Ammosaurus

Ammosaurus was a small, early sauropodomorph that inhabited eastern North America during the Early Jurassic period. Its remains were unearthed in the brownstone quarries of the Connecticut River Valley, a region famous for pioneering early dinosaur discoveries. Reaching about two to two and a half metres in length, Ammosaurus possessed a lightly built frame with a moderately elongated neck and grasping hands tipped with curved thumb claws. Although sometimes considered a junior synonym of Anchisaurus, several recent phylogenetic analyses maintain Ammosaurus as a distinct, closely related genus. It was capable of both four-legged walking and rearing up onto its hind limbs to browse on elevated vegetation. Its small leaf-shaped teeth were suited for stripping ferns and conifers, helping paint an evocative picture of the early plant-eating dinosaurs that roamed the rift valleys of eastern North America.

Fossils were discovered in a brownstone quarry in Connecticut during bridge construction.

Where and when

Ammosaurus lived in the Early Jurassic, from 195 to 185 million years ago (Sinemurian-Pliensbachian age). Its remains come from United States, in the Portland Formation.

The numbers

Length 2.3 m (estimates run from 2 to 2.5 m). Mass about 28 kg. Hip height about 0.8 m. That is 1.4 human-lengths, or 0.21 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

Compare Ammosaurus with a bus Place on the timeline