DOI: 10.5061/dryad.tqjq2bvx2
title: Data from: Ups and downs of belemnite diversity in the Early Jurassic of Western Tethys

description: Although belemnites form a major clade of extinct cephalopods, the early
 stage of their diversification remains poorly known in time and space.
 Here we investigate the first diversification episodes of belemnites
 (order Belemnitida) using a new species-level database encompassing the
 Hettangian-Aalenian interval (Early Jurassic-earliest Middle Jurassic) and
 covering the Western Tethys. Rarefied richness shows a four-fold increase
 from the Planorbis chronozone to the Ibex chronozone, a strong decrease
 between the Margaritatus and Spinatum chronozones, followed by a drop in
 the Spinatum-Serpentinum interval that is coeval with the second-order
 Toarcian biological crisis. The Bifrons chronozone records a high richness
 that departs significantly from those of the surrounding chronozones. A
 last richness peak in the Dispansum chronozone precedes a decrease towards
 the Aalenian. Biogeographic analyses do not reveal any clear large-scale
 provincialism for belemnites, in sharp contrast with ammonoids. Such a
 long-term homogeneous spatial distribution of belemnites is probably due
 to: (1) the relatively poorly-documented fossil record of belemnites,
 especially in Mediterranean localities and (2) contrasted dispersal
 abilities of belemnites compared to ammonoids over the studied time
 interval.
description: The database of the present work is constructed upon a
 near-exhaustive, species-level taxonomic revision of the available
 literature, covering 150 years of palaeontological investigations
 (1867-2018): 64 publications (Appendix S1) were selected according to the
 criteria described hereafter and analysed. Some publications are
 monographs dealing with a large palaeogeographic area, whereas others are
 more geographically restricted. Only rarely were data from the authors’
 own samples or from museum collections added (Appendix S2). Because
 published data are far from being homogeneous, we constructed a dataset
 respecting several strict criteria. Data from the literature have been
 evaluated only if they contained specimen illustrations (drawings and/or
 photographs) in order to check the original species attribution.
 Occurrences that were simply cited were ignored. Once this first criterion
 was validated, geographical and stratigraphic information were checked. In
 cases where one of these two types of data was not adequately reported for
 a species, the latter was rejected from the dataset. In terms of temporal
 resolution, we retained only occurrence data available at the resolution
 of the ammonite chronozone. Finally, a consistent taxonomic evaluation has
 been made by the same experts (RW & PN) over the entire dataset in
 order to check for synonymy and for a qualitative appreciation of
 intra-specific variability. The result is the taxonomic appendix given in
 full (Appendix S3). Species richness was evaluated
 using raw data but also sample-based and coverage-based rarefaction and
 extrapolation (Appendix S4). Biogeographic contrasts
 among belemnite assemblages were tested statistically using ANOSIM. This
 non-parametric technique tests for significant differences in similarity
 between two or more assemblages based on a distance measure, here the
 Raup-Crick coefficient. All these biogeographical analyses were conducted
 at the scale of the chronozone, sub-stage and stage with the software PAST
 3.15. The results are given in Appendix S5.
description: # Data from: Ups and downs of belemnite diversity in the Early Jurassic of
 Western Tethys Dataset DOI:
 [https://doi.org/10.5061/dryad.tqjq2bvx2](https://doi.org/10.5061/dryad.tqjq2bvx2) ## Description of the data and file structure The database of the present work is constructed upon a near-exhaustive, species-level taxonomic revision of the available literature, covering 150 years of palaeontological investigations (1867–2018): 64 publications (Neige et al. 2020, Appendix_S1_Biblio.rtf) were selected according to the criteria described here-after and analysed. Some publications are monographs dealing with a large palaeogeographical area (e.g. Doyle1990, 1992), whereas others are more geographically restricted (e.g. Schumann 1974). Only rarely were data from the authors’ own samples or from museum collections added (Neige et al. 2020, appendix S2). Because published data are far from being homogeneous, we constructed a dataset respecting several strict criteria. Data from the literature were evaluated only if they contained specimen illustrations (drawings and/or photographs) in order to check the original species attribution. Occurrences that were simply cited were ignored. Once this ﬁrst criterion was validated, geographical and stratigraphical information was checked. In cases where one of these two types of data was not adequately reported for a species, the latter was rejected from the dataset. In terms of temporal resolution, we retained only occurrence data avail-able at the resolution of the ammonite chronozone. Finally, a consistent taxonomic evaluation has been made by the same experts (RW & PN) over the entire dataset to check for synonymy and for a qualitative appreciation of intra-speciﬁc variability (Appendix_S2_Complete_Data.csv, Appendix_S3_Taxo.rtf). Two other appendices are given concerning taxonomic (Appendix_S4_ICE&_Chao2.csv) and paleobiogeographical (Appendix_S5_ANOSIM_vs_pour_csv.csv) analysis.