Chindesaurus

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Chindesaurus
Chindesaurus in an artistic reconstruction of life

Chindesaurus in an artistic reconstruction of life

Temporal occurrence
Upper Triassic ( Carnian to Norian )
235 to 208.5 million years
Locations
Systematics
Sauropsida
Archosauria
Ornithodira
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Chindesaurus
Scientific name
Chindesaurus
Long & Murry , 1995

Chindesaurus ("Chinde Point Lizard") is a genus of original (basal) lizard basin dinosaurs from the Upper Triassic of North America, but the exact systematic position has not been conclusively clarified.

The genus, which reached about three meters in length, is named after the first place it was found near the Chinde Point in the western United States. The only species described is Chindesaurus bryansmalli .

All fossil finds come from the Chinle Formation, whose rocks are dated to a period of approx. 235 to 208 million years ( Carnium and Norium ) before our time. This makes it one of the oldest dinosaurs discovered in North America to date.

Systematic position

In 1995, Long and Murry Chindesaurus provisionally assigned to the Herrerasaurids in their first scientific description . Sereno (1997) and Bittencourt and Kellner (2004) endorse this proposal. Other editors, however, do not recognize any unambiguous Herrerasauriden characteristics in Chindesaurus , therefore Hunt (1996) and Lucas and Heckert (1996) assign the genus to Theropoda . The most recent work by Langer (2004), Irmis et al. (2007) and Nesbitt et al. (2007) describe it as the original lizard basin dinosaur (Irmis (2005) places it among the Dinosauriformes and thus outside of the dinosaurs).

Fossil finds

A partial skeleton of Chindesaurus was first discovered in 1985 in the Petrified Forest National Park in the US state of Arizona, mixed with fossil material from a Shuvosaurid, an archosaur related to the crocodiles (Suchia). The location of this specimen, the holotype (PEFO 10395), is the "Dinosaur Hollow", which lies in the Petrified Forest member of the Chinle Formation. However, no material of the skull important for the systematic determination has been found.

If Chindesaurus is a Herrerasaurid, it would be the first and youngest member of this group to be found in North America. Its fossils were associated with archosaurs such as the aetosaurs , phytosaurs and rauisuchia , whose small to medium-sized representatives this suspected carnivore may have hunted. This indicated a greater geographical and temporal distribution of the Herrerasauride than previously known.

A second find (PEFO 33982) also comes from the Petrified Forest Member. The fossil material comes from the park's “Giving Site”, from the same stratigraphic level as the “Dinosaur Hollow”. It consists of parts of the ilium , the proximal (upper) part of the thigh bone (femur) and several vertebral bodies .

Paleocommunities of the Upper Triassic

Another find of Chindesaurus in the 220 to 210 million year old Noric sedimentary rocks of the “Hayden Quarry”, an excavation site on the grounds of the Ghost Ranch in the US state of New Mexico , was published by Irmis et al. 2007. A fossil faunal community was found here, which in addition to the basal Saurischier Chindesaurus included a real theropod from the group of Coelophysoids as well as two dinosauromorpha (a quadruped , herbivorous dinosaur form similar to Silesaurus and the dinosauromorph Dromomeron romeri ). These findings show for the first time a coexistence for at least 15 to 20 million years of early dinosaurs with the dinosauromorphs, the group of archosaurs from which the dinosaurs descended. They suggest that the rise of dinosaurs as the dominant group of terrestrial vertebrates of the Mesozoic (Mesozoic) contrary to previous opinion did not take place due to sudden displacement or replacement of these precursors in the Upper Triassic, but extended over a longer period and only after the turn of the Lower Jurassic , about 200 million years ago.

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , p. 69, Online ( Memento of the original of July 13, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / press.princeton.edu
  2. ↑ a b Max C. Langer: Basal Saurischia. In: David B. Weishampel , Peter Dodson , Halszka Osmólska : The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 25-46, here p. 46, doi : 10.1525 / california / 9780520242098.003.0004 .
  3. ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide C ( Memento June 11, 2011 in the Internet Archive ), July 7, 2003 (last updated)
  4. ↑ a b The Paleobiology Database: Chindesaurus
  5. ^ The Paleobiology Database: Classification of RA Long and PA Murry 1995
  6. ↑ a b Randall B. Irmis, Sterling J. Nesbitt, Kevin Padian , Nathan D. Smith, Alan H. Turner, Daniel Woody, Alex Downs: A Late Triassic Dinosauromorph Assemblage from New Mexico and the Rise of Dinosaurs. In: Science . Vol. 317, No. 5836, 20 July 2007, pp. 358-361, doi : 10.1126 / science.1143325 .
  7. ↑ a b Randall B. Irmis: The vertebrate fauna of the Upper Triassic Chinle Formation in northern Arizona. In: Sterling J. Nesbitt, William G. Parker, Randall B. Irmis: Guidebook to the Triassic formations of the Colorado Plateau in Northern Arizona. Geology, paleontology, and history (= Mesa Southwest Museum. Bulletin. No. 9, ISSN  1558-5212 ). Mesa Southwest Museum - Southwest Paleontological Society, Mesa AZ 2005, pp. 63-88, online (PDF; 1.82 MB) .
  8. ^ A b William G. Parker, Randall B. Irmis, Sterling J. Nesbitt: Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. In: Museum of Northern Arizona. Bulletin Series. No. 62, 2006, ZDB -ID 986625-5 , pp. 160-161, online (PDF; 509.58 kB) .
  9. ↑ The Natural History Museum, London 2007 ( Memento of the original of July 13, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / internt.nhm.ac.uk
  10. ^ William G. Parker, Randall B. Irmis: Advances in late triassic vertebrate paleontology based on new material from Petrified Forest National Park, Arizona. In: Andrew B. Heckert, Spencer G. Lucas (eds.): Vertebrate paleontology in Arizona (= New Mexico Museum of Natural History. Bulletin. 29). New Mexico Museum of Natural History and Science, Albuquerque NM 2005, pp. 45-58, here p. 52, digitized .
  11. ^ "Fact Sheet For" : Randall B. Irmis, Sterling J. Nesbitt, Kevin Padian, Nathan D. Smith, Alan H. Turner, Daniel Woody, Alex Downs: A Late Triassic Dinosauromorph Assemblage from New Mexico and the Rise of Dinosaurs. In: Science . Vol. 317. No. 5836, 20 July 2007, pp. 358-361, doi : 10.1126 / science.1143325 .

literature

  • Robert A. Long, Phillip A. Murry: Late Triassic (Carnian and Norian) tetrapods from the southwestern United States (= New Mexico Museum of Natural History and Science. Bulletin. 4, ISSN  1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque 1995, online .

Web links