Original dataset, coded matrix, and Bayesian phylogenetic trees of three Late Ordovician brachiopod genera (Atrypida: Anazygidae)
Data files
Jul 01, 2025 version files 156.51 KB
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Final_topology.tre
928 B
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README.md
4.22 KB
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Supplementary_Data_1.xlsx
58.16 KB
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Supplementary_Data_2.pdf
90.54 KB
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Topology1_w_external_internal.tre
883 B
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Topology2_wt_internal.tre
876 B
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Topology3_grouping_constraints.tre
908 B
Abstract
The Late Ordovician was a pivotal interval in Earth’s history, marked by rapid diversification and a significant accumulation of biodiversity across marine ecosystems. This period witnessed the flourishing of brachiopods, which were a dominant component of the Paleozoic Evolutionary Fauna—a group primarily composed of filter-feeding, sessile benthic organisms that played a critical role in the structure and function of Paleozoic marine communities. In this study, we focus on reconstructing the evolutionary relationships and biodiversity dynamics of a key lineage within this group: the atrypid brachiopods of the family Anazygidae. This family includes the genera Anazyga, Catazyga, and Zygospira, which are particularly important for understanding morphological innovation, biogeographic patterns, and ecological adaptation during a time of major evolutionary expansion. By integrating phylogenetic analysis with biodiversity assessments, our study sheds light on the evolutionary history and ecological significance of these brachiopods during the Late Ordovician radiation.
Dataset DOI: 10.5061/dryad.v9s4mw773
Description of the data and file structure
Multiple datasets of internal and external characters were incorporated into one single file (Excel file, Supplementary Data 1). Characters were coded in an original dataset with continuous (measured in millimeters) and discrete characters; more information about the character states is found on the "Metadata" sheet (Supplementary Data 1). Later, all characters were converted to categorical character states (0-6), missing (?), or absent/gap (-) (NEXUS and NEXUS Metadata sheets, Supplementary Data 1). The created NEXUS file was incorporated into a Bayesian phylogenetic framework under the fossilized birth-death (FBD) in BEAST2. If you wish to access more information on the rates used and statistics involving the model, please contact me at mandrad2@vols.utk.edu, and I will be happy to share the files with you. The model recovered topologies that were most robust when incorporating only external characters (Paper text), however, alternative topologies are equally available (PDF file, Supplementary Data 2). Moreover, all recovered topologies indicate that species previously assigned to Anazyga and Zygospira do not separate into discrete clades but are intermixed within a single monophyletic group. Consequently, we propose a systematic revision based on external characters that recognizes two monophyletic genera: Catazyga, which includes most species historically assigned to Catazyga, and Zygospira, which includes most species historically assigned to Zygospira and Anazyga. One new species, Zygospira idahoensis is described, and one former subspecies is elevated to species status as Zygospira multicostata. The Anazygidae is estimated to have originated around 453 million years ago in the Sandbian Stage. Recovered diversification rates indicate that the highest speciation and extinction rates occurred in the late Katian (Katian 3) state, when the total number of species in the clade reached its peak. This was followed by an abrupt decline in biodiversification rates lead to an extinction episode in the Katian 4 Stage for all lineages. Therefore, Catazyga and Zygospira are interpreted as early Late Ordovician atrypids that experienced both rapid radiation and extinction during the last phase of the Ordovician Radiation in the Katian Stage.
Files and variables
File: Supplementary_Data_1.xlsx
Description: Supplementary Data 1 is an Excel file with four sheets. The first (Data) includes the raw measurements per specimen and their associated museum code, the second (Metadata) is the metadata with the character names and character states. The continuous measurements are all in millimeters when appropriate, or in angles; no conversions were made. In addition, I also incorporated the coded NEXUS file (NEXUS) and the associated metadata (NEXUS Metadata). NEXUS file was used in BEAST2.6.6
File: Supplementary_Data_2.pdf
Description: Supplementary data 2 is a PDF file with screenshots of the alternative tree topologies.
File: Topology1_w_external_internal.tre
Description: Bayesian phylogeny estimated using both external and internal morphological data and without constraints within the subfamily Anazygidae. The former taxonomic nomenclature is shown. Posterior probability: -327.56.
File: Topology2_wt_internal.tre
Description: Bayesian phylogeny estimated using external morphological data only and without constraints within the subfamily Anazygidae. The former taxonomic nomenclature is shown. Posterior probability: -318.77.
File: Topology3_grouping_constraints.tre
Description: Bayesian phylogeny estimated using both internal and external characters with grouping constraints reflecting the previously published generic assignments. The former clade’s taxonomic nomenclature is shown. Posterior probability: -342.19.
File: Final_topology.tre
Description: The .tre preferred topology. A better view of the tree can be seen on Figure 3.