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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).
Cornovichthys is an extinct genus of jawless fish in the super class Anaspidomorphi. It is known from the Middle Devonian of Scotland. Cornovichthys is also classified as a rare agnathan and shares similarities with the fauna found in the Late Devonian Escuminac Formation of Canada. The passage also states that while Cornovichthys may have been ...
Agnatha, the jawless vertebrates was formerly a superclass of jawless fishes. Most species are prehistoric or extinct, however there are about 60 modern species in the Agnaths superclass, divided into two classes: Class Myxini (family Myxinidae) - the hagfish. Class Cephalaspidomorphi or (disputed) Hyperoartia - the lampreys
Traquairaspis is a genus of extinct heterostracan agnathan fish known from the Silurian and Early Devonian periods.It is predominantly known from Late Silurian fluvial deposits from Wales and England: some species were also found in shallow water marine environment in Canada and North America.
About 64 families are monotypic, containing only one species. [2] Class Agnatha (jawless fish) Subclass Cyclostomata (hagfish and lampreys) Subclass Ostracodermi (armoured jawless fish) † Class Chondrichthyes (cartilaginous fish) Subclass Elasmobranchii (sharks and rays) Subclass Holocephali (chimaeras and extinct relatives) Class Placodermi ...
Traquairaspidiformes is an order of extinct heterostracan agnathan fish known from the Silurian and Early Devonian periods.Fossils are predominantly known from Late Silurian fluvial deposits from Wales and England: some species were also found in strata representing shallow water marine environment in Canada and North America.
The silver lamprey is an eel-like fish with an attenuate body composed of 49–52 clearly defined segments (i.e. myomeres, between the last gill slit and the anus).Silver lampreys possess a cartilaginous skeleton, and adults generally grow to a length of 12 inches and are silvery or bluish in color when spawning.
Over half of all living vertebrate species (about 32,000 species) are fishes (non-tetrapod craniates), a diverse set of lineages that inhabit all the world's aquatic ecosystems, from snow minnows (Cypriniformes) in Himalayan lakes at elevations over 4,600 metres (15,100 feet) to flatfishes (order Pleuronectiformes) in the Challenger Deep, the ...