Eusthenopteron

Eusthenopteron is an extinct genus of lobe-finned fishes that lived in the Late Devonian. Its fossils preserve limb-like fin bones shared with early tetrapods, illuminating the transition from fish to land vertebrates.

Sarcopterygii: Sarcopterygii is the vertebrate group comprising lobe-finned fishes and their tetrapod descendants. Eusthenopteron belongs to this lineage, whose paired fins contain internal bones.
Fin-to-limb transition: The fin-to-limb transition is the evolutionary transformation of paired fish fins into limbs capable of supporting movement on land. Eusthenopteron documents an early stage, with limb-like bones still housed in fins.
Miguasha National Park: Miguasha National Park in Quebec preserves a celebrated Late Devonian fossil fish assemblage. Its fossil beds yielded many of the specimens that established Eusthenopteron’s anatomy.
Edward Drinker Cope: Edward Drinker Cope was an American paleontologist who described numerous fossil vertebrates in the nineteenth century. Cope named Eusthenopteron from fossils collected in Quebec in the late nineteenth century.
Tetrapodomorpha: Tetrapodomorpha is the sarcopterygian lineage more closely related to tetrapods than to living lungfish or coelacanths. Eusthenopteron is an early member of the fish lineage leading toward tetrapods.
Humerus: The humerus is the single upper-arm bone connecting the shoulder to the forearm in tetrapods. A corresponding proximal bone occurs in Eusthenopteron’s pectoral fin skeleton.
Escuminac Formation: The Escuminac Formation is a Late Devonian fossil-bearing sedimentary formation in Quebec, Canada. Most well-known Eusthenopteron fossils come from this formation’s ancient aquatic deposits.
J. F. Whiteaves: J. F. Whiteaves was a British-Canadian paleontologist who studied and described Canadian fossils. Whiteaves formally described Eusthenopteron in 1881 from material collected at Miguasha.
Tetrapod: Tetrapods are vertebrates descended from the first four-limbed animals, including amphibians, reptiles, birds, and mammals. The shared ancestry of Eusthenopteron and tetrapods frames its evolutionary significance.
Radius and ulna: The radius and ulna are the paired bones of the tetrapod forearm, extending from the humerus to the wrist. Two bones distal to the proximal fin element echo the tetrapod forearm arrangement.

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