Brighstoneus simmondsi: Paleontologists Unearth New Species of Iguanodontian Dinosaur

Friday, November 12, 2021

Reconstruction of the head of Brighstoneus simmondsi. Image credit: John Sibbick.

A new genus and species of iguanodontian dinosaur has come to light in Isle of Wight rocks dating to the Lower Cretaceous Period.

The newly-identified dinosaur species roamed our planet during the Barremian age of the Cretaceous period, some 127 million years ago.

Scientifically named Brighstoneus simmondsi, the creature was about 8 m (26 feet) in length and weighed about 900 kg.

It belonged to Iguanodontia, a major group of ornithischian dinosaurs that originated in the Middle Jurassic epoch and became increasingly widespread and diverse during the Cretaceous period.

The partial skeleton of Brighstoneus simmondsi was recovered from the Wessex Formation of the Isle of Wight, southern England.

“Until now, iguanodontian material found from the Wealden Group on the Isle of Wight has usually been referred to as one of these two dinosaurs: with more gracile fossil bones assigned to Mantellisaurus and the larger and more robust material assigned to Iguanodon,” said Jeremy Lockwood, a Ph.D, student in the School of Environment, Geography and Geosciences at the University of Portsmouth and the Department of Earth Sciences at the Natural History Museum, London, and his colleagues.

“However, when we were examining the specimen, we came across several unique traits that distinguished it from either of these other dinosaurs.”

“For me, the number of teeth was a sign. Mantellisaurus has 23 or 24, but this has 28. It also had a bulbous nose, whereas the other species have very straight noses. Altogether, these and other small differences made it very obviously a new species.”

The discovery of Brighstoneus simmondsi suggests that there were far more iguanodontian dinosaurs in what is now the United Kingdom during the Early Cretaceous epoch than previously thought.

“We’re looking at six, maybe seven million years of deposits, and I think the genus lengths have been overestimated in the past,” Lockwood said.

“If that’s the case on the island, we could be seeing many more new species. It seems so unlikely to just have two animals being exactly the same for millions of years without change.”

“The describing of this new species shows that there is clearly a greater diversity of iguanodontian dinosaurs in the Early Cretaceous of the United Kingdom than previously realized,” said Dr. Susannah Maidment, a paleontologist in the Department of Earth Sciences at the Natural History Museum, London.

“It’s also showing that the century-old paradigm that gracile iguanodontian bones found on the island belong to Mantellisaurus and large elements belong to Iguanodon can no longer be substantiated.”

The team’s paper was published in the Journal of Systematic Palaeontology.


Jeremy A.F. Lockwood et al. A new hadrosauriform dinosaur from the Wessex Formation, Wealden Group (Early Cretaceous), of the Isle of Wight, southern England. Journal of Systematic Palaeontology, published online November 10, 2021; doi: 10.1080/14772019.2021.1978005