A team of fossil hunters, led by collector Steve Etches, has uncovered what is thought to be the most complete Jurassic pliosaur skull ever found.

Embedded high up on a cliff in Dorset, UK, Etches and his collaborator Chris Moore spent weeks suspended on the cliff face, digging out the fossil before winching it to safety. “This is the pinnacle, really, of the things that I’ve been involved with,” Etches told New Scientist. “All I want from that is more information. The science is the thing that draws me in,” he says. “What does it show you? What does it tell you?”

“It’s very likely a new species,” says Judyth Sassoon, a leading expert on pliosaurs at the University of Bristol, UK.

Of particular interest is the fossil’s large sagittal crest, a ridge of bone at the rear of the skull. “The height of the crest might be an indication of differences between the male and female sexes,” she says.

Intriguingly, the crest may not be fully formed, suggesting the animal was still a juvenile. With its already huge 1.7-meter-long skull and the potential for growth, this adds further evidence to the idea that pliosaurs were much larger than previously thought. “We have fragmentary data from the Kimmeridgian [Era, in the late Jurassic Period] – vertebrae or paddle bones and so on – that suggest that there were larger pliosaurs around. We just haven’t found the skulls yet,” says Sassoon.

In addition, CT scans of sensory pits found on the reptile’s snout reveal that these were connected to blood vessels and sensory nerves able to detect changes in pressure, which could have helped pliosaurs hunt prey. The specimen has a complete set of teeth in an interlocking jaw, so scientists now understand more than ever about pliosaurs’ hunting and eating abilities.

The skull will go on show to the public next year at the Etches Collection in Dorset, UK, and is the subject of a new BBC documentary with David Attenborough, called Attenborough and the Giant Sea Monster, due to air on BBC One and BBC iPlayer on 1 January 2024.