Plateosaurus

Plateosaurus ("broad lizard") is a sauropodomorph dinosaur of Late Triassic Europe.

Description
Plateosaurus is often known as a "prosauropod", although it is more correctly known as a form of basal sauropodomorph. It had a fairly typical body shape of these animals, with a small head, long neck, stocky body, and long tail. Plateosaurus was bipedal, and had digitigrade feet.

Fully grown specimens of Plateosaurus engelhardti reached 5 to 10 meters in length, while those of P. gracilis reached only 4 to 5 meters in length.

Classification
Plateosaurus is a primitive sauropodomorph, and gives its name to the clade Plateosauria. Although many species have been named in the past, only two species of Plateosaurus (P. engelhardti and P. gracilis) are currently considered valid.

History
In 1834, Johann Friedrich Engelhardt discovered miscellaneous vertebrae and leg material near Nuremburg, Germany. Three years later, they were described by Hermann von Meyer as Plateosaurus engelhardti. Since then, hundreds of specimens have been discovered throughout Europe.

In 1997, workers on an oil rig in the North Sea discovered a fossil in a sandstone drill core. It was later determined to be a fragment of Plateosaurus limb bone.

Posture
The posture of Plateosaurus has been the subject of much debate. Friedrich von Huene assumed that Plateosaurus was bipedal, while paleontologist Otto Jaekel believed it was quadrupedal. Both scientists were well acquainted with the animal's remains.

The debate was settled in 2007 when Matthew Bonnan and Phil Senter showed that basal sauropodomorphs could not pronate their hands (which allows for quadrupedal locomotion). They found that quadrupedal mounts of Plateosaurus were achieved by switching the position of the radius and ulna in the animal's arm, and such a posture could not occur in real life. This indicated that Plateosaurus was strictly bipedal. The dinosaur's center of mass also rests firmly over the hind limbs.

Diet
The teeth of Plateosaurus are similar to those of modern herbivorous reptiles such as iguanas. In 2000, Paul Barrett speculated that Plateosaurus may have supplemented its herbivorous diet with small animals or carrion on occasion.