Crab fossil looks like a bizarre mash-up of shrimp and lobster parts

April 26, 2019, 8:27 a.m.
Artistic reconstruction of Callichimaera perplexa: the 'strangest crab that has ever lived.'
Photo: Oksana Vernygora/University of Alberta

When paleontologists unearthed dozens of fossils from the Andes Mountains in Colombia, they were puzzled by the creatures' odd assortment of features. They were such a hodgepodge of different bodily structures that the scientists called the new discovery the platypus of the crab world.

"We started looking at these fossils and we found they had what looked like the eyes of a larva, the mouth of a shrimp, claws of a frog crab, and the carapace of a lobster," said lead author Javier Luque, postdoctoral paleontologist at the University of Alberta and at Yale University, in a release. "We have an idea of what a typical crab looks like — and these new fossils break all those rules."

More than 70 of the fossilized crabs were discovered in soft clay in the Andes mountain range in Colombia. The area was once a shallow coastal sea during the Cretaceous period, 90 to 95 million years ago when these animals were alive.

The researchers named the crab Callichimaera perplexa, which means "perplexing beautiful chimera." A chimera is a mythological creature that has a jumble of body features from various animals.

Researchers recovered more than 70 of the specimens in soft clay from the Andes Mountains in Colombia. Researchers recovered more than 70 of the specimens in soft clay from the Andes Mountains in Colombia. (Photo: Daniel Ocampo R./Vencejo Films)

Although the fossils were only about the size of a quarter, they were very well preserved. That allowed paleontologists to be able to see detailed features such as the crab's enormous bulging eyes and paddle-like legs.

"It's common to find novel body forms in older rocks, for instance from the Paleozoic when life was exploding into many new forms," said Luque. "This discovery, from the mid-Cretaceous, illustrates that there are still surprising discoveries of more recent, weird organisms waiting to be found, especially in the tropics. It makes you wonder 'what else is out there for us to discover?'"