University of Manchester paleontologist Dean Lomax and his colleagues have identified a new genus and species of leptonectid ichthyosaur from a fossil specimen found in Dorset, England.
A nearly complete skeleton of a dolphin-sized ichthyosaur was found near the Golden Cape in 2001 by Dorset fossil collector Chris Moore.
The specimen includes a skull with a huge eye socket and a long sword-like snout and represents a new genus and species.
The fossil dates from the Pliensbachian period of the Early Jurassic, between 193 and 184 million years ago.
“I remember the first time I saw the skeleton in 2016. I knew then that it was unusual, but I did not expect it to play such a key role in filling the gap in our understanding of the complex faunal turnover during the Pliensbachian period,” Dr Lomax said.
“This time is very important for ichthyosaurs, as several families have gone extinct and new ones have emerged, but the new species is what we might call the 'missing piece of the ichthyosaur puzzle.'
“It is more closely related to late Early Jurassic species, and its discovery helps pinpoint when the faunal transition occurred, which occurred much earlier than expected.”
“This is the first described genus of Early Jurassic ichthyosaur from this region in more than 100 years.”
Skeleton and skull Xyphodragon golden capensis. Image credit: Dean Lomax.
Named Xyphodragon golden capensisthe new ichthyosaur was about 3 m (10 ft) long and fed on fish and squid; the remains even show that these may be traces of his last meal.
“This skeleton provides important information for understanding the evolution of ichthyosaurs, but also contributes to our understanding of what life must have been like in Britain's Jurassic seas,” said Dr Erin Maxwell, an ichthyosaur expert at the State Natural History Museum Stuttgart.
“The limb bones and teeth are deformed in a way that indicates serious injury or disease while the animal was still alive, and the skull appears to have been bitten by a large predator—likely another much larger species of ichthyosaur—giving us the cause of death of this individual.”
“Life in the Mesozoic oceans was a dangerous prospect.”
The authors identified several features Xyphodragon golden capensis which have never been observed in any ichthyosaur.
The most unusual is the strange and unique bone around the nostril called the lacrimal, which has jagged bone structures.
“Thousands of complete or nearly complete ichthyosaur skeletons are known from pre- and post-Pliensbachian strata,” said Professor Judy Massar, an ichthyosaur expert at the State University of New York at Brockport.
“The two faunas are quite distinct, with no common species, although the overall ecology is similar.”
“It is clear that a major change in species diversity occurred sometime during the Pliensbachian period.”
“Xyphodragon golden capensis helps determine when the change occurred, but we still don't know why.”
study was published this month in the magazine Articles on paleontology.
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Dean R. Lomax etc.. 2025. A new ichthyosaur with a long, narrow snout illuminates complex faunal turnover during the undersampled Early Jurassic (Pliensbachian) interval. Articles on paleontology 11 (5): e70038; doi: 10.1002/spp2.70038
