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The first surviving crab fossils from the dinosaur era have been discovered

BingMag.com The first surviving crab fossils from the dinosaur era have been discovered

Scientists have succeeded in finding a completely healthy fossil of a dinosaur crab that is more than 100 million years old. Once caught in the Cretaceous, a small crab came out of the water and landed, but was caught in amber that preserved it until 100 million years later. This is what a group of scientists are guessing based on a perfectly healthy fossil. In a new article published in the journal Science Advances, they report the oldest modern-day crab ever discovered among fossils.

This new species of real crab (which They are also called Brachyuran (legs that are only 5 mm long and are called "Cretapsara Athanata"). This naming is a combination of the name of the period in which the crab lived and Apsra, the sacred spirit of the waters and clouds in South and Southeast Asia. The word "Athanatos" also means immortal and cleverly refers to the survival of this fossilized crab over time.

BingMag.com The first surviving crab fossils from the dinosaur era have been discovered p id="caption-attachment-982463" class="wp-caption-text"> The first crab caught in amber from the dinosaur era
Credit: Xiao Jia (Longyin Amber Museum)

Fossils of non-marine crabs have been found since ancient times trapped in amber. Most amber fossils are insects, and the crab fossils previously discovered are incomplete and usually contain only paw parts. But this recent finding is so complete that not a single hair seems to have been cut.

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    This finding is particularly important because, according to older theories about the genetic history of crabs, it raises the time limit for the existence of non-marine crabs by 20 to 50 million years and provides a new insight into what is called the evolution of crabs in the Cretaceous. "If the crab tree of life," said Javier Luque, one of the authors of the Harvard University article, " Reconstruct and perform some molecular DNA analysis, predicting that non-marine crabs were separated from their marine ancestors more than 125 million years ago. But the problem was that the surviving and traceable fossils are very young, dating back 75 to 50 million years. "So the new fossil from the Middle Cretaceous allows us to fill the gap between the predicted extrapolation predicted by molecular experiments and the existing fossils of crabs." It is part of the amber collection of the Longyin Museum in China, which the museum bought in 2015 from local Myanmar miners. Luke, who has been studying the evolution of crabs for more than 10 years, has heard about and been curious about this specimen. , The Smithsonian Institution of Tropical Research, Yale University, University of Alberta, Berkeley University, Yunnan University, and the Royal Museum of Saskatchewan.

    BingMag.com The first surviving crab fossils from the dinosaur era have been discovered

    Three-dimensional modeling of the first crab caught in amber since the time of the dinosaurs
    Credit: Elizabeth Clark and Javier Luque

    " Lida Xing "( Lida Xing, another author of the article from the University of China, was the leader of a team that used a micro-CT scan of the fossil to reconstruct a three-dimensional fossil model. This reconstruction is so precise that it allows scientists to see not only the crab's body but also soft tissues such as its tentacles, large eyes and parts of its mouth. Among the fine hairs that cover these areas.

    Although C. Athanata bears a striking resemblance to today's beach crabs, the research team found that it had gills and no lung tissue. This indicates that the crab was at least semi-aquatic; And this is unusual because most of the crab fossils found in amber tissue to date belong to the tropics and tree crabs, which explains why they are trapped in amber.

    According to the authors, at least 12 families There have been lung-like tissues that have evolved independently in their gills since the Cretaceous, allowing them to live in fresh or dry water. "In the C. Athanata fossil, we are dealing with an animal that is probably not marine but not entirely terrestrial," Luke said. "According to fossil records, non-marine crabs evolved 50 million years ago, but this animal is twice that age." Thus C. Athanata provides strong evidence that crabs were transferred to land and freshwater in the age of the dinosaurs and not in mammals as previously thought.

    BingMag.com The first surviving crab fossils from the dinosaur era have been discovered

    Bottom and top view of the body of a crab captured in amber
    Credit: Javier Luque, Lida Xing

    But if C. Athanata is not completely terrestrial, how is it trapped in amber? Luke et al. Suggest that this species may have been a completely saltwater or freshwater crab, an amphibian, or even a semi-terrestrial species. It may also have been a tree crab that lived on the forest floor or near the shallow water of the forest floor.

    . "Important pieces of the puzzle may be scarce or as yet undiscovered, and fossils trapped in amber provide a unique picture of the anatomy, biology and ecology of extinct creatures that could not be accessed otherwise."

    • The oldest fossil of a living thing, 3.6 billion years old

    Cover photo: Graphic design of the dinosaur crab Cretapsara Athanata
    Credit: Artwork by Franz Anthony, courtesy of Javier Luque (Harvard University)


Source: ArsTechnica

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