Definition

Noun: 1. An obsolete taxonomic group of crustaceans: In older biological classification systems, 'Entomostraca' was a term used to group together several classes of small crustaceans, typically those with a bivalve carapace or shell. This grouping is no longer considered scientifically valid, as it was an artificial assemblage not based on shared evolutionary ancestry. The classes historically included were Branchiopoda (e.g., fairy shrimp, water fleas), Copepoda (e.g., cyclops), Ostracoda (seed shrimp), and Cirripedia (barnacles).

Usage Notes

• The term 'Entomostraca' is archaic and not used in modern scientific taxonomy. It is primarily encountered in historical texts or older scientific literature.
• In contemporary biology, the organisms once grouped under 'Entomostraca' are classified separately based on their distinct evolutionary relationships. The term has been superseded by more accurate phylogenetic classifications.

Examples

• "In 19th-century zoology texts, barnacles and water fleas were often classified under the Entomostraca."
• "The obsolete subclass Entomostraca contrasted with the Malacostraca (e.g., crabs, shrimp) in older classification schemes."

Advanced Usage

• The term may appear in discussions about the history of science or the evolution of biological taxonomy to illustrate how classification systems have changed.

Variants and Related Words

• Entomostracan (noun/adjective): A member of the former group Entomostraca; of or relating to this group.
  • Example: "The fossil was an entomostracan specimen."

Synonyms

• (None in modern technical use) Historically, it was an umbrella term. Modern equivalents would be the specific class names: Branchiopods, Copepods, Ostracods, and Cirripedes.

Different Meanings

• There is only one specific meaning for this term, which is the obsolete taxonomic grouping described above. It does not have common alternative meanings.

Noun

1. in some older classifications includes the Branchiopoda and Copepoda and Ostracoda and Cirripedia; no longer in technical use