Melanorosaurus

Chapter • Meet the dinosaur

Overview

Melanorosaurus was a heavily built plant-eating dinosaur from the Late Triassic of southern Africa. At roughly six and a half to eight metres long and weighing somewhere between one and nearly two tonnes, it ranked among the largest land animals of its day. Its body was carried on four sturdy, pillar-like limbs, and the thigh bone was straight and massive, just as in the true sauropods that followed. The neck was moderately long, the head small relative to the body, and the tail was held out horizontally from the hips as a counterweight – it never dragged along the ground. The skin was almost certainly scaly; there is no evidence for feathers in sauropodomorphs, and feather-like structures in dinosaurs are known from entirely different branches of the family tree. Unlike many of its two-legged relatives such as Plateosaurus and Massospondylus, Melanorosaurus most likely walked on all fours all the time. The proportions of its limbs, the broad hips and the robust shoulder girdle all point to an animal built to carry weight rather than to sprint. Its hands could not be rotated palm-to-palm in the way seen in bipedal forms; instead they were on their way to becoming weight-bearing columns, an important step towards the true sauropod condition. No reliable top speed can be calculated from the fossils, but a steady, purposeful walk is the most plausible picture. Melanorosaurus was a herbivore. Its teeth were spoon-shaped with coarse serrations along the edges, well suited to snipping conifer foliage, fern fronds and fresh shoots but poor at chewing. Food was instead ground down in a muscular gut, possibly with the help of swallowed stones, and broken down by fermentation in a capacious body. With its head on a fairly long neck the animal could browse both ground-level plants and greenery a couple of metres up without constantly shifting its heavy frame. The genus was described in 1924 by the South African palaeontologist Sidney Haughton. The name means "black mountain lizard" and refers to the discovery site of Thaba 'Nyama in the eastern part of South Africa. The known material includes vertebrae, parts of the pelvis and bones from both fore- and hindlimbs, and later finds from the lower Elliot Formation have filled out the picture. In the 2000s Adam Yates and Matthew Bonnan re-examined the skeleton and showed how closely Melanorosaurus approaches the earliest true sauropods. Exactly which specimens belong to the species is still debated, and some previously referred bones have since been assigned to other dinosaurs.

Chapter • Where it lived

Habitat

Melanorosaurus lived during the Late Triassic, in the Norian stage roughly 227–208 million years ago, in what is now the Eastern Cape and Free State of South Africa and neighbouring parts of Lesotho. The fossils come from the lower Elliot Formation of the Karoo Basin, with the type locality at Thaba 'Nyama ("Black Mountain"). The landscape was one of broad floodplains crossed by meandering rivers, with strongly seasonal rainfall and stands of conifers, ginkgos, cycads and ferns. The same plains supported other early sauropodomorphs such as Eucnemesaurus and Blikanasaurus, along with crocodile-line archosaurs, rhynchosaurs and early mammal-like synapsids.

Chapter • Wild behavior

Behavior & Ecology

Did you know?

Chapter • Scientific place

Taxonomy