Artiopoda including Trilobita

Gnathobases are known to occur in Artiopoda, including in trilobites, the most well-known artiopod group, as well as others like Sidneyia.

In Mandibulata

Mandibles, the eponymous appendages of the Mandibulata, may have originated from thoracic legs possessing gnathobasic endites.

Crustacea