Eshanosaurus
"Eshan lizard"
Type species Eshanosaurus deguchiianus
- Lived
- 201 to 200 million years ago, Early Jurassic
- Diet
- Herbivore
- Group
- Theropods, Therizinosauridae
- Found in
- China
- Named by
- Xu et al. 2001
Where its fossils were found
The evidence
Today
200 million years ago
Habitat
The Lufeng Formation records plains with rivers and shallow lakes in what is now China. Lufengosaurus, Yunnanosaurus and Sinosaurus lived in this region.
Field notes
About Eshanosaurus
What it was like
Eshanosaurus is known only from part of a lower jaw with teeth. The jaw looks like that of a therizinosaur, one of the long-clawed plant eaters with meat-eating ancestors.
If that is right, it would be by far the oldest therizinosaur and one of the oldest relatives of birds. Many scientists doubt this and think the jaw may come from an early long-necked plant eater instead.
Its world
It lived in the Early Jurassic in what is now southwestern China. Its jaw comes from the Lufeng Formation, where the plant eaters Lufengosaurus and Yunnanosaurus and the crested hunter Sinosaurus also lived.
How it was found
Xu and colleagues named Eshanosaurus in 2001, from a single find.
Field gallery
More views of Eshanosaurus
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 Eshanosaurus.
The evidence
The science behind Eshanosaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- An incomplete left lower jaw preserves many small teeth with finely serrated edges.
- The teeth sit inward from a broad shelf of bone along the outside of the jaw.
- The preserved front of the jaw bends downward, and the teeth become smaller toward the back.
Borrowed from relatives
- If it was a therizinosaur, Falcarius provides comparisons for its missing head, limbs and tail; Falcarius hand claws were recurved but not as long as those of later therizinosaurs.
Still unknown
- Experts disagree about whether it was a therizinosaur or an early sauropodomorph.
- The shape of its body, limbs and skull beyond the preserved jaw, including whether it had a toothless jaw tip.
- Whether the jaw's reported Early Jurassic age can be confirmed.
Discovery timeline
- 2001Named itXu, Zhao & Clark
- 2009Family treeBARRETT
- 2012Family treeSenter, Kirkland & DeBlieux
- 2026Family treeLiao et al.
Key papers
The research behind what we know of Eshanosaurus
Named it
Described a toothed lower jaw and identified it as an exceptionally early therizinosaur.
A new therizinosaur from the Lower Jurassic lower Lufeng Formation of Yunnan, China. Journal of Vertebrate Paleontology 21: 477-483
Read the paper : A new therizinosaur from the Lower Jurassic lower Lufeng Formation of Yunnan, China (opens in a new tab)Family tree
Compared the jaw and teeth with other plant eaters and found stronger support for a therizinosaur identity than a sauropodomorph identity.
THE AFFINITIES OF THE ENIGMATIC DINOSAUR ESHANOSAURUS DEGUCHIIANUS FROM THE EARLY JURASSIC OF YUNNAN PROVINCE, PEOPLE’S REPUBLIC OF CHINA. Palaeontology 52: 681-688
Read the paper : THE AFFINITIES OF THE ENIGMATIC DINOSAUR ESHANOSAURUS DEGUCHIIANUS FROM THE EARLY JURASSIC OF YUNNAN PROVINCE, PEOPLE’S REPUBLIC OF CHINA (opens in a new tab)Family tree
Revisited the Eshanosaurus debate and urged caution because many of its proposed therizinosaur features also occur in sauropodomorphs.
Martharaptor greenriverensis, a New Theropod Dinosaur from the Lower Cretaceous of Utah. PLoS ONE 7: e43911
Read the paper : Martharaptor greenriverensis, a New Theropod Dinosaur from the Lower Cretaceous of Utah (opens in a new tab)Family tree
An analysis that assumed Eshanosaurus was a therizinosaur placed it between Falcarius and Jianchangosaurus; it could not test that assumption.
A new therizinosaur from the Early Cretaceous Jehol Biota and ecomorphological patterns among early therizinosaurians. Journal of Systematic Palaeontology 24
Read the paper : A new therizinosaur from the Early Cretaceous Jehol Biota and ecomorphological patterns among early therizinosaurians (opens in a new tab)
Close relatives
Other members of Therizinosauridae
Sources: Wikidata