genus Callyptocephalella.

Muzzopappa, P. and Nicoli, L. 2010. A glimpse at the ontogeny of the fossil neobatrachian frog Calyptocephalella canqueli from the Deseadan (Oligocene) of Patagonia, Argentina. Acta Palaeontologica Polonica 55 (4): 645–654.

 

Predation bite-marks on a peirosaurid crocodyliform

0 comentarios Publicado por Leonardo Filippi en 15:09


Predation bite-marks on a peirosaurid crocodyliform from the Upper Cretaceous of Neuquén Province, Argentina


Lucas Ernesto Fiorelli

Abstract. Bite marks and injuries caused by intraspecific predation or aggressive social behavior are uncommon in fossil vertebrates, and in the fossil record of suchian archosaurs they are extremely unusual. A peirosaurid crocodyliform collected from the Upper Cretaceous beds of the Neuquén Group (northern Patagonia, Argentina) shows abundant bite marks and injuries. These injuries are spread across all the preserved parts of the specimen, with the highest concentration of bite marks, perforations and breakage in the caudal region. Characteristics of these injuries are analyzed, and their possible origin and related taphonomic aspects are assessed. Results indicate that the injuries were not produced by intraspecific fighting, but probably by the predating action of a theropod dinosaur.

Resumen. El hallazgo de marcas de mordeduras y lesiones por predación o comportamiento social agresivo intraespecífico en vertebrados fósiles es poco frecuente. En el registro fósil de arcosaurios suquianos tales evidencias son extraordinarias. Aquí se reporta un crocodiliforme peirosáurido del Cretácico Superior del Grupo Neuquén (norte de Patagonia, Argentina) con abundantes marcas de mordeduras y lesiones. Estas heridas están localizadas en todas las partes preservadas del espécimen, con una alta concentración de mordeduras, perforaciones y roturas en la región caudal. En el presente trabajo, se analizan las características de las lesiones, y también sus posibles causas y los aspectos tafonómicos relacionados. Los resultados muestran que las mordeduras fueron hechas por la acción de un predador y no por peleas intraespecíficas.

Fiorelli, L. E., 2010. Predation bite-marks on a peirosaurid crocodyliform from the Upper Cretaceous of Neuquén Province, Argentina. Ameghiniana 47 (3): 387-400.

 

Cranial endocast of the Giganotosaurus carolinii

3 comentarios Publicado por Leonardo Filippi en 13:53

Cranial endocast of the carcharodontosaurid theropod Giganotosaurus carolinii Coria & Salgado, 1995


Ariana Paulina Carabajal and Juan Ignacio Canale


A complete endocast of Giganotosaurus carolinii Coria & Ssalgado, 1995 was made in latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby allowing the description of the endocranial anatomy of the specimen. The endocast was compared with the other few known natural or artificial theropod endocasts, including the two species of the African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus, the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and was probably utilized by cranial nerve IX. The length of the endocast of Giganotosaurus, including the olfactory bulbs, is approximately 19 % longer than the endocast in Carcharodontosaurus saharicus.


Paulina Carabajal, A. & Canale, J. I. ,2010: Cranial endocast of the carcharodontosaurid theropod Giganotosaurus carolinii Coria & Salgado, 1995. – N. Jb. Geol. Paläont. Abh., DOI: 10.1127/0077-7749/2010/0104; Stuttgart.

 

Homenaje al Dr. José Fernando Bonaparte

1 comentarios Publicado por Leonardo Filippi en 16:13

Homenaje al Dr. José Fernando Bonaparte

Proyección documental
Charlas informativas


Miércoles 3 de noviembre de 2010 – 17 Hs.

Auditorio del Museo Provincial de Ciencias Naturales
Prof. Dr. Juan A. Olsacher.
Etcheluz y Ejército Argentino. Zapala. Neuquén.


Presentación a cargo del Ggo. Alberto Garrido, director del Museo Provincial de Ciencias Naturales “Prof. Dr. Juan A. Olsacher”. Dirección Provincial de Minería. Zapala, provincia del Neuquén.

Proyección:
“El hombre detrás de los huesos” es un documental de crónica humana, que aborda la vida de José Bonaparte. Un paleontólogo ejemplar. Un hombre que fue más allá de sus propios limites, autodidacta en su formación. Perseverante, tenaz y visionario en su trabajo. Sus hallazgos son reconocidos a nivel mundial. Una vida dedicada a la búsqueda del conocimiento con anhelos y frustraciones, con dichas y desdichas, con alegrías y culpas. Una vida que hoy sigue y seguirá buscando. José Bonaparte es el hombre detrás de los huesos. Un largometraje de 52 minutos realizado por Lic. Paola Echecury.

Charlas Informativas:
Participación especial de:

Dr. Leonardo Salgado, investigador de CONICET – INIBIOMA, Director del Museo de Geología y Paleontología de la Universidad Nacional del Comahue, Neuquén. Realizó su tesis bajo la dirección del Dr. Bonaparte. Anécdotas y vivencias nos acercan a conocer más sobre la vida de este paleontólogo.

Prof. Leonardo S. Filippi. Paleontólogo. Investigador Asociado al Museo Provincial de Ciencias Naturales “Prof. Dr. Juan A. Olsacher”, Zapala, Neuquén. Nos cuenta sobre sus primeras experiencias en este fascinante mundo de la paleontología compartiendo trabajos de campo junto al Dr. Bonaparte.

 

A new herrerasaurid from Ischigualasto

0 comentarios Publicado por Leonardo Filippi en 7:35

A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formationof northwestern Argentina




Oscar A. Alcober and Ricardo N. Martínez

Herrerasauridae comprises a basal clade of dinosaurs best known from the Upper Triassic of Argentina and Brazil, which have yielded remains of Herrerasaurus ischigualastensis and Staurikosaurus pricei, respectively. Systematic opinion regarding the position of Herrerasauridae at the base of Dinosauria has varied. Here we describe a new herrerasaurid, Sanjuansaurus gordilloi gen. n., sp. n., based on a partial skeleton from Carnian-age strata of the the Upper Triassic Ischigualasto Formation of northwestern Argentina. The new taxon is diagnosed by numerous features, including long, band-shaped and posterolaterally oriented transverse process on the posterior cervical vertebrae; neural spines of the sixth to eighth dorsal vertebrae, at least, bearing acute anterior and posterior processes; scapula and coracoid with everted lateral margins of the glenoid; and short pubis (63% of the femoral length). Phylogenetic analysis placed Sanjuansaurus within a monophyletic Herrerasauridae, at the base of Th eropoda and including Herrerasaurus and Staurikosaurus. The presence of Sanjuansaurus at the base of the Ischigualasto Formation, along with other dinosaurs such as Herrerasaurus, Eoraptor, Panphagia, and Chromogisaurus suggests that saurischian dinosaurs in southwestern Pangea were already widely diversifi ed by the late Carnian rather than increasing in diversity across the Carnian-Norian boundary.

Alcober OA, Martinez RN (2010) A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina. ZooKeys 63 : 55 – 81.

 

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