Besanosaurus

Besanosaurus (meaning ) is an extinct genus of Middle Triassic ichthyosaur from Monte San Giorgio of Italy and Switzerland, containing the single species B. leptorhynchus. Besanosaurus was named by Cristiano Dal Sasso and Giovanni Pinna in 1996, based on the nearly complete flattened skeleton BES SC 999, the holotype specimen. This skeleton is preserved across multiple thin rock slabs spanning when assembled and took thousands of hours to prepare. Additional specimens from Monte San Giorgio that have previously been considered separate genera, including a partial skull named Mikadocephalus and a well-preserved, largely complete skeleton, have been reinterpreted as additional specimens of Besanosaurus. Putative specimens of Besanosaurus have been discovered in the Norwegian archipelago of Svalbard and Germany, although their attribution to this genus remains disputed.

As an ichthyosaur, Besanosaurus had flippers for limbs and a fin on the tail. Besanosaurus is a large ichthyosaur, with the largest known specimen estimated to measure about long. It has a long, slender body with a small head and long tail. The snout of Besanosaurus is long and thin, and contains numerous small pointed teeth. In the upper jaw, the teeth are mostly set into sockets but the rearmost teeth are implanted in a groove. The lower jaw bears enlarged coronoid processes for the anchorage of jaw muscles. There are 61 vertebrae in front of the hips, two in the hip region, and at least 138 in the tail. The tail made up more than half the animal's length and displays a downward bend. The forelimbs are longer than the hindlimbs, and the humeri are round and squat. The phalanges (finger and toe bones) are elliptical in the forelimbs but constricted in the hindlimbs.