Echinosaurus - Echinosaurus

...They are called acanthognathus because they have sharp spines on their dorsal, pectoral and anal fins (some books say sticklebacks, but sticklebacks are a completely different species of fish that belong to the Teleostei superfamily of the Actinopterygii subclass of the Osteichthyes). Acanthognathus was once considered to be closely related to cartilaginous fishes and was sometimes translated as echinoid sharks, but recently the theory that they are closer to the ancestors of bony fishes has gained momentum. Acanthognathus has well-developed eyes and many have teeth in their jaws. ...

*Some of the terminology that refers to "spinosaurs" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…背びれ，胸びれ，しりびれなどに鋭いとげがあるので棘魚類とよばれている(トゲウオ類と書かれている本もあるが，トゲウオ類は現生の硬骨魚綱条鰭（じようき）亜綱真骨上目に属するまったく別の魚類である)。棘魚類はかつて軟骨魚類に近縁とされ，棘鮫（きよくこう）類と訳されたこともあったが，最近は硬骨魚類の祖先に近いという説が強い。棘魚類はよく発達した眼をもち，あごには歯があるものが多い。…

※「棘鮫類」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報