Pristerognathus

Pristerognathus

• South Africa, Pristerognathus - Assemblage Zone of the Beaufort Group

Pristerognathus was a carnivorous synapsides land vertebrate of the family of Theriodontia, ancestors of mammals. He lived in the Permian about 255 million years ago and was first described in 1895 by Harry Govier Seeley basis of a skull piece, which he had found in the Karoo in South Africa. After Pristerognathus the Pristerognathus - Assemblage Zone was named one of the layers of sediment on the Beaufort Group.

Features

The skull had Pristerognathus of bainitic described by Robert Broom in 1904 a length of more than 30 centimeters (measured at the bottom of the occipital bone to the end of the snout ) and a width of 15 centimeters at the widest point between the temples. The head was built relatively low. The synapside skull window was larger than the orbit, reaching 30% of the skull length. 75 to 80% of the lower jaw were made ​​from dental. The mouth was filled with simple, conical teeth in the upper jaw were long canines. Overall Pristerognathus was up to 2 m long.

Like the later mammals Pristerognathus was not continuously larger, but grew up as a young animal very quickly and then finished in early adult stage its growth.

Species

There have been described three types of Pristerognathus:

• Pristerognathus bainitic Broom, 1904
• Pristerognathus platyrhinus
• Pristerognathus polyodon Seeley, 1895

System

The self- discovered by Harry Govier Seeley in 1889 and 1895 described skull fragment of Pristerognathus polyodon indicates a somewhat larger animal out bainitic as Pristerognathus. The type specimen of P. polyodon, which is now preserved in the British Museum, is a weathered piece of the skull, of the six upper and three lower incisors were obtained, but does not allow for precise information about the number of molars. Therefore Pristerognathus polyodon has often been referred to as nomen dubium. According to some scholars, including Sidney Henry Haughton, based on the description insufficient material that could not be clearly assigned to a particular taxon. Other researchers have, however polyodon Pristerognathus and Pristerognathus bainitic considered the same way.

Swell

• Pristerognathus Dinosaurs - about.com