Observations on Triassic ichthyosaurs.: Part XIV:: The Middle Triassic mixosaurid Phalarodon major (v. HUENE, 1916) from Switzerland and a reconsideration of mixosaurid phylogeny

A fragmentary skull of a mixosaurid, including much of the upper and lower jaws and dentition, is described from the Lower Muschelkalk of Schwaderloch, Kanton Aargau, N Switzerland. The specimen represents the first diagnostic find of a mixosaurid from the Germanic facies of the Middle Triassic in Northern Switzerland. It can be referred to the species Phalarodon major because of autapomorphies of the lower dentition. Otherwise this species is only known from a fragmentary lower jaw from the Lower Muschelkalk of SW Germany. It thus provides much new information on the antomy of this little known mixosaurid. As the specimen is much smaller than the holotype, it is certainly a juvenile. It further substantiates the evidence that the genus Phalarodon was a regular component of the Lower Muschelkalk fauna, but that its representatives in the Germanic Basin were endemic. A re-analysis of the ingroup phylogeny of mixosaurids supports the results of previous studies. The recently described Mixosaurus callawayi represents a phalarodontine mixosaurid that is provisionally referred to the genus Phalarodon.