DOI: 10.5061/dryad.dz08kps8b
title: Phylogenetic position and stratigraphic uncertainty of a new flexible crinoid from the Ordovician–Silurian boundary of Anticosti Island (Quebec, Canada)

description: Fossil crinoids from the Ordovician–Silurian boundary interval (~ 443.8
 million years) are known from relatively few locations worldwide due to a
 near-global unconformity that formed from eustatic sea level fall. This
 rock record bias has severely hindered study of the timing, magnitude,
 biogeographic signature, and extinction mechanisms of the Late Ordovician
 mass extinction (LOME). Crinoids underwent a significant faunal transition
 between the Late Ordovician and early Silurian that resulted in major
 shifts between dominant clades, but the driving mechanisms and precise
 timing of this transition remain unclear. Anticosti Island (Quebec,
 Canada) preserves one of the few Late Ordovician–early Silurian
 successions of highly fossiliferous, shallow-water rocks that includes the
 O–S boundary, making fossils from this region instrumental for better
 understanding the LOME and Ordovician–Silurian crinoid faunal turnover.
 Here, we report on a new flexible crinoid, Anticosticrinus natiscotecensis
 n. gen. n. sp., from the Ordovician-Silurian boundary of Anticosti Island.
 Phylogenetic analysis of Middle Ordovician-early Silurian flexibles
 recovers Anticosticrinus natiscotecensis n. gen. n. sp. as a member of
 Family Anisocrinidae. We quantified stratigraphic age uncertainty of A.
 natiscotecensis using a Bayesian approach for estimating tip-occurrence
 times in a phylogenetic context. Although results do not provide
 unequivocal support for the specimen’s precise stratigraphic age, the
 maximum a posteriori estimate indicates a late Hirnantian age. Regardless
 of its true age, recognition of Anticosticrinus natiscotecensis provides
 additional data for evaluating the timing of extinction in flexible
 crinoids, their diversification and increasing dominance during the
 Silurian, and crinoid faunal turnover between the Ordovician and Silurian.
description: # Phylogenetic position and stratigraphic uncertainty of a new flexible
 crinoid from the Ordovician–Silurian boundary of Anticosti Island (Quebec,
 Canada) Dataset DOI: [10.5061/dryad.dz08kps8b](10.5061/dryad.dz08kps8b) ##
 Description of the data and file structure Nexus file containing character
 data for 25 species of flexible crinoids and commands to conduct the three
 phylogenetic analyses presented in: Cole, Wright, and Hopkins,
 Phylogenetic position and stratigraphic uncertainty of a new flexible
 crinoid from the Ordovician-Silurian boundary of Anticosti Island (Quebec,
 Canada), Journal of Paleontology. ### Files and variables #### File:
 Flexibles\_phylogenetic\_analyses.nex **Description:** This nexus file
 includes a summary of the characters and character states associated with
 the matrices/analyses; and character data and commands to run the
 following three phylogenetic analyses: (1): Maximum parsimony (PAUP*) (2):
 Bayesian inference (topology only; MrBayes) (3): Bayesian fossil
 tip-dating (divergence time estimation; MrBayes) To run an analysis from
 the .nex file, be sure that the correct matrix and commands have their
 brackets (i.e., []'s) removed, then execute the .nex file in the
 appropriate program (PAUP* or MrBayes). ## Code/software Programs needed
 to execute phylogenetic analyses are: * PAUP* v4.0a149 (Swofford, 2003)
 for the parsimony analysis * MrBayes 3.2.6 (Ronquist et al., 2012) for the
 Bayesian inference and Bayesian fossil tip-dating analyses References:
 Swofford, D.L., 2003, PAUP*: phylogenetic analysis using parsimony (*and
 other methods), version 4: Sinauer Associates, MA. Ronquist, F.,
 Klopfstein, S., Vilhelmsen, L., Schulmeister, S., Murray, D.L., and
 Rasnitsyn, A.P., 2012, A Total-Evidence Approach to Dating with Fossils,
 Applied to the Early Radiation of the Hymenoptera: Systematic Biology, v.
 61, p. 973–999.