Crocodiles, alligators, caiman, and gharials are all referred to as crocodilians. Crocodiles are survivors of a time known as the Age of Reptiles, a time when dinosaurs roamed the earth, dating from 265 million years ago to roughly 66 million years ago.
At the end of the Triassic period, about 210 million years ago, a small, reptile appeared which has been named Terrestrisuchus and is thought to be the direct ancestor of our modern-day crocodiles. The terrestrisuchus, as it name implies, was primarily a land-dwelling reptile, running about on either two or four legs and eating smaller lizards.
The ankle joints of the reptiles are similar to present day crocodilians. It is one of the main links between them.
All four forms of crocodilians resemble each other. The alligator has a broad, rounded, shovel-like snout while the gharials snout is long and narrow. The snouts of the caiman and the crocodiles are between these extremes, although a long, tapered snout is most common. All crocodilians have their eyes and nose on the top of the skull so that they can see and breathe while the rest of their body is submerged.
All crocodilians have powerful jaws. Their sharp teeth are designed for grasping and tearing, with small prey swallowed whole, while larger prey is torn apart and the pieces swallowed. The teeth are periodically replaced with up to 50 sets of teeth by the time the crocodilian is old. Baby crocodilians feed heavily on insects and small fish. Crocodilians swallow stones to aid in digestion of food. Crocodilians' digestive system is powerful enough to dissolve the bones of their prey. When food is plentiful, they store fat in their tails and body. The fat enables them to go long periods without eating.
croc2jpg
There is slight webbing between some of the digits of the Morelet's crocodile. This is an aid to swimming, even though most of the propulsion in swimming is done by the crocodile's tail. It was longed believed that the crocodilians used their tails to sweep their prey off its feet and into the water. It is now known that most of the prey is caught after a silent, stealthy stalk and a startling swift attack. Mammalian prey is caught and pulled underwater to drown before being torn to pieces and eaten. Some crocodilians will actually gallop for a short distance in pursuit of prey on land.
Because it has the largest range of the four New World crocodiles, Crorodylus acutus, is perhaps the best known. In North America, its range is restricted to the regions of the Florida Keys, although it goes up fresh water canals around the Everglades. It is found on the islands in the Caribbean, Mexico, Central America, Colombia, Venezuela, Ecuador, and Peru. A distinguishing feature of all the crocodiles is that the fourth tooth, on either side of the lower jaw, is so long it protrudes through holes in the upper jaw. The American crocodile also can be distinguished from all other crocodiles because it has less bumpy osteoderms on its back. It is rare to find any specimens of this crocodile today that measure over 4 metres (13 1/2 feet) in length.
All crocodiles have a gland in their mouth that allows them to extract and eject salt from saltwater so it can be drunk. This gland is more efficient in some species than others.
American crocodiles dig tunnels as a refuge from the heat during droughts. This is known as aestivation
American crocodiles use their hind feet to make a hole in the peat in which to lay their eggs. The female lays from 40 to 60 eggs. She then makes a tunnel for herself close to the nest to stand guard over the eggs. After a 3 month period of incubation she will help the young to hatch by opening the nest.
croc4jpg
The populations of the American crocodile have greatly declined. One reason is that it was hunted for it skin. Another reason is because dams and canals have diverted so much fresh water from streams for agriculture that the salt content of bays and estuaries is too high for the young to survive.
:SugarwareZ-064:
At the end of the Triassic period, about 210 million years ago, a small, reptile appeared which has been named Terrestrisuchus and is thought to be the direct ancestor of our modern-day crocodiles. The terrestrisuchus, as it name implies, was primarily a land-dwelling reptile, running about on either two or four legs and eating smaller lizards.
The ankle joints of the reptiles are similar to present day crocodilians. It is one of the main links between them.
All four forms of crocodilians resemble each other. The alligator has a broad, rounded, shovel-like snout while the gharials snout is long and narrow. The snouts of the caiman and the crocodiles are between these extremes, although a long, tapered snout is most common. All crocodilians have their eyes and nose on the top of the skull so that they can see and breathe while the rest of their body is submerged.
All crocodilians have powerful jaws. Their sharp teeth are designed for grasping and tearing, with small prey swallowed whole, while larger prey is torn apart and the pieces swallowed. The teeth are periodically replaced with up to 50 sets of teeth by the time the crocodilian is old. Baby crocodilians feed heavily on insects and small fish. Crocodilians swallow stones to aid in digestion of food. Crocodilians' digestive system is powerful enough to dissolve the bones of their prey. When food is plentiful, they store fat in their tails and body. The fat enables them to go long periods without eating.
croc2jpg
There is slight webbing between some of the digits of the Morelet's crocodile. This is an aid to swimming, even though most of the propulsion in swimming is done by the crocodile's tail. It was longed believed that the crocodilians used their tails to sweep their prey off its feet and into the water. It is now known that most of the prey is caught after a silent, stealthy stalk and a startling swift attack. Mammalian prey is caught and pulled underwater to drown before being torn to pieces and eaten. Some crocodilians will actually gallop for a short distance in pursuit of prey on land.
Because it has the largest range of the four New World crocodiles, Crorodylus acutus, is perhaps the best known. In North America, its range is restricted to the regions of the Florida Keys, although it goes up fresh water canals around the Everglades. It is found on the islands in the Caribbean, Mexico, Central America, Colombia, Venezuela, Ecuador, and Peru. A distinguishing feature of all the crocodiles is that the fourth tooth, on either side of the lower jaw, is so long it protrudes through holes in the upper jaw. The American crocodile also can be distinguished from all other crocodiles because it has less bumpy osteoderms on its back. It is rare to find any specimens of this crocodile today that measure over 4 metres (13 1/2 feet) in length.
All crocodiles have a gland in their mouth that allows them to extract and eject salt from saltwater so it can be drunk. This gland is more efficient in some species than others.
American crocodiles dig tunnels as a refuge from the heat during droughts. This is known as aestivation
American crocodiles use their hind feet to make a hole in the peat in which to lay their eggs. The female lays from 40 to 60 eggs. She then makes a tunnel for herself close to the nest to stand guard over the eggs. After a 3 month period of incubation she will help the young to hatch by opening the nest.
croc4jpg
The populations of the American crocodile have greatly declined. One reason is that it was hunted for it skin. Another reason is because dams and canals have diverted so much fresh water from streams for agriculture that the salt content of bays and estuaries is too high for the young to survive.
:SugarwareZ-064: