How to Identify a Crocodile Skull

Compare an alligator and a crocodile skull side by side, using actual skulls, models or photographs. Skulls can be purchased for comparison. Some are anatomically correct models cast in polyurethane resin, but natural skulls from farmed animals and from legally harvested nuisance individuals are also available. The most common natural skulls available are those of the American alligator and the Nile or the Australian saltwater or crocodile. Those of rarer species are far more likely to be replicas and can be very expensive.

Look carefully at the shape of the muzzle or snout. The alligator's muzzle tends to be blunted or rounded and shaped like the letter U, while the crocodile's tends to be more pointed and shaped more like the letter V. This is not always true, but is a good general guideline. Both skulls may appear pitted, but this is not due to posthumous damage -- the marks show that the skin on the head was attached directly to the bone of the skull.

Look at the way the jaws come together. The upper jaw of the alligator is a little wider than the lower jaw and the upper teeth overhang the lower teeth when the alligator's mouth is closed. In the crocodile, the upper and lower jaws are the same width and the teeth interlock. Nearly all the crocodile's teeth show when its mouth is closed, making it appear to be grinning.

Look for an enlarged fourth tooth on each side in the front of the lower jaw, rather like the tusks of a hog. In the alligator this tooth fits into a socket in the upper jaw and is hidden when the jaws are closed. In the crocodile, it overlaps the upper jaw and is visible when the jaws are shut. Checking for this dental variation is the easiest way to distinguish between the two.