Құрып кеткен Avaceratops динозавры

Extinct genus of ceratopsian dinosaurs

Avaceratops is a genus of small herbivorous ceratopsian dinosaurs which lived during the late Campanian during the Late Cretaceous Period in what are now the Northwest United States. Most fossils come from the Judith River Formation.

The first remains of Avaceratops were found by Eddie Cole in the Judith River Formation of Montana, in 1981, on land of the Careless Creek Ranch, owned by rancher Arthur J. Lammers. They were preserved scattered throughout the remains of a prehistoric stream bed. The fossil was formally named and described by Dodson in 1986, as the type species Avaceratops lammersi. It was the first ceratopsid named since Pachyrhinosaurus in 1950. However, Dodson objected against this change, arguing the genitive singular might also refer to a single family name. This alternative name has found no acceptance. The holotype, ANSP 15800, consists of a partial skeleton containing the lower skull, a left lower jaw, vertebrae, a complete shoulder girdle and most elements of forelimbs and hindlimbs. The type specimen might represent a juvenile or a subadult individual, Dodson in 1986 being inclined to consider it almost fully grown. In 1999, Penkalski and Dodson described a second skull, MOR 692, again of a larger individual. This specimen includes the upper skull, with the nose and brow horns. However, the assignment of the latter to Avaceratops has been questioned due to differences in relative chronological position, skull morphology, and lack of intermediate forms; thus, Avaceratops is only represented by the type specimen.

Avaceratops was originally by Dodson considered to have been an exceptionally small species. He estimated the holotype length at and assumed it had almost attained adult size. Another change in the image of Avaceratops brought about by MOR 692 concerned the brow horns. These were first thought to be rather short, although this was purely speculative, the holotype not having preserved them. The new skull showed postorbital horn cores with a length of .

Avaceratops, like all ceratopsians, was a herbivore. During the Cretaceous, flowering plants were "geographically limited on the landscape", so it is likely that this dinosaur fed on the predominant plants of the era: ferns, cycads and conifers. It would have used its sharp ceratopsian beak to bite off the leaves or needles. The habitat of Avaceratops was heavily forested and wet.