Opisthocoelicaudia
"tail bones hollow at the back"
- Lived
- 72 to 66 million years ago, Late Cretaceous
- Diet
- Herbivore
- Length
- about 12 m (39 ft)
- Group
- Sauropods, Saltasauridae
- Found in
- Mongolia
- Named by
- Borsuk-Bialynicka 1977
Size comparison
To scale
Scale in metersOutline: typical sauropod shape
Where its fossils were found
The evidence
Today
70 million years ago
Habitat
Rivers and floodplains spread across the landscape preserved in Mongolia's Nemegt Formation. Tarbosaurus, Therizinosaurus and Deinocheirus were among its neighbors.
Field notes
About Opisthocoelicaudia
What it was like
Opisthocoelicaudia was a titanosaur, a long-necked plant eater about 12 meters (39 feet) long. That is small for a sauropod. The bones of its tail had an unusual joint shape, rounded at the front and cupped at the back, which gives the genus its long name.
Its skeleton is nearly complete but lacks the head and neck. Bite marks on the bones suggest a large meat eater fed on the body.
Its world
It lived about 72 to 66 million years ago, at the end of the Cretaceous, in what is now Mongolia. Its bones come from the Nemegt Formation, a land of rivers where Tarbosaurus, Therizinosaurus, Deinocheirus and Gallimimus lived.
How it was found
Borsuk-Bialynicka named Opisthocoelicaudia in 1977. Only one find is known, but it is one of the best preserved sauropods from the Late Cretaceous.
Field gallery
More views of Opisthocoelicaudia
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 Opisthocoelicaudia.
The evidence
The science behind Opisthocoelicaudia
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- A nearly complete skeleton from the shoulders back shows a stocky body with sturdy limbs.
- The front tail vertebrae have joints rounded at the front and hollow at the back.
- Its hand bones formed upright semicircular columns with greatly reduced fingers.
Borrowed from relatives
- Almost the whole body behind the neck is known from its own bones.
- Rapetosaurus and Tapuiasaurus provide possible models for the missing head and neck.
Still unknown
- The shape of its skull and the length of its neck.
- Whether it and Nemegtosaurus were different animals.
- Its skin covering and color.
Often drawn wrong
- Older restorations gave it a deep, boxy head like Camarasaurus, following an outdated view of its family relationships.
Discovery timeline
- 1977Named itBorsuk-Bialynicka
- 2001Close relativeCurry Rogers & Forster
- 2011Close relativeZaher et al.
Key papers
The research behind what we know of Opisthocoelicaudia
Named it
Named and described a remarkably complete skeleton with unusual tail joints, preserved without its head or neck.
A new camarasaurid sauropod <i>Opisthocoelicaudia skarzynskii</i> gen. n., sp. n. from the Upper Cretaceous of Mongolia. Palaeontologia Polonica 37: 5-64
No link available
Close relative
Described Rapetosaurus with a skull and skeleton, providing a titanosaur comparison for the missing head of Opisthocoelicaudia.
The last of the dinosaur titans: a new sauropod from Madagascar. Nature 412: 530-534
Read the paper : The last of the dinosaur titans: a new sauropod from Madagascar (opens in a new tab)Close relative
Described the elongated skull of Tapuiasaurus, offering another comparison for reconstructing the missing face of Opisthocoelicaudia.
A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians. PLoS ONE 6: e16663
Read the paper : A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians (opens in a new tab)
Close relatives
Other members of Saltasauridae
Sources: Wikidata