Abstract

Three major groups of Llandoverian to Eifelian chonetids are recognized: the Chonetidae, the Anopliidae, and the Chonostrophiidae. The relationship of these groups to each other and to the enigmatic genera Notiochonetes and Allanetes are not known. Protochonetes is considered to have given rise to Strophochonetes, Chonetes, Parachonetes, Eccentricosta, Dawsonelloides n.g., and possibly Longispina; Chonetes to have given rise to Eodevonaria and Plebejochonetes n.g.; Plebejochonetes n.g. to Plicodevonaria n.g. Chonostrophia was derived from Chonostrophiella, Shagamella n.g. and Eoplicanoplia n.g. are considered to share a common ancestry, Shagamella n.g. gave rise to Anoplia; Eoplicanoplia n.g. to Plicanoplia n.g. which, in turn, gave rise to Cyrtoniscus n.g. Lower Devonian chonetids are notably provincial in their geographic distribution. Seven new genera are defined: Plebejochonetes n.g. from the lower Devonian and Eifelian of Europe & Turkey; Plicodevonaria n.g. from the lower Devonian and Eifelian of Europe, Turkey, Morocco, and Burma; Dawsonelloides n.g. from the lower Devonian of the northern Appalachians; Shagamella n.g. from the Ludlow of Britain and Venezuela; Eoplicanoplia n.g. from the Ludlow of North America; Plicanoplia n.g. from the lower Devonian of North and South America; and Cyrtoniscus n.g. from the lower Devonian of northeastern North America. The family Anopliidae is revised. The family Eodevonariidae Sokolskaja, is placed in the synonomy of the Chonetinae.

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