Tardigrade trapped in amber is a never-before-seen species
Scientists discovered an incredibly rare fossil suspended in 16 million-year-old amber: a never-before-seen species of tardigrade, a pudgy, aquatic critter that rarely crops up in the fossil record.
Modern-day tardigrades, also known as water bears or moss piglets, can be found in just about any environment with liquid water, from the depths of the ocean to the thin water films that coat terrestrial mosses. The tiny creatures are famous for their survival skills; by expelling most water from their bodies and drastically slowing their metabolism, tardigrades enter a state akin to suspended animation in which they can withstand extreme temperatures, pressure and radiation.
But although tardigrades are nearly impossible to destroy when alive, their small size and lack of hard tissue mean that very few tardigrade fossils have ever been discovered — only three, to be exact. The species of two of these fossils, found in Canada and New Jersey, have been formally named; the other, found in West Siberia, remains unnamed.
Related: 8 reasons why we love tardigrades
But now, in a new study published Tuesday (Oct. 5) in the journal Proceedings of the Royal Society B: Biological Sciences, scientists have introduced a newfound species of tardigrade that they discovered in amber from the Dominican Republic. The fossil dates to the Miocene epoch (23 million to 5.3 million years ago) and is so well preserved that the team was able to place the newfound water bear, named Paradoryphoribius chronocaribbeus, within the tardigrade “tree of life.”
“There’s really only two clear tardigrades from the fossil record,” referencing the two fossils whose species are known, “so this is really exciting to find a third,” said Frank Smith, an evolutionary developmental biologist and assistant professor at the University of North Florida who was not involved in the new study. And thanks to the quality of the fossil, the researchers were able to apply the same techniques used to identify living tardigrades, which helped the team determine how the newfound species relates to modern-day water bears, Smith said.
The tardigrade measures less than 0.02 inches (0.6 millimeters) long, so how did the researchers spot it? It was really a matter of luck, first author Marc Mapalo, a doctoral student in the Department of Organismic and Evolutionary Biology at Harvard University, told Live Science.
Mapalo’s collaborators at the New Jersey Institute of Technology initially acquired the amber to look for ants captured in the material; the team, led by evolutionary biologist Phillip Barden, studies the evolution of social insects such as ants and termites.
“They’d had the amber for months, but they’d only been looking at ants,” Mapalo said. But at some point, a sharp-eyed lab member noticed a stumpy, caterpillar-like shape with teeny, clawed legs jutting out of its underside. Lo and behold, they’d found a tardigrade floating in the amber, alongside three ants, a beetle and a flower.
“It…
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