30708 - Top Beautiful 3.43 Inch Crotalocephalina (Crotalocephalus) gibbus Lower Devonian Trilobite Prionocheilus It is the canine tooth

It is the canine tooth of a primitive mammal that lived together with the dinosaurs during the Cretaceous period

Ptychagnostus spinosus

Type: Prionocheilus verneuili

which probably functioned as gills

30708 - Top Beautiful 3.43 Inch Crotalocephalina (Crotalocephalus) gibbus Lower Devonian Trilobite Prionocheilus It is the canine toothCrotalocephalina sp, Pibyl and Vanek 1964 (trilobite) Trilobita Phacopida Cheiruridae Parent taxon: Cheiruridae according to P. A. Jell and J. M. Adrain 2002 See also Sepkoski 2002 Sister taxa: Acanthoparyphinae, Anasobella, Ancyginaspis, Arcticeraurinella, Areia, Areiaspis, Borealaspis, Bornholmaspis, Ceraurinium, Ceraurinus, Cerauroides, Cerauromeros, Cerauropeltis, Ceraurus, Chacomurus, Cheirurinae, Cheirurus, Chiozoon, Contracheirurus,