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Although intra-species trilobite diversity seems to have peaked during the Cambrian, [30] trilobites were still active participants in the Ordovician radiation event, with a new fauna taking over from the old Cambrian one. [31] Phacopida and Trinucleioidea are characteristic forms, highly differentiated and diverse, most with uncertain ...
Phillipsiidae is a family of proetid trilobites, the various genera of which comprise some of the last of the trilobites, with a range that extended from the Kinderhookian epoch of the Lower Mississippian, to the end of Changhsingian age at Permian-Triassic extinction event in the latest Permian period.
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. [1] The most conspicuous character is the wide perforated fringe of the head.
Trinucleioidea is a superfamily of trilobites. Traditionally placed within the Asaphida, it is now sometimes considered its own order, Trinucleida. [1] [2] Damghanampyx ghobadipour fossil from Lashkark Formation, Ordovician, Damghan, Iran
Triarthrus is an average size trilobite (up to about 5 centimetres or 2.0 inches) and its moderately convex body is about twice as long as wide (excluding spines). Like in all Olenidae, the headshield (or cephalon ) of Triarthrus has opisthoparian sutures , and the right and left free cheeks that they define are yoked.
The first harpetid trilobites appear in the Upper Cambrian, and the last species die out at the end of the Devonian period. Harpetid trilobites are characterized among trilobites by bearing a comparatively large, semicircular brim around the cephalon (head) which is often perforated by small pores. This brim is thought to serve as a filter ...
Redlichia is a genus of redlichiid trilobite in the family Redlichiidae, with large to very large species (up to 35 centimetres or 14 inches long).Fossils of various species are found in Lower Cambrian ()-aged marine strata from China, Korea, Pakistan, the Himalayas, Iran, Spain, southern Siberia, and Antarctica, and from Middle Cambrian ()-aged marine strata of Australia.
Dalmanites is genus of trilobites with an average (about 8 centimetres or 3.1 inches long), moderately vaulted exoskeleton with an inverted egg-shaped outline (about 1.5× longer than wide). Its headshield (or cephalon ) is semicircular, with robust (genal) spines extending from the side of the cephalon back to approximately the 8th thorax segment.