Translator Disclaimer
30 August 2019 Fusion or hypertrophy?: the unusual arms of the Petalocrinidae (Ordovician-Devonian: Crinoidea)
Author Affiliations +
Abstract

Using polarized light microscopy, the large, triangular or cylindrical second brachial plate of the Petalocrinidae is demonstrated to be a compound brachial formed through fusion of brachial plates along the distal margin of the growing arms. Based on the number of ambulacral bifurcations, brachials from the primibrachitaxis through at least the quintibrachitaxis may have been fused to form this large plate. In Petalocrinus, fused brachials form a second brachial that assumed the same crystallographic orientation, but in Spirocrinus, multidirectional extinctions preserve some of the original multiplate arrangement.

Copyright © 2019, The Paleontological Society
William I. Ausich, Yingyan Mao, and Yue Li "Fusion or hypertrophy?: the unusual arms of the Petalocrinidae (Ordovician-Devonian: Crinoidea)," Journal of Paleontology 93(5), 966-970, (30 August 2019). https://doi.org/10.1017/jpa.2019.25
Accepted: 30 March 2019; Published: 30 August 2019
JOURNAL ARTICLE
5 PAGES


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