DOI: 10.5061/dryad.m37pvmdfn
title: Supplementary data for: A Cnidarian affinity for Salterella and Volborthella: Implications for the evolution of shells

description: This is the supplementary material for the publication "A Cnidarian
 Affinity for Salterella and Volborthella: Implications for the Evolution
 of Shells" in the Journal of Paleontology. It includes 22 figures and
 3 data tables of material used in the analyses in the publication. The
 Cambrian Explosion saw the widespread development of mineralized
 skeletons. At this time, nearly every major animal phylum independently
 evolved strategies to build skeletons either through agglutination or
 biomineralization. Although most organisms settled on a single strategy,
 Salterella Billings, 1865 employed both strategies by secreting a
 biocalcitic exterior shell that is lined with layers of agglutinated
 sediments surrounding a central hollow tube. The slightly older fossil,
 Volborthella Schmidt, 1888, shares a similar construction with
 agglutinated grains encompassing a central tube, but lacks a
 biomineralized exterior shell. Together these fossils have been grouped in
 the phylum Agmata Yochelson, 1977, although no phylogenetic relationship
 has been suggested to link them with the broader metazoan tree, which
 limits their contribution to our understanding of the evolution of shells
 in early animals. To understand their ecology and place them in a
 phylogenetic context, we investigated Salterella and Volborthella fossils
 from the Wood Canyon and Harkless formations of Nevada, USA, the Illtyd
 Formation of Yukon, Canada, and the Shady Formation of Virginia, USA.
 Thin-section petrography, acid maceration, scanning electron microscopy,
 energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray
 tomographic microscopy were used to provide new insights into these
 enigmatic faunas. First, morphological similarities in the aperture
 divergence angle and ratio of central tube diameter to agglutinated layer
 thickness suggest Salterella and Volborthella are related. Second, both
 fossils exhibit agglutinated grain compositions that are distinctive from
 their surrounding environments and demonstrate selectivity on the part of
 their producers. Finally, the calcitic shell composition and simple layers
 of blocky prismatic shell microstructure in Salterella suggest a possible
 cnidarian affinity. Together these data point to these organisms being
 sessile, semi-infaunal filter or deposit feeders, and an early
 experimentation in cnidarian biomineralization chronicling a hypothesized
 transition from an organic sheath in Volborthella to a biomineralized
 shell in Salterella.
description: # Supplementary data for: A Cnidarian affinity for Salterella and
 Volborthella: Implications for the evolution of shells Dataset DOI:
 [10.5061/dryad.m37pvmdfn](10.5061/dryad.m37pvmdfn) ## Description of the
 data and file structure This supplementary data is provided to support the
 publication "A Cnidarian Affinity for Salterella and Volborthella:
 Implications for the Evolution of Shells" published in the Journal of
 Paleontology. ### Files and variables #### File:
 Supplementary_Material_Vayda_Salterella.rtf **Description:** Data included
 in this file include a map and accompanying table of all published
 occurrences of *Salterella* and *Volborthella* with locality information,
 geological information, and references; photographs of all thin sections
 used for measurement data collection in this study; tables with
 measurement data used for figures 7 and 8 in the main text, slide number
 and specimen numbers correspond to the photographed thin sections,
 information for how the measurements were taken is provided in the main
 text; figures of the EDS maps used to produce figure 10 in the main text.
 ## Code/software A word processor is necessary to open this file.  ##
 Access information Other publicly accessible locations of the data: * none
 Data was derived from the following sources: * self collected