Chindesaurus

Chindesaurus live in an artistic reconstruction

• North America (Arizona, New Mexico)

Chindesaurus ( " Chinde Point - lizard" ) is a genus of initial ( basal ) lizards Beck dinosaurs from the Upper Triassic of North America, but the exact systematic position is not entirely clear.

The genus, which reached about three meters in length, is named after the Erstfundort near the Chinde Points in the western United States. Only species described is Chindesaurus bryansmalli.

All fossils are from the Chinle Formation, whose rocks are dated to a period of about 235-208 million years ago ( Carnium and Norian ) before our time. He is one of the oldest yet discovered in North America dinosaurs.

Systematic position

1995 Long and Murry arranged Chindesaurus in their scientific provisionally the first description Herrerasauriden to. Sereno (1997) and Bittencourt and Kellner ( 2004), align themselves with this proposal. Other editors, however, recognize in Chindesaurus no unambiguous Herrerasauriden features, therefore arrange Hunt ( 1996) and Lucas and Heckert (1996 ), the genus to the Theropoda. Recent edits by Langer (2004), Irmis et al. (2007) and Nesbitt et al. (2007) describe it as original lizard dinosaur Beck ( Irmis (2005) places him among the Dinosauriformes and thus outside of the dinosaurs ).

Fossil finds

First time, a partial skeleton of Chindesaurus in Petrified Forest National Park was discovered in 1985 in the U.S. state of Arizona, mixed with fossil material of a Shuvosauriden, one with the crocodiles ( Suchia ) related archosaurs. The reference of this specimen, the holotype ( PEFO 10395 ), is the " Dinosaur Hollow ," which is located in the Petrified Forest Member of the Chinle formation. However, it has been found no material important for the systematic determination of the skull.

If Chindesaurus is a Herrerasauride, he would be the first found in North America and at the same time youngest members of this group. Its fossils were associated with archosaurs as the Aetosauria, Phytosauria and Rauisuchia whose small to medium sized representatives might have hunted these alleged predators. This indicated a larger geographical and temporal spread of Herrerasauride as previously known.

A second fund ( PEFO 33982 ) also comes from the Petrified Forest Member. The fossil material comes from the locality "Giving Site" of the park, from the same stratigraphic level as the " Dinosaur Hollow". It consists of parts of the ilium ( ilium ), the proximal (upper) part of the thigh bone (femur ) and several vertebrae.

Paläogemeinschaften the Upper Triassic

Another finding of Chindesaurus in the 220-210 million year old sedimentary rocks of the Noric "Hayden Quarry ", an excavation site on the grounds of the Ghost Ranch in the U.S. state of New Mexico, published Irmis et al. 2007th Here are a fossil Faunengemeinschaft that a true theropods from the group of Coelophysoiden included in addition to the basal Saurischier Chindesaurus and two Dinosauromorpha found ( a quadrupedal, herbivorous Dinosauriformen similar Silesaurus and Dinosauromorphen Dromomeron Romeri ). These findings show for the first time a co-existence for at least 15 to 20 million years of early dinosaur with the Dinosauromorphen, that group of archosaurs, descended from the dinosaurs. They suggest that the rise of the dinosaurs as the dominant group of land vertebrates of the Mesozoic era ( Mesozoic ), contrary to previous opinion did not take place by sudden displacement or replacement of these precursors in the Upper Triassic, but extended over a longer period and until after the turn of the Lower Jurassic, was completed about 200 million years.