First complete dinosaur skeleton ever found is ready for its closeup at
last

Date:
August 27, 2020
Source:
University of Cambridge
Summary:
The first complete dinosaur skeleton ever identified has finally
been studied in detail and found its place in the dinosaur family
tree, completing a project that began more than a century and a
half ago.



FULL STORY ==========================================================================
The first complete dinosaur skeleton ever identified has finally been
studied in detail and found its place in the dinosaur family tree,
completing a project that began more than a century and a half ago.


==========================================================================
The skeleton of this dinosaur, called Scelidosaurus, was collected more
than 160 years ago on west Dorset's Jurassic Coast. 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.

So, what did Owen do with this find? He published two short papers
on its anatomy, but many details were left unrecorded. 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.



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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.

"Nobody knew that the skull had horns on its back edge," said
Norman. "It had several bones that have never been recognised in any
other dinosaur. It's also clear from the rough texturing of the skull
bones that it was, in life, covered by hardened horny scutes, a little
bit like the scutes on the surface of the skulls of living turtles. In
fact, its entire body was protected by skin that anchored an array of
stud-like bony spikes and plates." Now that its anatomy is understood,
it is possible to examine where Scelidosaurus sits in the dinosaur
family tree. It had been regarded for many decades as an early member
of the group that included the stegosaurs, including Stegosaurus with
its huge bony plates along its spine and a spiky tail, and ankylosaurs,
the armour-plated '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," said Norman. "It has now -- at last! -- been described in
detail and provides many new and unexpected insights concerning the
biology of early dinosaurs and their underlying relationships. It seems
a shame that the work was not done earlier but, as they say, better late
than never."

========================================================================== Story Source: Materials provided by University_of_Cambridge. Original
written by Sarah Collins. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. David B Norman. Scelidosaurus harrisonii (Dinosauria: Ornithischia)
from
the Early Jurassic of Dorset, England: biology and phylogenetic
relationships. Zoological Journal of the Linnean Society, 2020;
DOI: 10.1093/zoolinnean/zlaa061 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200827101819.htm

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