Macrogryphosaurus

• Argentina ( Portezuelo Formation)

• Macrogryphosaurus gondwanicus

Macrogryphosaurus is a genus ornithopoder dinosaurs and a basal representative of the Iguanodontia. So far, a single fragmentary skeleton without skull is known, which was found in the Portezuelo Formation in the Upper Cretaceous ( Coniacian ) of Argentina. The genus was described in 2007 with the single species Macrogryphosaurus gondwanicus scientifically. The most closely related genus and sister genus is Talenkauen, is combined with the Macrogryphosaurus to Elasmaria mentioned group. Macrogryphosaurus was about six feet long, two-legged herbivores, who was distinguished among other things by thin, the side of the fuselage arranged ossified plates.

Features

The holotype specimen is estimated to have a length of 6 meters; have not yet fused seams between the vertebral arches and vortex centers in some vertebrae suggest, however, that this individual was not yet fully grown. Macrogryphosaurus was thus one of the largest ornithopod South America outside the Hadrosauridae.

Of the total of ten cervical vertebrae are preserved eight, the first and second cervical vertebrae ( the atlas and axis ) are missing. As with the closely related sister genus Talenkauen the third cervical vertebra shows well-developed Epipophysen ( appendages that are located across the postzygapophyses ); a feature that is unusual for ornithischians. The dorsal series is completely preserved in the anatomical composite and consists of 14 vertebrae, a small number of ornithopods. Unique for ornithopods and thus an autapomorphy of Macrogryphosaurus is the Hyposphen of the last dorsal vertebra well developed. The tail is only handed fragmentary; known are 16 mostly incomplete caudal vertebrae. Other autapomorphies are the three-beam breastbone ( sternum ) and his four flattened, twisted and distally elongated ribs. However, of these four sternal ribs are only three survived. Bony, approximately circular and 1 to 3 mm thick plates were arranged along the sides. Such ossification have been otherwise found in only ornithopod in the sister genus Talenkauen and in Thescelosaurus. Unlike these genres in Macrogryphosaurus one of these plates was located in front of the sternum, which is another autapomorphy.

System

Macrogryphosaurus was a basal Iguanodontia within the Euiguanodontia and also closely related to the South American Talenkauen santacrucensis from the Maastrichtian. The descriptor came to the conclusion that Macrogryphosaurus Talenkauen and form a new, monophyletic group Elasmaria. As synapomorphies (shared derived characteristics ) of this group they lead to the thin ossified plates as well as the well-developed Epipophysen of the third cervical vertebra.

Fund and naming

The skeleton was discovered in 1999 during an expedition of the Universidad Nacional del Comahue on the west bank of the Mari - Menuco Lake in the Argentine province of Neuquen. Stratigraphically the Fund comes from the Portezuelo formation, a layer link in the Neuquén Group. The rocks of the discovery site have been dated to the Coniacian. The specimen found ( holotype, specimen number MUCPv -321 ) consists of the incomplete spinal column, ribs, sternum, four bony plates, and two iliac bones ( Ilia ), the pubic bone ( pubis ) and the ischium ( ischium ). The skeleton was articulated in Fund position and pointed his belly up, with the neck and back spine was straight.

Macrogryphosaurus means as much as "big, enigmatic lizard" (Greek macro - "large", grypho - " enigmatic " saurus - "lizard "). The species name gondwanicus points to the former southern continent Gondwana, on the lived this dinosaur.

Swell

• JO Calvo, JD Porphyrius, FE Novas: Discovery of a new dinosaur from the Ornithopod Portezuelo Formation ( Upper Cretaceous ), Neuquén, Patagonia, Argentina. In: Arquivos do Museu Nacional. 65, No. 4, 2007, pp. 471-483.

• Ornithischia
• Bird Beck dinosaur