The Jurassic flora of Sardinia

The most important Middle Jurassic flora of Italy comes from several localities of central-eastern Sardinia. The plant fossils belong to three important collections, collected from the Genna Selole Formation and stored at the museum “D. Lovisato” of the Cagliari University (collection A) and at the Narodni Museum of Prague (collection B) as well as at the Natural History Museum of Venice (Scanu et al., 2015, 2016). The study of the first two collections shows that the Sardinian Jurassic flora includes at least 22 genera of horsetails (stems and strobili), ferns (Marattia; Phlebopteris, Coniopteris, Dicksonia, Eboracia, Hausmannia, Todites, Cladophlebis), seed ferns (?Ptilozamites, Sagenopteris), cycadophytes (Cycadeospermum, Nilssonia, Pterophyllum, Ptilophyllum, Williamsonia, Weltrichia, Taeniopteris), Czekanowskiales (Czekanowskia), conifers (Geinitiza, Brachyphyllum, Elatocladus) and seeds (Carpolithes). Lycophytes and ginkgophytes are lacking in the flora. This study increases the diversity of the Italian Jurassic floras to 49 genera in total. A comparison with other Middle Jurassic floras in Europe evidenced an affinity with the Middle Jurassic flora of Yorkshire (England), while the geographically nearer Lower Jurassic flora of Rotzo (northern Italy) shows remarkable differences in composition. These differences may be related to different ecological conditions and taphonomic selection (Barbacka et al., 2014). Comparison to the Yorkshire flora (the most diverse European Jurassic flora) shows that 19 genera are preserved in both floras, including ferns (Cladophlebis, Coniopteris, Dicksonia, Eboracia, Marattia, Hausmannia, Phlebopteris, and Todites), seed ferns (Sagenopteris), cycadophytes (Nilssonia, Pterophyllum, Ptilophyllum, Weltrichia, Williamsonia), conifers (Brachyphyllum, Elatocladus, Geinitzia), Czekanowskiales (Czekanowskia) and Carpolithes seeds. Leaves of Ptilophyllum pectinoides together with its female reproductive organ Williamsonia hildae and its male reproductive organ Weltrichia whitbiensis are present in both floras. Given that the Sardinian flora is composed of 22 genera only, the similarity between the two floras is striking. Collection B of the Lovisato Collection, stored at the Narodni Museum, is under study but preliminary results give important insights in the original composition of the Lovisato collection and in the plant diversity of this Middle Jurassic flora. The collection stores type material described by Krasser and completes the collection A stored in Cagliari. While cycadophytes are the dominant group in Collection A, they are rare in Collection B. On the other hand, sphenophytes and conifers that are rare with a low diversity in Collection A, but are among the most important groups (both in diversity and abundance) in Collection B. Moreover, Collection B also contains the crustacean Estheria sp., coming from the same stratigraphic level as the plant remains.