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Trilobita

(Infraphylum)

Overview

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(Gr. treis, tria, trion: three; lobos: lobe) The most primitive arthropod class, known from more than 3900 fossil species. Inhabitants of Palaeozoic seas, the trilobites appeared first in the early Cambrian, had their widest distribution and greatest diversity in the Cambrian and Ordovician Periods, and became extinct in the Permian. The body was divided into three regions: an anterior cephalon, comprising at least five, fused segments; a mid-body or thorax, with a varying number of segments; and a hind region or pygidium. All three regions were divided by a pair of furrows running the length of the body, giving a trilobite appearance (i.e. a median or axial lobe, flanked on either side by a lateral lobe). The mouth was situated in the middle of the central surface of the cephalon. Paired gill-bearing limbs were attached to the membranaceous, pleural skeleton. X-ray studies show the eyes to have resembled the compound eyes of living arthropods (see Trilobite Eye). Trilobites ranged in size from 0.5 mm long planktonic (see Plankton) forms to those nearly 1 m in length; most species were 3 to 10 cm long. There were 9 orders: Redlichiida, Agnostida, Naraoiidae, Corynexochida, Lichida, Phacopida, Ptychopariida, Asaphida and Proetida.

Taxonomy

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The Infraphylum Trilobita is a member of the Phylum Arthropoda. Here is the complete "parentage" of Trilobita:

The Infraphylum Trilobita is further organized into finer groupings including:

Families

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Abadiellidae

[more]

Acastidae

Acastidae is a family of trilobites in the order Phacopidae, suborder Phacopina, superfamily Acastoidea, containing the following genera: [more]

Acrocephalitidae

[more]

Agnostidae

Agnostidae is a family of agnostid trilobites. Like most agnostids, they were eyeless and only bore two thoracic segments. They ranged in benthic waters across the globe from 530 to 461 million years ago, containing the following genera, among others: [more]

Agraulidae

[more]

Alsataspidae

[more]

Anomocaridae

[more]

Archaeaspidae

[more]

Asaphidae

Asaphidae is a family of trilobites in the order Asaphida, containing the following genera: [more]

Asaphiscidae

[more]

Aulacopleuridae

[more]

Auritamiidae

[more]

Bathycheilidae

Bathycheilidae is a family of trilobites comprising the genera Bathycheilus, and Eulomina. [more]

Bathynotidae

[more]

Bathyuridae

[more]

Bestjubellidae

[more]

Bohemillidae

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Bolaspididae

[more]

Brachymetopidae

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Burlingiidae

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Calmoniidae

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Calodiscidae

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Calymenidae

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Carmonidae

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Cedariidae

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Celmidae

[more]

Centropleuridae

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Ceratopygidae

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Cheilocephalidae

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Cheiruridae

The family Cheiruridae was a family of phacopid trilobites of the suborder . Its members, as with other members of the suborder, had distinctive pygidia modified into finger-like spines. They first appeared near the very beginning of the Ordovician, and persisted until the Devonian. [more]

Cheiruroididae

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Chenghuiidae

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Chengkouaspidae

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Clavagnostidae

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Condylopygidae

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Conocoryphidae

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Coosellidae

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Corynexochidae

[more]

Crepicephalidae

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Cyclopygidae

[more]

Dalmanitidae

[more]

Damesellidae

Odontopleurida is an order of trilobites, containing the following taxa: [more]

Diaphanometopidae

[more]

Diceratocephalidae

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Dikelokephalidae

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Dikelokephalinidae

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Dimeropygidae

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Dinesidae

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Dionididae

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Diplagnostidae

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Dolerolenidae

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Dorypygidae

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Edelsteinaspidae

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Ellipsocephalidae

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Elvinndae

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Emmrichellidae

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Emuellidae

[more]

Encrinuridae

Encrinuridae is a family of trilobite within the order Phacopida that lived in what would be Africa, Asia, Australia, Europe, North America, and South America from the middle Ordovician to the early Devonian from 479 to 412.3 million years ago, existing for approximately 66.7 million years. [more]

Entomaspididae

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Eodiscidae

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Eurekiidae

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Fallotaspidae

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Gigantopygidae

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Glaphuridae

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Hammatocnemidae

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Harpetidae

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Harpididae

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Hebediscidae

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Holanshaniidae

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Holmiidae

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Holotrachelidae

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Homalonotidae

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Hungaiidae

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Idahoiidae

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Ignotogregatidae

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Illaenidae

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Inouyiidae

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Ityophoridae

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Jaktidae

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Judomiidae

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Kainellidae

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Kaolishaniidae

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Kingstoniidae

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Kueichowiidae

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Lecanopygidae

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Leiostegiidae

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Lichakephalidae

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Lichidae

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Liostracinidae

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Lisaniidae

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Liwiidae

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Loganellidae

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Lonchocephalidae

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Longduiidae

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Lorenzellidae

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Mapaniidae

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Marjumiidae

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Mayiellidae

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Menneraspidae

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Menomoniidae

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Metadoxididae

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Metagnostidae

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Monkaspidae

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Naraoiidae

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Neltneriidae

[more]

Nepeiidae

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Nevadiidae

[more]

Nileidae

[more]

Norwoodiidae

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Odontopleuridae

Odontopleurida is an order of trilobites, containing the following taxa: [more]

Ogygopsidae

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Olenellidae

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Olenidae

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Onchonotopsidae

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Opipeuteridae

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Orientellidae

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Orometopidae

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Oryctocephalidae

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Pagodiidae

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Papyriaspidae

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Parabolinoididae

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Paradoxididae

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Peronaspidae

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Phacopidae

Phacopidae is a family of trilobites of the order Phacopida, including the following genera: [more]

Phalacromidae

[more]

Phillipsiidae

[more]

Phillipsinellidae

[more]

Pilekiidae

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Pliomeridae

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Proasphiscidae

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Proetidae

Proetidae is a family of trilobites. The first appeared in the Upper Ordovician, and were among the last surviving trilobites, occurring until the Carboniferous. The family Proetidae contains the following genera: [more]

Prosopidiscidae

[more]

Protolenidae

[more]

Pterocephaliidae

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Pterygometopidae

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Ptychagnostidae

[more]

Ptychaspidae

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Ptychopariidae

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Raphiophoridae

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Redlichiidae

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Redlichinidae

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Remopleurididae

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Rhyssometopidae

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Rorringtoniidae

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Saukiandidae

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Saukiidae

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Selenopeltidae

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Shirakiellidae

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Shumardiidae

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Solenopleuridae

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Sphaeragnostidae

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Spinagnostidae

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Staurocephalidae

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Styginidae

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Taihungshaniidae

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Telephinidae

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Tengfengiidae

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Trinucleidae

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Tsinaniidae

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Tsunyidiscidae

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Weymouthiidae

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Wuaniidae

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Yinitidae

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Yukoniidae

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Zacanthoididae

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At least 23 species and subspecies belong to the Family Zacanthoididae.

More info about the Family Zacanthoididae may be found here.

Sources

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Last Revised: August 25, 2014
2014/08/25 12:55:11