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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 ...
A few living forms, such as the coelacanth are also referred to as prehistoric fish, or even living fossils, due to their current rarity and similarity to extinct forms. Fish which have become recently extinct are not usually referred to as prehistoric fish. Lists of various prehistoric fishes include: List of prehistoric jawless fish; List of ...
Thelodonti (from Greek: "nipple teeth") [4] is a class of extinct Palaeozoic jawless fishes with distinctive scales instead of large plates of armor. There is much debate over whether the group represents a monophyletic grouping, or disparate stem groups to the major lines of jawless and jawed fish. Shielia taiti
Arandaspida is a taxon of very early, jawless prehistoric fish which lived during the Ordovician period. Arandaspids represent some of the oldest known vertebrates. The group represents a subclass within the class Pteraspidomorphi, and contains only one order, the Arandaspidiformes.
Sacabambaspis is an extinct genus of jawless fish that lived in the Ordovician period. Sacabambaspis lived in shallow waters on the continental margins of Gondwana . [ 1 ] It is the best known arandaspid with many specimens known.
Oeselia mosaica is a fossil jawless fish and is the only species in its genus and in the family Oeseliidae (Oesel being the old name for Saaremaa Island in Estonia). It is a member of an extinct family of thelodonts or jawless fishes. The family and genus were established along with the description of the species by Tiuu Märss in 2005.
Anaspida ("shieldless ones") is an extinct group of jawless fish that existed from the early Silurian period to the late Devonian period. [2] They were classically regarded as the ancestors of lampreys , [ 3 ] but it is denied in recent phylogenetic analysis, [ 4 ] although some analysis show these group would be at least related. [ 5 ]