Palaeonisciformes

fossil fish order

Also known as: palaeonisciform

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July 1, 2026

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The Palaeonisciformes were an order of extinct, primitive ray-finned fishes that existed from the Devonian to the Lias periods. These fish, belonging to the family Palaeoniscidae, were characterized by an elongated body covered in rhombic plates, small pectoral and ventral fins, a single dorsal and anal fin, and a heterocercal tail. Their skulls were covered with bony plates, and their jaws bore small teeth.1

The Palaeonisciformes represent the basal actinopterygian stock from which all other chondrosteans and holosteans evolved. They were the most common fishes of their time, though they were relatively small and had peculiar jaws and tails compared to modern fish. While they gave rise to many different types of fish, almost all were eventually replaced by modern teleosts.2

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chondrostean
Evolution
…were those of the order Palaeonisciformes, a label derived from a Greek word meaning “ancient scale.” Like the living members of Chondrostei, the order Palaeonisciformes is not a natural group but rather a series of families connected by interrelationships that are poorly understood. These fishes possessed essentially the same feeding…
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…were those of the order Palaeonisciformes, a label derived from a Greek word meaning “ancient scale.” Like the living members of Chondrostei, the order Palaeonisciformes is not a natural group but rather a series of families connected by interrelationships that are poorly understood. These fishes possessed essentially the same feeding…
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fish
Actinopterygii: ray-finned fishes
Palaeonisciformes often had large eyes placed far forward, long mouths with the upper jaw firmly bound to the fully armoured cheek, and a relatively weak lower jaw muscle. They gave rise to a great variety of types, with elongate bodies and jaws, bottom-living types that…
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Palaeonisciformes often had large eyes placed far forward, long mouths with the upper jaw firmly bound to the fully armoured cheek, and a relatively weak lower jaw muscle. They gave rise to a great variety of types, with elongate bodies and jaws, bottom-living types that…
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sturgeon
…group of fishes called the palaeonisciforms, which appeared at the end of the Silurian Period (about 419 million years ago). The genera Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus contain living species of sturgeons.
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…group of fishes called the palaeonisciforms, which appeared at the end of the Silurian Period (about 419 million years ago). The genera Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus contain living species of sturgeons.
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