Heterodontosaurus is a genus of dinosaur belonging to the group Ornithischia. It lived during the Early Jurassic period, approximately 200 to 190 million years ago. The first fossils of Heterodontosaurus were discovered in South Africa in the 1960s, making it one of the earliest known dinosaurs from this region. This dinosaur stood as the earliest ornithopod, displaying numerous features critical to the group's evolutionary success, such as grinding teeth, fleshy cheeks, and the capability to run on hind legs, all observed in their ancestral form in this species.

Heterodontosaurus, a small dinosaur measuring approximately 3 to 4.9 feet (1 to 1.5 meters) in length, belonged to the ornithischian group and possessed distinct features that set it apart from other dinosaurs. Various studies estimated its weight to be around 1.8 kg (4.0 lb), 2.59 kg (5.7 lb), and 3.4 kg (7.5 lb).

The most notable characteristic of Heterodontosaurus was its heterodont dentition, from which its name is derived. Its jaws housed three distinct types of teeth: large, chisel-like front teeth for slicing vegetation, canine-like fangs for tearing plant material, and smaller cheek teeth for grinding food. It excelled at grinding plant material, surpassing other contemporary dinosaurs in this aspect.

Additionally, Heterodontosaurus featured a relatively large, elongated tail, that could have served as a counterbalance to its body and contributing to its agility.