Are torosaurus triceratops

Some suggest that Triceratops fossils are actually the fossils of young Torosaurus. However, Triceratops were extremely common and existed before Torosaurus did. If Torosaurus were adult Triceratops, their should be fossils of Torosaurus that were as old as the oldest fossils of Triceratops. Thus, I don't think that Torosaurus was the same as Triceratops.