Evolution of fish
Devonian: Age of fishes

Evolution of fish

Section Title: Devonian: Age of fishes
Table Section Text: None

Devonian (419–359 mya): The start of Devonian saw the first appearance of lobe-finned fish, precursors to the tetrapods (animals with four limbs).

D e v o n i a n	Early Devonian	Early Devonian (419–393 Ma):

-	Psarolepis	Psarolepis (speckled scale) is a genus of extinct lobe-finned fish that lived around 397 to 418 Ma. Fossils of Psarolepis have been found mainly in South China and described by paleontologist Xiaobo Yu in 1998.

-	Holoptychius	Holoptychius is an extinct genus from the order of porolepiform lobe-finned fish, extant from 416 to 359 Ma. It was a streamlined predator about 50 centimetres (20 in) long (though it could grow up to 2.5 m), which fed on other bony fish.

-	Ptyctodontida	The ptyctodontids (beak-teeth) are an extinct monotypic order of unarmored placoderms, containing only one family. They were extant from the start to the end of the Devonian.

-	Petalichthyida	The Petalichthyida was an order of small, flattened placoderms that existed from the beginning of the Devonian to the Late Devonian.

-	Laccognathus	Laccognathus (pitted jaw) was a genus of amphibious lobe-finned fish that existed 398–360 Ma. They were characterized by the three large pits (fossae) on the external surface of the lower jaw, which may have had sensory functions.

Middle Devonian	Middle Devonian (393–383 Ma): Cartilaginous fishes, consisting of sharks, rays and chimaeras, appeared about 395 Ma.

-	Dipterus	Dipterus (two wings) is an extinct genus of lungfish from 376–361 Ma. It was about 35 centimetres (14 in) long, mostly ate invertebrates, and had lungs, not an air bladder.

-	Cheirolepis	Cheirolepis (hand fin) was a genus of ray-finned fishes. It was among the most basal of the Devonian ray-finned fishes and is considered the first to possess the "standard" dermal cranial bones seen in later ray-finned fish.

-	Cladoselache	Cladoselache was the first abundant genus of primitive shark, appearing about 370 Ma. It grew to 6 feet (1.8 m) long, with anatomical features similar to modern mackerel sharks.

-	Coccosteus	Coccosteus (seed bone) is an extinct genus of arthrodire placoderm. The majority of fossils have been found in freshwater sediments, though they may have been able to enter saltwater.

-	Bothriolepis	Bothriolepis (pitted scale) was the most successful genus of antiarch placoderms, if not the most successful genus of any placoderm, with over 100 species spread across Middle to Late Devonian strata across every continent.

-	Pituriaspida	Pituriaspida (hallucinogenic shield) is a class containing two bizarre species of armoured jawless fishes with tremendous nose-like rostrums. They lived in estuaries around 390 Ma.

Late Devonian extinction: 375–360 Ma. A prolonged series of extinctions eliminated about 19% of all families, 50% of all genera and 70% of all species.

Late Devonian	Late Devonian (383–359 Ma):

-	Dunkleosteus	Dunkleosteus is a genus of arthrodire placoderms that existed from 380 to 360 Ma. It grew up to 10 metres (33 ft) long and weighed up to 3.6 tonnes.

-	Titanichthys	Titanichthys is a genus of giant, aberrant marine placoderm that lived in shallow seas. Many of the species approached Dunkleosteus in size and build.

Materpiscis02.JPG	Materpiscis	Materpiscis (mother fish) is a genus of ptyctodontid placoderm from about 380 Ma. Known from only one specimen, it is unique in having an unborn embryo present inside, and with remarkable preservation of a mineralised placental feeding structure (umbilical cord).

-	Hyneria	Hyneria is a genus of predatory lobe-finned fish, about 2.5 m (8.2 ft) long, that lived 360 million years ago.

-	Rhizodonts	Rhizodonts were an order of lobe-finned fish that survived to the end of the Carboniferous, 377–310 Ma. They reached huge sizes.

Sentence(s)

Cartilaginous fishes, consisting of sharks, rays and chimaeras, appeared by about 395 million years ago, in the middle Devonian.

final_sentence: Cartilaginous fishes, consisting of sharks, rays and chimaeras, appeared by about 395 million years ago, in the middle Devonian.