Achelousaurus
Live reconstruction of Achelousaurus
- USA
- Achelousaurus horneri Sampson, 1995
Achelousaurus is a genus of bird Beck dinosaurs from the group of Ceratopsidae within the ceratopsians.
Features
With an estimated 6 feet in length Achelousaurus was a medium-sized representatives of Ceratopsidae. His physique resembled that of the other dinosaurs of this group. It was built stocky animals with powerful limbs, the hind legs were much longer than the front legs.
The head was big and bulky. The muzzle was pointed, and was formed as with all ceratopsian from the Rostralknochen ( in front of the upper jaw ) and the Praedentale ( in front of the lower jaw). The dentition was like all Ceratopsidae from dental batteries that are in rows spaced teeth that are replaced by the following tooth when worn. Like all ceratopsians he was herbivorous.
On the nasal bone was in contrast to most related Centrosaurinae no horn, but a thickened, bony hump. There was also over each eye, a relatively high bone crest. These structures were probably, possibly used in dealing with other dogs to areas or mating privileges.
The neck shield was formed as with all Ceratopsidae from the parietal and squamosal. He was thin and had paired windows. At the rear edge of the shield were two large spines.
Discovery and designation
From Achelousaurus three partially preserved skull and partial skeleton preserved body are known. The fossil remains were discovered in the Two Medicine Formation in Montana, USA, and first described in 1995. The genus name is derived from the Greek river god Achelous, which, in the legend of Hercules, a horn was broken off - an allusion to the lack of this dinosaur in contrast to related species horns. Type species and only known species is A. horneri. The finds are (late Campanian ) dated to the Late Cretaceous to an age of about 76 to 72 million years.
System
Achelousaurus is incorporated within the Ceratopsidae in the Centrosaurinae. Its closest relative may have been the also characterized by the lack of nose horn Pachyrhinosaurus. Together they formed the tribe Pachyrhinosaurini. Cladogram after Naish:
Centrosaurus
Achelousaurus
Pachyrhinosaurus