Selected examples from literature on “soft body”-preservation of fossil conchostracans (clam shrimp)

The conchostracans (clam shrimp) are bivalved crustaceans that belong taxonomically to the branchiopod Diplostraca. Their chitinous carapace valves are often only some millimetres, or rarely view centimetres, in total length. Most records of fossil conchostracans have been made in fine-grained sediments that have been deposited under quiet water conditions in ponds or lakes. The fossil valves are preserved as imprints and casts in sediments, but their chitinous shell substance or its derivate can be preserved as well. In contrast, preservation of the conchostracan body parts are rare in the fossil record. For the present study, the literature of fossil conchostracans has been reviewed, in order to compile a listing of occurrences that bear fossilized soft parts of the conchostracan body. In result, more than 20 fossil occurrences of conchostracan “soft body” preservation were recorded. These examples are presented herein, based on the referenced literature.