The buccal apparatus with radula of a ceratitic ammonoid from the German Middle Triassic

Abstract

Complete ammonoid mouth parts including both mandibles and the radula are rare. A newly prepared specimen of Ceratites penndorfi of the late Anisian from the Franconian Muschelkalk reveals one such anaptychus-type jaw apparatus including several more or less clearly recognisable structures such as the shapes and proportions of the inner and outer lamellae of both mandibles. The lower mandible has a short inner and a long outer lamella with an ovoid outline, while the upper mandible has a slightly arched rostrum and the inner lamella carries two wings. The radula, as far as it is preserved, appears to be homodont with oblique, simply conical, monocuspidate teeth. These structures are here illustrated, described and interpreted as both mandibles and oesophageal remains. Additional structures of organic origin are preserved such as the radula, but others are difficult to interpret. Some, if not all, of these structures also were body parts of the ceratite, such as perhaps the radular support and/or the oesophagus. All mouth parts, which are preserved in the specimen described herein, are carbonised except for the radula remains, which are phosphatic. The taphonomy of ceratite mouth parts in the Muschelkalk is shortly discussed.