Answer
Crocodilians are descended from the Archosauria clade of the Diapsida. Diapsids have skulls with a pair of postorbital openings on each side of the skull--one above and one below the orbit.
Archosaurian characteristics include a tringuloid ante-orbital fenestra ( anterior opening of the skull into the orbit), and a fully divided ventricle.
Other animals that belong to this group are extinct dinosaurs, (pterosaurs) and living birds. The Crocodilia and their relatives-- alligators, gharials, caymans--belong to the Pseuduosuchia; dinosaurs and birds belong to the Ornithosuchia.
Crocodilian features include a long skull with massive jaw musculature, and teeth in sockets. They also have a complete secondary palate like mammals.
The jaw adaptations and heavy jaw musculature enable crocodilians to open their mouths wide and deliver a fast and powerful bite (closure of the mouth). The complete secondary palate enables a croco =dilian animals to breathe when its mouths is full with food or water.
Crocodilians can move quickly and some are aggressive and dangerous. They are able
to attack and kill large animals ( cattle, deer) including humans.
Crocodilians are oviparous ;females lay eggs ( about 50-60 at a time) which they cover with with dead vegetation or bury in sand. Crocodilians are good parents. They guard their eggs . When the eggs begin to hatch the mother responds to the calls of the hatchlings (from within the eggs) by opening up the nest and and assisting the hatchlings to escape eggs and nest.. The young may also get maternal assistance to reach the water.The mother then protects the young for about two years, often supplementing their food supply,
Work Step by Step
The descent of Crocodilians from ancestral amniotes was as follows:
Ancestral amniotes>Reptiles>Diapsids>Archosaurs>>>Crocodilians. Dinosaurs, non-avian dinosaurs, and birds are also descended from Archosaurs, but Crocodilians are the only living nonavian Archosaurs.
