Prehistoric fish are those primitive species that are identified only through fossil data and archaeological evidence. As we all know, fish were the first forms of vertebrates to flourish on the planet, and were followed by amphibians and terrestrial animals. It is very intriguing to discuss the characteristics of ancient fish and how other advanced lifeforms have evolved from them. (Note: The branch of study that deals with prehistoric fish is referred to as paleoichthyology.) Prehistoric Fish List The first species of fish was thought to have existed in the Cambrian period of the Paleozoic era. When we say 'prehistoric fish', we refer to those species that survived from the Cambrian period to the Tertiary period. Fossil records suggest that ostracoderms, jawless fish with shelled skin, were the earliest species that survived somewhere about 510 million years ago. They became extinct in the Devonian period. They were followed by placoderms, the jawed fish, which thrived from the early Devonian to the late Devonian period. Likewise, several species came and went with time. Listed below are prehistoric species of fish, which are now extinct. List of Jawless Fish

• Myllokunmingia
• Drepanaspis
• Arandaspis
• Boreaspis
• Haikouichthys
• Doryaspis
• Pteraspis
• Thelodus
• Tremataspis
• Hemicyclaspis
• Pharyngolepis
• Astraspis
• Errivaspis
• Dartmuthia
• Jamoytius

List of Placoderms and Acanthodians

• Pterichthyodes
• Bothriolepis
• Cretoxyrhina
• Coccosteus
• Dunkleosteus
• Cretoxyrhina
• Groenlandaspis
• Materpiscis
• Gemuendina
• Ctenurella
• Cheiracanthus
• Culmacanthus
• Ischnacanthus
• Acanthodes

List of Cartilaginous Fish

• Carcharocles megalodon
• Carcharocles angustidens
• Deltoptychius
• Cladoselache
• Heliobatis
• Helicoprion
• Cobelodus
• Ischyodus
• Otodus obliquus
• Sclerorhynchus
• Scapanorhynchus
• Hybodus
• Stethacanthus
• Squalicorax
• Spathobathis

List of Basal Ray-finned Fish

• Canobius
• Moythomasia
• Cheirolepis
• Aspidorhynchus
• Pycnodus
• Platysomus
• Semionotus
• Dapedium
• Palaeoniscum
• Saurichthys
• Perleidus
• Lepidotes

List of Modern Ray-finned Fish

• Sphenocephalus
• Enchodus
• Hypsidoris
• Hypsocormus
• Pholidophorus
• Knightia
• Protobrama
• Leptolepis
• Berycopsis
• Gyrosteus
• Thrissops
• Gryouchus
• Eobothus

List of Fleshy-lobed Fish

• Eusthenopteron
• Strunius
• Griphognathus
• Dipnorhynchus
• Gyroptychius
• Holoptychius
• Chinlia
• Osteolepsis
• Dipterus
• Macropoma

Prehistoric 'Survivors' Recently extinct species of fish are not included in the category of prehistoric fish; rather, they are studied under the category of extinct fish. There are some prehistoric species that are found alive even today. They are called the 'living fossils'. Believed to be already extinct, these species made an appearance from nowhere and took the scientific fraternity by surprise. These fish are very rare in occurrence and possess certain features similar to those of extinct forms. Coelacanth A living coelacanth (Latimeria Chalumnae) was discovered for the first time in 1938 by a South African museum curator. The characteristic feature of this marine species is their paired lobed-fins, which resemble legs in function. Owing to this feature, this species is considered the base organism for evolution of amphibians. White Sturgeon Sturgeon is known to have evolved around 200 million years ago. It is the largest freshwater fish of those times, measuring about 20 feet in length and weighing approximately 1,500 pounds. Sturgeon is popular for the acrobatic behavior it displays when it is threatened or hooked. With several conservation programs in place, the population of white sturgeon has increased to about 50,000. Frilled Shark A frilled shark was caught in Japan by a fisherman in 2007. Later, it was handed over to Japan's Awashima Marine Park. It is another rare prehistoric fish that lives in the deepest part of the ocean. Scientists were unaware as to why this bottom dwelling fish was swimming near the surface. Unfortunately, the fish died after a few hours, leaving the curiosity of scientists unanswered. According to scientists, Dunkleosteus terrelli was a giant prehistoric fish belonging to the placoderms. It had the most powerful jaws of any fish. Be it a shark or huge crustacean, this marine beast gutted anything that came its way. Taking its powerful jaws into consideration, Dunkleosteus was believed to be the dominant predator of the Devonian period. Scientists though, are unsure about its level in the food chain. Nevertheless, species like Dunkleosteus terrelli make living fossils the subject of common interest among scientists and eccentric explorers.