A new species of large plant-eating dinosaur that roamed the Isle of Wight about 125m years ago has been identified.
The specimen, which has 149 bones in total, is the most complete dinosaur discovered in the UK in a century, researchers said.
Comptonatus chasei is named after the late fossil hunter Nick Chase and the place where it was found, the cliffs of Compton Bay. It weighed as much as an African elephant and belongs to a group of herbivorous dinosaurs known as iguanodontians, bulky creatures often described by palaeontologists as the “cows of the Cretaceous period [145m-66m years ago]”.
“This really is a remarkable find,” said Dr Jeremy Lockwood, a retired GP and scientific associate at the Natural History Museum, who helped with the dinosaur’s excavation and spent years studying the bones of the skeleton.
“It helps us understand more about the different types of dinosaurs that lived in England in the early Cretaceous. This adds to recent research that shows that Wessex was one of the world’s most diverse ecosystems.
“This animal would have been around a tonne (1,000kg), about the size of a large male American bison. Evidence from fossil footprints found nearby shows it was likely to be a herding animal, so possibly large herds of these heavy dinosaurs may have been thundering around if spooked by predators on the floodplains over 120m years ago.”
For the study, published in the Journal of Systematic Palaeontology, the researchers analysed every part of the fossil, including skull, teeth, spine and leg bones, as well as a pubic hip bone “about the size of a dinner plate”.
Lockwood said it was unclear why the hip bone, found at the base of the abdomen, was so big, but added: “It [the bone] was probably for muscle attachments, which might mean its mode of locomotion was a bit different, or it could have been to support the stomach contents more effectively, or even have been involved in how the animal breathed, but all of these theories are somewhat speculative.”
When Comptonatus was discovered, the specimen was thought to be a different type of dinosaur called Mantellisaurus, three-toed plant-eaters that lived in Britain more than 120m years ago.
But Lockwood said that Comptonatus differed from Mantellisaurus because of the “unique features in its skull, teeth and other parts of its body”.
He said: “Its lower jaw has a straight bottom edge, whereas most iguanodontians have a jaw that curves downwards.”
Dr Susannah Maidment, a senior researcher and palaeontologist at the Natural History Museum, said Comptonatus demonstrated the fast rates of evolution in iguandontian dinosaurs during that time period.
The work could help researchers understand how ecosystems recovered after an extinction event at the end of the Jurassic period (200-149m years ago), she added.
Comptonatus was discovered in 2013 by Chase, who died of cancer just before the Covid-19 pandemic. It took several years for the specimen to be prepared for analysis by Lockwood and his colleagues.
Lockwood said: “Nick had a phenomenal nose for finding dinosaur bones. He collected fossils daily in all weathers and donated them to museums. I was hoping we’d spend our dotage collecting together as we were of similar ages, but sadly that wasn’t to be the case.
“Despite his many wonderful discoveries over the years, including the most complete Iguanodon skull ever found in Britain, this is the first dinosaur to be named after him. It leaves me with a mixture of excitement at having been able to deal with such a rare specimen and also a sense of relief.”
Eight extinct species from the Isle of Wight have been named in the past five years, which Lockwood said showed that the Isle of Wight and nearby areas may have once had one of the world’s most diverse ecosystems.
The Comptonatus specimen is now part of the collection at the Dinosaur Isle museum in Sandown on the Isle of Wight.
Dr Martin Munt, a curator at the museum, said: “Most of Nick’s most important finds have remained on the island – a lasting legacy. We can look forward to many more new types of prehistoric creatures being discovered from the island’s cliffs and collection.”
