DOI: 10.5061/dryad.30k44
title: Data from: Water vascular system architecture in an Ordovician ophiuroid

description: Understanding the water vascular system (WVS) in early fossil echinoderms
 is critical to elucidating the evolution of this system in extant forms.
 Here we present the first report of the internal morphology of the water
 vascular system of a stem ophiuroid. The radial canals are internal to the
 arm, but protected dorsally by a plate separate to the ambulacrals. The
 canals zig-zag with no evidence of constrictions, corresponding to
 sphincters, which control pairs of tube feet in extant ophiuroids. The
 morphology suggests that the unpaired tube feet must have operated
 individually, and relied on the elasticity of the radial canals, lateral
 valves and tube foot musculature alone for extension and retraction. This
 arrangement differs radically from that in extant ophiuroids, revealing a
 previously unknown Palaeozoic configuration.
description: 3D Maya model of
 Protasterina flexuosa Arm3D Maya model of portion
 of the arm of Protasterina flexuosa constructed using extracted volumes of
 micro-CT scans of CMC 25001. See legend of figure 2 in main text of
 publication for details.WVS
 Model.mbAmbulacral Ossicle
 Triangular MeshRaw STL triangular mesh
 of P. flexuosa ambulacral ossicle used in Maya model. See legend of figure
 2 in main text of publication for details.Ambulacral.stlLateral Ossicle Triangular MeshRaw STL triangular mesh of P. flexuosa lateral ossicle used in Maya model. See legend of figure 2 in main text of publication for details.Lateral.stlOssicle A Triangular MeshRaw STL triangular mesh of P. flexuosa ossicle A used in Maya model. See main text of publication for ossicle description and legend of figure 2 for details regarding the creation of this file.Ossicle_A.stlStructure B Triangular MeshRaw STL triangular mesh of P. flexuosa structure B used in Maya model. See main text of publication for structure description and legend of figure 2 for details regarding the creation of this file.Structure_B.stlWater Vascular SystemRaw STL triangular mesh of P. flexuosa water vascular system used in Maya model. See legend of figure 2 in the main text of publication for details.WVS.stlScan A: Protasterina flexuosa (CMC 25001)Micro-CT scan of Protasterina flexuosa (CMC 25001) using the North Star Imaging micro-CT scanner housed at Vanderbilt University (Tennessee, USA). 1170 two-dimensional images were generated with a voxel size of 29.3 microns at a voltage of 100kV and current of 62 microamps. Volume was reconstructed using EFX-CT. Users should contact authors prior to file use other than corroborating data presented in paper.Scan A.zipScan B: Protasterina flexuosa (CMC 25001)Micro-CT scan of Protasterina flexuosa (CMC 25001) using a Nikon XTek XT H225 scanner (Tokyo, Japan). 3200 two-dimensional images were generated with a voxel size of 6.0 microns at a voltage of 85 kV and current of 90 microamps. Volume was reconstructed using Nikon CTPro 3D (Tokyo, Japan). Users should contact authors prior to file use other than corroborating data presented in paper.Scan B.zipScan CMicro-CT scan of Protasterina flexuosa (CMC 25001) using a Nikon XTek XT H225 scanner (Tokyo, Japan). 3200 two-dimensional images were generated with a voxel size of 10.4 microns at a voltage of 85 kV and current of 90 microamps. Volume was reconstructed using Nikon CTPro 3D (Tokyo, Japan). Users should contact authors prior to file use other than corroborating data presented in paper.