The Cretaceous crab revolution refers to a major diversification event of Brachyura crabs (also known as true crabs) that took place during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

, from 145 to 66 million years ago. Nearly 80% of modern groups of crabs originated during this event. The Cretaceous Crab Revolution is a smaller component of the greater Mesozoic marine revolution.

Early diversification

The oldest known true crab is '' Eoprosopon klugi'' and ''Eocarcinus praecursor'' from the Early to Middle Jurassic. While that

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

crab, and a few other

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

species, establish that crabs existed in older time periods, crabs did not truly diversify into numerous species until the beginning of the Cretaceous. During this time, crabs evolved into many different body plans and lifestyles, including the carcinized body shape like that of blue crabs that many people are familiar with. At the same time, many families of crabs evolved away from the carcinized body plan, termed decarcinization. The Cretaceous Crab Revolution also witnessed the evolution of more unusual body forms in crabs, including the enigmatic '' Callichimaera perplexa.'' This rapid diversification allowed true crabs to inhabit many different environments including fresh water environments,

coral reefs A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

, swimming within the water column, and many others.

References

Cretaceous Crabs {{cretaceous-stub