Class
Petromyzonti (Lampreys)
Entosphenus tridentatus. Photo: (c) spow9781, some rights reserved (CC BY-NC)
Cephalaspidomorphs are a group of jawless fishes named for Cephalaspis of the osteostracans. Most biologists regard this taxon as extinct, but the name is sometimes used in the classification of lampreys, because lampreys were once thought to be related to cephalaspids. If lampreys are included, they would extend the known range of the group from the Silurian and Devonian periods to the present day.
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