A new chapter in Britain’s prehistoric story has opened with the discovery of a striking dinosaur on the Isle of Wight. The animal, named Istiorachis macarthurae, lived around 125 million years ago and was distinguished by a remarkable sail-like structure running along its back. Unlike many paleontological breakthroughs that begin in the field, this one came from a careful re-examination of fossils already held in museum collections. Dr Jeremy Lockwood, a retired doctor now pursuing his doctorate at the University of Portsmouth, noticed that certain bones previously attributed to known iguanodontians had unusually elongated neural spines. These spines revealed the presence of a new species rather than a variant of the established ones.

The name chosen for the dinosaur reflects both its anatomy and its connection to the island’s maritime heritage. Istiorachis combines the Greek words for sail and spine, while macarthurae honors Dame Ellen MacArthur, the yachtswoman who set a world record for solo circumnavigation in 2005. Just as MacArthur captured the public imagination with her voyage, the dinosaur’s sail was almost certainly meant to capture attention within its own world. Scientists believe that such extravagant structures were unlikely to serve purely practical purposes like regulating body temperature. Instead they were probably used for visual display, helping males compete for mates or ward off rivals in a dynamic of sexual selection that can still be observed in many modern reptiles.

The find also highlights the hidden potential of museum collections. The fossils had been preserved at the Dinosaur Isle Museum, waiting for a new set of eyes to see them differently. Lockwood’s work has already transformed understanding of small iguanodontians in Britain. Where once scientists believed there were only a couple of species in the Isle of Wight’s Early Cretaceous rocks, his research has multiplied that number several times over, revealing a far more diverse ecosystem than previously imagined. Professor Susannah Maidment of the Natural History Museum has praised the work, noting that it shows just how much scientific value remains locked away in existing collections.

The Isle of Wight is already famous as one of Europe’s richest dinosaur localities. Its cliffs and quarries preserve layers of the Wealden Group, particularly the Wessex Formation, which offer glimpses of floodplains and forests teeming with life in the Early Cretaceous. Alongside predators and armored dinosaurs, these newly described iguanodontians paint a picture of a thriving community of herbivores, each species carving out its own ecological niche. Istiorachis stood about two meters tall and likely weighed close to a tonne, comparable to a modern bison. Its distinctive silhouette would have made it one of the most eye-catching inhabitants of this ancient landscape.

Far from being a mere curiosity, the discovery deepens our understanding of how evolution experimented with form and function. The sail of Istiorachis reminds us that not all adaptations are about efficiency or survival in the harshest sense. Sometimes nature produces structures for display, communication, or the subtle competitions of mating rituals. In this case, a set of unusual spines turned out to be a prehistoric banner, raised above the Isle of Wight’s floodplains more than a hundred million years ago, and now raised again in the imagination of scientists and the public alike.