Data from: Sustained shift in the morphology of organic-walled microfossils over the Ediacaran-Cambrian transition

Tingle, Kelly E.1 ; Anderson, Ross2; Kelley, Neil1; Darroch, Simon3

Published Jun 19, 2025 on Dryad. https://doi.org/10.5061/dryad.zs7h44jjn

Data files

Jun 19, 2025 version files 168.80 KB

Acritarch_data.csv

88.52 KB
Boxplots_code.R

13.45 KB
FigS5_subsampling_code.R

11.06 KB
FormationAges.xlsx

20.58 KB
NMDS_code.R

13.98 KB
README.md

21.21 KB

Abstract

The early (~1650 – 540 mya) history of eukaryotes was punctuated by several major – but enigmatic – environmental perturbations that potentially influenced the evolution of the Proterozoic biosphere, and the changing structure of Earth systems leading up to the Cambrian Explosion of animals. Reconstructing the manner in which eukaryotes responded to these events represents an innovative lens with which to understand what these perturbations actually represent, as well as the links between geosphere and biosphere during a critical period in eukaryotic evolution. In this study, we analyze organic-walled microfossil size and morphology across the Ediacaran-Cambrian transition. We illustrate that the decrease in vesicle diameter –previously shown to occur across the Ediacaran-Cambrian transition – began in the Ediacaran following the ‘Shuram’ carbon isotope excursion. This size decrease was accompanied by an increase in relative process length across the Ediacaran-Cambrian transition, which has not been previously quantified. Finally, following the ‘Shuram’ excursion, we illustrate a sustained shift in overall morphology. This shift in morphology may have been driven by nutrient stress enhanced by environmental change and/or the increased importance of planktonic lifestyles, highlighting the expansion of microbial eukaryotes into the plankton as a key step in the establishment of modern marine food webs.

Dataset DOI: 10.5061/dryad.zs7h44jjn

Description of the data and file structure

This dataset was compiled from morphological data from 33 publications that included systematic descriptions of Ediacaran-Cambrian acritarch assemblages. Vesicle size, process length, and host lithology were recorded and taxa were scored for two continuous characters and 23 presence/absence characters largely focused on process morphology. We used R to create boxplots for acritarch size and visualize acritarch morphospace with nonmetric multidimensional scaling. We ran sensitivity tests using various subsampling analyses. Empty cells reflect values not applicable or published (such as process length or number of specimens reported, see below).

Files and variables

File: NMDS_code.R

Description: This is code used to create and analyze the morphospace in this manuscript with NMDS.

File: FigS5_subsampling_code.R

Description: This is code used to run subsampling analyses of acritarch size data.

File: Boxplots_code.R

Description: This is code used to create the boxplots in this manuscript and gather statistical data on acritarch size.

File: Acritarch_data.csv

Description: This is the dataset used in this manuscript. See Supplementary Figure 1 for illustration of morphological characters.

Variables

- Genus: Genus name
- Species: Species name
- Age: Age bins, BSE (Before and including the ‘Shuram’ excursion [635–567 Ma]), PSE (Post the ‘Shuram’ excursion [566–539 Ma]), and EC (early Cambrian [538–509]).
- Formation: Formation name
- Lithology: Host lithology category - siliciclastics, carbonate, chert and phosphorites
- VD: average vesicle diameter (µm) (if cell is empty, then a diameter was not reported)
- PL : average process length (µm) (if cell is empty, then there are no processes or a length was not reported)
- PL_VD: ratio of average process length to average process diameter (if cell is empty, then there are no processes or a length was not reported)
- Num: number of specimens reported by author in publication (if cell is empty, then number of specimens was not reported)
- Vesicle_size: 1=<100 µm, 2=100-200µm, 3=>200µm
- Process_length: 0=absent, 1= <10%, 2=10-40%, 3= >40%
- The following variables are scored for presence (1) or absence (0) except for reference:
- Process_irregular: irregularly arranged processes
- Process_dense: densely arranged processes
- Process_branching: distally branching processes
- Process_hollow: hollow processes
- Process_cylindrical: cylindrical shaped processes
- Process_bulbous: bulbous shaped processes
- Process_hooked: distally hooked processes
- Process_conical: conical shaped processes
- Process_domed: domed shaped processes
- Process_heteromorphic: heteromorphic processes
- Process_expandedbase: processes with exbanded base
- Process_thin: processes <1 µm
- Process_blunt: blunt tipped processes
- Process_pointed: pointed tipped processes
- Process_rounded: rounded tipped processes
- Process_funnel: funnel tipped processes
- Process_CWVI: processes are open (communicate with) to vesicle interior
- OuterWall: processes are within outer wall
- Flange: equatorial flange
- Surface_ornamentation: surface ornamentation
- Colonial or aggregate: colonial or aggregate form
- Vesicle: presence of vesicle
- Ref: Reference of publication
- Median_age: Median or plotting age (Ma, millions of years) assigned to formation based on available age constraints (see FormationAges.xlsx)

File: FormationAges.xlsx

Description: This is a list of available age constraints for the formations in this analysis.

Code/software

All analyses were performed using the statistical computing software R, v. 4.3.1. Three scripts are included that create boxplots, perform NMDS analysis and perform subsampling analyses.

Access information

Data on microfossil size, morphology and formation age estimates was collected from the following sources:

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