Update of the dimorphic genus Olorizia (Ataxioceratidae, Ammonitina) and establishment of the species Olorizia calandina sp. nov.

Abstract

Abstract Ataxioceratinae of the genus Olorizia are characteristic ammonites of the Kimmeridgian eastern Iberian platform. Olorizia was established as a dimorphic monospecific genus that included a single species (Olorizia olorizi) endowed with a remarkably wide phenotypic variability. Its morphological plasticity allowed to recognize three morphotypes. They are interpreted as endemic forms and the product of in situ evolution, through a cladogenetic split from the autochthonous lineage of Ardescia Atrops during the early Kimmeridgian (cron Platynota); they are also interpreted as one of the greatest exponents of morphological specialization of the group due to the achievement of costulation with double connections (ataxioceratoid and subpolyplocoid ribs). In this work, a new dimorphic species is stablished, Olorizia calandina sp. nov.; the scarce graphic illustration of specimens of the various morphotypes of Olorizia olorizi existing to date is also corrected and the change of institution for the custody of fossil remains is reported, as well as the new identification acronyms.