Fossil echinoid (Echinoidea, Echinodermata) diversity of the Early Cretaceous (Hauterivian) in the Paris Basin (France)

Abstract This dataset inventories occurrence records of fossil echinoid specimens collected in the Calcaires à Spatangues Formation (CSF) that crops out in the southeast of the Paris Basin (France), and is dated from the Acanthodiscus radiatus chronozone (ca. 132 Ma, early Hauterivian, Early Cretaceous). Fossil richness and abundance of the CSF has attracted the attention of palaeontologists since the middle of the nineteenth century. This dataset compiles occurrence data (referenced by locality names and geographic coordinates with decimal numbers) of fossil echinoids both collated from the literature published over a century and a half, and completed by data from collection specimens. The dataset also gives information on taxonomy (from species to order and higher taxonomic levels), which has been checked for reliability and consistency. It compiles a total of 628 georeferenced occurrence data of 26 echinoid species represented by 22 genera, 14 families, and 9 orders.


Introduction
The Calcaires à Spatangues Formation (CSF) consists of shallow marine sediments deposited in the southeast of the Paris Basin (France) during the very Early Cretaceous (early Hauterivian, Acanthodiscus radiatus chronozone) about 132 million years ago, at the maximum of a second order sea level rise (Bulot et al. 2000;Courtinat et al. 2006;Bodin et al. 2009). Preserved deposits of near-shore and shallow marine environments are not common in Western Europe for that time-interval where deep-sea basin and deep shelf sediments predominated (Canérot and Cugny 1982;Rat et al. 1987;Schootbrugge et al. 2000). Deposits of the CSF yield a diversified, speciose and locally abundant fossil fauna, essentially composed of benthic invertebrates among which echinoids are common and locally very abundant (Cornuel 1841;Rat et al. 1987;Courtinat et al. 2006). In that respect, the CSF is a window on the little known benthic communities that thrived in shallow marine environments in the Early Cretaceous.
Fossil richness of the CSF has attracted the attention of palaeontologists since the middle of the nineteenth century (Cotteau 1857(Cotteau -1878(Cotteau , 1862(Cotteau -1867Valette 1908;Corroy 1925;Rat et al. 1987;Walter 1996;Saucède et al. 2012). Fifty-four echinoid species were described in the CSF in all, half of them (26 species) based on type specimens collected in the CSF. However, many nominal species are geographically restricted and morphologically little differentiated. Of the 54 echinoid species ever described, Saucède et al. (2012) recognized only 26 species that belong to 16 different families, among which regular (13 species) and irregular (13 species) echinoids are represented in equal proportion. This still represents a high level of fossil echinoid diversity for that time-period, which can be explained by a putative high beta-diversity due to the numerous microhabitats present in shallow marine environments at that time and by the richness of cassiduloid echinoids, the group being particularly well-diversified in coarse sediment environments in the Early Cretaceous (Kier 1962).

Project details
Project title: Inventory of the fossil echinoid diversity of the Early Cretaceous (Hauterivian) in the Paris Basin (France).

General spatial coverage
The sampling area focuses on the Calcaires à Spatangues Formation that crops out in the southeast of the Paris Basin (France) (Fig. 1A). The study area extends over the six following French departments: Cher, Nièvre, Yonne, Aube, Haute-Marne, and Meuse.

Method
Method step description. Specimens were both collected in the field and consulted in public collections of Université de Rennes 1 (Rennes, France), Université de Bourgogne (Dijon, France), and Muséum national d'Histoire Naturelle (Paris, France). Identification of specimens was performed at species level based on descriptions by G Cotteau (1857G Cotteau ( -18781862-1867, A Valette (1908), G Corroy (1925), P Rat et al. (1987), and T Saucède et al. (2012). Taxonomy was updated when it proved necessary following Kier (1962), Durham et al. (1966), Smith (1984), and Kroh and Smith (2010). Though paraphyletic, some family names have been used for convenience (Nucleolitidae Agassiz & Desor, 1847;Toxasteridae Lambert, 1920). The accuracy and geographic coordinates of localities where collection specimens came from was checked based on geological grounds (BRGM sources). Dubious localities were discarded. Study extent description. The Calcaires à Spatangues Formation consists of shallow marine sediments that were deposited in the southeast of the Paris Basin (France) during the early Hauterivian (Acanthodiscus radiatus zone). These deposits are rich and diversified in a benthic fauna among which echinoids predominate. The systematic status of echinoids of the Calcaires à Spatangues Fm. was revised so as to update the list of echinoid species reported in the Formation and better assess its remarkable diversity. Of the 54 echinoid species ever described, 26 species are recognized that belong to 16 different families, among which regular (13 species) and irregular (13 species) echinoids are represented in equal proportion.
Data resources: the data underpinning analyses of the paper are deposited at GBIF, the Global Biodiversity Information Facility, http://ipt.pensoft.net/ipt/archive. do?r=hauterivian_echinoids_of_the_paris_basin