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Taxonomy of commonly fossilised invertebrates

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The Ordovician cystoid Echinosphaerites (an extinct echinoderm of the Class Rhombifera) from northeastern Estonia; encrusted by a graptolite (black branches).

The taxonomy of commonly fossilized invertebrates combines both traditional and modern paleozoological terminology. This article compiles various invertebrate taxa in the fossil record, ranging from protists to arthropods. This includes groups that are significant in paleontological contexts, abundant in the fossil record, or have a high proportion of extinct species. Special notations are explained below:

  • [ ! ]: Indicates clades that are important as fossils or abundant in the fossil record.
  • [ – ]: Indicates clades that contain a large proportion of extinct species.
  • [ † ]: Indicates completely extinct clades.

The paleobiologic systematics that follow are not intended to be comprehensive, rather, they are designed to encompass invertebrates that (a) are popularly collected as fossils and (b) extinct. As a result, some groups of invertebrates are not listed.[1]

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.[2]

Invertebrate clades that are important fossils (e.g. ostracods, frequently used as index fossils), and clades that are very abundant as fossils (e.g. crinoids, easily found in crinoidal limestone),[3] are highlighted with a bracketed exclamation mark [ ! ].

Domain of Eukaryota/Eukarya

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Quinqueloculina, a foraminiferan (a type of protist) from Donegal Bay, Ireland.

Eukaryotes are cellular organisms bearing a central, organized nucleus with DNA.

Sub-domain of Opisthokonta

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Opisthokonts; the animal-related kingdoms. These include proto-spongal choanoflagellates; proto-fungal microsporidians; and true fungi; true animals.

  • most life forms documented, extinct or extant.
    • excludes: many molds; all one-celled protists (protoctists); all algae; all green plants.

Kingdom of Animalia / Metazoa - All Invertebrates and Vertebrates

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Metazoans are multicellular "true" animals (multicellular creatures that capture and ingest their organic food).

  • comprises most living and deceased species which have ever been recorded, extinct or extant.

Sub-kingdom of Parazoa

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Parazoans are typically sessile, basal non-eumetazoans. They are the most primitive animals, comprising simple, colonial, attached, bottom-dwelling marine invertebrates.

Phylum Archaeocyatha/Archeocyatha/Archaeocyathida/Archeocyathida/Pleospongia [†]

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Cone-shaped archaeocyathids/archeocyathids; cup-shaped archaeocyathans/archeocyathans; reef-building pleosponges; calcareous "ancient-cups".

Includes fossil genera such as Archaeocyathus, Cambrocyathus, Atikonia, Tumuliolynthus, Kotuyicyathus, Metaldetes, Ajacicyathus and Paranacyathus.

Archaeocyatha is sometimes classified as a class of Porifera below.

Pattersonia ulrichi Rauff, 1894; an Ordovician hexactinellid sponge near Cincinnati, Ohio.
Tetractinella trigonella at MUSE - Science Museum in Trento

Quintessential true sponges; marine, colonial, pore-bearing animals; organized collar-flagellates; poriferans - today mostly siliceous – half of all documented species of Porifera are fossils and extinct.[4]

Porifera may eventually be broken up into separate phyla:

Sub-kingdom of Eumetazoa

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Eumetazoans; true metazoans (typically mobile, multicellular animals).

Eumetazoa contains most of the living and deceased species of recorded life, including most invertebrates (extinct and extant), as well as all vertebrate animals.

Super-phylum of Radiata

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Radiates; non-bilaterian eumetazoans.

Aulopora (a tabulate coral) from the Silica Shale (Middle Devonian), northwestern Ohio.

Cnidarians/coelenterates:

Super-phylum of Lophotrochozoa / Protostomia # 1

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Lophotrochozoan bilaterians, such as flatworms, ribbon worms, lophophorates, and molluscs.

Phylum Bryozoa/Ectoprocta/Polyzoa

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Heterotrypa, a trepostome bryozoan from the Corryville Formation (Upper Ordovician) in Covington, Kentucky.

