Science

First complete dinosaur skeleton ever finds its final place in the dinosaur family tree

Scientists have finally completed the full study of the first complete dinosaur skeleton ever and have put it in its correct place in the dinosaur family tree.

The entire project lasted for more than one hundred and fifty years. The dinosaur skeleton was found 160 years ago on west Dorset’s Jurassic Coast. The dinosaur has been named Scelidosaurus. Carbon dating indicated that the rocks in which it was fossilised are around 193 million years old, close to the dawn of the Age of Dinosaurs. This remarkable specimen – the first complete dinosaur skeleton ever recovered – was sent to Richard Owen at the British Museum, the man who invented the word dinosaur.

Back when it was discovered, its founder Owen did not reconstruct the animal as it might have appeared in life and made no attempt to understand its relationship to other known dinosaurs of the time. In short, he ‘re-buried’ it in the literature of the time, and so it has remained ever since: known, yet obscure and misunderstood.

Over the past three years, Dr David Norman from Cambridge’s Department of Earth Sciences has been working to finish the work which Owen started, preparing a detailed description and biological analysis of the skeleton of Scelidosaurus, the original of which is stored at the Natural History Museum in London, with other specimens at Bristol City Museum and the Sedgwick Museum, Cambridge.

The results of Norman’s work, published as four separate studies in the Zoological Journal of the Linnean Society of London, not only reconstruct what Scelidosaurus looked like in life, but reveal that it was an early ancestor of ankylosaurs, the armour-plated ‘tanks’ of the Late Cretaceous Period.

For more than a century, dinosaurs were primarily classified according to the shape of their hip bones: they were either saurischians (‘lizard-hipped’) or ornithischians (‘bird-hipped’).

However, in 2017, Norman and his former PhD students Matthew Baron and Paul Barrett argued that these dinosaur family groupings needed to be rearranged, re-defined and re-named. In a study published in Nature, the researchers suggested that bird-hipped dinosaurs and lizard-hipped dinosaurs such as Tyrannosaurus evolved from a common ancestor, potentially overturning more than a century of theory about the evolutionary history of dinosaurs.

Another fact that emerged from their work on dinosaur relationships was that the earliest known ornithischians first appeared in the Early Jurassic Period. “Scelidosaurus is just such a dinosaur and represents a species that appeared at, or close to, the evolutionary ‘birth’ of the Ornithischia,” said Norman, who is a Fellow of Christ’s College, Cambridge. “Given that context, what was actually known of Scelidosaurus? The answer is remarkably little!”

Norman has now completed a study of all known material attributable to Scelidosaurus and his research has revealed many firsts.

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