DOI: 10.5061/dryad.s4mw6m9kb
title: Data from: Background extinction due to species specialization? Insights from a high-resolution Jurassic ammonoid case study (Dactylioceratidae)

description: 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.
description: 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.