Rhynchosaur

Live reconstruction of Paradapedon

• Worldwide except Australia and Antarctica.

The Rhynchosauria are an extinct group of herbivorous reptiles from the Triassic. They were found among others in Europe, North America, Brazil, India and East and South Africa.

Features

The plump, short-legged animals were characterized by a reduced dentition in the anterior and posterior tooth plates in the jaw. The Zwischenkieferbein, the foremost bone in the upper jaw was toothless and formed a hook-shaped, protruding "beak ". In the rear jaw area, the individual teeth were sitting on large bony plates. The worn teeth of the front edge were replaced by newly formed at the posterior border of the bone plate teeth.

During the evolution of the skull of Rhynchosauria grew wider and wider than long in the late forms. The original upper Temporalöffnung the Diapsiden expanded enormously in the Rhynchosauriern to offer the great adductor muscles of the jaw area. The largest Rhynchosauria reached lengths up to 2.5 meters.

Phylogeny

The first Rhynchosauria, the genera Rhynchosaurus, Mesosuchus and Howesia, appeared in the Early Triassic. In these forms the premaxilla bears some teeth. Later genera lost these teeth, the head was increasingly wider, the larger animals.

In the Middle Triassic, the Rhynchosauria were often given to larger terrestrial vertebrates in South America, India and East Africa. In the Upper Triassic remained only a few, closely related genera left ( including Scaphonyx, Paradapedon and Hyperodapedon ).

At the end of the Triassic, the group died out.

System

The Rhynchosauria were asked earlier because of a superficial similarity in skull anatomy and dentition, together with the (now called ) Sphenodontia ( tuatara and extinct relatives) as Rhynchocephalia to the shed lizards ( Lepidosauria ).

It was later realized that has the skull anatomy only in primitive features in common and the dentition is markedly different. Today it puts them in the trunk line of the Archosauria to the Archosauromorpha.

Genera

• Mesosuchus
• Howesia
• Stenaulorhynchus
• Rhynchosaurus
• Ammorhynchus
• Teyumbaita
• Hyperodapedon
• Bentonyx
• Fodonyx
• Isalorhynchus
• Mesodapedon (probably a synonym of Stenaulorhynchus )
• Paradapedon (probably a synonym of Hyperodapedon )
• Scarphonyx (probably a synonym of Hyperodapedon )