The Nose Crest Dinosaur
Weight: 3 tons
Found In: United States
Achelousaurus is a ceratopsid dinosaur, the same group that includes the better known Triceratops. Like other ceratopsids, it was four-legged, that is, it walked on all four legs.
What does the name Achelousaurus mean?
The name Achelousaurus is a combination of two words. Achelous’ is the name of the patron deity of the Greek Achelous. According to Greek mythology, he had fought with Hercules over the nymph Deianeira. During this battle, he became a bull. Hercules tore off one of his horns and forced him to capitulate.
Nasal crest of the Achelosaururs
Achelousaurus has only a prominent nasal crest or “boss”, while another ceratopsid, Einiosaurus, has a fully developed nasal horn. In connection with this ‘lost’ horn, the dinosaur was named ‘Achelousaurus’. The suffix ‘-saurus’ is derived from the Greek word ‘sauros’, which is translated as ‘lizard’ in English. Therefore, the name Achelousaurus means ‘the lizard of Achelous‘.
History of its name
A. horneri’s binomial name honors paleontologist Jack Horner, who led the expedition that led to the discovery of the Achelousaurus holotype. The naming was done by scientist Scott Sampson. The scientists involved in the naming process most likely recognized the irony of the generic name meaning “hornless” and the specific name having the word “horn” in it, but did not change it because it was still funny.
History of the Achelosaururs discovery
Fossils attributed to Achelousaurus were discovered in the Two Medicine Formation in Montana, USA. They were found in 1987 and the scientist responsible for the discovery was Jack Horner.
They remained unclassified due to certain confusing features in the skull, but finally found their place in the taxonomic tree in 1995, with the help of Scott Sampson.
Three skulls attributed to Achelousaurus were found in Montana in the initial excavation. Some posterior cranial bones were also found, but the skull was sufficient to recognize the bones as belonging to a ceratopsid.
What is Two Medicine?
The Two Medicine Formation is a natural geological rock structure located in Montana, USA. It is composed of fossils from the Campanian period of the Cretaceous period. It is composed mainly of sandstone, which was deposited there by streams, rivers and other bodies of water.
This formation has discovered many dinosaurs and other species of reptiles. Scolosaurus, Achelousaurus, Cerasinops, Troodon, along with many bivalves, turtles and lizards are some of the fossilized organisms found here.
Classification of Achelousaurus
The Achelousaurus is an Ornitian dinosaur or “hippie-bird”. It is classified in the family Ceratopsidae, sub-family Centrosaurinae, tribe Pachyrhinosaurini and clade Pachyrostra.
The classification of this dinosaur has been a subject of debate. Some scientists believe that it is an intermediate species between Pachyrhinosaurus and Einiosaurus. The Pachyrhinosaurus does not have a nasal horn, while the Einiosaurus has a large, curved horn on its nasal bone. Other scientists believe that the three or at least two of these dinosaurs are different stages of development from each other.
While this issue cannot be resolved until new evidence is discovered, Achelousaurus can be considered a separate genus until then.
When and where did the Achelosaururs live?
Achelousaurus is a dinosaur that existed on earth during the late Cretaceous Period. The time range of its existence is estimated to be between 79 and 60 million years ago, mainly found in the Two Medicine Formation area in the United States, where it reproduced for years and that is where its remains were found.
Description of Achelousaurus
- The distinctive feature of Achelousaurus is the structure of its skull and jaws.
- Its snout is similar to the beak and the nasal bone has a thick crest. It also has two horns located behind its orbital cavity. Such special structures are seen in all ceratopsides.
- The Achelousaurus was a medium-sized dinosaur. It weighed about two to three tons and was expected to be about 6 meters long.
- Its diet was herbivorous and it was probably preyed upon by other larger carnivorous theropods.
- The skull of Achelousaurus expands, as do other ceratopids. It consists of long nasal bones, which form a beak-like structure towards its tips.
- The nasal bone also has a thick ridge, where other ceratopsids have a similar one. Some species have no projections on their nasal bones, making the ridge look like part of a broken horn.
Curiosities about Achelousaurus
The head of this dinosaur was very big. It had a strong prominence on its nasal bone, along with a fan as a flywheel and two large horns towards the back of its head.
The function of these horns is unknown. They could possibly be secondary sexual characters or could be used as offensive and defensive tools. In addition, some scientists believe that ceratopsides show sexual dimorphism.