Achelousaurus

Achelousaurus horneri is a genus of centrosaurine ceratopsid dinosaur. It lived during the Late Cretaceous Period of what is now North America, about 74. 2 million years ago. It is thought to have been a herbivore and it appears to have had a high metabolic rate, though lower than that of modern mammals and birds. It had rough bosses above the eyes and on the snout where other centrosaurusines often had horns in the same positions.

About Achelousaurus in brief

Achelousaurus horneri is a genus of centrosaurine ceratopsid dinosaur. It lived during the Late Cretaceous Period of what is now North America, about 74. 2 million years ago. The genus is known from a few specimens consisting mainly of skull material from individuals, ranging from juveniles to adults. It has been suggested that it was the direct descendant of the similar genus Einiosaurus and the direct ancestor of Pachyrhinosaurus. The first two genera would be transitional forms, evolving through anagenesis from Styracosaurus. It is thought to have been a herbivore and it appears to have had a high metabolic rate, though lower than that of modern mammals and birds. It had a bony neck-frill at the rear of the skull, which sported a pair of long spikes, which curved towards the outside. Adult Achelousosaurus had rough bosses above the eyes and on the snout where other centrosaurusines often had horns in the same positions. The exact shape in life is uncertain. According to some scientists the bosses were used in fights, with the animals butting each other’s heads, and for display. All known specimens were recovered from the Two Medicine Formation in Glacier County, Montana during excavations conducted by the Museum of the Rockies, which still houses the specimens. The discoveries came about by an accidental chain of events. In the spring of 1985, paleontologist John \”Jack\” R. Horner was informed that he would no longer be allowed to exploit the Willow Creek site, where he had studied the Maiasaura Egg Mountain nesting colony for six years.

In August 1985, Horner’s associate Bob Makela discovered a rich fossil site on the land of the farmer Ricky Reagan, which was called the Dinosaur Ridge Quarry and contained fossils of horned dinosaurs. In June 1988, another site was discovered in the vicinity of the Blacktail Creek North Creek – the Canyon Bone Bed. During the summer of 1989, graduate student Scott D. Sampson discovered another horned dinosaur skull near the Canyon Bed. In 2010, volunteer volunteer Sidney M. Hostetter located another Hornedosaurus specimen, which had been secured on a grain truck and was driven to the museum in Bozeman, Montana. The discovery of the bones led to the naming of the genus AchelOUSaurus in 1994. The generic name means \”Achelous lizard\”, in reference to a Greek mythological figure, and the specific name refers to Horner. The species is now considered to be the most basal of the ceratosaurines, with other genera such as St. Rubeosaurus and Einosaurus being more closely related to it. It was the first paleontological investigation in the Blackfeet Indian Reservation since the 1920s. The fossils were found on Landslide Butte, which proved to contain, apart from eggs, more than a dozen skeletons of a Horned dinosaur later named Einiusaurus.

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