Gigantic Sea Scorpions, Some Larger Than Humans, Hunted in Ancient Oceans

Let us switch back the arms of time. Just before extinction knocked dinosaurs off their pillar, before the “Terrific Dying” extinction wiped out 95 p.c of all organisms – we had the Paleozoic Period.


In the course of this age in Earth’s historical past, concerning 541 million and 252 million a long time back, arthropods (animals with exoskeletons these kinds of as insects, crustaceans, scorpions, and horseshoe crabs) had been discovering the extremes of sizing, from tiny to huge.

In truth, some Paleozoic arthropods stand for the greatest animals on Earth at the time. If you had been to choose a swim in the Paleozoic oceans, you may possibly have been lucky (or regrettable) sufficient to uncover just one of the most fearsome of these extinct arthropods: the sea scorpions, Eurypterida.

Our new study, published in Gondwana Investigation, is the most complete selection of info on these intriguing creatures that when roamed Australian waters.

400 million years old A. Eurypterus remipes fossil. (H. Zell/Wikipedia/CC BY-SA)four hundred-million-yr-previous Eurypterus remipes fossil. (H. Zell/Wikimedia/CC BY-SA)

A sight to behold

Even though Eurypterida looked broadly like scorpions (with a related physique condition, albeit constructed for swimming), they had been not. They had been a lot more like the cousins of modern scorpions.

An fantastic component of the sea scorpion evolutionary story is how they healthy into the narrative of Paleozoic gigantism.

Sea scorpions consist of the greatest maritime predators to have ever arisen in the fossil history, such as just one species thought to have been a lot more than 2.five metres very long (eight foot very long), Jaekelopterus rhenaniae. Back again then, some of these giants had been properly in the same location in their foodstuff world-wide-web as the modern great white shark.


These likely agile swimmers would have utilized their significant front limbs, armed with claws, to grab their prey, which they would then crush concerning the enamel-like buildings on their legs (known as gnathobasic spines).

Whilst we’re not certain exactly what these significant animals ate, it really is likely fish and smaller sized arthropods would have been on the menu. And if human beings had been around swimming in the sea, it’s possible us much too!

The size of the largest extinct sea scorpions, relative to a human. (Slate Weasel/Wikimedia/Modified)The sizing of the greatest extinct sea scorpions, relative to a human. (Slate Weasel/Wikimedia/Modified)

A intriguing (but murky) historical past

Australia is famous for its array of curious animals, such as exceptional modern species these kinds of as the platypus. And this uniqueness extends much into the fossil history, with sea scorpions currently being a situation in point.

But the scientific history and analyze of Australian sea scorpions has been patchy. The initial documented specimen, published in 1899, consisted of a fragmented exoskeleton portion discovered in Melbourne.

Prior to our new study examining the completeness of the group in Australia, there had been about 10 records – and only just one other endeavor to pool almost everything collectively. As these kinds of, the diversity and spread of these fossils was fairly unsure.


For us, revisiting these wonderful fossils resulted in a several outings to distinctive Australian museums. We also had specimens sent to us at the College of New England to look at in person.

This journey of paleontological discovery uncovered quite a few sea scorpion fossils than hadn’t earlier been pointed out. As a result, we now have proof of a doable six distinctive teams that existed in Australia.

Collating these specimens collectively in our most latest publication, we illustrate the Pterygotidae (the family members of sea scorpions that reached 2.five metres very long) dominated the group’s Australian fossil history. Even though this had been pointed out before, the abundance of content from distinctive spots and time intervals, primarily from Victoria, was unexpected.

Timeline of Pterygotidae (blue) and Adelophthalmidae (orange) sea scorpions. (<a href=Bricknell et al. Gondwana Researcher, 2020)” width=”seven-hundred” style=”width: a hundred%”/>Illustrations and timeline of Pterygotidae sea scorpions in blue, and Adelophthalmidae in orange. (Bricknell et al., Gondwana Researcher, 2020)

Back again to the resource

Aside from showcasing the greatest variety of Australian sea scorpions, our paper also outlines the general lack of info on these animals.

In spite of there currently being substantially fragmented content, there is only just one (largely) full specimen, Adelophthalmus waterstoni, measuring just five.7cm very long.


Long term study will include revisiting the websites where by these specimens had been at first collected, in the hope of obtaining a lot more full specimens. Not only will this support doc Australian sea scorpion species far better, it will also let for a a lot more full understanding of the environments in which they lived.

Ultimately, just one matter is obvious – there is substantially left to uncover about these titans that swam as a result of Australia’s prehistoric oceans.

The authors thank Natalie Schroeder Geoscience Australia for her support with this task.The Conversation

Russell Dean Christopher Bicknell, Article-doctoral researcher in Paleobiology , College of New England and Patrick Mark Smith, Technological Officer – Paleontology, Australian Museum.

This short article is republished from The Dialogue below a Inventive Commons license. Read through the initial short article.