Massospondylus

Chapter • Meet the dinosaur

Overview

Massospondylus was a slender, long-necked plant-eater that walked on two legs. Adults reached roughly four to six metres in length, though much of that was neck and a long, tapering tail that acted as a counterweight. The skull was small compared with the body and carried spatula-shaped, coarsely serrated teeth suited to cropping soft vegetation. The forelimbs were shorter than the hind limbs but powerfully built, and each hand bore a large curved thumb claw. Studies of the wrist show that the animal could not turn its palms downwards, which strongly suggests that adults were obligate bipeds and used their hands for grasping, hooking down branches and possibly defence. Massospondylus is one of the best-known early dinosaurs, with more than eighty individuals recovered from southern Africa. Bone histology reveals clear growth lines, indicating that growth rate varied from year to year, probably tracking alternating wet and dry seasons. Most studied individuals reached adult size after about fifteen years. The occurrence of several skeletons in the same beds has been read as evidence that the animals at least occasionally gathered in groups, but there is no proof of structured herds. The diet consisted mainly of plants: conifers, ferns, cycads and other low-growing greenery. The teeth could not chew, so food was probably swallowed whole and broken down in a large gut. Gastroliths have been reported in association with some skeletons, but later work has questioned whether they truly functioned as a bird-like gastric mill. A few researchers have suggested that juveniles may have been omnivorous, though this remains debated. Richard Owen named Massospondylus in 1854 from vertebrae sent to London from Harrismith in South Africa. The original material was destroyed when the Royal College of Surgeons was bombed during the Second World War, and in 2010 a new neotype skeleton with a skull was designated from South African material. The most spectacular discoveries come from Golden Gate Highlands National Park, where nests containing eggs and embryos were found - among the oldest dinosaur nesting sites known anywhere in the world.

Chapter • Where it lived

Habitat

Massospondylus lived during the Early Jurassic, roughly 200-183 million years ago, in what is now South Africa, Lesotho and Zimbabwe. Its fossils come mainly from the upper Elliot Formation and the Clarens Formation, rocks laid down in a semi-arid landscape of seasonal rivers, sandy flats and migrating dunes. Vegetation was concentrated along riverbanks and around temporary waterholes, where conifers, ferns and cycads grew. The single most important locality is Golden Gate Highlands National Park in the Free State, where the Rooidraai site has yielded eggs, embryos and hatchlings.

Chapter • Family life

Breeding

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy