The exceptional discovery of a 100 million year old crab trapped in amber

Cretapsara athanata est une nouvelle espèce de crabe datant du Crétacé et dont un spécimen a été préservé dans de l'ambre. © Luque et al., 2021

Today there are sea, freshwater and land crabs. When did the transition from the marine environment to other environments occur during the evolution of this group? An exceptional fossil provides some answers to this question.

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During the evolution of metazoans, some groups have caused environmental changes from the aquatic environment to the terrestrial environment. TO How easy was this change? This change is obsolete and is definitely harder to measure today as it is more than the duration of a human life over time.

Study of adaptations and Ecology Creatures in their environment, landscape and aquatic (marine or Sweet), Allow to estimate a difficulty Species The living environment must change permanently. A. from a marine environment Freshwater environment It is also rare in animals because it is particularly physiologically needed in marine and freshwater life Thing Osmoregulation. Changes in living environment indicate that organisms are and will be competing with organisms of the same ecological importance. Exposed to new predators.

There are Crabs Terrain andPure water, Belonging to the Euphrates group. These are – step Molecular Pylogenesis (As opposed to dating fossils) – deviated from them Marine relative In recent times Cretaceous Low, i.e., about 125 million years ago. The problem with these molecular data is that they are difficult to relate to fossil data because most Fossil remains of these crabs Bombs and pincers from the Upper Cretaceous to the Quaternary, between 73 million years ago and the Holocene. In the absence of complete fossils, it is difficult to understand how the crabs left their marine life and how many times they did so during the evolution of the group.

A waterfall race about 100 million years ago

An international team of researchers has published another exceptional finding in the journal Scientific progress About the evolution of the Euphrasius. Researchers describe a new type of crab that belongs to this group, which they named Creditsara Adana From a specimen preserved in amber. This model was discovered in Myanmar (Southeast Asia) and 99 million years ago (Cretaceous).

This crab is one of the oldest groups of Euphrasius and reveals a combination of the ancestral and descendant roles of the group. Through microtomography, its exceptional protection makes it possible X-rays, His elders Eyes Compounds, its antennas and even Kills. The posture and appearance of the shell suggests that it was added to the amber while the animal was still alive.

Particles added to amber contain fibers Drink And insect wastes, whether amber came from a forest environment and the crab lived in freshwater or உவர் Near the end, the authors believe it C. அதனடா Probably more waterfall than land, but Euphrasius already freed themselves from the marine environment 100 million years ago.

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