Dimorphism and endemism in Hebetoxyites (Ammonoidea, lower Bajocian) from the Iberian Range (Spain)

Abstract

New findings of lower Bajocian, haploceratid ammonites (Cephalopoda, Mollusca) of the genus Hebetoxyites from the Albarracín area are described and revised alongside specimens previously collected from the Iberian Range. Three species have been identified: H. hebes Buckman, H. incongruens Buckman and H. mouterdei Fernández-López. Indigenous populations of these Tethyan species in the Iberian carbonate platform system, including macroconchs and microconchs, are interpreted as immigration and colonization of shallow-water marine environments by Submediterranean taxa during a short interval of the early Bajocian. As peramorphic result of palingenetic evolution, a chronocline from strongly ribbed, stout forms of the Ovale Zone (including H. mouterdei), to oxycones with blunt, simple or irregularly branched ribbing of the Laeviuscula Zone (including H. incongruens), through intermediate forms belon-