Università degli studi di Modena e Reggio Emilia

In 2017 attention was brought back to the specimen V7158 from the Verona Natural History Museum. The fossil is a small fragment of an ichthyosaur rostrum discovered in the XIX century in the Verona territory (northeastern Italy) representing one of the first findings of Ichthyosauria in Italy. The specimen, after long oblivion, was re- discovered in the 1990s but until now was never officially described. In this paper we provide morphological analysis, taxonomic attribution, taphonomic analysis and age determination to V7158 as well as a detailed reconstruction of the peculiar history of this discovery. From our re-description, V7158 can be doubtfully attributed to Ophthalmosauridae and firmly assigned to the Tithonian. Age determination and the recognition of the source formation (Rosso Ammonitico Veronese, RAV) were achieved by means of calcareous nannofossils associated with the matrix of V7158 and through fieldwork activity in the area of discovery. Though fragmentary, the specimen is histologically very well preserved, a feature unusual for the taphonomic regime of the RAV and most likely restricted to its upper unit.

Axial remains of a large ichthyosaur and a medium-sized anacoracid shark from the deep-water sediments of the Cenomanian of the Northern Apennines (Northern Italy) are described in detail. The specimens were found closely associated (less than 0.3 m apart), and offer an invaluable window into the taphonomy and dead-fall stages of pelagic vertebrates in a Mesozoic abyssal plain. The anacoracid shark remains, initially misinterpreted as an ichthyosaur, consist of eight articulated vertebrae embedded in a block of dark arenaceous matrix, and represent the first occurrence of an articulated shark from the Northern Apennines. The ichthyosaur remains consist of seven discoidal vertebrae and several unidentified fragments. Due to the absence of diagnostic skeletal elements, both specimens are assigned only at higher taxonomic levels. The two fossils, which come from the same outcrop and possibly from the same stratigraphic horizon, share a common taphonomic history, in terms of both their preservation and diagenesis. Mineralogy of the matrices of both is dominated by manganese micro-nodules, consistent with the deposition of polymetallic nodules in bathyal-abyssal settings. Biostratinomic processes that impacted the two specimens also provide insight on the development of Mesozoic marine vertebrate-falls in the deep-sea. Localized pyrite framboids inside the bone spongiosa are possible evidence of the sulfophilic stage (microbially mediated sulfur mobilization during lipid decay) in the ichthyosaur fall. Burrows assigned to Taenidium on the surface of the shark block, interpreted as worm-like feeding burrows or arthropod locomotion and feeding trails, might represent evidence of the enrichment opportunistic stage. Although intriguing, we have no evidence to support the hypothesis that this peculiar association of two pelagic predators is due to ecological interaction between the two animals.

In 2016 a new Cretaceous ichthyosaur rostrum fragment (IG 251372) was found near Gombola, Modena Province, northern Italy. Two rostral fragments and a partial humerus were previously reported from the same locality. Despite their fragmentary nature, all these finds are relatively well preserved, with just slightly deformed shape and teeth still in place. Here we describe IG 251372, relying on CT-scan technology to allow visualization of the fossil internal structure. The new specimen has been ascribed to the sub-family Platypterygiinae based on the sub-rectangular profile of the tooth roots. Tooth crowns are robust and show a similar density of enamel ridges to many other Cretaceous ichthyosaurs historically referred to the genus Platypterygius. A detailed taphonomical analysis was performed on the material from Gombola. The ichthyosaurs previously ascribed to Platypterygius are now identified only to the subfamily level. CT-scans revealed an anterior neurovascular network within both the premaxilla and the dentary, here interpreted as mandibular and maxillary/ophthalmic divisions of the trigeminal nerve. Axial sections and videos show how these intraosseous channels emerge within the dental and premaxillary fossae. Cross section imaging of tooth roots showed an alternating pattern of tooth resorption and eruption, providing additional information on dental replacement in ichthyosaurs. IG 251372 has been attributed to the Albian-Cenomanian by means of nannofossils contained within the matrix, making it the first ichthyosaur from the Northern Apennines to be directly dated.