who named it?
Scott D. Sampson
Achelousaurus
In 1994, Achelousaurus horneri was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to a Greek mythological figure, and the specific name refers to Horner. 
what is achelousaurus? It is a genus of centrosaurine ceratopsid dinosaur. describe its social behavior? They were herding animals, due to the large number of known bone beds containing multiple members of the same ceratopsian species. where did it get its name? It is named after a Greek mythological figure.
wiki:6127068
Achelousaurus [SEP] Introduction
Achelousaurus ( ) is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 74.2 million years ago. The first fossils of "Achelousaurus" were collected in Montana in 1987, by a team led by Jack Horner, with more finds made in 1989. In 1994, Achelousaurus horneri was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to a Greek mythological figure, and the specific name refers to Horner. The genus is known from a few specimens consisting mainly of skull material from individuals, ranging from juveniles to adults.