Exceptional preservation of embryos in the actinopterygian Saurichthys from the Middle Triassic of Monte San Giorgio, Switzerland

Abstract

New excavations in the famous Monte San Giorgio area, close to the historical sites where the Cassina beds crop out (Lower Meride Limestone, Early Ladinian), revealed an interesting vertebrate fauna, including several specimens of the actinopterygian fish Saurichthys. Among the prepared specimens, three specimens of Saurichthys contain embryos, and in one example the embryos are preserved with traces of the soft parts, most probably phosphatized musculature. This discovery is of particular relevance because fossil embryos with preserved soft parts are extremely rare. In addition, although viviparity had previously been described for Saurichthys, the new specimens are rather better evidence and add further support to this reproductive mode.