DOI: 10.5061/dryad.6djh9w166
title: Data from: Newly discovered morphology of the Silurian sea spider Haliestes and its implications

description: The three-dimensionally preserved Haliestes dasos from the Silurian
 (Wenlock) Lagerstätte is the most complete fossil sea spider and the
 oldest unambiguous pycnogonid known from the fossil record. The discovery
 of two new specimens to add to the holotype reveals new features including
 proximal annulations of the appendages and segmentation of the trunk end,
 critical details for comparison with pycnogonids from the Devonian
 (Emsian) Hunsrück Slate and for the interpretation of the evolutionary
 significance of Palaeozoic genera. There is some evidence of sexual
 dimorphism. H. dasos was nektobenthic and its morphology indicates an
 unusual mode of feeding compared to living pycnogonids. The new
 morphological features of H. dasos are closely similar to those in
 Palaeoisopus problematicus from the Hunsrück Slate and it clearly belongs,
 together with that species, in stem Pycnogonida and not the crown group.
description: Specimens of Haliestes dasos were serially-ground and
 photographed at 20 μm intervals using a digital micropscope camera. The
 images were aligned, edited, and used to generate 3D virtual fossils with
 SPIERS software-suite (http://spiers-software.org). Data provided are (a) registered image-sets from serial-grinding,  one set per 'part', and (b) VAXML/STL format models of specimens generated using SPIERS and manual editing (segmentation) and mark-up of the data into separate anatomical elements.
description: Models are in VAXML/STL format. These are ideally viewed with
 SPIERSview (open source and available at http://spiers-software.org), but the mesh-models comprise a series of STL format files which can be combined and viewed in any mesh-viewing software. Note that meshes are correctly positioned within a single coordinate-space to facilitate the latter mode. 
description: # Title of Dataset *** Serial tomography datasets and 3D models for three
 specimens of Haliestes dasos (Euarthropoda, Pycnogonida) from the Silurian
 of Herefordshire, UK. Specimens are accessed in the Oxford University
 Museum of Natural History, and are: OUMNH PAL 29571 (Holotype) OUMNH PAL
 29656 OUMNH PAL 29661 ## Description of the data and file structure ###
 Overview Data for all three specimens comprises: (a) RGB images in bmp
 format representing tomographic datasets from 20-micron interval manual
 serial grinding. These have been registered and cropped to ROI. For each
 specimen they comprise multiple parts, each representing separate
 fragments of the original specimen that were subjected to serial grinding.
 Scaling information (pixels-per-mm of images etc) is provided in
 description.txt files within each archive. (b) Mesh-models constructed
 from RGB images using the SPIERS software package,
 http://spiers-software.org. These are in VAXML format (see also
 http://spiers-software.org) - they can be viewed using the SPIERsview
 element of the SPIERS software suite, or the STL files that comprise the
 model can be imported into any other mesh software. ### Directory
 structure The archive contains this readme file and six zip achives, named
 as 'specimen\_type.zip', where specimen is the specimen number
 ('29571', '29656', '29661'), and type is
 either 'vaxml' or 'tomograms'. 'vaxml'
 archives each comprise: * one vaxml metadata file * one directory
 containing STL files describing morphology 'tomograms' archives
 each comprise: * one Description.txt file with information on scaling and
 number of images for each 'part' * a directory for each
 'part' containing tomographic images in .bmp format ##
 Sharing/Access information N/A ## Code/Software N/A