2. Superorder: Archosaurs
• a group of diapsid reptiles that first evolved
from Archosauriform ancestors .
• They are represented today by birds and
crocodiles.
• are set apart by having socketed teeth
• four-chambered hearts
4. CROCODILIANS
• From the Middle Triassic
• Include the subtropical and tropical alligators,
crocodiles, caimans, and a single species of
gavials.
• They have survived major upheavals such as the
break up of the continents and the ice ages.
6. Gharial - Gavialis Gangeticus
American alligator - Alligator mississippiensis
7. Distinctive Features
• powerful jaws
• protective scales
• streamlined body
• long tail
• eyes and nostrils that are positioned on top
of the head
• elongated snout
8. Common Characteristics
• They usually lay around in the water
motionless.
• Their eyes and snouts are the only part of
their body that stays above the water.
• Crocodilians have sharp teeth for capturing
large prey.
• semi-aquatic predators
9. Common Characteristics
• They have an extra transparent eyelid on each eye that
can be closed to protect their eye when underwater.
• They have a flap of skin at the back of their throat that
prevents water from seeping in when they attack prey
underwater.
• They can also close their nostrils and ears in a similar
manner to prevent the unwanted influx of water.
10. CROCODILIANS
• Their features have changed very little from
those of their prehistoric ancestors, proving
that their body form has been highly
successful in nature.
11. Crocodiles Alligators Gavial Caiman
Shape Slender and Broad and long and slightly
of triangular round narrow more
snout pointed
protrud on the hidden hidden
ing lower jaw inside a inside a
fourth socket on the socket on
tooth upper jaw the upper
jaw
