Rare Jurassic mammal fossil from Scotland is new species

By Elsa Panciroli, Research Fellow

This week my colleagues and I announced the discovery of a new species of mammal from the time of dinosaurs. It is one of two rare skeletons we’re studying from the Isle of Skye in Scotland. These mouse-like animals lived in the Middle Jurassic (166 million years ago), and tell us about the evolution of mammals in the time of dinosaurs.

The two fossils belong to Borealestes serendipitous and Borealestes cuillinensis. B. serendipitous was the first Jurassic mammal ever found in Scotland, known originally from pieces of fossil jaw found on Skye in 1971. In our new paper, we describe the skull of a partial skeleton of this species, found in 1972 by the original discoverer of the site, Dr Michael Waldman and his colleague Prof Robert Savage. But this exceptional fossil lay unstudied for over 40 years. Only now is it giving up its secrets thanks to powerful synchrotron X-ray scans, which reveal the anatomy in incredible detail.

The other fossil skeleton was found in 2018 by my colleague Prof Richard Butler. After taking it back to the lab and CT-scanning it, we realised it was a new species. We named it Borealestes cuillinensis in honour of the Cuillin mountain range on Skye (Gaelic: An Cuiltheann), a stunningly jagged set of peaks that overlooks where the discovery was made.

The fossil jaw of new species, Borealestes cuillinensis, moments after its discovery. By Elsa Panciroli

Most ancient mammals are only known from a few teeth and jaws, so these skeletons are exceptionally rare. They are currently the most complete Jurassic mammals described from the UK.

The Middle Jurassic is an important time in animal evolution, because it marks an increase in the diversity of lots of different groups. Just afterwards, in the Late Jurassic, there are many new species of mammals, amphibians, small reptiles and dinosaurs, which flourish into the Cretaceous period. All of this diversity began in the Middle Jurassic, but fossils from that time are rare, making it difficult to unpick the causes of these changes. This means that any material from that time period is extremely important to our understanding of the course of evolution, and the drivers of animal diversity.

Fieldwork team on the Isle of Skye: (L to R) Roger Benson (University of Oxford), Richard Butler (University of Birmingham), Elsa Panciroli (OUMNH and National Museums Scotland), Stig Walsh (National Museums Scotland).

Our team have been carrying out fieldwork and research on Skye for the last decade. It includes researchers from National Museums Scotland and the universities of Oxford and Birmingham. We are working on many more exciting fossils from the island, so keep an eye out for the next discovery!

Read the paper ‘New species of mammaliaform and the cranium of Borealestes (Mammaliformes: Docodonta) from the Middle Jurassic of the British Isles’ published today in the Zoological Journal of the Linnean Society.

Top image: Digital reconstruction of two Jurassic mammal skulls. (c) Matt Humpage

Animating the extinct

This sumptuous video features on our brand new Out of the Deep display and brings to life the two large marine reptile skeletons seen in the cases. The Museum exhibition team worked with Martin Lisec of Mighty Fossils, who specialise in palaeo reconstructions. Martin and his animators also created a longer video explaining how the long-necked plesiosaur became fossilised, as well as beautiful illustrations of life in the Jurassic seas. 
Martin explains the process of animating these long-extinct creatures:

The first step was to make 3D models of all the animals that would appear in the films or illustrations. After discussion with the Museum team, it was clear that we would need two plesiosaurs (one short-necked, known as a pliosaur, one long-necked), ammonites, belemnites and other Jurassic sea life. Now we were able to define the scale of detail, size and texture quality of the model.

In consultation with Dr. Hilary Ketchum, the palaeontologist on the project, we gathered important data, including a detailed description of the discovered skeletons, photographs, 3D scans, and a few sketches.

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We created the first version of the model to determine proportions and a body shape. After several discussions with Hilary, some improvements were made and the ‘primal model’ of the long-necked plesiosaur was ready for the final touches – adding details, mapping, and textures. We could then move on to create the other 3D models.

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The longer animation was the most time-consuming. We prepared the short storyboard, which was then partly changed during the works, but that is a common part of a creative job. For example, when it was agreed during the process that the video would contain description texts, it affected the speed and length of the whole animation – obviously, it has to be slower so that people are able to watch and read all important information properly.

A certain problem appeared when creating the short, looped animation. The first picture had to precisely follow the last one – quite a difficult goal to reach in case of underwater scenery. Hopefully no-one can spot the join!

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At this moment we had a rough animation to be finalised. We had to make colour corrections, add effects and sound – everything had to fit perfectly. After the first version, there were a few more with slight adjustments of animation, cut and text corrections. The final version of both animations was ready and then rendered in different quality and resolution for use in the display and online.

The last part of the project was creating a large illustration, 12,000 x 3,000 pixels, which would be used as a background for a large display panel. Text, diagrams and a screen showing the animations would be placed on this background, making the composition a little tricky. We agreed that the base of the illustration would be just the background. The underwater scene and creatures were placed in separate layers so that it would be easy to adjust them – move them, change their size, position etc.

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In the first phase, we had to set the colour scale to achieve the proper look of the warm and shallow sea, then we made rough sketches of the scene including seabed and positions of individual creatures. We had to make continuous adjustments as the display design developed.

Then we finished the seabed with vegetation, gryphaea shells and plankton floating in the water. The final touch was to use lighting to create an illusion of depth for the Jurassic creatures to explore.

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More Out of the Deep videos are available on the Museum website.

The fossils of Stonesfield

A Spotlight Specimens special for Oxford Festival of Nature

By Eliza Howlett, Earth Collections manager

There was a time, more than 160 million years ago, when most of Oxfordshire was covered by a warm, clear, shallow sea. Offshore, the waters were agitated by waves and storms, but closer to land these forces were buffered by a submerged sandbank, and calm lagoons developed.

The area that is now Stonesfield was part of this lagoonal environment, and the fossils that have been found there provide a wonderful window into the living world of this Middle Jurassic sea.

So how would these sea creatures compare with British marine life today? Some things would have been very familiar. On the sea bed you would have found a huge variety of bivalves, or clams, along with lobsters, crabs and sea urchins; the waters above would have been full of fish, including several different types of shark.

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This fossilised limpet shell has its original colouration preserved

But there would have been other things too: squid-like belemnites, and nautiloids and ammonites with coiled shells, and tentacles like an octopus. Instead of dolphins and porpoises there would have been sea crocodiles and sea turtles, and in the skies above, flying reptiles known as pterosaurs rather than the usual sea birds.

And there’s more. Stonesfield fossils also include plants and animals washed in from nearby land: the leaves and seeds of conifers and cycads, beetle wing cases, reptile eggs, and the remains of both dinosaurs and mammals.

The jaw of the first named dinosaur, Megalosaurus bucklandii, found in Stonesfield, Oxfordshire
The lower jaw of the first named dinosaur, Megalosaurus bucklandii, found in Stonesfield, Oxfordshire in the early 19th century

One particularly spectacular find was the lower jaw of the carnivorous dinosaur Megalosaurus, nine metres long in life and weighing about a tonne. Megalosaurus became the first creature to be named a ‘dinosaur’, in 1824. Less obvious, but equally significant, are the tiny jaws of some of the shrew-like mammals that would have lived alongside the dinosaurs: Phascolotherium, Amphitherium, Amphilestes and Stereognathus – the first Jurassic mammals known to science.

Along with the preservation of delicate items such as dragonfly wings and the leg of a cricket, and the original colour patterns on some sea snails, limpets and barnacles, the fossil material from Stonesfield is really quite special.

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