On the Cretaceous ichthyosaur remains from the Northern Apennines (Italy)

Several remains of Cretaceous ichthyosaurs are described from the “Chaotic Complex” Formation of the Northern Apennines, South of Modena and Bologna. Owing to the fragmentary preservation of the material, specific classification is impossible. However, the rostrum bone configuration of the Italian and of other Cretaceous species could indicate that, during Cretaceous time, at least two different lineages of ichthyosaurs were co-evolving.In one lineage the maxilla extends more anteriorly than the nasal: it is represented by Platypterygius birjukovi (Ochev & Efimov, 1985) from the Russian lower Cretaceous and by P. americanus (Nace, 1939) from the Albian-Cenomanian of Wyoming.In the second lineage the maxilla is shorter and extends anteriorly at about the same level as the nasal: it is represented by Platypterygius bedengensis (Efimov, 1997) from the Russian Hauterivian and by P. longmani (Wade, 1990) from the Australian Albian.In the studied material, two of the fragments (Rostrum 1 and Rostrum 3) show a short maxilla and therefore probably are members of the second lineage.