Sefapanosaurus

Chapter • Meet the dinosaur

Overview

Sefapanosaurus zastronensis was a medium-sized plant-eating sauropodomorph from the Early Jurassic of southern Africa. It grew to roughly four to six metres long and probably weighed somewhere between a couple of hundred kilograms and half a tonne. Its build followed the classic "prosauropod" body plan: a long neck, a small head (still unknown for this species), a deep barrel-shaped body and a long muscular tail carried clear of the ground. The forelimbs were relatively robust with broad wrist bones, suggesting the animal could put weight on all fours when moving slowly, while still rearing onto its hind legs to browse higher or to move quickly. Sefapanosaurus belongs to Sauropodiformes, the group that sits close to the transition towards the true giant sauropods. The animal's signature feature is its ankle bone, the astragalus, which has a distinctly cross-shaped upper surface. That detail gave the dinosaur its name: "sefapano" means cross in Sesotho, the language spoken in Lesotho and neighbouring parts of South Africa. Its vertebrae and hand bones also differ from those of other South African sauropodomorphs such as Massospondylus, Aardonyx and Antetonitrus, and it was this combination of features that revealed the fossils belonged to a separate species. As a herbivore, Sefapanosaurus most likely browsed on ferns, cycads, conifers and other low to medium-height plants along the floodplains. No teeth are known for the species, but close relatives had small, leaf-shaped, coarsely serrated teeth suited to cropping vegetation rather than chewing it. Food was probably processed instead in a muscular gut, in some cases with the help of swallowed stones. The fossils were collected as early as the 1930s at the farm Damplaats near the town of Zastron in the Free State, South Africa, from the upper Elliot Formation. The material — neck, back and tail vertebrae, a shoulder blade, upper arm bone, hand and foot bones, and thigh and lower leg elements — sat in museum collections for decades and was long assumed to belong to already-known species. Only in 2015 did a research team led by Alejandro Otero describe it as a new genus and species, Sefapanosaurus zastronensis. The discovery showed that the sauropodomorph fauna of southern Africa in the Early Jurassic was considerably more diverse than previously thought.

Chapter • Where it lived

Habitat

Sefapanosaurus lived about 200–190 million years ago, in the Early Jurassic, on the floodplains of what is now the Free State province of South Africa. The fossils come from the upper Elliot Formation at the farm Damplaats outside Zastron. The landscape was semi-arid and strongly seasonal: seasonal rivers and temporary lakes alternated with long dry spells, and vegetation of ferns, cycads and conifers clustered along the watercourses. The same beds have produced abundant remains of Massospondylus, Aardonyx and early ornithischians, making the Elliot Formation one of the world's most important windows onto Early Jurassic life.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy