Daemonosaurus chauliodus CM 76821 (Sues et al. 2011) Late Triassic ~210 mya was originally considererd a basal theropod dinosaur and close to Herrerasaurus. Here Daemonosaurus nested as a basal phytodinosaur, basal to Sauropodomorpha, Ornithischia and Pseudornithischia. Derived from a sister to Pampadromaeus, Daemonosaurus phylogenetically preceded Scelidosaurus, Thecodontosaurus, Poposaurus and Pisanosaurus.

Distinct from Pampadromaeus, the skull of Daemonosaurus had a shorter rounder rostrum. The premaxillary teeth were larger and more sharply curved. The post-narial process of the premaxilla was elongated and enlarged. The nasal was larger and more exposed laterally. The maxilla was shorter. The antorbital fenestra was much smaller. The lateral temporal fenestra was anteroposteriorly narrow. The squamosal included a larger posterior process. The postorbital was more robust. The coronoid process was raised. The mandibular fenestra was smaller. The mandible was short enough to include a predentary bone, but one was not reported. The anterior dentary fang fit into a depression between the premaxilla and maxilla, as in Heterodontosaurus.

Along with Pampadromaeus, Daemonosaurus nests as the basalmost ornithischian AND sauropodomorph in this segment of the reptile family tree. Due to these relationships with plant-eating clades, Daemonosaurus may have used its over-sized banana-shaped fangs to pull leaves and needles off of twigs.

Paleontologists have always agreed that the plant-eating ornithischians and sauropodomorphs were derived from carninorous ancestors.

Paleontologists have also wondered about those large fangs seen in Heterodontosaurus, Massospondylus and Yinlong. Now the origin of the Phytodinosauria (Sauropodomorpha + Ornithischia) has been illuminated and the mystery behind the large fangs of Heterodontosaurus has been resolved.

Sues H-D, Nesbitt SJ, Berman DS and Henrici AC 2011. A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society B, published online

wiki/Daemonosaurus