An illustrated and revised catalogue of Mesozoic radiolarian genera — objectives, concepts and guide for users

This revision paper represents the final report by the InterRad Mesozoic Working Group on the taxonomy and stratigraphy of Mesozoic radiolarians at generic level. The review reports 915 genera and encompasses the type species' illustration of all described nominal genera of Mesozoic radiolarians (superorder Polycystina) from 1867, when the first Mesozoic radiolarian was described, to 2008. This work is organized as an image catalogue of genera, where each type species is re-illustrated with a graphic scale bar indicating its magnification. Associated with each image is the most basic information that allows the reader quick location of the original publication where both genus and type species were described and/or illustrated. The review undergone here confirms the taxonomic validity of all genera according to the ICZN rules. Order and family assignment, synonymies and stratigraphic ranges are also fully analyzed. The review is divided in two parts: the Triassic and the Jurassic-Cretaceous. This division is justified by the low number of taxa crossing the Triassic-Jurassic boundary and by the significant change in morphologic patterns and faunal composition that occurred in the latest Triassic. A further reason justifying such division is the very low number of nomina dubia recorded in the Triassic, as opposed to the higher number in the Jurassic-Cretaceous interval. The main purpose of this catalogue is to enable radiolarian paleontologists to arrive to a satisfactory taxonomic system and establish the standards for future description of new radiolarian genera. The revision also includes a brief stratigraphic synthesis (generic range charts) which are only accessible in the electronic version of the journal.