Question

What are the adaptations in reptiles to lead a complete terrestrial life.

Answer 1

Hint: Changes seen in reptiles to survive on land. These changes may be seen first time in reptiles or they may be adopted from their ancestors during the process of evolution.

Complete answer:
Reptiles are the first true terrestrial, creeping, amniotic tetrapods. Their body is divided into head, neck, and tail. Skin is dry and rough and the exoskeleton is in the form of horny epidermal scales, shields, and claws. They first appear in reptiles. Each half of the lower jaw is formed by six bones. They have procoelous vertebrae. Axis and atlas are the first two cervical vertebrae that facilitate the independent movement of the head from the rest of the body. They have specialized olfactory structures called Jacobson's organs that are highly developed in lizards and snakes. The muscular copulatory organ is present in males. Hemipennis is seen in lizards and snakes. Internal fertilization and eggs are cleidoic and megalecithal.

Additional Information: - Reptiles are exothermic amniotes that are formed from the extinct labyrinthodont amphibians during the Carboniferous period
- the incompletely chambered heart is present and the circulation is a closed type. Conus arteriosus is absent but sinus venous is present
- 12 pairs of cranial nerves are present
- inner border of external auditory meats contains a tympanic membrane. Columella Auris is a single ear ossicle present in the middle ear.

Note: All the reptiles have an incomplete heart but four Chambered hearts are found in crocodiles.
All the reptiles have 12pairs of cranial nerves but in snakes, only 10 pairs of cranial nerves are seen.
Examples of reptiles: marine green turtle, sphenodon, crocodile, lizard, etc.