Crab from the age of dinosaurs discovered trapped in amber

Archaeologists exploring a forested region of Southeast Asia have made a discovery that will undoubtedly mark an important moment in their careers: they find the carcass of a crab trapped in a piece of amber dating back 99 million years, a period when dinosaurs were among their everyday predators. This is the first time that a preserved crab specimen dating from this period has been discovered.

And that’s not the only record this surprisingly well-preserved “time traveler” has broken, as it’s also the most complete crab fossil ever discovered, according to the researchers, who note that the specimen, Cretapsara athanata At 5 mm in length, it is remarkably similar to modern crabs.

Other researchers had reported the discovery of a lobster fossil in a piece of amber dating back 15 million years in Mexico. However, this new sample, which comes from Myanmar, fills important gaps in our understanding of the evolution of cancers, including the differences between different types of cancers. Details have been published in the magazine science progress.

‘It’s simply breathtaking’

« We are talking about exceptional preservation, that is, not a single hair is missing says Javier Luc of Harvard University. ” And despite its small size, we saw a lot of great details including the gills. It is simply breathtaking ».

Although molecular estimates put the origin of non-marine crabs at around 130 million years ago, no evidence of these crabs has been found after 75 million years so far. Since this fossil looks like a freshwater crab, it can trace the history of this group back to nearly 25 million years.

The discovery represented a new species that the team named Cretapsara. “Creta” to refer to the Cretaceous period and “Apsara” to evoke the “spirit of clouds and water” in Southeast Asian mythology, to honor the local culture and heritage. So the full name becomes C. athanata (Cretapsara athanata).

Luque and his colleagues analyzed the sample under a standard microscope and X-ray microscopy, then clearly identified the eyes, antennae, pincers, mouthparts, fine hair and eight legs of the animal, including one that detached from the body, Luque says. himself from the tree resin he had been swallowing “like a time capsule”.

Understand the evolution of cancers and similar types

Despite the small size of this specimen (barely 2 mm wide), which could be a juvenile, it has many points in common with existing cancers. ” He has this shell [coquille supérieure] Round, highly developed walking legs, large eyes, and a small tail folded under the body “He explains.” All these features are of a modern type ».

However, according to Lucky, this species also has some distinctive differences that link it to its primitive origins, including deep grooves on the shell, in contrast to the smooth tops of today’s crabs. The breast is much narrower, more like a shrimp or lobster breast than the broad breast of modern crabs. ” This is not a missing link, but a distant cousin to the current crab ‘, he explains.

The gills of the crab indicate that it lives primarily in water, unlike today’s terrestrial crabs whose lung-like air pockets share the gill body space. ” It really is a baffling and exciting point ‘ says Locke. How can an aquatic animal enter the sap of a tree in a forest? Gives food for thought ».

« The plausible explanation is that the crab was on a short land trip between two bodies of water when it got trapped. Loki’s explanation. « However, her misfortune revealed a “priceless” scientific treasure: the resin hardens quickly in water – “like super-glue,” so it rarely produces fossils.. It’s sad for the animal, but it was basically the only possibility we had of knowing that it existed ».

Luque and colleagues’ research aims to understand how some ancient species evolved into crabs, as well as evolved and diversified over time into the modern forms we see today. ” Each fossil we discover challenges our preconceptions about when and where many organisms arose, often prompting us to go back in time.s,” Luque concludes.

Resources : science progress & Harvard university