Acanthomorpha (meaning "thorn-shaped") is an extraordinarily diverse taxon of teleost fishes with spiny fin rays.

[3] A key anatomical innovation in acanthomorphs is hollow and unsegmented spines at the anterior edge of the dorsal and anal fins.

[5] Another shared feature is a particular rostral cartilage, associated with ligaments attached to the rostrum and premaxilla, that enables the fish to protrude its jaws considerably to catch food.

[6] Rosen coined the name in 1973 to describe a clade comprising Acanthopterygii, Paracanthopterygii, and also ctenothrissiform fossils from the Cretaceous period, such as Aulolepis and Ctenothrissa.

[7] The oldest acanthomorphs were initially reported by Louis Agassiz from the Cenomanian Sannine Formation of Lebanon, and were considered as such for over a century until slightly older remains were identified from the end-Albian of Mexico.