Caimans inhabit Central and South America. They are relatively small crocodilians, with the smallest being Cuvier's dwarf caiman (Paleosuchus palpebrosus), which grows to 1 m (3 ft) long, and the largest being the black caiman (Melanosuchus niger), which can grow to 4 m (13 ft) or more. Caimans are distinguished from alligators, their closest (and more widely-known) relatives, by a few defining features: a lack of a bony septum between the nostrils, ventral armor composed of overlapping bony scutes formed from two parts united by a suture, and relatively longer, more slender teeth than those that alligators possess. Several extinct forms are known, including Purussaurus, a giant Miocene genus that grew to 12 m (39 ft) and the equally large Mourasuchus, which had a wide duck-like snout.
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