| Diet | Carnivore |
| Height | 3m |
| Length | 8.5m |
| Weight | 2.3 tonnes |
| Speed | 25 km/h |
| Environment | Land |
| Era | Jurassic |
| Period | Late Jurassic |
| Type | Theropod |
| Location | United States |
Creosaurus was originally described as a distinct theropod dinosaur by Othniel Charles Marsh in 1878, during the height of the famous 'Bone Wars' in American palaeontology. However, modern scientific analysis has revealed that Creosaurus is actually the same animal as the well-known predator Allosaurus fragilis, making it what scientists call a 'junior synonym'.
This large theropod lived during the Late Jurassic period, roughly 155-145 million years ago, in what is now the western United States. Like Allosaurus, Creosaurus would have been a formidable apex predator, standing about 3 metres tall at the hip and measuring approximately 8.5 metres in length. It possessed the characteristic theropod features of powerful hind legs, relatively small arms, and a large skull filled with sharp, serrated teeth perfect for slicing through flesh.
As a carnivore, this dinosaur would have hunted other dinosaurs in the Morrison Formation ecosystem, including sauropods, stegosaurs, and smaller ornithopods. Its robust build and powerful jaw muscles suggest it was capable of taking down large prey, whilst its long tail provided balance during high-speed pursuits.
The original Creosaurus fossils were quite fragmentary, consisting mainly of vertebrae and limb bones, which is why it took many decades for palaeontologists to realise they belonged to an animal already known as Allosaurus. This case highlights how the incomplete nature of the fossil record can sometimes lead to the same dinosaur being named multiple times.
As Creosaurus is now known to be the same as Allosaurus, it shared the same distinctive features: a large skull with prominent ridges above the eyes, powerful jaws lined with sharp teeth, and relatively small but muscular arms ending in three-fingered hands with large claws. Its long, powerful tail made up about half its total body length.
Being the same animal as Allosaurus, Creosaurus would have been an active predator that likely hunted both alone and possibly in loose groups when targeting very large prey. It probably used its speed and powerful bite to bring down prey, with evidence suggesting it may have engaged in territorial disputes with other large theropods.
As Creosaurus is considered synonymous with Allosaurus, it rarely appears in popular media under its original name, though Allosaurus itself is featured prominently in films like Jurassic World: Fallen Kingdom.
Creosaurus was first described by Othniel Charles Marsh in 1878. The original fossils were discovered at Morrison Formation, Colorado, USA.
