‘Badass survivors of Earth’s first mass extinction’: Prague fossil discovery sheds new light on early life
A fossil of a previously unknown arthropod species, Soomaspis labutai, has been uncovered in rubble during construction work on Prague Metro’s D line. Hidden beneath the city for nearly half a billion years, the find offers new clues about how some life forms survived Earth’s first mass extinction.
So what did the creature actually look like? I put that question to Lukáš Laibl from the Geological Institute of the Czech Academy of Sciences.
"It was a tiny arthropod, an animal with jointed legs and a jointed outer covering, or exoskeleton. It was related to trilobites, which people often recognize because they have a very hard shell or carapace. This animal, however, was only soft-bodied. Its body was more similar to something like a spider, meaning it was quite soft, which makes its preservation as a fossil especially surprising. Normally, fossils preserve only hard parts like shells or bones, not soft tissues."
I understand it’s related to a species found in southern Africa. What does that tell us about its history?
"It’s interesting because Europe, including Prague, and South Africa today are almost on opposite sides of the world. But when this animal lived, during the Paleozoic, around 448 to 450 million years ago, both regions were located along the margins of a massive continent called Gondwana. This continent was mostly situated in the southern hemisphere, not far from the South Pole. Prague and South Africa were on opposite edges of this same landmass, which suggests that these animals inhabited areas all along the margins of Gondwana."
What makes this discovery so important? What does it add to what we already know about early life?
"It tells us something about how certain animals managed to survive major climatic changes. The related species from South Africa lived at the very end of the Ordovician period, after the first mass extinction. However, the specimen discovered in Prague lived before that extinction. This shows that this group of animals persisted through the event.
"We know that this extinction was caused by global cooling and glaciation, essentially an ice age. Many animals at the time, including some trilobites and other marine invertebrates, went extinct. But not these animals. They were somehow able to survive.
"We think this is because they lived in very deep marine environments and were adapted to conditions with low oxygen. Essentially, they were extremely ‘badass’ animals, able to survive in harsh environments, which likely helped them endure the mass extinction."
You said it probably lived in deep water. If we could go back in time, what would the place we now call Prague have looked like?
"It would have been covered by sea. As far as you could see, there would be a relatively deep marine environment, not as deep as an open ocean, since it was along the continental margin, but still around 100 to 200 meters deep. The water would have been quite cold because the region was located not far from the South Pole, so it wouldn’t have been ideal conditions for swimming."
Going back to the discovery itself, how was the fossil found? Was it luck or careful expert work?
"I think it was a combination of both. Fossil hunting always involves an element of luck because you never know whether a fossil will be inside the rock you split open. But it also requires expertise. You need to know where to look and which types of rocks are most promising.
"The colleague who found it, Radek Labuťa, is a very skilled and patient collector. The fossil itself is quite small, about two centimetres long, and not very distinct. Some people might not even notice it when looking directly at it. So it was definitely thanks to his experience and careful observation that he was able to recognize it and collect it."
And we should note that the species was named in honour of its discoverer…
"Exactly. His name is Radek Laubuťa and this species is called Soomaspis labutai. The previously discovered species from southern Africa belongs to the same genus but is a different species called Soomaspis splendida, named after the Soom Shale, its original locality. This newly discovered one is also classified as Sumaspis, but since it is a different species, it has been named Soomaspis labutai. "
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