The real crab that fills the key gap in evolution

When Javier Luque observed this 100 million-year-old piece of amber, his first thought was not whether the crustaceans trapped in it would help fill a key gap in the evolution of crabs

Luque has been studying crab evolution for more than ten years.

Luque said: "They are very good aquarium pets all over the world.

This work was supported by the National Science Foundation, the National Natural Science Foundation of China, the National Geographic Society of the United States, the Central University Fundamental Research Fund, the Yale Institute of Biosphere Research, and the Natural Sciences and Engineering Research Council of Canada

"In a way, it's like finding a fish in amber," said Luque, a postdoctoral researcher in the Department of Biology and Evolutionary Biology at Harvard University

However, Luque and his team were a bit lucky because the amber found in the jungles of Southeast Asia provided researchers with the opportunity to study a particularly complete sample, believed to be the oldest modern-looking crab discovered so far

The size of this crab is about the width of an eraser on a pencil.

Real crabs (known as Brachyurans) are in contrast to "fake crabs" (known as Anomurans), which are not academically crabs, but are sometimes referred to as "hermit crabs" or "king crabs

Previous fossil records consisted mainly of fragments of claws, indicating that non-marine crabs came to land and freshwater approximately 75-50 million years ago

Luque said: "If we are to reconstruct the crab's tree of life-establish a genealogy family tree-and perform some molecular DNA analysis, then it is predicted that non-marine crabs split from their marine ancestor 125 million years ago

Researchers now believe that the Cretaceous crab revolution-when crabs (true or false) diversified all over the world and began to evolve their characteristics-which looked like the body shape of a crab-was not what was previously thought One-time event

The newly discovered fossil is named Cretapsara athanata, "Immortal Cretaceous Cloud and Water Spirit"

The research team used micro-CT scans to clearly see small tissues, such as the crab’s antennae, legs and mouthparts covered with fine hairs, large compound eyes, and even its gills

This research is a collaboration between Harvard and China University of Geosciences, including 10 from Yale University, Smithsonian Tropical Research Institute, Panama, University of Alberta, UC Berkeley, Yunnan University, and Royal Saskatchewan Museum.

This amber fossil specimen is preserved in the Longyin Amber Museum in Yunnan, China