The head of a fearsome fossilized marine reptile found on the Jurassic Coast of Dorset, UK, is so unique that it has snapped up a world record.
At approximately 95% intact by surface area, the specimen – which has been dubbed “Sea-Rex” – represents the most complete Pliosaurus skull ever discovered.
Pliosaurs – of which the group Pliosaurus included some of the biggest examples, surpassing more than 10 m (33 ft) from nose to tail – were among the most formidable predators ever to prowl Earth’s oceans.
Indeed, they boasted the most powerful bite for a marine reptile ever, estimated at between 33,000 and 48,000 Newtons (N).
This is two to three times greater than that of the saltwater crocodile (Crocodylus porosus), which as well as being today's heaviest reptile also out-chomps all other living animals, with a crushing force of up to 16,414 N. (For context, humans typically have a top biting power of just 700 N.)
The prehistoric cranium recovered from the coastal cliffs near Kimmeridge in Dorset is just under 2 m (6 ft 6 in) in length, 0.6 m (2 ft) wide and dates back some 150 million years. Back then, this region of the planet would have been covered by more tropical waters.
While Pliosaurus crania of a similar size are not unheard of (and it's worth noting that it's believed this specimen was a juvenile and so not fully grown when it died), it’s the unprecedented condition of this one that truly sets it apart.
As well as comprising almost all its original bones – along with 130 razor-sharp teeth – it was found lying upright, essentially in its original 3D form, with the jaws still interlocked as they would have been in life.
The remains are so exceptional that it’s hoped they will help us to infer much more about not just the biology of these fairly enigmatic animals but also their behaviour and how they lived. For instance, the upper jaw is scattered with what appear to be sensory pits (similar to those seen in crocodiles today) that likely helped detect the movements of prey.
Pliosaur expert Dr Judyth Sassoon from the University of Bristol, who has been analysing the skull, told GWR: “I have studied many Kimmeridgian pliosaurs but have never seen one that is quite so well preserved as [this].
“It contains a lot of anatomical details in a single specimen that are only found partially preserved in other specimens.”
If a specimen contains clearly visible anatomical features, it can help us in two ways. Firstly, anatomical details can contribute phylogenetic information, which enables us to understand pliosaurs as an evolving group. Secondly, they can help us to understand how the animal was constructed, leading to a better understanding of its lifestyle. For example, by retaining details of its sensory apparatus, the skull can provide insights into hunting and feeding modes which not only tell us about the individual, but can be generalized to other similar pliosaurs – Dr Judyth Sassoon, University of Bristol
The superlative skull first came to light in April 2022 when amateur fossil hunter Phil Jacobs identified the tip of the snout while scouring the beach below the cliffs.
He immediately alerted local palaeontologist Dr Steve Etches to his unusual find. It was a thrilling moment as Dr Etches can attest, recalling his reaction to the news: “What first went through my head was not only how amazing the discovery was but the realization that the skull was hidden somewhere in the cliff and the tantalizing excitement of the possibility of what [else] was there…”
After obtaining permissions to embark on a dig and assembling an experienced team, the excavation project finally got underway in August. Having used a drone to pinpoint where the snout-tip most likely had fallen from, they now faced the daunting challenge of trying to unearth the remaining pliosaur while hanging from ropes, some 15 m (49 ft) above the shore!
Climbing specialists Tim and Pam Fogg, who mastermind the practical logistics of filming in difficult locations such as canyons and caves for nature and adventure documentaries, were recruited, along with a number of other fossil experts and volunteers – not to mention some local farming equipment.
Through a combination of multidisciplinary collaboration, innovative engineering and dogged determination, the mission was a success – despite also having to contend with some wild summer storms and a ticking-down clock, as Dr Etches revealed: “Towards the end of the excavation, we were running out of time due to some of the team having to start another project.
“It was a monumental task. There was a lot to undertake and having a tight deadline created a lot of pressure. During this time, we faced the very real possibility that we might fail to extract the skull, let alone in one piece.”
Thankfully, in spite of all the challenges the skull was lifted out from its long-time cliffside abode without any major hitches. This was, of course, a moment of great relief and celebration, but the hard work was far from over.
Next came the painstaking process of carefully revealing the bones from the rock in which they had been encased for millions of years. Fortunately, this is a forte of Dr Etches, who has been collecting and restoring petrified organisms from this region since he was a boy. He is now deemed a global expert on Jurassic fossils, having been awarded a first-of-its-kind MBE for services to palaeontology and opened his very own museum.
But even a specialist like Dr Etches conceded that this was no easy task, and the full process of cleaning and restoration – including re-attaching the snapped-off section of snout – took about 10 months: “It was very demanding,” he acknowledged.
“The skull was left in storage for a few months and that resulted in the drying and subsequent shrinkage of the mudstone that contained the skull. This broke a lot of the bones, some of which shifted during the transportation and the up-righting.”
The dramatic story was the subject of a BBC documentary aired in January 2024, hosted by Sir David Attenborough (UK). Even after 70 years in this game, the reaction of the longest-serving TV naturalist was proof that exceptional finds like this still have the ability to amaze him.
“…although I was aware of the tip that was first discovered, I hadn’t fully appreciated how big the whole head would be – and it’s enormous. So sheer scale was what first impressed me,” Attenborough revealed.
“The thing about the skull is that it’s not only by far the most informative part of the body, it is by far the most delicate too. And it’s the detail, and that is so rare to find it. And this is as near perfect as it can possibly get.”
At the start of 2024, the restored skull was put on public display at the Etches Collection in Kimmeridge, close to where it was found. The museum has now launched a fundraiser as they seek to return to the site to try and uncover the rest of the body.
Dr Etches urged would-be donors to spare what they can: “The excavation of the remaining pliosaur body is a race against time and nature… especially since we could lose important pieces of the specimen due to rapid cliff erosion.
“Any help that people can provide towards this unique fundraising opportunity, where you will play an incredible part in making palaeontological history, would be truly grateful.”
If successful, who knows, Guinness World Records may soon be looking into another record for the most complete Pliosaurus skeleton...
As Dr Sassoon surmised: “If the rest of the skeleton were to be found intact, it could potentially be the most unique pliosaur specimen anywhere in the world.”
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