Why this small Jurassic dinosaur possessed a set of teeth unlike any other reptile

Nature · Published 3 October 2026 Swipe more like this →

In short: Named for its unusual dentition, Heterodontosaurus tucki defied the reptilian norm by sporting three distinct types of teeth. While most dinosaurs relied on a single tooth shape, this small, bipedal herbivore featured incisors, canine-like tusks, and chisel-like cheek-teeth, sparking decades of debate over whether it was a hunter or a grazer.

Discovered in South Africa and named in 1962, Heterodontosaurus tucki lived during the Early Jurassic, roughly 200 to 190 million years ago. It remains the most complete and best-known member of the family Heterodontosauridae. Measuring between 1.18 and 1.75 meters in length, this dinosaur was a small but robust animal, characterized by a triangular skull and a unique arrangement of teeth that set it apart from its contemporaries.

The genus name, meaning different-toothed lizard, highlights its most striking feature: heterodonty. Unlike typical reptiles, which possess uniform teeth, Heterodontosaurus had a toothless keratinous beak at the front of its jaws, followed by small incisor-like teeth and prominent, canine-like tusks. A large gap, or diastema, separated these from eleven chisel-like cheek-teeth designed for processing plant material. This sophisticated dental anatomy allowed for efficient feeding, though the exact function of the tusks remains a subject of intense academic scrutiny.

While traditionally classified as a herbivore, some researchers have proposed that Heterodontosaurus may have been an omnivore. The presence of serrated tusks and long, clawed forelimbs has led some to suggest it could have engaged in facultative carnivory, perhaps seizing small prey to survive during the dry season. Others argue the tusks were used for defense or display, noting that they appear early in development, which contradicts the idea that they were purely for male-on-male combat. Whether it was a nimble, bristled grazer or an opportunistic hunter, this dinosaur remains a pivotal reference point for understanding the evolution of ornithischian dinosaurs.

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