[9][10] While at one point considered a species of Platecarpus,[6] recent phylogenetic analyses have placed it between the (then) plioplatecarpines Ectenosaurus and Selmasaurus, maintaining a basal position within the plioplatecarpinae.

The phylogenetic relationship of Angolasaurus indicates that individuals of this genus possessed a tail fluke, more forward-lying nostrils,[14] and keeled scales for hydrodynamic efficiency.

[8] The most recent major phylogenetic analysis conducted on the mosasauridae placed Angolasaurus as basal to the clade composed of the russellosaurine subfamilies Tylosaurinae and Plioplatecarpinae, and part of neither.

[8] Angolasaurus bocagei, recovered only from the Itombe Formation, shared its habitat with the tylosaurine species Tylosaurus (formerly Mosasaurus) iembeensis and the durophagous shallow-water turtle Angolachelys.

[citation needed] Other Turonian aquatic reptiles from the Eagle Ford Formation include the plesiosaurs Polyptychodon, Libonectes, Cimoliasaurus, and Plesiosaurus, and the mosasaur Clidastes.