Last year the Palaeontographical Society contributed funding towards the excavation of the largest ichthyosaur ever discovered in the UK. In this blog palaeontologist and lead excavator, Dr Dean Lomax, tells us about the discovery and excavation, and its significance for palaeontology.
In January 2021, Dr Mark Evans and I were contacted about an exciting discovery of several large vertebrae found at Rutland Water Nature Reserve by Joe Davis, Conservation Team Leader at Leicestershire and Rutland Wildlife Trust. We were first alerted to the find by Vicky Ward at the University of Leicester, who was contacted for advice after the initial discovery was made. Upon examining photos of the vertebrae, it was instantly clear that they belonged to a large ichthyosaur and could represent a spectacular find. The inland nature of the discovery is also highly unusual, and the overall lack of marine reptile fossils from the area raised the profile of the find even further. Quite serendipitously, the specimen had only been exposed due to the lowering of the water levels of one of the reserve’s lagoons for maintenance work. However, due to the needs of the wildlife and the natural setting of the reserve, the water levels had to be raised again on February 19.
In a race against time, on Monday 15 February a small team of experts (myself, Dr Mark Evans, Nigel Larkin and Darren Withers) visited the site to examine the series of bones and assess how much more of the specimen was preserved. Incredibly, by the end of the day we had revealed what appeared to be a practically complete, very large ichthyosaur. However, due to the damp, wintery conditions, the fact the skeleton was substantially more complete and larger than we had anticipated, and the need for the nature reserve to imminently raise the water levels for the wildlife, it was agreed that the skeleton should be carefully reburied to be excavated when conditions were more favourable.
While patiently waiting for a suitable point in the year for the water levels to be lowered in the lagoon again, without adversely affecting the wildlife, working in collaboration with Nigel Larkin (a specialist palaeontological conservator with experience in collecting and conserving large marine reptiles) and Dr Mark Evans (a marine reptile expert and local palaeontologist from the British Antarctic Survey and University of Leicester), I put together a detailed dig schedule outlining a plan to excavate the “Rutland Ichthyosaur” later in the year. This included formulating a competent team of experienced palaeontologists and volunteers who would assist in the excavation and recovery of the specimen. This included vertebrate palaeontologist Dr Emma Nicholls who is the Senior Curator of Natural Sciences at the Horniman Museum and Gardens in London, Emily Swaby who is currently a PhD student at the Open University and who completed her master’s degree with me on ichthyosaurs (which we transformed into a published paper), along with members of the local Peterborough Geological and Palaeontological Group, who have a wealth of experience excavating fossil marine reptiles.
Due to the pandemic, and the site presenting challenging, muddy terrain covered in bird droppings, we had to go through a lengthy risk assessment process and would have to abide by the various rules and regulations set by Anglian Water and Leicestershire and Rutland Wildlife Trust. This also meant that we would be restricted in relation to the number of people who could be on the dig each day. Everyone involved had to sign a NDA which meant that we could not tell anyone what we were doing. During this timeframe, to keep things moving towards an excavation date, we had various meetings with the landowners, Anglian Water, as well as staff from Rutland Water Nature Reserve and Rutland County Council, who were all supportive of the discovery and excavation plans going forward. The excavation date was eventually set for 23rd to 29th August, when the least amount of disruption would be caused to the running of the nature reserve.
The excavation commenced according to schedule but as soon as the site was cleaned up and the skeleton was fully exposed it became obvious that this discovery was far more scientifically important and interesting than even we had anticipated. The specimen was larger and more complete than expected, and significantly had some really interesting taphonomic information preserved. As a result, it would have been impossible to achieve our objectives in the originally planned seven-day-dig whilst preserving all the information as fully as possible. After discussions with members of staff from the nature reserve and Anglian Water, we were kindly granted permission to extend the length of the excavation. To maximise our time, we worked long days, from near sunrise to sunset. In total, the dig took just over twice as long as initially planned, at 14.5 calendar days (where we usually worked 12 hours each day), and this was spread over three weeks.
