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Trapped in amber: Fossilized dinosaur-era crab bridges evolutionary gap

Trapped in amber: Fossilized dinosaur-era crab bridges evolutionary gap

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Once upon a time, during the Cretaceous period, a tiny crab wandered out of the water onto land and somehow got trapped in amber, which preserved it for 100 million years. At least that’s what a team of scientists hypothesize might have happened in a new paper announcing their discovery of the oldest known modern-looking crab yet found in the fossil record. The paper was published in the journal Science Advances.

This brand new type of “true crab” (aka a brachyuran) measures just five millimeters in leg span plus has been dubbed Cretapsara athanata. The name is meant to honor the period in which the crab lived and Apsara, a South and Southeast Asian spirit of the clouds in addition to waters. “Athanatos” means “immortal, ” a sly reference to the particular fossilized crab being frozen within time.

It’s rare to find nonmarine crab fossils from this era trapped inside amber; most such amber fossils are those of insects. And typically the previously discovered crabby fossils are incomplete, usually consisting of pieces of claws. This latest find is so complete that it doesn’t seem to be missing even a single hair. The find is of particular interest because it pushes back this time frame for when nonmarine crabs crawled onto land by 25 to 50 million years—consistent with long-standing theories on often the genetic history of crabs—and offers new insight into the so-called Cretaceous Crab Revolution , when crabs diversified worldwide.

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