Oryctocephalids (Corynexochida: Trilobita) of the Lower-Middle Cambrian boundary interval from California and Nevada

Seven species of oryctocephalids occur in the Lower to Middle Cambrian boundary strata of the southern Great Basin. These include Oryctocephalites palmeri n. sp. and an Oryctocephalinae species from the uppermost Lower Cambrian (upper Olenellus Biozone); Oryctocephalus indicus (Reed, 1910), Microryctocara nevadensis n. gen. and n. sp., and Oryctocephalites rasettii n. sp. near the base of the Middle Cambrian (lower Plagiura Biozone); and Oryctocephalus primus Walcott, 1886, and Oryctocephalus nyensis Palmer, 1979, from slightly higher strata (upper Plagiura Biozone). Oryctocephalus and Oryctocephalites are emended based on a cladistic analysis of Oryctocephalinae Beecher, 1897.