Trichiurides sagittidens was a predatory teleost known almost entirely from distinctive laniary teeth. The teeth are tall, narrow and strongly recurved, with a sharp cutting edge and a large posterior barb. This is direct evidence for a prey-grasping dentition designed to resist escape once a fish or other soft-bodied animal had been impaled.

Its precise systematic position remains uncertain because isolated teeth provide far less anatomical information than a skull or skeleton. The feeding function, however, is much clearer than the ancestry: these were specialised predatory teeth, not crushing or grazing structures. The species is therefore best understood as a tooth-defined carnivorous morphotype within the London Clay teleost fauna.