Parent H., Scherzinger A., Schweigert G. (2008) Sexual phenomena in Late Jurassic Aspidoceratidae (Ammonoidea). Dimorphic correspondence between Physodoceras hermanni (BERCKHEMER) and Sutneria subeumela SCHNEID, and first record of possible hermaphroditism // Paleodiversity. Vol.1. P.181-188. Pdf: http://www.palaeodiversity.org/pdf/Palaeodiversity_1_12_181-188.pdf
New collections of the dimorphic ammonite species Physodoceras hermanni (Berckhemer) [M] and Sutneria subeumela Schneid [m] from the Upper Jurassic (Beckeri Zone, Subeumela Subzone, subsidens horizon) of Swabia demonstrates first time evidence of intra-sexual polyphenism in Aspidoceratidae. In the macroconchs two size classes demonstrate different times of maturity, leading to small and large adults. In the microconchs, besides a continuous size range of adults, a unique case of possible sexual change in a subadult stage is observed that could point to the occurrence of hermaphroditism in ammonites.
