Placodus

Placodus, skeletal reconstruction in the State Museum of Natural History Stuttgart

• Poland
• Israel
• Germany

• P. gigas ( Agassiz, 1833)

Placodus is a genus of diapsiden reptiles from the Lower Triassic ( 249-228 mya ). It belongs to an extinct group of marine reptiles, the Sauropterygia (fins lizards ).

Description

Placodus had a strongly built, broad triangular skull, which was largely closed, and was about 20 cm long. The lower temporal window was completely gone, reduced the top to a narrow slit. The closed skull has evolved from a Diapsidenschädel developed with two temporal windows, but it is already so specialized that there are no closely related Non - Placodontier - Diaspidenform can be determined. The squamosal ( squamosal ) was large and offered wide attachment points for powerful jaw adductors. The maximum bite force was in the region of the largest teeth.

Dentition

The dentition consisted of three spatulate teeth on each premaxillary bone ( premaxilla ), four molars on each upper jaw bone ( maxilla ), three or four teeth on each dentary ( the tooth-bearing lower jaw bone) and a total of six palate teeth. The palate teeth were flat, very wide and covered by a thick enamel overlay.

Postkranialskelett

The hull was 28 vertebrae only slightly more stretched front of the sacrum than in terrestrial reptiles. The sacrum had three vertebrae. About the Neuralfortsätzen the trunk vertebrae were a number of osteoderms. The body bottom was protected by strong abdominal ribs. The tail was long and thin. The limbs, especially carpal bones and tarsal bones were only weakly ossified. Overall Placodus was about 1.5 meters long.

Way of life

He probably lived at the flat shores of the Tethys and fed on hard-shelled invertebrates, such as mussels or brachiopods that he scraped the Prämaxillarzähnen of the rocks and with the strong molars crushed ( Durophagie ).