Relationships
The Vampyromorphida are characterized by such apomorphies as the possession of photophores, a peculiar type of uncalcified endoskeleton (the gladius), eight webbed arms, and the two velar filaments. Until fairly recently known only from the modern species and some fossil remains tentatively allocated to this group, a batch of Middle Jurassic (Lower Callovian specimens, from 165–164 mya) found at La Voulte-sur-Rhône demonstrated vampyromorphid cephalopods clearly were in existence for far longer than had been believed.
These were described as Vampyronassa rhodanica. The supposed vampyromorphids from the Kimmeridgian-Tithonian (156–146 mya) of Solnhofen, Plesioteuthis prisca, Leptoteuthis gigas, and Trachyteuthis hastiformis, cannot be positively assigned to this group; they are large species (from 35 cm in P. prisca to > 1 m in L. gigas) and show features not found in vampyromorphids, being somewhat similar to the true squids, Teuthida.
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