What we had uncovered was the largest ichthyosaur skeleton ever found in Britain. A real Jurassic giant, measuring a staggering 10 metres long. The skeleton is also practically complete, almost fully articulated right down to the penny-sized vertebrae at the very tip of the tail and includes a huge, nearly 2-metre-long skull. It is probably also the first time this ichthyosaur species has definitely been discovered in the UK. A truly remarkable discovery.
The taphonomy of the skeleton – what happened to the animal after it died – is especially interesting. The ichthyosaur is lying on its back and side, somewhat ‘belly up’, with the skull distorted in such a way that we are given an intriguing three-dimensional view of various parts, including the left and right lower jaw and braincase elements. The skeleton is almost fully articulated, and although parts of the vertebral column, along with both forefins and one of the hindfins have become slightly detached, these remain associated. The left hindfin, however, is beautifully preserved, with most of the fin fully intact. Some of the elements at the distal end of this hindfin are scattered and this may be the result of scavenging. In support of this assertion, other parts of the skeleton seem to show scavenging also. For example, some isolated ichthyosaur teeth (likely to be from another individual) were found in direct association with some of the disarticulated parts of the skeleton, further implying some form of scavenging and thus cannibalism.
An important part of the excavation was to understand the ancient environment in which the ichthyosaur lived. Whilst removing the matrix from the bones, the team were careful to look out for and collect additional fossils in the associated matrix, which included numerous molluscs, principally ammonites and belemnites. In some cases, specimens lay directly on the bones. We also collected a wide variety of fossils found in the general vicinity, again of ammonites and belemnites, but also bivalves, nautili, gastropods, and several ichthyosaur vertebrae from other individuals, which further highlights the significance of the site and provides an insight into the ancient life of this small corner of Rutland. It is also important to mention that two partial, but much smaller, ichthyosaur skeletons were found in the 1970’s when Rutland Water was being constructed.
Of the few large ichthyosaur skeletons previously discovered in the UK, those collected historically have poorly recorded information, with details of where they were found and their age often completely unknown. Based on previous studies of the geology of Rutland Water, along with the index fossils found during the excavation, we know that this site dates from approximately 180 million years ago, from the Early Jurassic Toarcian Stage of the Whitby Mudstone Formation. However, to determine exactly which stratigraphic horizon the specimen comes from and therefore date the site more specifically, various samples of matrix were also collected to study microfossils. This part of the project was led by Dr Ian Boomer from the University of Birmingham. Analysing the samples, Dr Boomer discovered numerous microfossils which pinpointed the exact horizon in which the ichthyosaur is preserved and determined the age to be between 181.5 and 182 million years old.
To ensure that every last detail of the ichthyosaur was recorded prior to it being removed from the ground, a traditional hand-drawn detailed plan was recorded on graph paper at a 1:10 scale, but also team member Steven Dey of ThinkSee3D took thousands of photographs of the fully exposed skeleton to create a high-definition 3D digital model, through a technique called photogrammetry. You can see it here on Sketchfab. Having an accurate photogrammetry model was vitally important for the excavation. Not only does this technique provide a virtual record of the fossil and its taphonomy whilst still lying undisturbed in the ground, but it also means that the information can be utilised as part of the research in a publication and to enhance the eventual museum display and educational outputs. The digital model will also act as an important reference when the skeleton is being removed from the plaster field jackets and cleaned and prepared.
The skeleton was preserved in relatively soft Jurassic clay, with some nodularisation around the pectoral girdle. Whilst many of the vertebrae were in good condition, the skull, lower jaw, ribs, and some limb bones were found to be fragile and heavily cracked. Because of the fragile nature of many of the bones, and because we wanted to preserve the integrity of the interesting taphonomic information, we decided that once the skeleton had been carefully measured, recorded, photographed and scanned in detail, the whole skeleton should be lifted in a series of plaster jackets strengthened with wooden splints. This is the main reason that the excavation took longer than planned. Another reason is that the weather was unseasonably cold and damp: together with being consistently downwind from a large body of water, this meant that the plaster took a very long time to set, much longer than normal. Fortunately, towards the end of the excavation we enjoyed several warm days, and this helped the largest field jackets to set properly.
