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::: Info Dinosauria :::

Noticias, resúmenes e información

jueves, marzo 23, 2006

DINOSAURIO DE EXTENSO CUELLO

Un equipo de paleontólogos estadounidenses descubrió en China al dinosaurio con el cuello más extenso en promedio que el de cualquier otro animal que pobló la Tierra hace millones de años.

El nuevo dinosaurio, de la familia de los saurópodos y que fue llamado "Erketu ellisoni", poseía un cuello de 7.3 metros de largo.

El animal fue desenterrado en el desierto de Gobi, en el oeste de China, por un equipo de científicos del Museo Estadounidense de Historia Natural de Nueva York.
El cuello del "Erketu Ellisoni" era más corto que el de su pariente diplodocus, pero medía más de la mitad de la extensión del dinosaurio, convirtiéndolo en el saurópodo que proporcionalmente poseía el cuello más extenso.

martes, marzo 07, 2006

Cría de Triceratops horridus



Ha sido presentado un cráneode 30 cm de longitud de un bebé de Triceratops horridus, de un año de edad y un tamaño de 90 cm. En la imagen un molde de éste que fué hayado en la formación Hell Creeck de Montana.Mas información en UC Bercley News

Ornitópodo Juvenil


Juvenile ornithopod (Dinosauria: Rhabdodontidae) remains from the Upper Cretaceous (Lower Campanian, Gosau Group) of Muthmannsdorf (Lower Austria)

Geobios, In Press, Available online 6 March 2006 Sven Sachs and Jahn J. Hornung


The fragmentary remains of a juvenile rhabdodontid ornithopod from the Coal-bearing Complex of the Gosau Group (Lower Campanian, Grünbach syncline) at Muthmannsdorf near Wiener Neustadt, Lower Austria are revised. The material, probably belonging to a single
individual, includes a right dentary (lectotype of Iguanodon suessi Bunzel, 1871, designated herein), teeth, a fragmentary parietal, fragments of scapula, ?radius, femur, tibia, two vertebrae (lost) and a manual ungual.

The lectotype dentary does not provide clear autapomorphies or sufficient diagnostic features to determine its position within the Rhabdodontidae at generic level. By this "Iguanodon suessi" Bunzel, 1871 and the genus "Mochlodon" Seeley, 1881, to which it was latter referred as type species, cannot be characterized sufficiently by differential diagnosis and these are best considered nomina dubia.
Based upon combined character comparisons (mainly postcranial features) the Muthmannsdorf ornithopod is referred herein to Zalmoxes Weishampel, Jianu, Csiki and Norman, 2003, a genus so far known from the late Maastrichtian of Romania. It probably but not evidently represents a yet unnamed species, most closely related to Zalmoxes shpiperorum Weishampel, Jianu, Csiki and Norman, 2003. At the present state of knowledge the Austrian material is not further diagnostic at the species level and kept in open nomenclature as Zalmoxes sp.

Origen y radiación de los Terápsidos


The origin and early radiation of the therapsid mammal-like reptiles: a palaeobiological hypothesis

T. S. KEMP Jour. Evolutionary Biology (In Press)

The replacement of the basal synapsid pelycosaurs by the more `mammal-like' therapsids in the Permian was an important event in the history of tetrapods because it initiated the eventual transition to the mammals. It is also an example of taxon replacement in the fossil
record that is unusually amenable to explanation, based on a combination of analysis of the biological significance of the inferred character changes, with the stratigraphic, palaeogeographic and palaeoecological circumstances of the time. An hypothesis is
presented in which the origin of the therapsids resulted from a correlated progression of character evolution leading to higher levels of metabolic activity and homeostatic regulation of the body.
It was a response to the availability of a seasonally arid, savanna-like biome. The subsequent explosive radiation of therapsids was associated with habitat expansion made possible by the Mid-Permian development of geographical continuity between that biome and the
temperate biomes. The final extinction of the pelycosaurs was a case of incumbent replacement by the new therapsid lineages.

Mesosaurus tenuidens


The cranial skeleton of the Early Permian aquatic reptile Mesosaurus tenuidens: implications for relationships and palaeobiology

SEAN PATRICK MODESTO Zoological Journal of the Linnean Society Volume 146 Issue 3 Page 345–368 - March 2006

The cranial osteology of the aquatic reptile Mesosaurus tenuidens is redescribed on the basis of new and previously examined materials from the Lower Permian of both southern Africa and South America.
Mesosaurus is distinguished from other mesosaurs in exhibiting an absolutely larger skull and possessing relatively longer marginal teeth. The teeth gradually angle outwards as one progresses anteriorly in the tooth row and become conspicuously procumbent at the tip of the snout. The suggestion that mesosaurs used their conspicuous dental apparatus as a straining device for filter feeding is based upon erroneous reconstruction of a high number of teeth in this mesosaur. Reinterpretation of the morphology and the organization of the marginal teeth of Mesosaurus suggests that they were used to capture individually small, nektonic prey. General morphological aspects of the skull support the idea that Mesosaurus
was an aquatic predator and that the skull was well adapted for feeding in an aqueous environment. The anatomical review permits critical reappraisal of several cranial characters that have appeared in recent phylogenetic analyses of early amniotes. Emendation of problematic characters and reanalysis of amniote phylogeny using a slightly modified data matrix from the literature strengthens the hypothesis that mesosaurs form a clade with millerettids, procolophonoids and pareiasaurs within Reptilia.

Reconstrucción del Hombro de Dromaeosaurus


An integrative phylogenetic and extrapolatory approach to the
reconstruction of dromaeosaur (Theropoda: Eumaniraptora) shoulder
musculature

SANDRA C. JASINOSKI, ANTHONY P. RUSSELL and PHILIP J. CURRIE

Zoological Journal of the Linnean Society
Volume 146 Issue 3 Page 301–344 - March 2006



Dromaeosauridae is the sister taxon of the Avialae; thus, an investigation of dromaeosaur shoulder girdle musculature and forelimb function provides substantial information regarding changes in the size and performance of the theropod shoulder girdle musculature leading to avian powered flight. Twenty-two shoulder girdle muscles were reconstructed for the dromaeosaurid shoulder apparatus, based on phylogenetic inference, which involves the comparison of lepidosaurian, crocodilian and avian musculature, and extrapolatory inference, which involves a secondary comparison with functional analogues of theropods. In addition to these comparative methodologies, osteological correlates of shoulder musculature preserved in eumaniraptorans are identified, and comparisons with those of extant archosaurs allow these muscles to be definitively inferred in dromaeosaurids. This muscle reconstruction provides a foundation for subsequent investigation of differences in muscular attachment and function, based on scapulocoracoid morphology, across the theropod lineage leading to birds.