Data from: Background extinction due to species specialization? Insights from a high-resolution Jurassic ammonoid case study (Dactylioceratidae)

Published Nov 17, 2025; Updated Dec 03, 2025 on Dryad. https://doi.org/10.5061/dryad.s4mw6m9kb

Data files

Nov 17, 2025 version files 542.24 KB

Dec 03, 2025 version files 542.23 KB

Abstract

The extinction of clades outside mass extinction events remains an understudied aspect of evolutionary dynamics. This study examines the Dactylioceratidae, an ammonite family that disappeared during the Early Jurassic, outside a recognized mass extinction event. By using high-resolution taxonomic (species-level) and temporal (sub-chronozone) data, we assess its evolutionary trajectory, from diversification to extinction. Our analysis reveals that Dactylioceratidae experienced an initial expansion in diversity and geographic range, followed by increased specialization. Morphological disparity and diversity peaked before a sharp decline, suggesting a possible link between ecological specialization and extinction risk. This pattern aligns with hypotheses proposing that over-specialization limits adaptability, leading to extinction under background conditions. In contrast to mass extinctions driven by sudden catastrophic events, background extinctions may be influenced by gradual ecological changes and evolutionary constraints. By comparing the case of Dactylioceratidae with broader ammonoid trends, this study provides insights into long-term extinction mechanisms. These findings are relevant for understanding both past and present biodiversity crises, shedding light on how species’ evolutionary strategies impact their survival over time.

This README file was generated on 2025-11-14 by Pascal Neige

Dataset title

Background extinction due to species specialization? Insights from a high-resolution Jurassic ammonoid case study (Dactylioceratidae)

Date of Data Collection

Compilation of data and measurements made from june 2022 to june 2024.

Contributors

Pascal Neige, Université Bourgogne Europe, CNRS, Biogéosciences UMR 6282, 21000 Dijon, France
Twan van Tiel, Université Bourgogne Europe, CNRS, Biogéosciences UMR 6282, 21000 Dijon, France

Overview

This supplementary dataset, integral to our research paper, contains data crucial for understanding the key findings of our study. It includes a classification of Dactylioceratids (Supplementary Table S1), the calculation of geological ages used to generate figures of the paper (Supplementary Table S2), the complete database (Supplementary Table S3), the complete list of publications taken into account to constitute the database (Supplementary Table S4), and Dactylioceratidae computed sampling coverage.

This study is based on a database compiled by Pascal Neige, listing 136 valid species of Dactylioceratidae (see explanations in Supplementary_Table_S3) figured in scientific literature between 1815 and 2023 (see complete list of scientific literature used here in Supplementary_Table_S4).

Content: Supplementary files

These files provide comprehensive support for our research findings. They include raw data (scientific literature used to constitute the database, presence / absence of species according to time and space, measurements and shape ratios) and a result (sampling coverage) which complete the published paper.

Supplementary_Table_S1.rtf

Classification and supra-specific taxa recognized as members of the family Dactylioceratidae (following Howarth 2013). The list includes genera synonyms and names of authors who erected taxa names.

Note that some authors propose a different classification. Here, the adopted classification aligns with the Treatise (Howarth 2013).

Supplementary_Table_S2.rtf

Chronostratigraphic (based on Page 2003) and radiochronological (based on Hesselbo et al 2020) frameworks used here.

The radiochronological framework is calculated from the most recently published version of the Geological Time Scale (Gradstein et al 2020) for the period under consideration (Hesselbo et al. 2020).

As the age of the subchronozones is unknown, it was arbitrarily chosen to divide them into equal durations based on the ages given for the chronozone bases by Hesselbo et al (2020).

Supplementary_Table_S3.csv

Retained species and raw data.

Species: selected species for the study. To ensure data reliability, only species that met the following criteria were included, (1) taxonomic validity: species were considered valid according to zoological nomenclature rules, incorporating expert revisions (e.g., Howarth 2013; Rulleau et al. 2013) and (2) illustrated specimens: only publications containing figured specimens with clear taxonomic, chronological, and geographical information were included. This approach prevented the integration of unchecked or unverifiable data. Species names following the supra-specific nomenclature of Howarth (2013).
Chronostratigraphic data (20 columns): presence (1) /absence (0) of species in each subchronozone from the “Masseanum sz” Subchronozone to the “Vitiosa sz” Subchronozone. Subchronozones according to Cariou and Hantzpergue 1997 and Page 2003.
Paleogeographic data (28 columns): presence (1) /absence (0) of species across the 28 spatial units (from “NEZ” to “TUN”; see Fig. 1). Fossil occurrences were recorded from 28 spatial units worldwide grouping fossiliferous localities. Correspondance between spatial units codes and geography: ALP (Alps), APE (Apennines), ARG (Argentina), ATA (Atacama), ATL (Atlas), BCO (British Columbia), CAL (Calabria), CAR (Carpathian Mountains), CHI (North Chile), CRI (Crimea), EHI (East Himalaya), GRE (Greenland), IRA (North Iran), JAP (Japan), LUS (Lusitanian Basin), NEZ (New Zealand), NWE (Northwest Europe), ORE (Oregon), PAB (Paris Basin), QCI (Queen Charlotte Islands), QEI (Queen Elizabeth Islands), SCO (Scotland), SIB (Siberia), SFR (South France), SWE (Southwest Europe), TIM (Timor), TUN (Tunisia), YUK (Yukon)
Shell measurements: from “T” to “h” (9 columns, and see Fig. 2 for exact location of measurements on the shell). Measurements made in cm. Note that some measurements were taken from photographs not at a 1:1 scale. This does not affect the results, as all measurements were transformed into shape ratios. So do not used measurements as raw data...
Calculated shape ratios: from “D” to “WE” (7 columns) ; D=c/d, S=b/a, W=(d/e)², AH=f/a, U=o/T, RW=b/T and WE=a/h

Supplementary_Table_S4.rtf

Complete bibliography used to construct the database used here. Only papers which meet the criteria to select a species for the study (see before: Supplementary_Table_S3) are included here. A total of 342 scientific publications (articles and monographs) met these criteria.

Supplementary_Fig._S1.pdf

Dactylioceratidae sampling coverage computed for a standardized set of 8 domains (Southeast Asia, Northeast Tethys, Northwest Tethys, Southern Tethys, Australasia, Southwest America, Northwest America, Arctic) for each time bin. Sampling coverage represents the probability that a species present in the dataset is actually sampled.