• Collections
• Ichthyosaur
• Ichthyosauria
• Linear morphometrics
• Morphometrics
• Museum
• Palaeontology
• Species level identification
• Stenopterygius
• trophic niche reconstruction

Stenopterygius is a genus of ichthyosaurs mainly found in the Toarcian (Early Jurassic) strata of Central and Northern Europe. Stenopterygius fossils coming from the locality of Holzmaden (Württemberg area, Southern Germany) are famous for their exceptional preservation. Over time hundreds of specimens were found in the Holzmaden area, and since the 19th century, museums all over the world bought Stenopterygius fossils.Italian museums were no exception: many collections in Italy possess Stenopterygius fossils, but often they were not described, no photo of these specimens were taken, being overlooked by the scientific community over more than a century. At the same time, Stenopterygius taxonomy and systematics changed, and many museums did not update the labels of their specimens.
In this work, photographs, 3D models, measurements and updated species level identification of nineteen Stenopterygius specimens (fifteen original fossils and four casts), stored in five Italian museums are provided. These Stenopterygius fossils are particularly important to gather more information on interspecific variability of two Stenopterygius species: Stenopterygius quadriscissus, the most common one, and Stenopterygius triscissus. Three Stenopterygius triscissus specimens are hosted by the Museo di Storia Naturale dell’Università di Pisa (MSNUP), they belong to three different ontogenetic classes, which makes them very interesting to understand the ontogeny of this species.
CT scans of two of the MSNUP Stenopterygius triscissus were obtained, allowing to see parts of the skeletons embedded in matrix and other fossils present in the slabs, such as bivalves and ammonites.
In order to understand Stenopterygius trophic ecology, comparisons with other aquatic and semiaquatic vertebrates were carried out, recovering Gavialis gangeticus and Platanista gangetica as good modern analogues for Stenopterygius triscissus specimens and Delphinus delphis and Stenella coeruleoalba as analogues for larger Stenopterygius triscissus specimens. Concluding considerations on Stenopterygius taxonomy, palaeoecology, palaeogeographical distribution can be found in the discussion, followed by remarks on the body size of the sample of Stenopterygius specimens in the Italian collections and proposals for future work, regarding Stenopterygius material hosted by both Italian collections and museums all over the world.

The aim of this master thesis project is to describe, figure and identify to the species-level, several specimens of ichthyosaurs fossils belonging to the genus Stenopterygius, stored in Italian museums, but coming from the Württemberg area of Germany, in particular from Holzmaden.
These fossils, present in Italian collections, improve our understanding of the intraspecific and interspecific diversity of Stenopterygius, increasing the number of specimens that can be used to build allometric curves of several morphometric measurements, and more importantly giving statistical robustness to species-level identification morphometric analyses (see 3.4).
Many Stenopterygius specimens are described, figured and their measurements are available, but many more Stenopterygius fossils have been found in the Holzmaden area, and due to their exceptional preservation, they have been bought by private collectors or museums, as in the case of the specimens presented in this work. Sharing data on Stenopterygius fossils stored in collections outside of Germany, is of the uttermost importance, considering that Stenopterygius may constitute a good model organism for fossil marine vertebrates, being yet one of the best represented ichthyosaurs in the fossil record.
In order to reconstruct the trophic niche of these animals we provide comparisons with other vertebrates that thrive and feed in aquatic environments. Skull proportions, transverse rostrum sections and tooth shape of selected Stenopterygius specimens and other aquatic and semiaquatic vertebrates have been compared. Though this comparison focuses exclusively on the skull of these animals, it is useful to point out good modern analogues for the trophic ecology of Stenopterygius specimens of different ontogenetic stages.