''Thrissops'' (from el, θρῐ́ξ , 'hair' and el, ὄψις 'look') is an extinct genus of stem-

teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

fish from the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

periods. Its fossils are known from the Solnhofen Limestone, as well as the

Kimmeridge Clay The Kimmeridge Clay is a sedimentary deposit of fossiliferous marine clay which is of Late Jurassic to lowermost Cretaceous age and occurs in southern and eastern England and in the North Sea. This rock formation is the major source rock for North ...

. ''Thrissops'' was a fast predatory fish about long, that fed on other

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

.Orvar Nybelin, "Versuch einer taxonomischen revision der jurassischen Fischgattung Thrissops Agassiz", ''Nature'' (1964) It had a streamlined body with a deeply cleft tail and only very small

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s. ''Thrissops'' was one of the smaller members of the order

Ichthyodectiformes Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. The order is named after the genus '' Ichthyodectes'', established by Edward Drinker Cope in 1870. Ichthyodectiforms are usually considered to be some of the closest ...

, which also included giants like ''

Xiphactinus ''Xiphactinus'' (from Latin and Greek for " sword-ray") is an extinct genus of large (Shimada, Kenshu, and Michael J. Everhart. "Shark-bitten Xiphactinus audax (Teleostei: Ichthyodectiformes) from the Niobrara Chalk (Upper Cretaceous) of Kansas. ...

'' and '' Saurodon''.

References

Prehistoric ray-finned fish genera Late Jurassic bony fish Late Jurassic fish of Europe Ichthyodectiformes Solnhofen fauna Late Jurassic genus first appearances Tithonian genera Berriasian genera Valanginian genera Hauterivian genera Barremian genera Aptian genera Albian genera Cenomanian genera Late Cretaceous genus extinctions Taxa_named_by_Louis_Agassiz Fossil taxa described in 1833 {{paleo-rayfinned-fish-stub