Cyclopygidae

Cyclopygidae Temporal range: Ordovician PreꞒ Ꞓ O S D C P T J K Pg N
Cyclopygid cephalon, probably Symphysops stevaninae, 24mm, lateral view
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Trilobita
Order:	†Asaphida
Superfamily:	†Cyclopygoidea
Family:	†Cyclopygidae Raymond, 1925
Subfamilies
Cyclopyginae Raymond, 1925 Pricyclopyginae Fortey & Owens, 1987 Ellipsotaphrinae Kobayashi & Hamada, 1971 And see text for genera

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 down and had bioluminescent organs on the third thorax segment. Cyclopygids had between 7 and 5 thorax segments, a wide and stout axis, and short side lobes (or pleurae).