These fossil materials contained theropod vertebrae and marine crocodilian remains. Cuvier's dwarf caiman is the smallest living New World crocodilian. The spectacled caiman has the largest range of any caiman and any New World crocodilian. The freshwater crocodile is a relatively small crocodilian. The spectacled caiman is a small to medium-sized crocodilian. The saltwater crocodile is often claimed to be the largest living crocodilian. The American alligator is a relatively large species of crocodilian. An alligator is a crocodilian in the genus "Alligator" of the family Alligatoridae. The gharial is the most thoroughly aquatic crocodilian. Spectacled caimans have now filled the niche of crocodilian predator of fish in many areas. The false gharial is a large crocodilian. The gharial is the only living crocodilian with such visible sexual dimorphism. Baru is an extinct genus of Australian mekosuchine crocodilian. Gryposuchus is an extinct genus of gavialoid crocodilian. The crocodilian has perhaps the most complex vertebrate circulatory system.