337 Triassic Cyrtinoid Spiriferinacean Brachiopods from Western N. America

Cyrtinoid spiriferinacean brachiopods in samples from over fifty Late Triassic marine fossil localities in western North America include examples of three species of Spondylospira Cooper, 1942, one of which (S. tricosta) is new; one new species of Zugmayerella Dagys, 1963; and four new monotypic genera, represented by Dagyspirifer fascicostala, Phenacozugmayerella inimunicinata, Pseudospondylospira perplexa, and Vitimetula parva, all new species. In North America, all of these genera are limited to the Kamian and/or Norian. One species, Spondylospira incosta, n. sp. appears to be a good indicator of the early Norian. The family Laballidae of earlier workers is divided into the family Laballidae and the new family Spondylospiridae, based on absence or presence, respectively, of functional pedicle foramena; the latter family is divided into two new subfamilies, Spondylospirinae and Dagyspiriferinae, based on the form of those foramena.

Two features of cyrtinoid spiriferinacean species biogeography have tectonostratigraphic implications. First, there are no "Tethyan" species among them, and second, the nine species of cyrtinoid spiriferinaceans reported here are predominantly confined to the Americas, including both cratonal and terrane belt localities. Biogeographic evidence from the cyrtinoids, therefore, does not support close links between terranes of the present-day eastern and western Pacific.

Cyrtinoid spiriferinaceans provide abundant evidence of biogeographic "stitching" of various terranes. For example, Pseudospondylospira perplexa, Spondylospira lewesensis, and Spondylospira tricosta occur in localities that are craton-bound as well as in parautochthonous and allochthonous localities.    

Year published: 1991