An echinoderm Lagerstatte from the Upper Ordovician (Katian), Ontario: taxonomic re-evaluation and description of new dicyclic camerate crinoids

摘要

The Upper Ordovician (lower Katian) Bobcaygeon and Verulam formations from the Lake Simcoe region of Ontario contain a highly diverse echinoderm assemblage that is herein recognized as a Konservat-Lagerstatte. Although fossil crinoids have long been recognized from these formations, the fauna has not received a comprehensive taxonomic evaluation since Springer's classic 1911 monograph. Recent extensive collection and preparation of new material from the Bobcaygeon and Verulam formations near Brechin, Ontario recovered numerous exceptionally preserved crinoid specimens with arms, stems, and attachment structures intact. The Brechin Lagerstatte is the most taxonomically diverse Katian crinoid fauna, with more than 20 crinoid genera represented in this collection.