Ammosaurus

Foot skeleton of Ammosaurus ( drawing of Marsh 1989).

• Portland lineup, Connecticut

• Ammosaurus major

Ammosaurus is a basal ( original ) genus of dinosaur sauropodomorphen. She lived in the Jurassic of North America and by four incomplete, skull loose skeletons known to have been recovered in Connecticut from the layers of the Portland lineup. More, possibly belonging to this genus material comes from Nova Scotia and Arizona, although the Arizona material could also belong to Massospondylus. Several recent studies have come to the conclusion that Ammosaurus is identical to Anchisaurus; the name Ammosaurus would be invalid in this case.

The only valid type is Ammosaurus major. The name Ammosaurus means as much as " sand lizard" (Greek ammos - "Sand ", sauros - "lizard ").

Features

Ammosaurus was a small member of Sauropodomorpha; so does the holotype skeleton close to an animal, which had been 1.8 to 2.4 meters long. Galton and Upchurch (2004 ) indicate three features, which are distinguished from Ammosaurus Anchisaurus. However, Yates (2010) comes to the conclusion that two features of the pelvic bone artifacts could have been worse conservation and thus are not suitable for the system, while the third feature, the relatively small Halluxkralle of Anchisaurus to slightly for a separation of the two genera is. Consequently Yates Ammosaurus describes as a synonym of Anchisaurus.

System

Together with Anchisaurus forms Ammosaurus the family Anchisauridae. These forms are classic prosauropods, a group that ( as paraphyletic ) considered but today as invalid and is hardly ever used.

History of Research

The first skeleton found ( holotype, specimen number YPM 208) was excavated in 1884 by the famous paleontologist Othniel Charles Marsh in the valley of the Connecticut River near Manchester. Although this skeleton was apparently intact, Marsh harbored only the rear portion of the skeleton, consisting of three presacral vertebrae, the sacrum ( sacrum), pelvis and both hind legs. Initially described Marsh this find as a new species of Anchisaurus ( Marsh, 1889); Two years later he set up the new genus Ammosaurus.

Marsh wrote Ammosaurus the Coelurosauria to a group within the theropods. Friedrich von Huene (1914 ) presented a new family, the Ammosauridae, which he regarded as the most primitive group of Coelurosaurier. Only a re-examination of the genus by Galton (1971 ) showed that Ammosaurus was not a theropod, but rather a Prosauropode. He arranged this genus first one within the Anchisauridae; in a later publication ( Galton, 1990), however, he wrote them to the Plateosauridae.

Marsh described a second type, Ammosaurus solus, on the basis of pelvic and foot bones, which were found in the same quarry, from which the holotype specimen. Today, however, this species is identical with Ammosaurus major.