Trilobita - Trinucleida - Trinucleidae
Parent taxon: Trinucleidae according to H. J. Harrington and A. F. Leanza 1957
Sister taxa: Anebolithus, Auritolithus, Bergamia, Bettonolithus, Botrioides, Costonia, Cryptolithinae, Cryptolithoides, Cryptolithus, Deanaspis, Decordinaspis, Eirelithus, Famatinolithus, Furcalithus, Guandacolithus, Gymnostomix, Hanchungolithinae, Hanchungolithus, Incaia, Jianxilithus, Lloydolithus, Lordshillia, Marekolithus, Marrolithinae, Marrolithoides, Marrolithus, Microdiscus, Myinda, Myindella, Myttonia, Nankinolithus, Ningkianolithus, Novaspis, Onnia, Paratretaspis, Paratrinucleus, Parkesolithus, Protolloydolithus, Reedolithus, Reuscholithus, Salterolithus, Stapeleyella, Telaeomarrolithus, Trinucleinae, Trinucleus, Whittardolithus, Xiushuilithus, Yinpanolithus
Subtaxa: none
Ecology: fast-moving low-level epifaunal suspension feeder
Distribution: there are no occurrences of Tretaspidinae in the database