Alternative spelling: Librostoma
Full reference: R. A. Fortey. 1990. Ontogeny, hypostome attachment and trilobite classification. Palaeontology 33(3):529-576
Parent taxon: Trilobita according to M. C. Ebach and K. J. McNamara 2002
See also Fortey 1990 and Hughes 1994
Sister taxa: Aglagalia, Agraulaeva, Aguaraya, Aldonaiidae, Altajaharpes, Amechilus, Amgaspididae, Ampellatocephalina, Anacopodia, Antagmidae, Antatlaeva, Atopidae, Auritamidae, Avoninidae, Batchatiella, Bathynotidae, Beikedamaspis, Bergerolimbus, Burlingiidae, Changshaniidae, Chinensis, Corynexochida, Crossoura, Curiaspis, Cuyanaspis, Cyclolenzellina, Dalmanites troosti, Deltacare, Devonocoryphe, Edganocare, Elleria, Elleria morani, Ellipsocephaloididae, Ellipsuella, Entomostracites, Erbenochile, Eulomella, Eutrilobita, Fabulaspis, Faciura, Gentilaspis, Gigmpeltis, Goycoia, Harpetida, Helioproetoides, Holocephalinidae, Howelluella, Idiorapha, Ignotogregatidae, Indigestus, Irvingelloides, Ishpella, Isocolidae, Issafenia, Ityophoridae, Jamrogiidae, Jonotus, Juriietella, Kamlacus, Kanfuqingia, Leptopilus, Lichida, Llanoaspididae, Loxopeltis, Lusampa, Mapaniidae, Megalaspidicus, Meneghinella, Metapopristis, Monkaspididae, Moolatrilo, Moretaeva, Moretarva, Namanoiidae, Neochilonorria, Neomalungia, Neotaenicephalus, Nepeidae, Odontopleurida, Olenida, Onchonotopsidae, Opisthoparia, Orictocara, Otekmaspis, Otenaspella, Paichiashania, Paleoaethia, Parakingaspidoides, Pararania, Peculicephalina, Perissopyge, Phacopida, Piliolites, Pliomerellus, Poculicephalina, Polycyrtaspididae, Prodamesella, Proetida, Proparia, Pseudoacicaudus, Pseudoclelandia, Pseudocrecephalaspina, Pseudosalteria, Pseudosarkia, Pseudotermierella, Ptyttstrigis, Punctaspis, Redlichiida, Remopleuridacea, Repinaella, Resseria, Resseropsis, Rochaeva, Sarkiidae, Serksia, Serksioides, Sibiriopeltis, Sphaerocare, Spizharaspis, Stittaspis, Sukhanaspis, Sunaspididae, Taidonurus, Taplimella, Tazemmourtia, Thymurus, Toxotis, Trapezocephalina, Triarthrella, Trilobus, Tuberaspis, Tuyunaspis, Ulrickaspis, Utiidae, Westergardia, Winsteria, Wuaniidae, Zigzuella
Subtaxa: Asaphida Ptychopariida Trinucleida
Ecology: fast-moving low-level epifaunal carnivore