Geographical distribution: Alligator mississipiensis is found in the rivers of southern states of north america and A. sinensis occurs in the rivers of china.
- Head is broad with short, broasd and rounded snout.
- Body is covered with an exoskeleton of horny epidermal scales.
- The general color is greenish-black or dark-brown above and yellowish below.
- It measures two and a half to three and a half metres in length.
- Limbs pentadactyle with five fingers and four toes.
- The fingers are half-webbed and the toes are two-third webbed.
- The tail is laterally compressed.
- Mandibular symphysis is short extending only to the level of fourth or fifth tooth.
- Fourth mandibular tooth fits into a pit in the upper jaw.
- On either side 17-18 teeth in the upper jaw and 18-20 teeth in the lower jaw.
- The nasal bones divide the nasal groove by a median bony septum.
- The dorsal shield is formed by 6or 8 longitudinal series of keeled bony scutes.
- The neck is protected by two pairs of large scutes.
- Alligator mississipiensis is predators.