Antetonitrus

Antetonitrus is an early sauropodiform dinosaur from the Early Jurassic of South Africa, discovered in the Upper Elliot Formation. Spanning between eight and ten metres in length and tipping the scales at several tonnes, it was a massive animal for its time. Antetonitrus lived before the rise of the iconic Jurassic sauropods, which earned it a name meaning before the thunder. Its forelimbs were robust and clearly modified for quadrupedal weight-bearing, yet its hands still retained a degree of inward grasping capability and an opposing thumb. This anatomical blend places Antetonitrus as a vital transitional taxon, illustrating how basal sauropodomorphs evolved from bipedal forebears into the lumbering four-footed titans of the later Mesozoic.

Its forelimbs retained flexible thumbs despite being adapted for full quadrupedal walking.

Where and when

Antetonitrus lived in the Early Jurassic, from 201 to 195 million years ago (Hettangian-Sinemurian age). Its remains come from South Africa, in the Elliot Formation.

The numbers

Length 9 m (estimates run from 8 to 10 m). Mass about 3.9 t. Hip height about 2.5 m. That is 5.3 human-lengths, or 0.8 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Antetonitrus with a bus Place on the timeline