To highlight the great size of this ichthyosaur, the block containing the massive skull weighs just under a tonne, and the main body block weighs about a tonne and a half (in each case this comprises the fossil, the Jurassic clay in which it lies, and the encasing plaster of Paris and wooden splints). Nigel Larkin was responsible for leading on the jacketing and lifting of all the sections of the skeleton and did an incredible job throughout the excavation ensuring the specimen’s safety at all times. In all, it was a very complex operation to uncover, record, and collect this important specimen safely, in conditions that were often challenging. It involved all sorts of specialisms, materials, tools and techniques but it was completed in just three weeks.
To capture the excavation and to see the story unfold, the entire dig was recorded on camera, for future generations to enjoy. Two teams were involved in this process, one to highlight the amazing find for a TV show, as part of the BBC’s “Digging for Britain” series, and the other to capture the entire process from beginning to end, to be used by the landowners, nature reserve and eventual exhibition and museum archive.
The excavation was only phase one. Next, we will be applying for funding for phase two: to clean, conserve and prepare the entire skeleton for research and display. This work, to remove the plaster field jackets, provide adequate support for the specimen and reveal the bones as fully as possible will take at least 18 months to complete. Once fully prepared, it will give the team an opportunity to study the skeleton in more detail, to ascertain as much information as possible and formulate several research papers. Based on our assessment in the field, our preliminary analysis suggests that the ichthyosaur is probably an example of the Early Jurassic apex predator, Temnodontosaurus trigonodon, a species that is well-known from similar aged sites in Germany but has yet to be formally recognised in Britain. If this is the German taxon then it would extend the geographic range of the species and be the first confirmed definite report in the UK. The final phase of this project is to create an exhibition dedicated to the discovery of the “Rutland Ichthyosaur” and the ensuing research, which will go on public display in a local, accredited institution. As the specimen will remain local it will provide local people with a sense of pride and ownership, inspire all who see it and help to educate people about their local geology and the hidden history beneath their feet.
This is a sensational fossil find. Britain is the birthplace of ichthyosaurs, their fossils having been unearthed and scientifically studied here for over 200 years, with the first scientific finds dating back to Mary Anning and her early discoveries in Lyme Regis, along the Jurassic Coast. Yet, despite the thousands of ichthyosaurs discovered in Britain, none of them are both this large and complete. In fact, not only does this specimen represent the largest ichthyosaur skeleton ever found in Britain, it is also the most complete skeleton of a large prehistoric reptile ever discovered in the UK. And yes, that includes dinosaurs! It is a truly unprecedented discovery and one of the greatest finds in British palaeontological history.
I would like to take this opportunity to thank the Palaeontographical Society for providing essential financial support that helped to save this specimen for science.
A massive thank you to each of the team members involved: Nigel Larkin (University of Reading), Dr Mark Evans (British Antarctic Survey and University of Leicester), Dr Emma Nicholls (Horniman Museum), Darren Withers, David Savory and Mick Beeson (of the Peterborough Geological and Palaeontological Group), Emily Swaby (The Open University), Paul de la Salle (The Etches Collection), Carol Skiggs, Steve Dey (ThinkSee3D), Phil Rye, Dr Ian Boomer (University of Birmingham), Dr Tom Harvey (University of Leicester) and Matthew and Dawn Butler. Huge thanks also to various people at Anglian Water, Rutland Water, Leicestershire and Rutland Wildlife Trust, and Rutland County Council, especially Joe Davis, Joelle Woolley, Jake Williams, Claire Hornsby, Robert Clayton and Ari Volanakis for all of their hard work and enthusiasm in helping to make this happen.
This is an excellent example of how professional palaeontologists can work together with the public and a variety of organisations for the good of science, with this scientifically significant specimen being rescued and secured for future generations to enjoy and researchers to study.
Dr Dean Lomax