Revisión de los Equinoideos del Eoceno de España (Review of the Eocene Echinoids of Spain)

A comprehensive and exhaustive taxonomic study has been conducted on a significant sample
of 13.530 echinoid specimens from the Eocene of Spain. The specimens studied, originating from 350 sites across
146 localities, are housed in eight museums. These sites are distributed across various regions with marine Eocene
outcrops, located both on the Iberian Peninsula and in the Balearic Archipelago. As a result of this thorough review,
117 species belonging to 58 genera have been identified, described, and illustrated. The presentation of the data
follows modern principles of nomenclature, taxonomy, and systematics for the group, derived from the application
of systematic methodologies integrating cladistic analyses with biomolecular and morphological data. It is important
to highlight that, until now, no study of this magnitude had been conducted in our country for this group and geological epoch, the Eocene. To achieve accurate chronostratigraphic classification of the materials, contemporary
stratigraphic works have been consulted, and numerous field trips have been undertaken to confirm or rectify the
stratigraphic positions of the materials.
Among the significant contributions of this study is the discovery of new taxon records for Spain and numerous
extensions of paleobiogeographic distributions. Moreover, the examination of materials in an optimal state of preservation
has allowed for the improvement of descriptions of species whose morphological features were previously
known in a limited manner. Additionally, gaps in the knowledge of some insufficiently characterized genera have
been identified, suggesting future lines of research or revision works. A notable element of the research has been the
identification of species that have served as stratigraphic indicators, thanks to their restricted vertical distribution
and broad paleogeographic presence in the European and circum-Mediterranean regions. This finding has paved
the way for proposing biozonations with echinoids, which represents an innovative contribution to the group. An
exhaustive cataloging of materials whose specific determination was impossible due to poor preservation has also
been performed, highlighting their potential utility in future studies addressing their revision.
Furthermore, to facilitate researchers in the taxonomic determination work, comprehensive descriptions,
numerous illustrations, several taxonomic keys, and a complete echinological glossary are included, aiming to be
useful in future studies requiring knowledge of echinoids. Introductory sections on the disciplines of Paleoecology,
Taphonomy, and Ichnology of echinoids are also included, with the aim of establishing a foundation for future
research in these areas closely linked to Taxonomy. Finally, the Conclusions section compiles the numerous taxonomic,
chronostratigraphic, and paleogeographic contributions derived from this research.