Rock & Gem
The Indestructible Tardigrade Peers Out from Amber
Scientists have found a new fossil tardigrade hidden in a chuck of 16-million-year-old Miocene amber. Tardigrades, also known as water bears or moss piglets, look like plump microscopic caterpillars with claws. Found everywhere on Earth, they are almost impossible to kill. They’ve been subjected to extreme heat and radiation and have been savagely shoved into the vacuum of open space. They’ve been starved, deprived of oxygen, and forced into extreme pressures, high and low—all in the name of scientific discovery. Each time, to quote an old ad for Timex wristwatches, they take a licking and they keep on ticking!
Despite their current abundance, within the fossil record, tardigrades are exceedingly rare. Up to now, only three individual specimens of confirmed fossil tardigrades had been discovered, all in North American amber from the Cretaceous Period, or the tail end of the Age of Dinosaurs. But genetic analysis suggests the lineage extends far back in time, preceding even the Cambrian Period some 541 million years ago. It’s suggested that their fossil record is sparse because of their tiny size and non-biomineralizing bodies that are best preserved in amber, which doesn’t appear in the fossil record until the Mesozoic Era.
The latest find is barely a half-millimeter long and went unobserved by researchers who spent months studying other animals in a 16-million-year-old specimen from the Dominican Republic. It was considered just a speck of dirt until examined close-up via confocal laser microscopy. This showed it to be the first fossilized tardigrade from the Cenozoic Era. Dubbed Paradoryphoribius chronocaribbeus, it has been described in the Proceedings of the Royal Society by Marc A. Mapaolo, Javier Ortega-Hernandez (Harvard University) and colleagues, who consider tardigrades as a “ghost lineage” because of the lack of a fossil record for a creature that is so ubiquitous on today’s Earth. Luckily, that fossil record has now been increased by a factor of one!