The “Sword Dragon” Ichthyosaur Had Huge Eyes and a Deadly Snout

Meet the “Sword Dragon,” a new species of ichthyosaur – predatory prehistoric reptiles that dominated the oceans while dinosaurs ruled the earth.

The beautifully preserved fossilized skeleton was discovered on the United Kingdom’s Jurassic Coast, near an area called Golden Cap, in 2001, and was for years in the collections of the Royal Ontario Museum in Canada.

“They knew it was something interesting,” says Dean Lomax of the University of Manchester, UK.. “They were going to work on it, but they never did.”

Lomax and his colleagues have now prepared and identified the specimen, which has a huge eye socket and a long, sword-shaped snout. The fossil also has “piercing, needle-like teeth.” [that] are really designed to feast on soft-bodied prey like squid and fish,” says Lomax. “You can get a good idea of ​​what this thing would have been like in life, basically relying on very good vision to hunt, probably in dark conditions.”

The animal would have been about 3 meters long – about the size of a common bottlenose dolphin – and would have lived during a Lower Jurassic epoch called the Pliensbachian, around 193 to 184 million years ago.

It has features that have never been seen in an ichthyosaur before, including a unique bone around the nostril called the lacrimal with tooth-like structures. “The level of three-dimensional preservation, particularly of the cranial sutures and delicate structures such as the lacrimal and prefrontal projections, is exceptional,” says Aubrey Roberts of the Natural History Museum at the University of Oslo in Norway.

A dark mass between the ribs may have been his last meal, but the team could not determine what it was.

Because of its deadly snout, researchers named the ichthyosaur Xiphodracon goldencapensisor the Sword Dragon of Golden Cap.

The specimen also reveals something about the evolution of ichthyosaurs. “The main significance of this discovery is its age,” says Roberts. At the end of the Triassic, there were huge super-predatory ichthyosaurs, like Ichthyotitan – it is estimated to be nearly 25 meters long, as big as a blue whale. But these giant reptiles disappear from the fossil record after the end-Triassic extinction, around 201.4 million years ago, which also marks the start of the Jurassic period.

The remains of a wide variety of smaller ichthyosaurs have been discovered dating back to the Jurassic, Lomax says. Many are known before the Pliensbachian and many after, but there are two very distinct types, with no common species.

“Triassic ichthyosaurs were notoriously strange,” says Neil Kelley of Vanderbilt University in Tennessee. “And their Jurassic descendants have often been considered a little more ‘identical’ in sharing a superficially similar appearance to a dolphin.”

“Xiphodracon adds another hue to the broader rainbow of ichthyosaurs,” he says, contributing to the evidence. Jurassic ichthyosaurs led a variety of lifestyles, with different diets, swimming speeds and preferred habitats.

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