Bryozoans – half of all documented species of Bryozoa are fossils and extinct.[5]

  • Class Stenolaemata / Gymnolaemata [!] (mostly marine, calcareous bryozoans):
    • Order Cheilostomata [!] (living, rimmed-mouthed moss animals)
    • Order Cyclostomatida (uncontracted, round-mouthed bryozoans including fossil Stomatopora)
    • Order Cystoporata [†] (extinct, minor group of moss animals)
    • Order Trepostomata [†] [!] (changed-mouthed bryozoans such as extinct Constellaria and Monticulipora)
    • Order Cryptostomata [†] [!] (round hidden-mouthed bryozoans such as Archimedes, Fenestrellina and Rhombopora)
    • Order Ctenostomata [†] (uncommon, comb-mouthed bryozoans)
    • Order Phylactolaemata (living, fresh-water bryozoans)
Rhynchotrema dentatum, a rhynchonellid brachiopod from the Cincinnatian (Upper Ordovician) of southeastern Indiana.

Lampshells, brachiopods or "brachs," (not to be confused with the hard-shelled marine mollusks below) – 99% of all documented species of Brachiopoda are now extinct.

Phylum Annelida

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Segmented worms such as earthworms and leeches.

Phylum Mollusca

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Peltoceras solidum ammonite from the Matmor Formation (Jurassic, Callovian) in the Matmor Formation, Makhtesh Gadol, Israel.
Vermetid gastropod Petaloconchus intortus attached to a branch of the coral Cladocora; Pliocene of Cyprus.

Molluscs or mollusks, not to be confused with the hard-shelled marine brachiopods above.

Super-phylum of Ecdysozoa/Protostomia # 2

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Ecdysozoans, such as nematodes, horsehair worms, and molting bilaterians/panarthropods

Panarthropodic water bears.

Panarthropodic velvet worms, including proto-arthropodic fossils of Arthropleura and Aysheaia.

Elrathia kingii (trilobite) from the Wheeler Shale (Middle Cambrian), Utah.

Arthropods; jointed legged creatures with an exoskeleton.

Super-phylum of Deuterostomia / Enterocoelomata

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Second-mouthed bilaterians called deuterostomians, such as chordates and echinoderms.

Middle Jurassic (Callovian) crinoid pluricolumnals (Apiocrinites) from the Matmor Formation in Hamakhtesh Hagadol, southern Israel.

Echinoderms – 72% of all documented species of Echinodermata are fossils and extinct.[7]

Pendeograptus fruticosus graptolites from the Bendigonian Australian Stage (Lower Ordovician) near Bendigo, Victoria, Australia. Two overlapping, three-stiped rhabdosomes.

Hemichordates such as extant acorn worms – Less than half of the documented species of Hemichordata are fossils and extinct.

Phylum Chordata

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Both invertebrate and vertebrate chordates; are animals possessing a notochord.

Invertebrate subphyla

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Subphylum Vertebrata

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Deinosuchus hatcheri at the Natural History Museum of Utah.

See also

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References

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  1. ^ For superb anatomical illustrations and much-more comprehensive information, see Volume E (Archaeocyatha / Porifera) through Volume V (Graptolithina), published 1953 to 2006 (and continuing), of the Treatise on Invertebrate Paleontology, long-edited by Raymond C. Moore and Roger L. Kaesler (Boulder, Colorado: Geological Society of America; and Lawrence, Kansas: University of Kansas Press). But be warned that some terms therein employed – such as supersubphylum – can be unnecessarily wordy or abstruse. Incidentally, revised volumes have been recently published regarding the sponges/archaeocyatha (2004, ISBN 0-8137-3131-3) and the brachiopods (2006, ISBN 0-8137-3135-6).
  2. ^ The names of genera, orders, classes and phyla have been culled from dozens of sources, both current and decades-old. See the International Code of Zoological Nomenclature (ICZN), as well as Volume 1 and Volume 2 of Grzimek's Animal Life Encyclopedia (Farmington Hills, Michigan: Gale Group), edited by zoologists Michael Hutchin, Dennis A. Thorney and Sean F. Craig (2003).
  3. ^ For correspondingly ancient ecosystems, see the Treatise on Ecology and Paleoecology, Volume 2: Paleoecology, edited for years by Harry S. Ladd (1957 / 1971), and published by both the Geological Society of America (Boulder, Colorado) and the Waverly Press (Washington, D.C.).
  4. ^ The rates of extinction for sponges and other phyla are derived from W. H. Easton, 1960, Invertebrate Paleontology (New York: Harper and Brothers) and various modern sources.
  5. ^ For bryozoans and brachiopods, the same footnote as above.
  6. ^ For bivalves and cephalopods (both mollusks), see the above notation.
  7. ^ For the echinoderms, see the above footnote regarding W. E. Easton, 1960, Invertebrate Paleontology, and other sources.