Traditionally, the Myodocopa and

Podocopa The Podocopa are a subclass of ostracods. Members of the subclass Podocopa can be differentiated from the other subclass of ostracods ( Myodocopa) by the morphology of the second antenna Antenna ( antennas or antennae) may refer to: Science ...

have been classified as subclasses within the class

Ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

a, although there is some question about how closely related the two groups actually are. The Myodocopa are defined by possession of a poorly calcified

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

, and 8–9 articles in the exopod of the second

antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...

. The ventral margin of the carapace is not concave, and the valves do not overlap to a great extent. Although the carapace of myodocopans is poorly calcified, some

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 ...

s are known for the group. (In contrast, thousands of fossil species are named for the Podocopa). Of particular interest are those fossils for which the internal body parts (and not just the carapace) are preserved. This provides a lot more information about the likely relatives to the fossil taxa, including relatives still alive today. Two recent fossils of much interest have been found from

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleoz ...

deposits (dated at ). These fossils have well preserved internal body parts.

References

{{Taxonbar, from=Q898458 Arthropod subclasses Taxa named by Georg Ossian Sars