Today there are something like twenty-two species of reptile that make up the Order Crocodylia. Of these species; only thirteen are actually true crocodiles, the remainder are Alligators, Caiman and the extremely rare and endangered, long-snouted gavials, sometimes referred to as gharials. We often get asked how to tell the difference between a crocodile and an alligator. There are a number of anatomical differences between crocodiles and alligators, when observing these reptiles look for a large, fourth tooth in the lower jaw. When the mouth is closed this tooth fits into a notch in the upper jaw and the tooth remains visible even when the mouth is closed. If you can see this tooth, then you are looking at a crocodile.
There are only two species of Alligator left in the world. Firstly, as most people know, there is the American alligator (alligator mississipiensis), which can be found widely distributed across the south-eastern United States, most typically in the Florida Everglades. There is also a second extant species of alligator, although this one is much rarer and confined to the upper Yangtse River valley in China. Scientists had thought that the less aggressive alligator had been "weeded out" of its range by crocodiles, leaving the only representatives of the Alligatoridae family in these isolated pockets. The more efficient crocodiles grew faster and may have been better at consuming food but this is generally regarded as speculation - as in the case of the American alligator, this species competes with the native American crocodile (C. acutus). The American alligator can withstand cold spells far better than the American crocodile, and as a result, has a much more extensive range in the United States.
Crocodylia in the "New World"
The idea of a "less aggressive" member of the Order Crocodylia is also a contradiction in terms. In the USA, once an Alligator reaches a length in excess of 4 feet it is regarded as dangerous to people. Alligator incidents are frequent, beginning in the spring when the warmer weather makes these cold-blooded reptiles more active and they begin to roam more widely. Fortunately, attacks on humans are relatively rare, although they do occur especially where people have been foolish enough to encourage alligators by feeding them. In some parts of the southern United States, special warden teams have been formed who work on a twenty-four call out service capturing and removing alligators that have wandered into areas of human habitation and got into contact with people. Specimens over 3 metres long are exceptionally rare in the wild but these reptiles, with their powerful jaws are still extremely dangerous and should be treated with caution. There is even a countryside code which has been developed by park rangers - a sort of "dos and don'ts" when in American alligator territory.
Crocodylia in the "Old World"
The majority of fatal attacks occur in Asia and northern Australia. Whilst we at Everything Dinosaur, would contend that all species of crocodilian are dangerous and that even a baby crocodile emerging from its egg is quite capable of giving you a nasty bite on the end of your finger - perhaps two of the most dangerous species of crocodile in the world can be found in Asia and Australia.
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