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Which tetraodontiform family is considered the most primitive in the order?

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Scrawled filefish (Aluterus scriptus) — tetraodontiform Scrawled filefish (*Aluterus scriptus*)

Within the order Tetraodontiformes, the family Triacanthodidae (spikefishes) is considered the most primitive. These deepwater fishes are characterized by a nonstreamlined body, a truncated or rounded tail, and a deep caudal peduncle.12

While the order as a whole is notable for its diverse anatomical structures and reductive evolutionary trends—such as the loss of certain skeletal elements and fin spines—the Triacanthodidae retain more generalized characteristics compared to other members of the order.13