Teleost

Teleosts are the dominant fish of the present day. They arose in the Mesozoic era, and include 20,000 living species. The oldest teleost fossils date back to the late Triassic. They evolved from fish like bowfins in the clade Holostei. During the Mesozoic and Cainozoic they diversified. 96 percent of all known fish species are teleosts.

Teleost Temporal range: Triassic – Recent
Retroculus (Cichlidae); Hairy Blenny, Labrisomus; Ogcocephalus and Acanthurus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Subclass:	Neopterygii
Infraclass:	Teleostei

They are, in order of evolution, vertebrates, jawed fish (Gnathostomata), bony fish (Osteichthyes) and ray-finned fish (Actinopterygii).^[1][2][3]

Advantages

To account for their success, teleosts must have advantages over earlier fish. In general, teleosts tend to be quicker and more flexible than earlier bony fishes. Their skeletal structure has evolved towards greater lightness. Teleost bones are constructed from a scaffolding of struts, which makes them strong without adding weight.

Teleosts have a movable jaw and changes in the jaw muscles. These changes make it possible for them to protrude their jaws outwards from the mouth.^[4] This adaptation improves their ability to grab fast-moving prey.^[5][6]

Date of origin

The date of origin of the teleosts is a difficult problem. Two kinds of evidence are available. There is evidence from the fossil record that the first teleost comes from the late Triassic period.^[7][8]

This date is somewhat later than molecular divergence time estimates (molecular clock). A recent paper finds that fossil dates and molecular clock dates are similar to each other.^[9] These researchers state:

"Divergence times estimated from relaxed-molecular clock analyses yield a comprehensive time-scale of actinopterygian diversification that is remarkably close to ages inferred from the fossil record".^[9]

Osteichthyes

Actinopterygii 400 mya part of Chondrostei. So the former "Chondrostei" is paraphyletic (not a clade), and has been broken up by more recent studies.[9][10] Polypteridae (bichirs) part of Chondrostei: Acipenseriformes (sturgeons, paddlefish) Neopterygii 360 mya Holostei (bowfins, gars) 275 mya Teleostei 210 mya Sarcopterygii Actinistia (Coelacanths) Dipnoi (Lungfish) Tetrapods Amphibians Amniota Mammals Sauropsids (reptiles, birds)

Evolution of ray-finned fish

Teleost superorders

Teleostei

• Osteoglossomorpha (freshwater elephantfish, mooneyes, Arapaima)
• Elopomorpha (eels)
• Clupeomorpha (herrings, anchovies)
• Ostariophysi (carp, goldfish, minnows, catfish, piranha, electric eels)
• Protacanthopterygii (salmon, trout, pike)
• Stenopterygii (marine hatchetfish)
• Cyclosquamata (Bombay duck. lancetfish)
• Scopelomorpha (lanternfish)
• Lampridiomorpha (ribbonfish)
• Polymyxiomorpha (beardfish)
• Paracanthopterygii (cavefish, cod, anglerfish)
• Acanthopterygii (mullet, silverside, dory, flyingfish, stickleback, seahorse)
  • 16 Orders, and especially the Order Perciformes (40% of all fish): bass, cichlid, mackerel, tuna, perch, filefish, pufferfish, flatfish, goby, blenny, whiting, wrasse)