Trilobite families

Proetidae is a family of proetid trilobites. The first species appeared in the Upper Ordovician, and the last genera survived until the Middle Permian. However, if the closely related family Phillipsiidae is actually a subfamily of Proetidae, then the proetids of Proetidae survive until the end of the Permian, where the last perish during the Permian–Triassic extinction event.

Cyclopygidae is a family of asaphid trilobites from the Ordovician. Cyclopygids had an extratropical distribution, and there is evidence that they lived in darker parts of the water column (around 175m deep). Cyclopygids are characterized by enlarged eyes, with a wide angle of view, both horizontal and vertical, reminiscent of the eyes of dragonflies. These typically touch the glabella directly on the side. Cyclopygids all lack genal spines, but Symphysops carries a forward directed frontal spine on the glabella. It is presumed that at least the members of the genus Pricyclopyge swam upside do

Olenidae is a family of ptychopariid trilobites. Some genera, Balnibarbi and Cloacaspis, are thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived nutrition.

Odontopleuridae is a family of odontopleurid trilobites found in marine strata throughout the world. The family is Late Cambrian to Frasnian in age. The members of Odontopleuridae are known for their spinose appearance, having long, often numerous spines along the edges of their exoskeletons, and derived from ends of segments or tubercle ornaments.

Trinucleidae is a family of small to average size asaphid trilobites that first occurred at the start of the Ordovician and became extinct at the end of that period. It contains approximately 227 species divided over 51 genera in 5 subfamilies. The most conspicuous character is the wide perforated fringe of the head.

Agnostidae is a family of Agnostida trilobites. Like all Agnostina, they were eyeless and had only two thoracic segments. These trilobites inhabited benthic waters worldwide from 508 to 461 million years ago. The family includes the following genera, among others:

Yukoniidae S. Zhang, 1980 [nom. transl. et emend. Jell, in Whittington et al., 1997 ex Yukoniinae S. Zhang in W. Zhang, Lu et al., 1980] is a small family of trilobites, belonging to the Eodiscina.

Olenellidae is an extinct family of redlichiid trilobite arthropods. Olenellids lived during the late Lower Cambrian (Botomian/Toyonian) in the Olenellus-zone in the former paleocontinent of Laurentia and parts of what became the Famatinian orogen in what is now Argentina. This family can be distinguished from most other Olenellina by the partial merger of the frontal (L3) and middle pair (L2) of lateral lobes of the central area of the cephalon, that is called glabella, creating two isolated slits.

Damesellidae is a family of odontopleurid trilobites found in late Middle to Late Cambrian marine strata, primarily of China. Damesellids are closely related to the odontopleurids of Odontopleuridae, but are not nearly as spinose, nor possess spines as exaggerated as Odontopleuridae. Like Odontopleuridae odontopleurids, damesellids have broad, bar-shaped cranidia with ledge-like borders. Damesellidae may represent transitional forms between more primitive, possibly ancestral ptychopariids and more advanced odontopleurids.

The Paradoxididae are a family of trilobites, a group of extinct marine arthropods. They occurred during the late Lower Cambrian (Toyonian) and disappeared at the end of the Middle Cambrian. Representatives of this family have been found in the paleocontinents of Avalonia, Baltica, and Gondwana, now Canada (Nova-Scotia, New Brunswick, Newfoundland), USA (Massachusetts, South Carolina), England, Wales, Morocco, Spain, Czech Republic, Poland, Russia (Novaya Zemlya, Northern Siberia, North-East Yakutia), Mongolia, and Turkey. Species in this family can typically grow large to very large (over 30&

Acastidae is a family of trilobites in the order Phacopida, suborder Phacopina, superfamily Acastoidea, containing the following genera: {| border="0" cellpadding="05" | Acastava Acaste Acastella Acastellina Acastocephala Acastoides Acastopyge Armorigreenops Asteropyge Baniaspis Bellacartwrightia Bradocryphaeus Braunops Breizhops Centauropyge Chimaerastella Coltraneia Comura Cryphina Delocare Deloops Destombesina Dunopyge | Echinopyge Erbenochile Ewacaste Feruminops Gourdonia Greenops Gudralisium Hallandclarkeops Harringtonacaste Heliopyge Hexacosta Hollardops Kayserops Kennacryphaeus Klouceki

Eodiscidae is a family of agnostid trilobites that lived during the final Lower Cambrian (late Toyonian) and the Middle Cambrian. They are small or very small, and have a thorax of two or three segments. Eodiscidae includes nine genera (see box).

REDIRECT Fallotaspidoidea

Emuellidae are a small family of trilobites, a group of extinct marine arthropods, that lived during the late Lower Cambrian (late Botomian) of the East Gondwana supercontinent, in what are today South-Australia and Antarctica.

Asaphidae is a family of asaphid trilobites. Although the first genera originate in Upper Cambrian marine strata, the family becomes the most widely distributed and most species-rich trilobite family during the Ordovician.

Redlichiidae is a family of redlichiid trilobites which lived from the Botomian to the Middle Cambrian period. It contains the following genera, divided between five subfamilies:

Dalmanitidae is a family of trilobites in the order Phacopida that lived from the Floian (Ordovician) to the Devonian and includes 33 genera.