''Deltoptychius'' (from , 'triangle' and 'fold') is an extinct species of

cartilaginous fish Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeleto ...

related to the modern

chimaera Chimaeras are Chondrichthyes, cartilaginous fish in the order (biology), order Chimaeriformes (), known informally as ghost sharks, rat fish (not to be confused with rattails), spookfish, or rabbit fish; the last two names are also applied to B ...

s. It lived in the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

period in present-day United Kingdom. Fossils of the genus have been found in the

Glencartholm Volcanic Beds Formation Glencartholm is a location in Dumfries and Galloway, southern Scotland, along the River Esk. The Glencartholm Volcanic Beds contain a Palaeozoic (specifically Carboniferous) fossil fish site of international importance. Discovered in 1879, mos ...

of the

Upper Border Group Upper may refer to: * Shoe upper or ''vamp'', the part of a shoe on the top of the foot * Stimulant, drugs which induce temporary improvements in either mental or physical function or both * ''Upper'', the original film title for the 2013 found fo ...

in Scotland. Although it emerged over 300 million years ago, ''Deltoptychius'' was similar in appearance to modern-day chimaeras, possessing a long, whip-like tail and large, wing-like

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s that it probably used to glide through the water. ''Deltoptychius's'' large eyes allowed it to hunt in deep waters, crushing

shellfish Shellfish, in colloquial and fisheries usage, are exoskeleton-bearing Aquatic animal, aquatic invertebrates used as Human food, food, including various species of Mollusca, molluscs, crustaceans, and echinoderms. Although most kinds of shellfish ...

between solid tooth plates in its mouth.

References

Deltoptychiidae Carboniferous cartilaginous fish Carboniferous fish of Europe Prehistoric cartilaginous fish genera {{paleo-holocephalan-stub