The first complete dinosaur skeleton ever identified was finally studied in detail and found its place in the dinosaur’s family tree, completing a project that began more than half a century ago. Credit: John Sibbick
The first complete dinosaur skeleton ever identified was finally studied in detail and found its place in the dinosaur’s family tree, completing a project that began more than half a century ago.
The skeleton of this dinosaur, named Scelidosaurus, was collected more than 160 years ago on west Dorset’s Jurassic Coast. The rocks in which it was fossilized are about 193 million years old, near the breakfast sites 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.
So, what did Owen do with this find? He published two short papers on its anatomy, but many details were not included. Owen did not reconstruct the animal as it may have appeared in life and made no attempt to understand its relationship with other known dinosaurs of the time. In short, he ‘buried’ it in the literature of the time, and so it has remained since then: known, still obscure and misunderstood.
For the past three years, Dr. David Norman of the Cambridge Department of Earth Sciences has been working to complete the work that Owen began, preparing a detailed description and biological analysis of the skeleton of Scelidosaurus, the original of which is housed in the Natural History Museum. . in London, with other specimens in Bristol City Museum and 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 reconstructing what Scelidosaurus looked like in life, but revealing that it was an early ancestor of ankylosaurs, the armored ‘tanks’ of the Latvians Chalk Period.
For more than a century, dinosaurs were primarily classified according to the shape of their hip bones: they were either saurischians (‘lizard-hips’) or ornithischians (‘bird-hips’).
In 2017, however, Norman and his former PhD students Matthew Baron and Paul Barrett argued that these dinosaur family groupings needed to be rearranged, redefined, and renamed. In a study published in Nature, the researchers suggested that dinosaurs with bird hips and dinosaurs with lizards such as Tyrannosaurus evolved from a common ancestor, possibly turning over more than a century of theory about the evolutionary history of dinosaurs.
Another fact that emerged from her work on relationships with dinosaurs was that the earliest known ornithologists first appeared in the Early Jurassic. “Scelidosaurus is just like a dinosaur and represents a species that appeared at, or near, the evolutionary ‘birth’ of the Ornithischia,” said Norman, a Fellow of Christ’s College, Cambridge. Given this context, what was actually known about Scelidosaurus? The answer is remarkably small! ”
Norman has now completed a study of all known material that can be attributed to Scelidosaurus and his research has revealed many firsts.
“No one knew the head had horns on the back,” Norman said. “It had several bones that have never been recognized in any other dinosaur before. It is also clear from the rough structure of the skull bones that it was covered in life by hardened horny bones, a bit like the bones on it. “Surface of the skulls of living turtles. In fact, his entire body was protected by skin that anchored an array of stud-like bone spikes and plates.”
Now that his anatomy is understood, it is possible to investigate where Scelidosaurus sits in the family tree of the dinosaur. It was considered for many decades an early member of the group that included the stegosaurs, including Stegosaurus with its enormous bone plates along its spine and a prickly tail, and ankylosaurs, the armored ‘tanks’ of the dinosaur era, but that was based on a poor understanding of the anatomy of Scelidosaurus. Now it seems that Scelidosaurus is an ancestor of the ankylosaurs alone.
“It is unfortunate that such an important dinosaur, discovered at such a critical time in the early study of dinosaurs, was never properly described,” Norman said. ‘It has now – finally! – described in detail and provides many new and unexpected insights into the biology of early dinosaurs and their underlying relationships. It seems a shame that the work was not done sooner, but, as they say, better late than never. “
Reference: “Scelidosaurus harrisonii (Dinosaur: Ornithischia) from the Early Jurassic of Dorset, England: Biology and Phylogenetic Relations ”by David B Norman, FLS, 18 August 2020, Zoological Journal of the Linnean Society.
DOI: 10.1093 / soölinnean / zlaa061
