Systematics and evolutionary implications of Early Jurassic belemnites from the Peri-Mediterranean Tethys

Abstract

The systematic study of new belemnite assemblages from the Central Apennines and western Sicily revealed several new taxa for Italy. The specimens originate from Lower Jurassic sediments (Sinemurian–Toarcian), and their exact stratigraphic occurrence can be established by accompanying ammonite assemblages. The systematic analysis allows six genera of the suborder Belemnitina to be recognised (Subhastites, Passaloteuthis, Pseudohastites, Bairstowius, Cuspiteuthis, Megateuthis). The coeval occurrence of heterogeneous canaliculate belemnites (with alveolar grooves) was unexpected; their partially incomplete preservation does not allow assigning them safely to any existing genus, with the exception of a well-preserved specimen of Pachybelemnopsis sp. (with phragmocone, protoconch, and siphuncle). This represents the earliest known record of a belemnopseine belemnite. The Italian canaliculate belemnites are tentatively compared with canaliculate belemnites from the European Peri-Tethys, Japan, and New Zealand. A direct comparison is, however, hampered by the incomplete preservation of most of the herein reported specimens. The records of canaliculate belemnites in the Early Jurassic of Italy show remarkably heterogeneous rostrum morphologies, indicating an earlier diversification in belemnites than previously assumed.