A life reconstruction of Thescelosaurus in its habitatDV-0089Hell Creek Fm., Montana

Thescelosaurus

thess-EL-oh-SORE-us

"wonderful lizard"

DV-0089

Lived
72 to 66 million years ago, Late Cretaceous
Diet
Herbivore
Length
about 3.5 m (11 ft)
Group
Early ornithischians, Thescelosauridae
Found in
United States and Canada
Named by
Gilmore 1913

Field notes

About Thescelosaurus

What it was like

Thescelosaurus was a sturdy, plant-eating dinosaur that walked on two legs, balanced by a long, stiffened tail. It grew to roughly 3.5 meters (11.5 feet) long, with a small head, a toothless beak, and cheek teeth suited to grinding tough plants. Its legs were strong but built more for steady walking than for speed. Some paleontologists think it may have sheltered in burrows, as its close relative Oryctodromeus is known to have done.

Its world

Thescelosaurus lived across what are now the western United States and Canada during the Late Cretaceous, right up until the end of the Mesozoic about 66 million years ago. Its bones come from formations including Hell Creek, Lance, and Frenchman, found across Montana, North Dakota, South Dakota, Wyoming, Alberta, and Saskatchewan.

It shared this world with Triceratops, Tyrannosaurus, and the armored Ankylosaurus, among other dinosaurs of the time.

How it was found

Gilmore named Thescelosaurus in 1913, with forty-two fossil finds known since. It gives its name to Thescelosauridae, a family that also includes Parksosaurus and the burrowing Oryctodromeus. Living right until the mass extinction that ended the Mesozoic, Thescelosaurus was among the last non-avian dinosaurs on Earth.

The evidence

Where its fossils were found

Today

42 finds

70 million years ago

Map: C. R. Scotese, PALEOMAP

To scale

How big was Thescelosaurus?

0 m1 m2 m3 m4 m
Thescelosaurus: about 3.5 m (11 ft) · Person: 1.8 m (6 ft)Silhouette: typical early ornithischian shape

Lived alongside

Found in the same rock formations.

Close relatives

Other members of Thescelosauridae.

Sources: Paleobiology Database, WikidataNamed in: C. W. Gilmore. 1913. A new dinosaur from the Lance Formation of Wyoming. Smithsonian Miscellaneous Publications 61(5):1-5