Abrictosaurus Temporal range: Early Jurassic,
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Specimen NHMUK RU B54 | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Order: | †Ornithischia |
Family: | †Heterodontosauridae |
Subfamily: | †Heterodontosaurinae |
Genus: | †Abrictosaurus Hopson, 1975 |
Species | |
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Abrictosaurus was a heterodontosaurid dinosaur from the Lower Jurassic of what is now southern Africa. It was a small bipedal herbivore or omnivore, about 1.2 meters (4 feet) long, and weighing less than 45 kilograms (100 pounds).
Abrictosaurus is usually thought to be the most basal member of the family Heterodontosauridae.[1][2] Lycorhinus and Heterodontosaurus both had high-crowned cheek teeth, which went over each other in the jaw, making a continuous chewing surface analogous to those of Cretaceous hadrosaurids. Abrictosaurus had more widely-split cheek teeth, with lower crowns, more similar to other early ornithischians.
The family as a whole has canine-like tusks.[3] Tusks were clearly present on one of the two specimens of Abrictosaurus. The upper caniniform measured 10.5 millimeters (0.4 inches) high, while the lower reached 17 mm (0.67 in).[4][5]
Abrictosaurus had smaller, less powerful forelimbs than Heterodontosaurus and one fewer phalanx bone (finger joint) in both the fourth and fifth digits of the forelimb.[6]