Myodocopa
Encyclopedia
Traditionally, the Myodocopa and Podocopa
have been classified as subclasses within the class Ostracod
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
, and 8–9 articles in the exopod of the second antenna
. 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
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
deposits (dated at ). These fossils have well preserved internal body parts.
Podocopa
The Podocopa are a subclass of ostracods. This subclass can be differentiated from the other subclass by the morphology of the second antenna: the Podocopa have a relatively long endopod, whereas the Myodocopa have a relatively long exopod...
have been classified as subclasses within the class Ostracod
Ostracod
Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 65,000 species have been identified, grouped into several orders....
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
Carapace
A carapace is a dorsal 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 underside is called the plastron.-Crustaceans:In crustaceans, the...
, and 8–9 articles in the exopod of the second antenna
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
. 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
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
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
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
deposits (dated at ). These fossils have well preserved internal body parts.