Aquilops americanus was described
by Farke et al. 2018, “The taxon is interpreted as a basal neoceratopsian closely related to Early Cretaceous Asian taxa, such as Liaoceratops and Auroraceratops.” This may be due to taxon exclusion.
Aquilops is much more primitive
than neoceratopsians, like Chasmosaurus and Triceratops, according to the large reptile tree (LRT, 1304 taxa; subset Fig. 1) which nests Aquilops between Laquintasaura and Hexlinusaurus, both basal to the psittacosaur – ceratopsian split. Both were excluded from the Farke et al. study.
Distinct from Laquintasaura,
Aquilops has an eagle-like hooked rostral bone (Fig. 2) and retains an antorbital fenestra with fossa. It was likely a biped, based on phylogenetic bracketing. Here (Fig. 1) skull only Auroraceratops nests with skull-less Stenopelix at the base of the Neoceratopsia. Liaoceratops nests with Psittacosaurus and Yinlong. We’ll look at them in future posts.
Farke AA, Maxwell WD, Cifelli RL and Wedel MJ 2014. A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia. PLoS ONE. 9 (12): e112055. doi:10.1371/journal.pone.0112055