Crustacean

Class Branchiopoda

Geological history

Although crustaceans are rarer as fossils than trilobites are, a number of different types of crustaceans are common in the rocks of the Cretaceous period as well as those of the Caenozoic era. Most of the smaller crustaceans, such as shrimp, have an exoskeleton which is somewhat delicate and for this reason their fossil record is incomplete. However, crustaceans such as crabs and lobsters have a thicker exoskeleton which is reinforced with calcium carbonate and so their fossil record is much better. The fossil record of barnacles is scarce and little is known of their history prior to the Mesozoic era. Well preserved specimens are known from the rocks of the Cretaceous period and the Caenozoic era.

Related Topics:
Fossil - Trilobite - Cretaceous - Caenozoic - Exoskeleton - Calcium carbonate - Barnacle - Mesozoic

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The most well known crustaceans, the malacostraca (crabs, lobsters, crayfish, shrimp), although widespread today are only found sporadically as fossils. Most of the known fossil crabs are of forms which lived on the sea-floor or in a reef environment. In rocks such as the Gault clay from the Cretaceous period and the London clay from the Eocene period in England fossil crabs may be found. The 'Lobster Bed' of the Greensand formation from the Cretaceous period which occurs at Atherfield on the Isle of Wight in England contains many well preserved examples of the small glypheoid lobster Mecochirus magna. The lithographic limestones from the Jurassic period of Solnhofen in Germany have long been famed for the many exceptionally preserved crab, lobster and shrimp fossils they have yielded (such as Aeger, Eryon, and Pseudastacus).

Related Topics:
Fossil - Gault clay - Cretaceous - London clay - Eocene - England - Atherfield - Isle of Wight - Glypheoid - Jurassic - Solnhofen - Germany

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