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Mesozoic World

Fossil Traces Deep Dinosaur Roots

Edited from BBC News, 12 June 2007

Eocursor parvus

Scientists in 2007 were able to describe a new primitive dinosaur species, Eocursor parvus, which lived in the Late Triassic period, about 210 million years ago.

Unearthed in South Africa's Free State, the creature appeared to have been a small, agile plant-eater. The team behind its discovery were able to tell a Royal Society journal that Eocursor helped to shed light on the early evolution of the Ornithischia. This important group included the well known herbivorous dinosaurs, Triceratops and Stegosaurus.

The fossil specimen was first identified in 1993 but was only more recently appraised. It was by far the most complete example of a Triassic ornithischian known so far, comprising skull and skeletal material, including bones of the backbone, arms, pelvis and legs.

Gripping hands

In its day, Eocursor would have been little bigger than a fox. Its bone structure and light form suggested it moved swiftly. It would have eaten plants with its leaf-shaped teeth and had an unusually large, grasping hand. The lower leg bones were very long, suggesting that it would have been able to run fast on its hind legs to escape from predators.

The scientists said the creature provided the earliest evidence for the origins of many skeletal characteristics seen in the ornithischian group, including the backward-pointing pelvis. A comparison was carried out across a wide range of specimens and this indicated that Late Triassic ornithischians were really quite rare. The group then diversified in the subsequent early Jurassic, filling empty herbivorous niches following mass extinctions of other creatures.

It was already known that ornithischians were a very successful and important group of plant-eating dinosaurs which first appeared 220 million years ago, in the late part of the Triassic, as was explained Dr Richard Butler, a palaeontologist at the Natural History Museum, London, UK. The name Eocursor comes from the Greek eos, meaning 'dawn' or 'early', the Latin cursor meaning 'runner' and parvus meaning 'little'.

Gap filler

The earliest known dinosaurs at this time came from about 228 million years old, so this one was only just a bit younger than that. The fossil record for early meat-eating dinosaurs was slightly better; and for some of the other plant-eaters the record was also relatively reasonable. But for the ornithischians, there was very little until now; so in that sense this was a major find.

The assessment was reported in Proceedings of the Royal Society B: Biological Sciences. The research team included colleagues at the Iziko South African Museum in Cape Town and the University of Cambridge, UK.



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