Phacopina

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title: "Phacopina" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["phacopina", "prehistoric-animal-suborders", "arthropod-suborders", "early-ordovician-first-appearances", "famennian-extinctions"] description: "Extinct suborder of trilobites" topic_path: "general/phacopina" source: "https://en.wikipedia.org/wiki/Phacopina" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct suborder of trilobites ::

| fossil_range = | image = Reedops deckeri cephalon lateral.jpg | image_caption = Reedops deckeri, a trilobite of the suborder Phacopina | taxon = Phacopina | authority = Struve, 1959 | subdivision_ranks = Superfamilies | subdivision =

• Acastoidea
• Dalmanitoidea
• Phacopoidea

The Phacopina comprise a suborder of the trilobite order Phacopida. Species belonging to the Phacopina lived from the Lower Ordovician (Tremadocian) through the end of the Upper Devonian (Famennian). The one unique feature that distinguishes Phacopina from all other trilobites are the very large, separately set lenses without a common cornea of the compound eye.

Habitat

As far as currently known, all Phacopina species were marine bottom-dwellers.

Origin

The Early Ordovician genus Gyrometopus (superfamily Dalmanitoidea, family Diaphanometopidae) is probably close to the common ancestor of the Phacopina. Gyrometopus is phacopid in appearance, but a rostral plate is present, unlike in other Phacopina. However, the rostral plate does not divide the cephalic doublure into a left and right section, but instead the rostral suture defines a semicircle in the frontal ¾ of the doublure.

Description

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/f6/Zeliszkella_torrubiae_oblique_lateral.jpg" caption="doublure]]) has no sutures crossing it to form a rostral plate.
The thorax has 11 (rarely 10) segments, the side lobes (or pleurae) are furrowed, and the articulating facets distinct.Richter, R. Crustacea (Paläontologie). 1933Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997"] ::

Systematics

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/a7/Phacops_rana_crassituberulata_dorsal.jpg" caption="superfamilies]] and 7 families:"] ::

Superfamily Acastoidea

• Family Acastidae (examples: Coltraneia oufatenensis, Walliserops trifurcatus)
• Family Calmoniidae Superfamily Dalmanitoidea
• Family Dalmanitidae (examples: Dalmanites limulurus, Huntoniatonia oklahomae)
• Family Diaphanometopidae
• Family Prosopiscidae Superfamily Phacopoidea
• Family Phacopidae (examples: Phacops rana, Ductina vietnamica)
• Family Pterygometopidae

References

References

1. Struve, W. Suborder Phacopina, p. O461. In: Moore, R.C. (ed.). Treatise on Invertebrate Paleontology. Part O – Arthropoda (Trilobitomorpha). 1959
2. Moore, R.C. (ed.). Treatise on Invertebrate Paleontology. Part O – Arthropoda (Trilobitomorpha). 1959
3. [[Valdar Jaanusson. Jaanusson, V.]] Evolutionary processes leading to the trilobite suborder Phacopina. Fossils and Strata 4:209–218, fig. 1–5. 1975
4. Richter, R. Crustacea (Paläontologie). 1933
5. Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::