Cymbospondylus duelferi: 246M-Year-Old Fossil of Pregnant Ichthyosaur Found in Nevada

Tuesday, June 2, 2020

An artist's impression of a ichthyosaur reptile as it existed during the Jurassic period, 251 million to 145.5 million years ago

A 246 million-year-old extinct marine reptile that died with its unborn offspring still in its womb has been identified as a new species. 

Fossilised remains of the pregnant ichthyosaur, christened ‘Martina’ by the scientists, were found in a small mountain range in Nevada.  

The creature’s teeth, each about an inch in length, would have helped her tear up prey such as squid or fish in the sea that covered what is now the Western US state.

The 12-foot-long Martina is a species of ichthyosaur that hasn’t been found anywhere else, and has been given the scientific name Cymbospondylus duelferi

‘She was a pretty fierce lady,’ said Professor Martin Sander, a paleontologist at the University of Bonn, Germany.

Skull of the new Cymbospondylus (A and B) and its teeth (G). The preserved right half of the skull is still articulated with the right lower jaw. The left side of the skull and left lower jaw are not preserved. The tip of the long and narrow snout was lost to weathering

‘In Nevada you see this incredible explosion of ichthyosaurs. 

‘It is an incredible place and there is new stuff coming out all the time – everything we touch, new stuff is coming out of it.’   

At about 12 feet (3.6 meters) long she was smaller than other ichthyosaurs, some of which are as large as 60 feet (18 meters).

Despite her smaller body, Martina’s teeth were larger than expected for an ichthyosaur of similar size. 

Sander found the remains of Martina at an excavation site in the Augusta Mountains, 150 miles (241 kilometers) east of Reno, back in October 2011.

The German palaeontologist had been working summers in Nevada for 20 years by that point and he and his team were nearing the end of a two-week expedition in an ichthyosaur hotspot.   

Generally, when an excavation team packs up and leaves for the season, they know it might be months – or even years – before they return.

So Sander made the decision to take another last-minute trip around the site before they packed up and left, which is when he came across Martina.

‘The trick is you have to know what you are looking for,’ said Sander, who described that final stroll as ‘wandering around in the field’.

At an outcropping around 6,000 feet (1,828 meters) in elevation he spotted what appeared to be fossilised remains of an ichthyosaur spine. 

Further, there was evidence the large, prehistoric, swimming reptile had been pregnant when it died, likely with three offspring. 

‘I found it and realised pretty quickly what I was looking at,’ Sander said.

Sander found the remains of Martina at an excavation site in the Augusta Mountains, 150 miles (241 kilometers) east of Reno

The next day, with cold and snow closing in, the team packed up the exposed fossils for further research. 

They returned in 2014 and excavated the rest of the area and only now, six years later, they have published their findings in the Journal of Systematic Palaeontology.

The fetuses are, on average 68 per cent smaller than a single vertebrae in the medium-sized mother’s back, the team estimate. 

Cymbospondylus duelferi, from the early Triassic period, shows how quickly life evolved following the Permian-Triassic extinction event 252 million years ago, which is thought to have wiped out as many as 96 per cent of the world’s species. 

That ichthyosaurs of immense size and diversity are found dating back to a few million years later suggests the animals evolved relatively quickly.

‘The cool thing about it is they just diversified crazily fast,’ Sander said. 

Some of the earliest Ichthyosaur ancestors are thought to have ventured out onto land to lay eggs, but they later adapted to give birth to live offspring, meaning they could remain in the sea at all times. 

It’s much like the advantage a whale or dolphin has over a sea turtle – while the former give a live birth, the sea turtle is exposed, along with offspring, to danger by having to leave the water to lay eggs on shore.

‘Most of the reptiles that returned to the sea, they all evolved this ability from egg laying to giving birth to live young,’ Sander said. 

Martina is the second-oldest specimen of a pregnant ichthyosaur, after a 249-million-year-old specimen found in China.

She’s also one of two major ichthyosaur findings at the location in the Augusta Mountains.

Cymbospondylus has been interpreted as a pregnant female with a minimum number of three fetuses preserved

The other finding hasn’t yet been published in an academic journal, but it involves an ichthyosaur fossil Sander refers to as ‘the giant skull’, which may even prove the more significant of the two discoveries.    

While both Martina and the giant skull are exciting to researchers like Sander, they’ve also captured the imagination of people like craft brewer Tom Young, a former geologist and founder of Great Basin Brewing in Reno. 

It was his beer truck that researchers used to haul the giant skull from the Augusta Mountains to the Los Angeles Museum of Natural History.

Great Basin Brewing brews the Ichthyosaur, or ‘Icky’, IPA, described as a highly-evolved brew’.

Young said the company’s mission is to popularise paleontology in Nevada with help from beer. 

‘It is so important we preserve this and study these things to show where we are today and how we got here,’ he said. 

‘You marvel as a human and realise the importance of our being here now, but at the same time you are looking at us as part of this much larger, huge universe.’

Young has contributed thousands of dollars, and plenty of beer, to the research efforts and has hosted brewery fundraisers for members of the public who want to hear from the scientists.

The team said they’d like to see the state develop a repository for keeping ichthyosaur fossils recovered from public land.

Nevada’s Berlin-Ichthyosaur State Park retains fossils that are on display as they were found. 

But many significant finds are trucked to Berkeley or Los Angeles where there are repositories that meet federal standards.

‘It should give Nevada some great pride we have some the coolest and biggest and meanest things to evolve on Earth here in our backyard,’ Young said. 

Published in Science / Source: