One of the most complete sea monsters on record had been discovered along the UK’s Jurassic Coast, being perhaps the world’s most complete reptile fossil dating back to the Pliensbachian period. The rare and impressive specimen offers unprecedented insight into a period of time we know little about, and bridges a gap in our understanding of a strange and complex faunal turnover that was occurring at the time, around 190 million years ago.
The new-to-science species is an ichthyosaur nicknamed the “Sword Dragon of Dorset”, and its scientific name is equally impressive: Xiphodracon goldencapensis. It’s estimated to have been 3 meters (9.8 feet) long in life, and was discovered by fossil collector Chris Moore, who you may remember from that enormous pliosaur skull discovery a little while back.
In most ichthyosaurs, the bones often become flattened and fairly two dimensional, but this had stayed completely in three dimensions.
Chris Moore
“I spotted a section of tail vertebrae sticking out and then covered it up and got permission to dig in and have a look at what was there,” he said. “I followed the vertebrae and which carried on, and then found the rear paddles, and it carried on going: the rib cage was there, the front paddles, and then I got to the skull.”
“I hit this hard object, which turned out to be the skull, and it was preserved in three dimensions. In most ichthyosaurs, the bones often become flattened and fairly two dimensional, but this had stayed completely in three dimensions. The skull had the two eyes either side, and then this massive, long, sword-like rostrum with hundreds of tiny needle teeth.”
Falling into toxic gloop sucks for prehistoric animals, but it’s great news for fossil fans.
Image credit: Dr Dean Lomax
That excellent preservation is a trademark of the region that used to be a shallow tropical sea that was teeming with life. As well as being home to a lot of ichthyosaurs’ favorite foods like ammonites, fish, and belemnites (hence why so many are found here), it also had a mostly anoxic seabed. That meant when animals died and sank to the bottom, they fell into poisonous mud where there was nothing to disturb their remains. A top tip if you want to become a fossil.
Moore described the discovery as “in the mists of time”, which figures given there’s been a 24-year gap between its discovery and formal identification. When asked if this was unusual, Moore said, “This is exceptionally long, but in geological time, I suppose it’s nothing.”
It helps to fill in somewhat of an ichthyosaur void during this pivotal stage in their evolution.
Dr Dean Lomax
That gap unfolded because the specimen went off to the Royal Ontario Museum, where world ichthyologist expert Dr Chris McGowan was working. For whatever reason, the specimen didn’t get written up, and after McGowan retired, fellow ichthyology specialist Dr Dean Lomax asked Moore if he could take a look into it.
Now, a new paper on the fossil has revealed that this ichthyosaur is a new-to-science species, and an incredibly rare one at that. You see, while we’ve found thousands of complete or nearly complete ichthyosaurs from before and after the Pliensbachian, we hardly have any that lived during this time.
The original specimen remains in Ontario, but Moore told me he has since found a second specimen that’s on exhibition at Charmouth Heritage Coast Centre. “We have nicknamed it Gonzo due to its buckled jaw,” he said. “A result of nose-diving into the sediments on the sea bed 190 million years ago.”
The Sword Dragon of Dorset’s impressive teeth were adapted for hunting squid and fish.
Image credit: Dr Dean Lomax
It’s a particularly critical window in our understanding of the Jurassic timeline because at this time something big was happening that led to a massive and complex turnover of Earth’s fauna and the evolution of ichthyosaurs. So, does anyone know what was driving this chaotic switch up?
“Strangely enough, we don’t,” Lomax told IFLScience. “That’s what makes this new discovery extra special, in that it helps to fill in somewhat of an ichthyosaur void during this pivotal stage in their evolution.”
The specimen will help us to lock down when this big change occurred, but it’s got plenty else to offer in the way of unique traits, and may even contain preserved stomach contents.
The fossil is the only of its kind ever discovered, and possibly the most complete reptile from this geological time period we’ve ever found.
Image credit: Dr Dean Lomax
“There’s a lot of cool features with this fossil,” said Lomax. “If I was forced to pick just a few, I’d say that the extremely long, sword-like snout and massive eye are genuinely – pun intended – eye catching.”
“Staring into its eyes and looking at the long jaws with thin, pointed teeth you can really imagine this animal in life, hunting fish and squid. I’d also say that a bone around the nostril opening, called the lacrimal, is super weird. We’ve never seen anything like this type of bone before in any ichthyosaur.”
And if strange and unique fossils are your bag, you might want to check out the two-headed prehistoric creature that’s the cover star for Lomax’s latest book, The Secret Lives Of Dinosaurs.
The study is published in the journal Papers in Palaeontology.
Source Link: 190-Million-Year-Old “Sword Dragon Of Dorset” Likely The World’s Most Complete Pliensbachian Reptile
