Promegalops signeuxae was another early Eocene tarpon relative from the London Clay. Its cranial anatomy indicates an elongate-headed elopiform, a body plan associated in living relatives with active swimming and capture of smaller fishes and invertebrates. Because the species is known mainly from the head, details such as body depth, fin shape and exact prey remain uncertain.

Three-dimensional skull preservation reveals the organisation of the roof, orbit and posterior braincase. The species is part of a broader London Clay radiation of elopiforms, showing that tarpon-like fishes were already anatomically diverse in the warm marine environments of the Ypresian.