Evolution of fish

Evolution of fish is the history of vertebrate lineages that originated in water, from early jawless forms to modern fishes and the ancestors of land vertebrates.

Haikouichthys: A small Cambrian chordate known from fossils in China, often considered among the earliest vertebrates. Its fossils provide an early glimpse of vertebrate anatomy near the beginning of fish evolution.
Placodermi: An extinct group of armored jawed fishes that flourished during the Devonian Period. Placoderms show an early burst of jawed-fish diversity and varied feeding forms.
Devonian period: A geological period from about 419 to 359 million years ago, marked by major fish diversification. Its aquatic ecosystems hosted an unusually rich expansion of fish forms.
Cyclostomata: The living jawless vertebrate group comprising lampreys and hagfishes. Its members are surviving jawless vertebrates, unlike the many extinct forms once grouped with them.
Devonian diversification: The extensive radiation of fishes during the Devonian Period, sometimes called the Age of Fishes. Its ecological and anatomical variety set patterns that persisted in later aquatic ecosystems.
Conodonts: Extinct chordates known chiefly from microscopic tooth-like elements, with soft-bodied fossils revealing eel-like forms. Their fossils preserve some of the earliest evidence of vertebrate mineralized tissues.
Osteichthyes: The clade of bony vertebrates, including ray-finned fishes, lobe-finned fishes, and tetrapods. Bony fishes produced most living fish diversity and the ancestors of land vertebrates.
Dunkleosteus: A large armored placoderm predator from Devonian seas. It exemplifies the size and predatory specialization reached by some early jawed fishes.
Lamprey: An eel-shaped jawless vertebrate with a round, toothed oral disc. Lampreys offer a living comparison for studying the evolution of vertebrate jaws and feeding.
Evolution of tetrapods: The evolutionary transition from aquatic vertebrates to four-limbed vertebrates and their descendants. It carries one fish lineage into terrestrial habitats and vertebrate life on land.

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Fish anatomyNarrower topic: Anatomical similarities and differences provide evidence for relationships and change over time.