Scientists discover "once-in-a-generation" fossilized water bear in 16-million-year-old amber

Microscopic eight-legged invertebrates that resemble squishy bears are among the toughest creatures on Earth, with the ability to survive decades without food, extreme temperatures and even in the vacuum of space. Fossils of the creatures are extremely rare, with only two being found in history — until now. 

In a new study published on Wednesday, researchers said they have discovered a 16-million-year-old fossil of a tardigrade, otherwise known as a water bear or moss piglet, in a piece of amber from the Dominican Republic. There have been just two fossils of the creatures ever found before, despite the invertebrates continued inhabitance of the planet.

The latest discovery is the first tardigrade fossil to be recovered from the current Cenozoic era, which began 66 million years ago, and has led to the naming of a new genus and species of tardigrade, Paradoryphoribius chronocaribbeus.

The creature is believed to be the best-imaged fossil tardigrade to date. Researchers were able to get a detailed look at the creature, seeing parts of its mouth and the needle-like claws that are 20 to 30 times finer than a human hair. 

Finding a tardigrade fossil is a once-in-a-generation event, said Phil Barden, one of the researchers, in a statement put out by the New Jersey Institute of Technology. 

"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. Yet, they are like a ghost lineage for paleontologists with almost no fossil record," he said. "Finding any tardigrade fossil remains is an exciting moment where we can empirically see their progression through Earth history." 

There are roughly 1,300 species of tardigrades that have been discovered, and according to National Geographic, they have been found in various environments on Earth: the deep ocean, sand dunes and freshwater mosses. The creatures are extremophiles, according to National Geographic, and some of the species can survive up to 30 years without food, temperatures ranging from absolute zero to above boiling, and even in the vacuum of space. 

Finding tardigrades is no easy task, as they measure at just about a half millimeter in size. Barden tweeted on Wednesday that if it weren't for his co-author Brendon Boudinot, who spotted it next to the ants they had been analyzing, he "never would have spotted it."

The discovery was so exciting that even prompted one of the study's authors, Marc Mapalo, to write a song to celebrate the moment he received an email from his principal investigator, study co-author Javier Ortega Hernandez, about the news. 

"Tardigrade amber fossils, there were only two. ...Well now, there's three," he sings while playing the keyboard. "Now that you know there's three, there's another mystery. What could this fossil be? Well, look at our paper and you'll see." 

Barden said that the discovery is just "scratching the surface" of understanding tardigrades. 

"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."