CHARACTERISTICS: animals with a backbone; crocodilians have an elongated head with long jaws, and body covered with hard plates; birds have a hard beak and body covered with feathers KNOWN SPECIES: birds-9,500 to 10,000; crocodilians-22 SIZE RANGE: birds-less than 2.4 inches to 8.2 feet (less than 6 centimeters to 2.5 meters); crocodilians-3.9 feet to 20.7 feet (1.2 to 6.3 meters) WHERE THEY LIVE: in oceans and fresh waters, and on land