'Once-In-A-Generation Event': New Fossil Tardigrade Species Discovered In 16-Million-Year-Old Amber

A fossil that belongs to a new tardigrade species and genus has been discovered in Dominican amber. It is only the third tardigrade amber fossil to be named and described to date.

Tardigrades are famous for being able to withstand extreme conditions -- from being frozen to being hit with lethal doses of UV radiation. But apart from being exceptionally hardy creatures, tardigrades are also quite expansive in their range as they are found in all continents and in different environments, Harvard University noted in a news release. They have also been around for quite a long time.

"What is so remarkable is that tardigrades are a ubiquitous ancient lineage that has seen it all on Earth, from the fall of the dinosaurs to the rise of terrestrial colonization of plants," New Jersey Institute of Technology's (NJIT) Phil Barden, senior author of a new study published in Proceedings of the Royal Society B, said in the NJIT news release. "Yet, they are like a ghost lineage for paleontologists with almost no fossil record."

In their new study, the researchers described their discovery of a new modern-looking tardigrade species found in a 16-million-year-old Dominican amber from the Miocene era. It is only the third amber fossil tardigrade that's "fully described and formally named to date," Harvard University noted. The other two, both of which were from Cretaceous amber in North America, are the Milnesium swolenskyi and Beorn leggi.

Now called the Paradoryphoribius chronocaribbeus, the specimen is just about half a millimeter small and is the first fossil representative of the living tardigrade "superfamily" Isohypsibioidea. It is so small that it "wasn't spotted for months," Barden said, and the researchers had to use confocal laser microscopy to fully examine the specimen.

Through this method, the researchers were able to see some important characteristics of the species, including its claws and buccal apparatus. They also found that though it looks quite like the modern "water bears" we know today, it is actually so unique that the researchers determined it to be the first representative of a new genus.

"Even though externally it looked like a modern tardigrade, with confocal laser microscopy we could see it had this unique foregut organization that warranted for us to erect a new genus within this extant group of tardigrade superfamilies," Harvard University's Marc A. Mapalo, study lead author, said in the university news release. "Paradoryphoribius is the only genus that has this specific unique character arrangement in the superfamily Isohypsibioidea."

"Not only does this allow us to place this tardigrade in a new genus, but we can now explore evolutionary changes this group of organisms experienced over millions of years," he added in the NJIT new release.

Calling this a "once-in-a-generation event," Barden noted how the discovery shows how scientists are "just scratching the surface" in the understanding of tardigrade communities.

"This study provides a reminder that, for as little as we may have in the way of tardigrade fossils, we also know very little about the living species on our planet today," Barden said.