References:
Timothy Paton, Carlton Elliot Brett (2019) Revised stratigraphy of the middle Simcoe Group (Ordovician, upper Sandbian-Katian) in its type area: an integrated approach. Canadian Journal of Earth Science. DOI: 10.1139/cjes-2018-0023
Kammer TW, Sumrall CD, Zamora S, Ausich WI, Deline B (2013) Oral Region Homologies in Paleozoic Crinoids and Other Plesiomorphic Pentaradial Echinoderms. PLoS ONE 8(11): e77989. doi:10.1371/journal.pone.0077989