Scientific Illustration

lostbeasts:

Lotosaurus.
Unlike other known rauisuchians, Lotosaurus had no teeth, which suggests its diet may have consisted of either plant matter or shellfish. The sail on its back may have been used for temperature regulation or display.

Rauisuchians were essentially large, land-living crocodiles. They occupied the niche of large predators that was, at that point during the early Triassic, unoccupied by the small dinosaurs alive at the time.

I would be careful about using information from David Peters, see:

Why the world has to ignore ReptileEvolution.com