Megacephalosaurus

Megacephalosaurus is an extinct genus of short-necked pliosaur that inhabited the Western Interior Seaway of North America about 94 to 93 million years ago during the Turonian stage of the Late Cretaceous, containing the type and only species: M. eulerti.

Description

Two specimens pertaining to Megacephalosaurus are known. Both represent fossil skulls.

The genus name means "great-headed lizard". It is named after its large head which is the largest of any plesiosaur in the continent and measures up to 1.75 meters (5.7 ft) in length. Megacephalosaurus was one of the largest marine reptiles of its time with an estimated length of 6–9 meters (20–30 ft). Its long snout and consistently sized teeth suggest that it preferred a diet on smaller-sized prey.

Discovery and history

The first specimen of Megacephalosaurus was discovered by two teenage brothers named Frank and Robert Jennrich while collecting fossil shark teeth near Fairport, Kansas.

Remains representing the pliosaur include two fossil skulls, three ribs, and a neural arch. The fossils have been found in deposits of the Carlile Shale and Greenhorn Limestone in Kansas and elsewhere in the midwestern United States. First discovered in 1950, they were originally thought to have been giant fossils of a closely related pliosaur genus known as "Brachauchenius lucasi". But by 2013, paleontologists understood that such fossils belonged to a distinct animal. Megacephalosaurus was among the last known pliosaurs.

Classification

Megacephalosaurus is a member of the subfamily Brachaucheninae, which consists of pliosaurs that are currently only known during the Cretaceous period.

Paleoecology

Megacephalosaurus was among the last of the pliosaurs.