''Cheiracanthus'' (from , 'hand' and , 'spine') is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of a group of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

called

Acanthodii Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and ...

(or "spiny sharks"). It was a deep-bodied acanthodian about 12 in. (30 cm) in length. It had a

blunt Blunt may refer to: * Blunt (surname), a surname (and list of people with the name) * Blunt (cigar), a term used in the cigar industry to designate blunt-tipped, usually factory-rolled cigars * Blunt (cannabis), a slang term used in cannabis cult ...

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...

, upturned

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

, and

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. F ...

s protected by spines. Unlike many other acanthodians, it had one, solitary

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

. ''Cheiracanthus'' swam at mid-depth in

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s and

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s, seizing small prey in its gaping jaws. Whole fossils of this fish occur only in Mid-

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

rocks in

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

, but its distinctive small, ornamented scales crop up around the world, as far south as

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

Cheiracanthus murchisoni life restoration

References

Acanthodiformes Middle Devonian cartilaginous fish Devonian cartilaginous fish of Europe Devonian cartilaginous fish of North America Taxa named by Louis Agassiz Fossil taxa described in 1835 {{Paleo-fish-stub

See also

References