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Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
Thelodonti ('feeble-teeth') are a group of small, extinct jawless fishes with distinctive scales instead of large plates of armour. There is much debate over whether the group of Palaeozoic fish known as the Thelodonti (formerly coelolepids [11]) represent a monophyletic grouping, or disparate stem groups to the major lines of jawless and jawed ...
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known ...
A newfound fossil of a jawless fish is the oldest known vertebrate cranium preserved in 3D. The 455 million-year-old find could illuminate how vertebrate heads evolved.
The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate
Arandaspis prionotolepis. This list of prehistoric jawless fish is an attempt to create a comprehensive listing of all genera from the fossil record that have ever been considered to be jawless fish, excluding purely vernacular terms.
Pteraspidomorphi is an extinct class of early jawless fish. They have long been regarded as closely related or even ancestral to jawed vertebrates, but the few characteristics they share with the latter are now considered as basal traits for all vertebrates .
Pteraspis (from Greek: πτερόν pteron 'wing' or 'fin' and Greek: ἀσπίς aspís 'shield') is an extinct genus of pteraspidid heterostracan jawless fish.It lived from the Lochkovian to Eifelian epochs of the Devonian period in what is now Brazil (Eifelian Maecuru Formation), Britain (Lochkovian Ditton Group), Ukraine (Lochkovian Ivane Suite, Pragian Babin Sandstone) and Belgium.