Scientists find prehistoric crab trapped in amber for 100 million years

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Scientists have discovered the oldest crab ever trapped in amber for 100 million years.

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It dates back to the era of the dinosaurs – and a ‘missing link’ in evolution.

The tiny crustaceans are thought to be the ancestors of today’s red crabs – which migrate to the oceans in their millions to breed.


Its body is perfectly preserved – its claws, shell, bulging eyes and even gills.

Like fish, crabs also use respiratory organs to absorb oxygen from the water.

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Lead author Dr Xavier Luk from Harvard University, Boston, said: “The sample is fantastic, it’s one of a kind.

“It’s completely full and not missing a single body hair, which is remarkable.”

It is named as Kretapara Athanata – which translates as ‘the immortal soul of clouds and water’.

It is the most intact crab in the fossil record. It lived both on land and in the sea.

Dr Luke said: “The more we studied it, the more we realized that this animal was very special in many ways.”

Cretapara is remarkably modern in appearance – superficially resembling some of the shoreline descendants found today.

Its penetration into the sticky tree resin sheds fresh light on the development of crabs. Most looked quite different during the mid-Cretaceous era.

Well developed gills indicate an aquatic or semi-aquatic lifestyle. Crabs in amber are rare.

They have conquered land and sea at least 12 times since the dinosaurs disappeared 66 million years ago.

In doing so their gills evolved to incorporate lung-like tissue, which allowed them to breathe both in and out of water.

But Cretapara did not have lung tissue – indicating that the animal was not entirely on land.

Dr Luke said: “We were now dealing with an animal that is probably not marine, but also not entirely terrestrial.

“In the fossil record, non-marine crabs evolved 50 million years ago, but this animal is twice that age.”

Family tree modeling showed that true crab-looking forms emerged in the most recent common ancestor, more than 100 million years ago.

Cretapara bridges the gap – and confirms that they did indeed invade land and fresh water during the dinosaurs, rather than the mammal age.

The discovery greatly advances the evolution of non-marine crabs in time.

Measuring just one-fifth of an inch wide, Cretapara was a juvenile freshwater or amphibian species.

It may be a semi-terrestrial animal migrating from water to land.

The phenomenon has been compared to the iconic modern red crabs, where land-dwelling mother crabs leave their young in the sea.

They later emerge out of the water back to Christmas Island in the Indian Ocean.

Cretapara, described in Science Advances, could also have been a tree-climber—like a living group of tropical land descendants.

Known as the Sesarmidae, they first appeared during the Miocene 15 million years ago.

Dr Luke said: “These Miocene crabs are actually modern looking crabs and, as their extant relatives, they live in trees in small ponds of water.

“These arboreal crabs may be trapped in tree resin today, but would that explain why Cretapara is preserved in amber?”

The fossil crab was among a batch of dull and unpolished amber pieces collected by local miners and sold at a jewelry market in China six years ago.

This crab is a new branch in the ‘tree of life’ – rivaled only in completeness by the mysterious 95 million year old Calichimaera perplexa.

A very distant relative has been nicknamed the ‘platypus of the crab world’.

The surprising preservation of Calichimaera as a stone fossil consisted of soft tissue and delicate parts that are rarely fossilized.

Cretapasara and Calichimaera lived during the ‘Cretaceous Crab Revolution’.

This was a period when crabs diversified around the world and led to the emergence of the first modern groups while many others disappeared.

They first appear in the fossil record 200 million years ago.

Amber has a unique ability to evoke ancient plants and animals thanks to its transparency – opening a window into the past.

Cretapara joins a list of specimens, including the feathered tails of dinosaurs, that are invaluable for learning about the story of life on Earth.



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