In Central and South America, the alligator family is represented by five species of the genus Caiman, which differs from the alligator by the absence of a bony septum between the nostrils, and the ventral armour is composed of overlapping bony scutes, each of which is formed of two parts united by a suture. Some authorities further divide this genus into three, splitting off the smooth-fronted caimans into a genus Paleosuchus and the Black Caiman into Melanosuchus. Caimans tend to be more agile and crocodile-like in their movements, and have longer, sharper teeth than alligators.
C. crocodilus, the Spectacled Caiman, has the widest distribution, from southern Mexico to the northern half of Argentina, and grows to a modest size of about 2.2 meters. The largest is the near-threatened Melanosuchus niger, the Jacare-assu, Large, or Black Caiman of the Amazon River basin. Black Caimans grow to 16.5 feet (5 m), with the largest recorded size 5.79 m (19 ft). The black caiman and American Alligator are the only members of the alligator family that pose the same danger to humans as the larger species of the crocodile family.
Although the Caiman has not been studied in-depth, scientists have learned that their mating cycles (previously thought to be spontaneous or year-round) are linked to the rainfall cycles and the river levels, which increases chances of survival for their offspring.