Solve the mystery of the oldest crab from the age of the dinosaurs.. a fossil that is 100 million years old

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Fossils trapped in the amber of trees provide a unique snapshot of dissecting and understanding the ecology of extinct organisms.

The amber of trees is a gum secreted from the bark of extinct coniferous trees when a wound injures them so that they can protect themselves from diseases, but in very rare cases, scientists have discovered that amber contains an aquatic organism.

In a study published in the journal Science Advances, an international team of researchers described the first Cretaceous dinosaur-era crab preserved in amber.

The study used microcomputed tomography to examine and describe Kritapsara athanata, the oldest modern-looking crab (about 100 million years old) and the largest fossil crab ever discovered.

The crab fossil record extends back to the early Jurassic period, more than 200 million years ago. Unfortunately, non-marine crab fossils are scattered and largely limited to bits and pieces of animal carapace – the claws and legs found in sedimentary rocks – but the Kritapsara athanata specimen, She was absolutely amazing, she is so unique, so complete which is amazing.”

A group of scientists led by co-lead author Lida Xing, of the China University of Geosciences in Beijing, performed a CT scan of the fossil housed in the Longines Amber Museum in China.

The scans created a complete 3D reconstruction of the animal’s remarkable conservation, allowing the research team to see the animal’s entire body including delicate tissues, such as antennas and mouthparts lined with fine hairs, and discovered that the animal also had gills.

“The more we studied the fossil, the more we realized that this animal was very special in many ways,” Loki says. “The crab (Kretapsara athanata) has a remarkably modern appearance, superficially resembling some of today’s lobsters, unlike most crabs during the mid-Cretaceous period which It looked very different from modern crabs.”

“Aquatic animals are rarely preserved in the gum of trees that become amber, and the crabs that were previously found in amber belong to a living group of tropical land and tree-dwelling crabs known as (Cesarmidi) from the Miocene (15 million years ago)” “.

How, then, was the 100-million-year-old aquatic animal preserved in the amber of the tree, which is usually home to land-dwelling specimens, the researchers asked.

“Gills allow aquatic animals to breathe in water, but crabs have independently succeeded in invading land, brackish water, and freshwater at least 12 times since the age of the dinosaurs,” Loki says. Kritapsara did not have lung tissue, and only had well-developed gills indicating that the animal was not completely inhabiting the land.”

“We are now dealing with an animal that is not likely to be marine, but also not entirely terrestrial,” she says. “In the fossil record, non-marine crabs evolved 50 million years ago, but this animal is twice that age.”





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