Tochisaurus
"ostrich lizard"
Type species Tochisaurus nemegtensis
- Lived
- 72 to 66 million years ago, Late Cretaceous
- Diet
- Omnivore
- Group
- Theropods, Troodontidae
- Found in
- Mongolia
- Named by
- Kurzanov and Osmólska 1991
Where its fossils were found
The evidence
Today
70 million years ago
Habitat
It lived in a river landscape in what is now Mongolia. Dinosaurs from the Nemegt Formation include Tarbosaurus, Therizinosaurus and Gallimimus.
Field notes
About Tochisaurus
What it was like
Tochisaurus was a troodontid, a feathered, big-eyed theropod. It is known from a single foot.
Its world
It lived about 72 to 66 million years ago, at the end of the Late Cretaceous, in what is now Mongolia. Its bones come from the Nemegt Formation, a land of rivers shared with the huge predator Tarbosaurus, the long-clawed Therizinosaurus and the ostrich-like Gallimimus.
How it was found
Kurzanov and Osmólska named it in 1991. The type species is Tochisaurus nemegtensis.
Field gallery
More views of Tochisaurus
Scenes reconstructed from the available fossil evidence.
1 of 3
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 Tochisaurus.
The evidence
The science behind Tochisaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- It is known only from the long bones of a single left foot, between the ankle and the toes.
- The bone leading to the second toe is unusually narrow and reduced, suggesting that toe played a smaller role in supporting its weight.
- The bone leading to the fourth toe is the sturdiest, and the middle one narrows to a wedge near the ankle.
Borrowed from relatives
- The head is restored after Zanabazar, a better-known troodontid from the same formation.
- The arms, body and tail follow Jianianhualong, and the main weight-bearing toes follow Sinornithoides, both more complete troodontids.
- A feathered covering follows feather-preserving relatives such as Jianianhualong and Anchiornis.
Still unknown
- The shape of its toes and claws. No toe bones were found.
- Its skull shape, full body proportions and feather pattern.
- Its closest relative. A restudy found it distinct from the other troodontids of the Nemegt Formation, but no clear closest relative among them.
Discovery timeline
- 1991Named itKurzanov & Osmólska
- 2009Close relativeNorell et al.
- 2017Close relativeXu et al.
- 2021Family treeCau & Madzia
Key papers
The research behind what we know of Tochisaurus
Named it
Named Tochisaurus from a slender foot with a strongly reduced bone leading to the second toe.
Tochisaurus nemegtensis gen. et sp. n., a new troodontid dinosaur (Dinosauria, Theropoda) from Mongolia. Acta Palaeontologica Polonica 36: 69-76
No link available
Close relative
Described the skull and skeleton of Zanabazar, a better-known troodontid from the same formation that helps guide comparisons with Tochisaurus.
A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda). American Museum Novitates 3654: 1-63
Read the paper : A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda) (opens in a new tab)Close relative
Described Jianianhualong, a troodontid skeleton preserved with feathers that combines features of early and later troodontids.
Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features. Nature Communications 8
Read the paper : Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features (opens in a new tab)Family tree
Reexamined Borogovia and found it distinct from Tochisaurus and Zanabazar, supporting several different troodontids in the same formation.
The phylogenetic affinities and morphological peculiarities of the bird-like dinosaurBorogovia gracilicrusfrom the Upper Cretaceous of Mongolia. PeerJ 9: e12640
Read the paper : The phylogenetic affinities and morphological peculiarities of the bird-like dinosaurBorogovia gracilicrusfrom the Upper Cretaceous of Mongolia (opens in a new tab)
Close relatives
Other members of Troodontidae
Sources: Wikidata