Alxasaurus
"Alxa lizard"
Type species Alxasaurus elesitaiensis
- Lived
- 121 to 113 million years ago, Early Cretaceous
- Diet
- Herbivore
- Group
- Theropods
- Found in
- China
- Named by
- Russell and Dong 1994
Where its fossils were found
The evidence
Today
115 million years ago
Habitat
Its bones were buried in lake sediments in what is now northern China. Psittacosaurus, Bannykus and Penelopognathus also occur in the Bayangobi Formation.
Field notes
About Alxasaurus
What it was like
Alxasaurus was an early therizinosaur, one of the long-clawed plant eaters with meat-eating ancestors. It had a long neck, big hands with long claws, and small leaf-shaped teeth.
It was one of the first finds to show that therizinosaurs were theropods, relatives of meat eaters, and not something else.
Its world
It lived about 121 to 113 million years ago, in the Early Cretaceous, in what is now northern China. Its bones come from the Bayangobi Formation, where it shared the land with Psittacosaurus.
How it was found
Russell and Dong named Alxasaurus in 1994. Several skeletons were found during a joint dig by Chinese and Canadian scientists.
Field gallery
More views of Alxasaurus
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 Alxasaurus.
The evidence
The science behind Alxasaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- The partial type skeleton includes backbone, shoulder, hip, arm and thigh bones, showing long arms and a short tail in a two-legged dinosaur.
- Its preserved hand bones include finger bones and claws, and its right lower jaw held small, leaf-shaped teeth, including teeth near the front.
- A separately referred immature specimen preserves lower-leg and foot bones.
Borrowed from relatives
- Its covering is restored from Beipiaosaurus, a therizinosaur whose fossils preserve filament-like feathers.
- The missing upper skull is restored by comparison with Erlikosaurus, while Alxasaurus keeps its own toothed lower jaw.
- Falcarius supplies comparisons for remaining gaps in the hand, the hips and tail, and the ankles and toes.
Still unknown
- The shape of its upper skull.
- The extent and color of its feathers.
- How it used its hand claws.
Discovery timeline
- 1994Named itRussell & Dong
- 2009SkinXu, Zheng & You
- 2010Family treeZanno
Key papers
The research behind what we know of Alxasaurus
Named it
Described a long-armed, short-tailed dinosaur whose bones helped establish therizinosaurs as theropods.
The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People's Republic of China. Canadian Journal of Earth Sciences 30: 2107-2127
Read the paper : The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People's Republic of China (opens in a new tab)Skin
Described broad, filament-like feathers in Beipiaosaurus, the comparison for its covering.
A new feather type in a nonavian theropod and the early evolution of feathers. Proceedings of the National Academy of Sciences 106: 832-834
Read the paper : A new feather type in a nonavian theropod and the early evolution of feathers (opens in a new tab)Family tree
Compared therizinosaur skeletons and revised their relationships, placing Alxasaurus among the early branches of the group.
A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology 8: 503-543
Read the paper : A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora) (opens in a new tab)
Close relatives
Other members of Therizinosauroidea
Sources: Wikidata