Iguanacolossus
"iguana colossus"
- Lived
- 139 to 133 million years ago, Early Cretaceous
- Diet
- Herbivore
- Group
- Ornithopods
- Found in
- United States
- Named by
- McDonald et al. 2010
Where its fossils were found
The evidence
Today
135 million years ago
Habitat
It lived on inland plains with rivers and lakes in what is now Utah. Dinosaurs recorded in the Cedar Mountain Formation include Falcarius, Gastonia and Utahraptor.
Field notes
About Iguanacolossus
What it was like
Iguanacolossus was a large, heavily built relative of Iguanodon, a plant eater that probably walked on all fours much of the time. It is known from a partial skeleton of one animal.
Its world
It lived about 139 to 133 million years ago, in the Early Cretaceous, in what is now Utah. Its bones come from the Cedar Mountain Formation, whose lower layers also held the long-clawed Falcarius.
How it was found
McDonald and colleagues named it in 2010, at the same time as its smaller relative Hippodraco.
Field gallery
More views of Iguanacolossus
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 Iguanacolossus.
The evidence
The science behind Iguanacolossus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- A partial skeleton from one animal includes skull fragments, teeth, backbone, shoulder and hip bones, and parts of the hind limbs.
- Its broad shoulder blade and substantial bones support a heavily built body.
- The middle foot bone is straight, while the outer foot bone curves strongly outward.
Borrowed from relatives
- The missing front of the head and hands are restored by comparison with Iguanodon, including a broad beak and possible thumb spikes.
- The blunt ends of its foot claws are modeled on Hippodraco.
Still unknown
- The complete shape of its face.
- The arrangement of its fingers and toes.
- Its skin covering and color.
Discovery timeline
- 2010Named itMcDonald et al.
- 2012Family treeMcDonald
- 2016Its worldKirkland et al.
Key papers
The research behind what we know of Iguanacolossus
Named it
Named Iguanacolossus and Hippodraco from partial skeletons, adding distinct plant eaters to the early iguanodont family tree.
New Basal Iguanodonts from the Cedar Mountain Formation of Utah and the Evolution of Thumb-Spiked Dinosaurs. PLoS ONE 5: e14075
Read the paper : New Basal Iguanodonts from the Cedar Mountain Formation of Utah and the Evolution of Thumb-Spiked Dinosaurs (opens in a new tab)Family tree
Updated early iguanodont relationships and corrected the description of a thickened edge on the hip bone of Iguanacolossus.
Phylogeny of Basal Iguanodonts (Dinosauria: Ornithischia): An Update. PLoS ONE 7: e36745
Read the paper : Phylogeny of Basal Iguanodonts (Dinosauria: Ornithischia): An Update (opens in a new tab)Its world
Reviewed the rock layers, fossil sites and changing environments of the Cedar Mountain Formation, where Iguanacolossus was found.
The Lower Cretaceous in east-central Utah—The Cedar Mountain Formation and its bounding strata. Geology of the Intermountain West 3: 101-228
Read the paper : The Lower Cretaceous in east-central Utah—The Cedar Mountain Formation and its bounding strata (opens in a new tab)
Close relatives
Other members of Styracosterna
Sources: Wikidata