Devonian Fossil Fish Osteolepis macrolepidotus from Scotland
Ancient Tetrapod Ancestor

Osteolepis macrolepidotus

Class Sarcopterygii, Superorder Osteolepidida, Order Osteolepiformes, Family Osteolepidae

Geological Time: Middle Devonian

Size: 175 mm in length

Fossil Site: Cruday Quarry, Orkney, Scotland

Fossil Fish Osteolepis macrolepidotuDescription: The Osteolepiform fish are thought to be the ancestors of the Tetrapoda due to their paired lobed fins being homologous to the limbs, and the choanae (posterior nostril). Osteolepis possessed two rounded dorsal fins placed posteriorly, and a heterocercal tail with a larger lower lobe. They possessedTetrapod Ancestor Fossil Fishthick rhombic scales covered with a cosmine layer, resulting in the shine seen in this fossil. This ancient group of fish is thought to have given rise to the Tetrapod body plan. The fossil has a few additional skull fragments from another specimen.

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