It contains a single species, Helveticosaurus zollingeri, known from the nearly complete holotype T 4352 collected at Cava Tre Fontane of Monte San Giorgio, an area well known for its rich record of marine life during the Middle Triassic.

The long, flexible tail is similar to what can be seen in other extinct marine reptiles such as thalattosaurs, and it probably propelled itself through the water by means of lateral undulation.

However, Helveticosaurus also possessed a robust pectoral girdle and forelimbs that were well adapted for paddle like propulsion as a supplementary method of locomotion, as seen in secondarily aquatic tetrapods.

[1] Despite the dorsal vertebrae, which are very similar to those of placodonts, the genus lacks many of the autapomorphies characteristic of sauropterygians and thus evolved from a different ancestor, independently adapting a marine lifestyle.

SVT 203 was once referred to the ichthyosaur Grippia longirostris,[8] but the pubis, femur, metatarsals, and phalanges suggest that it is not from an ichthyopterygian, therefore making it more probable that it belongs to a taxon related, and possibly ancestral, to Helveticosaurus, although more material is needed to give a definitive confirmation.