Amphicoelias
AM-fee-SEE-lee-us
"hollow on both sides"
- Lived
- 149 to 145 million years ago, Late Jurassic
- Diet
- Herbivore
- Group
- Sauropods
- Found in
- United States
- Named by
- Cope 1877
Where its fossils were found
The evidence
Today
145 million years ago
Habitat
The Morrison Formation records rivers, floodplains and lakes with ferns, horsetails and conifer trees. Other dinosaurs from these rocks include Diplodocus, Stegosaurus and Allosaurus.
Field notes
About Amphicoelias
What it was like
Amphicoelias was a long-necked plant eater related to Diplodocus. It had long, slender legs and a long neck and tail, and its back bones are hollowed out on both ends, which gave the genus its name.
Very little of it is known, and no trustworthy size can be given. It is famous mostly for a second species, known only from a drawing of a giant back bone that was later lost; many scientists now treat that animal as a separate, doubtful case.
Its world
Amphicoelias is securely known from the Late Jurassic Morrison Formation of Colorado. Other material has been referred to the genus, but a detailed restudy restricted it to the original skeleton.
How it was found
Cope named Amphicoelias in 1877 from a partial skeleton found in Colorado. A later restudy found that other remains could not be confidently assigned to it.
Field gallery
More views of Amphicoelias
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 Amphicoelias.
The evidence
The science behind Amphicoelias
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- The original skeleton consists of back vertebrae, a fragment of a hip bone and a thigh bone.
- The thigh bone has a slender shaft with a rounded cross-section.
Borrowed from relatives
- Galeamopus provides a comparison for the missing head, neck, forelimbs and tail.
- Its compact hands, inner thumb claw and clawed hindfeet guide restoration of the missing feet.
Still unknown
- Its total length and weight.
- Its exact position within the diplodocoid family tree.
- Its skin covering and color.
Often drawn wrong
- Record-breaking sizes based on the lost giant vertebra once assigned to another species are often applied to the original animal.
Discovery timeline
- 1877Named itCope
- 2017Close relativeTschopp & Mateus
- 2021RedescriptionMannion, Tschopp & Whitlock
Key papers
The research behind what we know of Amphicoelias
Named it
Named Amphicoelias from a small set of sauropod bones, including back vertebrae and a slender thigh bone.
On Amphicoelias, a genus of Saurians from the Dakota epoch of Colorado. Proceedings of the American Philosophical Society 17: 242-246
No link available
Close relative
Described a much more complete Galeamopus skeleton, including skull and foot bones useful for restoring missing parts of Amphicoelias.
Osteology of Galeamopus pabsti sp. nov. (Sauropoda: Diplodocidae), with implications for neurocentral closure timing, and the cervico-dorsal transition in diplodocids. PeerJ 5: e3179
Read the paper : Osteology of Galeamopus pabsti sp. nov. (Sauropoda: Diplodocidae), with implications for neurocentral closure timing, and the cervico-dorsal transition in diplodocids (opens in a new tab)Redescription
Restudied the original bones, supported Amphicoelias as a distinct genus and removed several bones formerly assigned to it.
Anatomy and systematics of the diplodocoidAmphicoelias altussupports high sauropod dinosaur diversity in the Upper Jurassic Morrison Formation of the USA. Royal Society Open Science 8: 210377
Read the paper : Anatomy and systematics of the diplodocoidAmphicoelias altussupports high sauropod dinosaur diversity in the Upper Jurassic Morrison Formation of the USA (opens in a new tab)
Close relatives
Other members of Diplodocoidea
Sources: Wikidata