Thescelosaurus
thess-EL-oh-SORE-us
"wonderful lizard"
- 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
Size comparison
To scale
Scale in meters
Where its fossils were found
The evidence
Today
70 million years ago
Habitat
It lived on river floodplains, including those recorded in the Hell Creek Formation. Triceratops, Edmontosaurus and Tyrannosaurus lived in the same region.
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.
Field gallery
More views of Thescelosaurus
Scenes reconstructed from the available fossil evidence.
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Lived alongside
Found in the same rock formations
A rock formation can hold fossils laid down millions of years apart, so not every animal here met Thescelosaurus.
The evidence
The science behind Thescelosaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- Skeletons preserve a sturdy body, strong hindlegs, grasping hands and a long balancing tail.
- Skulls show a long, low head with a beak and rows of cheek teeth.
- Scans of the skull show large smell-processing regions and inner ears suited to detecting low sounds.
Borrowed from relatives
- Almost the whole body is known from its own bones; skin covering and color still need to be restored.
- Its burrowing relative Oryctodromeus helps explain why Thescelosaurus may have sheltered underground.
Still unknown
- Whether it dug burrows itself.
- Its skin pattern and color.
- How it cared for its young.
Often drawn wrong
- Its head was long and low, without a duck-billed dinosaur's crest or a horned dinosaur's frill.
- Its tail balanced the body above the ground rather than dragging behind it.
Discovery timeline
- 1913Named itGilmore
- 2014SkullBoyd
- 2023Its worldButton & Zanno
Key papers
The research behind what we know of Thescelosaurus
Named it
Named a sturdy plant eater from a partial skeleton found in the Lance Formation.
A new dinosaur from the Lance Formation of Wyoming. Smithsonian Miscellaneous Publications 61: 1-5
No link available
Skull
Described the skull in detail, including its teeth and the bones that distinguish Thescelosaurus from other small plant eaters.
The cranial anatomy of the neornithischian dinosaur Thescelosaurus neglectus. PeerJ 2: e669
Read the paper : The cranial anatomy of the neornithischian dinosaur Thescelosaurus neglectus (opens in a new tab)Its world
Skull scans revealed strong smell and balance systems, limited hearing of high sounds, and features consistent with spending time underground.
Neuroanatomy of the late Cretaceous Thescelosaurus neglectus (Neornithischia: Thescelosauridae) reveals novel ecological specialisations within Dinosauria. Scientific Reports 13
Read the paper : Neuroanatomy of the late Cretaceous Thescelosaurus neglectus (Neornithischia: Thescelosauridae) reveals novel ecological specialisations within Dinosauria (opens in a new tab)
Close relatives
Other members of Thescelosauridae
Sources: Wikidata