Cladistia, polypterids and their fossil relatives, are considered the sister group to all other extant ray-finned fishes (Actinopteri). They likely diverged from Actinopteri at least 330 million years ago. A closely related group, the Scanilepiformes, are known from the Triassic, and are likely ancestral to polypterids. The oldest polypterids are around 100 million years old, from the early Late Cretaceous of South America and Africa.
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^Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Publishing. 720 p.
^Dai Suzuki, Matthew C. Brandley, Masayoshi Tokita: CORRECTION: The mitochondrial phylogeny of an ancient lineage of ray-finned fishes (Polypteridae) with implications for the evolution of body elongation, pelvic fin loss, and craniofacial morphology in Osteichthyes. BMC Evolutionary Biology. Bd. 10, Art.-Nr. 209, 2010, doi:10.1186/1471-2148-10-209