American Species
In North America, the American alligator is the largest of the reptiles, according to the "National Audubon Society Field Guide to Reptiles and Amphibians." Alligators grow to reach lengths between 10 and 15 feet, with the longest recorded, including the length of the tail, reaching past 19 feet. The American crocodile, a much rarer species in North America, grows between 7 and 15 feet, but lacks the bulk that alligators feature. Alligators can weigh as much as 1,000 lbs.
The Chinese Alligator
The only other species of alligator is the Chinese alligator, a species that is rare in the wild. Captive and wild specimens of the Chinese alligator rarely exceed 6 1/2 feet long. The Chinese alligator lacks the weight of its American cousin, with the average individual weighing less than 100 lbs.
Large Crocs
The largest species of crocodile in the world is the saltwater crocodile. Specimens as long as 21 feet exist, reaching weights exceeding 2,000 lbs. Another huge crocodile species is the Orinoco crocodile, a species of northern South America that reportedly reached sizes of nearly 23 feet when the creature was more plentiful, according to the Crocodilian website, but now averages about 16 feet long. The Nile crocodile, with a range over much of Africa, averages around 16 1/2 feet in length.
Smaller Crocs
Among the smaller types of crocodile species is the slender snouted crocodile of Africa, a reptile averaging about 8 feet long. Australian freshwater crocodiles grow to be about 9 1/2 feet long. The smallest of the crocodiles is the African dwarf crocodile, with the longest being just a little bigger than 6 feet long.