Translator Disclaimer
1 January 2015 A reexamination of Yuknessia from the Cambrian of British Columbia and Utah
Steven T. LoDuca, Jean-Bernard Caron, James D. Schiffbauer, Shuhai Xiao, Anthony Kramer
Author Affiliations +
Abstract

To investigate the phylogenetic affinity of Yuknessia simplex Walcott, 1919, scanning electron microscopy was applied to the Burgess Shale (Cambrian Series 3, Stage 5) type material and to new material from the Trilobite Beds (Yoho National Park) and specimens from the Cambrian of Utah. On the basis of fine-scale details observed using this approach, including banding structure interpreted as fusellae, Yuknessia Walcott, 1919 is transferred from the algae, where it resided for nearly a century, to the extant taxon Pterobranchia (Phylum Hemichordata). Considered as such, Yuknessia specimens from the Trilobite Beds and Spence Formation (Utah) are amongst the oldest known colonial pterobranchs. Two morphs regarded herein as two different species are recognized from the Trilobite Beds based on tubarium morphology. Yuknessia simplex has slender erect tubes whereas Yuknessia stephenensis n. sp., which is also known in Utah, has more robust erect tubes. The two paratypes of Y. simplex designated by Walcott (1919) are formally removed from Yuknessia and are reinterpreted respectively as an indeterminate alga and Dalyia racemata Walcott, 1919, a putative red alga.

Copyright © 2015, The Paleontological Society
Steven T. LoDuca, Jean-Bernard Caron, James D. Schiffbauer, Shuhai Xiao, and Anthony Kramer "A reexamination of Yuknessia from the Cambrian of British Columbia and Utah," Journal of Paleontology 89(1), 82-95, (1 January 2015). https://doi.org/10.1017/jpa.2014.7
Accepted: 1 July 2014; Published: 1 January 2015
JOURNAL ARTICLE
14 PAGES


Share
SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top