Acrotemnus is an extinct genus of marine pycnodontid ray-finned fish known from Europe, North America, and Africa during the Turonian stage of the Upper Cretaceous.

[2][5] Acrotemnus was initially known from just the type species A. faba described by Louis Agassiz in 1843 from specimens collected in England.

In 2010, Shimada, Williamson & Sealey described a gigantic pycnodont known from a few tooth plates found in New Mexico as Macropycnodon megafrendodon, placing C. streckeri in the same genus.

[1] However, in 2021, Shimada, Portillo, and Cronin described a partial skeleton of a pycnodont from Texas as potentially being a specimen of A. streckeri.

This specimen revealed close similarities between the anatomy of Macropycnodon and Acrotemnus, leading to the lumping of the former into the latter.