It is also thought to be the first of its particular species — Temnodontosaurus trigonodon — to be found in Britain.
Marine reptiles that lived alongside the dinosaurs, ichthyosaurs resembled dolphins in body shape. They became extinct around 90 million years ago, after first appearing 250 million years ago.
The ichthyosaur was first uncovered in February last year in the Rutland Water Nature Reserve by Joe Davis, a conservation team leader from Leicestershire and Rutland Wildlife Trust, which operates the nature reserve in partnership with owner Anglian Water.
Then followed a large-scale excavation in August and September by a team of paleontologists, led by Dean Lomax, an ichthyosaur expert and current visiting scientist at the University of Manchester.
“The size and the completeness together is what makes it truly exceptional,” Lomax told CNN, adding that previous finds of ichthyosaurs in the UK had been “nowhere near as complete and as large as this.”
Lomax said it was the most complete large specimen — which he classified as being 10 or more meters in length — found globally. He said it was “a really fantastic discovery” as well as, for him, “a real career highlight.”
“This was a top of the food chain, apex predator,” he told CNN of the discovery. “So this would have been dining on other ichthyosaurs, it would have been eating large fish, it would have eaten, if could catch them, squids as well.”
However, Lomax said the discovery was the “tip of the iceberg,” with much left to uncover of the specimen after chunks of rock have been cleared away, with the possibility that the ichthyosaur’s last meal may have been preserved or even that the reptile could have been pregnant.
“It was just mind blowing,” Regan Harris, a spokeswoman for Anglian Water, told CNN. “I mean, you kind of couldn’t really believe your eyes when you were looking at it in front of you. But yeah, incredible.”
Harris, who was onsite for the excavation, said smaller ichthyosaurs had previously been found on the Rutland Water site, but the “sheer scale” and “well preserved” nature of this particular discovery made it unique.
Paul Barrett, Merit Researcher in the Earth Sciences Vertebrates and Anthropology Palaeobiology department at the Natural History Museum in London, said the Rutland ichthyosaur was “probably one of the largest fossil reptiles ever found, including dinosaurs.” Barrett was not involved in the find.
“It’s genuinely a really impressive, spectacular object,” Barrett told CNN. “Certainly one of the most impressive marine fossil discoveries from the UK that I can remember at least in the last 20 to 30 years or so.”
Barrett, whose work has covered dinosaurs and other extinct reptiles including ichthyosaurs, said the find confirmed the “cosmopolitanism” of the species, which had previously mainly been known in Germany.
The specimen is currently being treated by a specialist paleontological conservator, a process that will take 12-18 months. Following this, Harris said, the aim will be to put it on public display.
“We’re very proud of it, and I know the local community are as well,” she told CNN. “We very much want to bring it back home to Rutland and have it on display for people to enjoy.”
For Lomax, the lead researcher, one hope is to explore the Rutland Water site further, as six or seven vertebrae from other ichthyosaurs were also uncovered during the excavation.
He said the fact that “serendipitous things have happened to actually make this find” had not been lost on him.
“Honestly, it’s incredibly unusual,” Lomax told CNN. “Avid fossil hunters or paleontologists, they can search their entire careers and never find anything quite like this, even when you know where you’re looking.”