Pronunciation: AY-vuh-SEH-ruh-tops
Meaning: Ava's horned face
Author/s: Dodson (1986)
Synonyms: See below
First Discovery: Montana, USA
Discovery Chart Position: #322
Avaceratops lammersi
The first remains of Avaceratops were found strewn around a pre-historic stream bed now known as the Judith River Formation in 1981. Despite an obvious lack of horns due solely to the fact it was missing the part of the skull to which horns would normally be attached, it was classified as a ceratopsid — the dinosaurs known colloquially as "horn faces" — because of a customary albeit modest neck frill, and as a centrosaurine ceratopsid, which have the horniest faces of all, at least as adults.
Compared to its monstrous ceratopsian relatives, Avaceratops was small, which led some experts to muse that it was likely a juvenile example of another species, possibly the ultra-obscure Ceratops montanus, which isn't even a centrosaurine. The same folk won't entertain an infant specimen being installed as name-bearer simply because of the huge scope for change as the critter matures, much to the chagrin of its describer Peter Dodson, who was inclined to consider it almost fully grown. But the juvenile status of the holotype Avaceratops was seemingly confirmed with the discovery of a much larger skull in 1991, which increased its estimated total body length from 2.3 to 4.2 meters based on proportionate upscaling and should have been glorious news. However, eyebrows were raised once again due not only to its discovery 125km and 2 million years from the holotype quarry and the absence of any shared diagnostic characters but also the presence of 25cm brow horns that are strikingly similar to those of... Ceratops mantanus.
Avaceratops lammersorum (Olshevsky, 1990)Compared to its monstrous ceratopsian relatives, Avaceratops was small, which led some experts to muse that it was likely a juvenile example of another species, possibly the ultra-obscure Ceratops montanus, which isn't even a centrosaurine. The same folk won't entertain an infant specimen being installed as name-bearer simply because of the huge scope for change as the critter matures, much to the chagrin of its describer Peter Dodson, who was inclined to consider it almost fully grown. But the juvenile status of the holotype Avaceratops was seemingly confirmed with the discovery of a much larger skull in 1991, which increased its estimated total body length from 2.3 to 4.2 meters based on proportionate upscaling and should have been glorious news. However, eyebrows were raised once again due not only to its discovery 125km and 2 million years from the holotype quarry and the absence of any shared diagnostic characters but also the presence of 25cm brow horns that are strikingly similar to those of... Ceratops mantanus.
Monoclonius lammersi (Lehman, 1990)
Etymology
Avaceratops is derived from Ava (for Ava Cole, the wife of Eddie Cole who found the first specimen), and the Greek "ceras" (horned) and "ops" (face).
The species epithet, lammersi, honors the Lammers family, owners of the land where the holotype fossils were found.
Discovery
The first fossils of Avaceratops were discovered at Careless Creek Quarry in the Judith River Formation of Montana, USA, by fossil dealer Eddie Cole in September, 1981. The holotype (ANSP 15800) is a partial skull and skeleton. Two pieces of skull (USNM 4802 and USNM 2415) and a partial skull (MOR 692) all from larger, and presumed older, individuals were assigned to Avaceratops by Penalski in 1993 and Penkalski and Dodson in 1999. But their assignment was rejected by Ryan et al. in 2017 because they lack any shared diagnostic characters.
