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Images by Daniel Ocampo, Vencejo Films, and Javier Luque, Yale University; animation and 3D reconstruction by Alex Duque
The crab family has just grown larger and scientists suggest that we may even have to rethink our definition.
Of the hundreds of exceptionally well preserved specimens from the Middle Cretaceous period – 90 to 95 million years ago – recently discovered in Colombia and the United States, Callichimaera perplexa, a previously unknown species that combines traits of several species of extinct and living crabs and different life stages of crustaceans.
An artist impression of Callichimaera perplexa.
Elissa Martin, Yale Peabody Museum of Natural History
And this suggests that the body plan of the "real crab" has been lost and has changed again, according to paleontologist Javier Luque of Yale University in the United States, who led the international research team.
"Callichimaera perplexa is so unique and strange that it can be considered the platypus of the crab world, "he says.
"This suggests how new forms evolve and become so disparate over time.
"Usually, we think that crabs are large animals with large shells, strong claws, small eyes in long locks, and a small tail folded under the body.
"Well, Callichimaera challenge all these abominable features and force us to rethink our definition of what makes a crab a crab. "
Its small size, large compound eyes without cavities, curved claws, leg-shaped parts, apparent tail and long body are typical characteristics of pelagic crab larvae, says Luquehe, suggesting that many of its larval traits would have could be preserved and amplified. in miniaturized adults through changes in timing and rates of development.
It is a process called heterochrony, which can lead to the evolution of new body plans.
Callichimaera perplexa translates to "beautiful perplexed chimera", and Luque notes that she is cute and unusual.
The details of the new discoveries are published in an article of the journal. Progress of science.
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