DOI: 10.5061/dryad.x95x69pvt
title: Data from: Zooid size reduction in cyclostome bryozoans from the Late Triassic to the present-day

description: Body size evolution is a focus of palaeobiological interest, but few
 studies have examined long-term changes in the size of the modular zooids
 of colonial animals. Here we investigate changes in zooid size from the
 Late Triassic to the present-day among encrusting cyclostome bryozoans of
 a common morphotype attributed informally to ‘Berenicea’. We begin with
 the naïve hypothesis that cyclostome bryozoans should demonstrate size
 evolution similar to cheilostome bryozoans, which have maintained a
 constant mean zooid size. Unexpectedly, a striking pattern of decreasing
 zooid size through time was found in ’Berenicea’. We then hypothesized
 that decreasing levels of oxygen could make smaller zooid sizes more
 optimal because of their greater surface area/volume, i.e., cyclostome
 zooid size might be tracking a changing adaptive landscape over 200
 million years. Despite some evidence for a statistical
 correlation between ‘Berenicea' zooid size and oxygen, there is no
 hint of any causal relationship between them when formal timeseries
 analyses tools, based on linear stochastic differential equations, are
 applied. Furthermore, neither origination rates of cheilostomes, known to
 be superior spatial competitors, nor assemblage-level increases in
 cheilostome representation, are associated with ‘Berenicea' zooid
 size changes. However, there is some support for a switch in the tempo of
 cyclostome zooid size change at ca 165 to 160 and then again at ca 78 Ma.
description: Cyclostome form genus fossil
 '<em>Berenicea</em>' were collected over different
 field expeditions. They were cleaned and processed then scanning electron
 micrographs (SEMs) were taken of these specimens. The images of these
 specimens were then manually measured. The SEMs are supplied with this
 dataset, as are the measurements of the specimens from the SEMs.
description: # Data from: Zooid size reduction in cyclostome bryozoans from the Late
 Triassic to the present-day
 [https://doi.org/10.5061/dryad.x95x69pvt](https://doi.org/10.5061/dryad.x95x69pvt) ## Description of the data and file structure The SEM images provided in Berenicea SEM jpgs zip folder are the bases for the measurements given in the excel file 'Berenicea' zooid width data.xlsx ## Files and variables ### Folder: Berenicea_SEM_jpgs.zip **Description:**  Scanning electron micrographs of Berenicea. The individual file names correspond to the first column (SEM number) in the Excel file 'Berenicea' zooid width data.xlsx The metadata for each image is available in the column "Metadata" of the Excel file 'Berenicea' zooid width data.xlsx ### Folder: Code_and_Data.zip #### File: 'Berenicea' zooid width data.xlsx This is the main data file for the analyses. The following describes the columns in Sheet 1 * SEM number: corresponds to the file names in Berenicea_SEM_jpgs.zip * stage: geologic stage * taxon: taxonomic name given to the specimen in the SEM image * median age: median age of the given stage in millions of years ago * modern coordinates: modern latitude where the given specimen is collected, where N = north and S = south  * latitude/paleolatitude: paleolatitude converted from modern coordinate, given the stage assigned to the fossil (unconstrained = cannot be reliably converted) * Zooid width (1 through 5): width of a haphazardly selected zooid with the specimen, with no repeats. microns. * Metadata: extra information given for the specimen #### File:cylcostome ms.R R code to reproduce analyses in manuscript #### File: Mills:etal_2023_AREPS_02.xlsx oxygen data from Mills et al. 2023 for analyses (read in by the .R file) The data in this file are downloaded from the published paper: Mills, B. J. W., Krause, A. J., Jarvis, I. Ana Cramer, B. D. 2023. Evolution of atmospheric O2 through the Phanerozoic, revisited. Annual Review of Earth and Planetary Sciences, 51, 253–276. archived at [https://github.com/bjwmills/AREPS_2023_O2_estimate](https://github.com/bjwmills/AREPS_2023_O2_estimate) and figured in Mills et al. 2023 as Figure 6. The first column "Time" is in millions of years ago, and go forward in time in 1 million-year intervals for the modelled data.The next columns "Mid", "Min", and "Max," are the average, minimum, and maximum values of atmospheric oxygen (% atm), please see Mills et al. 2023 for the estimation. #### File: layerdata.RData extra data needed for .R file This file is from Lidgard et al. 2021 When fossil clades ‘compete': local dominance, global diversification dynamics and causation When read, it supplies the data required for the analyses from lines 600 onwards in the file cyclostome ms.R. This file has been previously published at [https://datadryad.org/dataset/doi:10.5061/dryad.zpc866t6s](https://datadryad.org/dataset/doi:10.5061/dryad.zpc866t6s) associated with Lidgard et al. 2021.