The Corynexochina (Trilobita): a poorly understood suborder

Abstract

Trilobites of this suborder from Europe and North America have not been studied in detail, in contrast to the attention given to relationships within the orders Agnostida and Ptychopariina. The basis of the Corynexochina is the type species of Corynexochus from the middle Cambrian of Sweden. The type material redescribed here is only the cranidium, and is inadequate for diagnosis of the genus. A species attributed to this genus occurring in the Cambrian of southern France is represented by entire dorsal exoskeletons and is urgently in need of redescription. Similar material is recorded in northern Spain. Both complete exoskeletons and growth stages of Corynexochina have been described from Cambrian strata in Russia, Australia, Morocco and China, showing the wide geographical range and varied morphology of the Suborder. The type species of two genera from boulders of middle Cambrian age found in Quebec, Canada, are redescribed from exceptionally well preserved, though small, specimens. They appear to represent a distinct group related to some of the Zacanthoididae. Families of Corynexochina are inadequately discriminated one from another, so that a family name can only be used with question. Until this is remedied, diagnosis of a new group is not possible.