Heterodontosaurus tucki

Heterodontosaurus tucki was a small, agile ornithischian from southern Africa. Its name refers to its strikingly differentiated dentition: a toothless beak at the jaw tip, enlarged tusk-like caniniform teeth and tightly packed cheek teeth with broad wear surfaces. A nearly complete skull and skeleton make it one of the best-known early ornithischians. The limbs show an animal primarily adapted for bipedal running but capable of using long, grasping hands. Bristle-like filaments are not preserved in Heterodontosaurus itself; they are commonly reconstructed from the related heterodontosaurid Tianyulong.

Its fossils occur between approximately 200.5 and 190.8 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

The short deep skull had a beak at the front, a gap in the tooth row, large upper and lower caniniforms, and tall cheek teeth that wore against one another. The jaw joint and tooth wear indicate sophisticated plant processing. Large eye sockets and a compact body accompanied long hind limbs. The forelimbs were relatively powerful, and the hand retained five digits: the inner three carried curved claws while the outer two were reduced. Fused lower-leg and ankle bones strengthened the hind limb.

• Beak, enlarged caniniforms and specialized cheek teeth in one jaw
• Broad tooth-wear surfaces suited to processing plants
• Short deep skull with large eye sockets
• Long grasping hands with three large clawed fingers
• Long hind limbs suited to bipedal movement
• Fused distal lower-leg and ankle bones

A British–South African expedition found the holotype skull SAM-PK-K337 near Tyinindini in 1961–1962. A. W. Crompton and Alan Charig named Heterodontosaurus tucki in Nature in 1962. A later expedition recovered the exceptionally complete skull and skeleton SAM-PK-K1332 near Voyizane; Albert Santa Luca, Crompton and Charig described its postcranial anatomy in 1976. The genus means different-toothed lizard, and the species honours George C. Tuck, whose company supported the original expedition.

Naming authors: A. W. Crompton, Alan J. Charig.

The upper Elliot and Clarens formations record river floodplains that became increasingly dry and dune-influenced during the Early Jurassic. Heterodontosaurus lived among early sauropodomorphs, crocodylomorph relatives, theropods and other small ornithischians. Seasonal conditions have sometimes been linked to speculative aestivation, but no Heterodontosaurus burrow or dormant individual is known.

Wear on the cheek teeth shows repeated processing of resistant vegetation. The caniniforms could have served in defence, display or competition and do not by themselves prove meat eating. Occasional animal food is possible for a small-bodied herbivore, but direct dietary evidence favours plant processing. Heterodontosaurus was primarily bipedal; its strong hands may have grasped vegetation or assisted during slow movement.

• Its jaws combined a beak, tusk-like teeth and tightly packed grinding teeth.
• The nearly complete SAM-PK-K1332 skeleton preserves much of the animal from skull to tail.
• Its long hands ended in three prominent claws despite its plant-processing dentition.
• The filamentous coat in modern reconstructions is inferred from the related Tianyulong, not directly preserved.

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1. 01
   A new ornithischian from the Upper Triassic of South Africa

   A. W. Crompton, Alan J. Charig · Nature 196, 1074–1077 · 1962

   Open source
2. 02
   A complete skeleton of the Late Triassic ornithischian Heterodontosaurus tucki

   Albert P. Santa Luca, A. W. Crompton, Alan J. Charig · Nature 264, 324–328 · 1976

   Open source
3. 03
   Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs

   Paul C. Sereno · ZooKeys 226, 1–225 · 2012

   Open source
4. 04
   Heterodontosaurus

   Natural History Museum, London

   Open source