Taxonomy of commonly fossilised invertebrates

The phylogenetic classification of invertebrates (extinct and extant) remains a work-in-progress. The taxonomy of commonly fossilized invertebrates combines both traditional (old) and modern (21st-century) paleozoological terminology. The paleobiologic systematics that follow are not intended to be comprehensive, rather encompass invertebrates that (a) are popularly collected as fossils and/or (b) extinct. As a result, some groups of invertebrates are not listed. If an invertebrate animal is mentioned below using its common (vernacular) name, it is an extant (living) taxon, but if it is cited by its scientific genus, then it is typically an extinct invertebrate known only from the fossil record. Invertebrate clades that are important fossils (e.g. ostracods, frequently used as index fossils), and/or clades that are very abundant as fossils (e.g. crinoids, easily found in crinoidal limestone), are highlighted with a bracketed exclamation mark [ ! ]. Invertebrate groups that contain a large proportion of extinct species are followed by a dashed notation [ – ]. Invertebrate clades which are now completely extinct are designated with a bracketed dagger [ † ]: Eukaryotes; eukaryotes are cellular organisms bearing a central, organized nucleus with DNA. most of the species which have been documented by biologists and paleontologists, extinct or extant, are eukaryotic. includes: a wide variety of single-celled protists; all algae; most plankton; most molds; the green plants; all animal-related kingdoms. does not include the primal, sub-nuclear, prokaryotic domains of Archaea and Bacteria – nor the enigmatic domain of Viruses. Opisthokonts; the animal-related kingdoms. Include: proto-spongal choanoflagellates; proto-fungal microsporidians; true fungi; true animals. most life forms documented, extinct or extant. excludes: many molds; all one-celled protists (protoctists); all algae; all green plants. Metazoans; multicellular "true" animals (multicellular creatures that capture and ingest their organic food).