New fossil uncovers a ‘sea monster’ of epic proportions

One of the largest fossils of its kind has been uncovered in an impressive discovery in Antarctica. It has shown us that the marine world before the extinction of the dinosaurs may have been even more weird and wonderful than it is today.

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A concept image of the new unamed elasmosaurus species

On a small desolate island off the coast of the Antarctic Peninsula researchers have uncovered an enormous fossil of a new species, which could have been one of the largest creatures swimming around at the time. The unnamed elasmosaurus species may have weighed as much as 15 tonnes and has been compared to a ‘sea monster’ due to its size and reptilian form. Dating back to the end of the cretaceous period the new species met its end alongside the dinosaurs shortly after its emergence into the world. It is another indication that life in the oceans millions of years ago was vastly different to what it is today. But what was the elasmosaurus really like and what sort of ‘monsters’ could have been swimming around today had it survived its extinction?

Finding the fossil

The discovery of the new elasmosaur has been a long time in the making. Researcher and explorer William Zinsmeister first identified the site of the discovery as far back as 1989. That location was Seymour Island, a small desolate island off the coast of the Antarctic Peninsula. Unfortunately extreme weather conditions on the island meant uncovering its secrets required significant time and funding to plan a proper expedition. In 2012 a group from CONICET (National Scientific and Technical Research Council of Argentina) led by palaeontologist Jose O’Gorman took up the challenge. Over the next five years he and his team slowly uncovered the pieces of this massive fossil whilst simultaneously battling the fierce conditions on the island. Work could only happen for a few weeks a year when overlapping with the Argentinian Antarctic Institute expeditions in the area. Some years conditions were too severe for any work to happen at all and the team would return home empty handed. But their hard work and persistence paid off when the fossil was finally finished, almost to completion, in 2017 and returned to Argentina. The results were published in Cretaceous Research earlier this year.

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A fully completed elasmosaurus fossil, not the new species but a close relative

Extreme elasmosaur

The new species is still as of yet unnamed due to some confusion and debate as to which taxonomic bracket it belongs in. What we do know is that it belongs to a group known as the elasmosaurs which in turn are a family of the plesiosaurs who were the largest marine creatures of the day. Jose O’Gorman who led the discovery told National Geographic that “For years it was a mystery … we didn’t know if they were elasmosaurs or not, they were some kind of weird plesiosaurs that nobody knew”. The plesiosaurs are the stereotypical ‘marine dinosaurs’ with a wide stunted body, four large flippers, an elongate neck and a narrow snake like head. Elasmosaurs were the largest species of the group and were the apex predators of the day feeding on a large array of different marine life with very few competitors. The new species is now believed to be part of a genus of elasmosaurs called Aristonectes who significantly differ in size and were abundant in the southern hemisphere. But regardless of which box it fits in the unnamed species is believed to be the largest of any known plesiosaurs with a body length of 40ft and a weight anywhere between 11.8-14.8 tonnes. In comparison most of the other larger elasmosaurs come in around the 5 tonne mark.

An untimely end

Despite having a very dinosaur like appearance the new species actually only just overlapped with their land based reptilian cousins. It is believed they emerged in the late cretaceous period around 30,000 years before the extinction event that killed off over 99% of life on earth at the time. That may seem like a long time but compared to the millions of years dinosaurs roamed the earth it really isn’t. It is the best sign yet that the oceans were quite possibly the most productive and inhabited they have ever been at the time the dinosaurs were wiped out. That is because for enormous creatures like the new elasmosaurs to survive and thrive for that time there must have been much more marine life to support a much more expansive food chain. Imagine then what the ocean could have looked like today if things had gone differently. It is likely that this new species were just the first in a new line of ‘sea monsters’ that would have dominated the ocean ecosystem. It may seem like science fiction but if the rock that killed the dinosaurs was a few thousand kilometres to the side it would most likely be our new reality.

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More elasmosaurs could have popped up in the early oceans had they not been wiped out along with the dinosaurs

Uncharted territory

There are still lots of gaps in our knowledge of the marine world before the dinosaurs were killed off. It is unsurprising considering there is still so much we are learning about our ocean today let alone millions of years ago. Discoveries like this are important because they help fill in the missing pieces and show us how the world we see around us today has taken shape. Just this year the discovery of a new whale ancestor in Peru has fundamentally changed what we knew about the evolution of cetaceans. Fossil records have also shown us how all life on earth originated in the oceans and hydrothermal vents have provided the most reasonable explanation of how. Marine species also include some of the most evolutionary unchanged animals on the planet, such as sharks and octopuses. As we continue to look deeper into our oceans and the animals that live, or have lived, in them. There is no telling what we might learn and discover about ourselves.


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