Lissodus sardiniensis, Fischer & Schneider & Ronchi, 2010

Fischer, Jan, Schneider, Jörg W. & Ronchi, Ausonio, 2010, New hybondontoid shark from the Permocarboniferous (Gzhelian-Asselian) of Guardia Pisano (Sardinia, Italy), Acta Palaeontologica Polonica 55 (2), pp. 241-264 : 255

Autecology of Lissodus sardiniensis sp. nov.

The size of L. sardiniensis sp. nov. is not clearly determinable because no articulated remains are preserved. On the basis of the assumption that teeth size/body length relations are similar to those in articulated remains of related forms ( Broom 1909; Brough 1935; Antunes et al. 1990), a length of 20–30 cm is predicted for the Sardinian species.

The teeth of L. sardiniensis sp. nov. are weakly heterodont with lower crowned teeth occuring laterally. Therefore, the mesials (morphotype I) and symphyseals (morphotype II) were most probably used for clutching and the laterals (morphotype III) for crushing prey. This characteristic dentition indicates a durophagous lifestyle ( Duffin 1985; Gebhardt 1988; Hampe 1991, 1996) as characterised by Recent rather small sharks of bottom dwelling habitat ( Cappetta 1987; Compagno 1990). It is generally assumed that benthic hard−shelled invertebrates such as gastropods, crustaceans, and bivalves were probably the preferred prey of Lissodus . However, nothing argues against L. sardiniensis sp. nov. capturing other soft prey lacking a shell, which is indicated by clutching or grabbing morphology of the mesial or symphyseal teeth. In the opinion of Boy (1998) and Boy and Schindler (2000) the occurrence of L. cf. zideki was not necessarily bound to the occurrence of hard shelly benthos, but might be based on taphonomic bias. Furthermore, the dermal denticles also support the assumption of a bottom−dwelling habitat. Reif (1981) and Cappetta (1987) correlate small placoid scales with hook− or thorn−like crowns together with typical slow swimming Recent sharks in habitats near or on the bottom. Scales similar to those described here as morphotype 2 occur in the Recent Echinorhinus brucus and Squalus acanthias , which live in near−ground habitats ( Reif 1981, 1985; Hampe 1996).