State reasons for each of the following:
- Echidna and platypus lay eggs but are considered as mammals.
- Forelimbs of birds are modified.
- Crocodiles have four-chambered heart but are still reptiles.
- They have mammary glands for the production of milk to nourish their young ones.
- To reduce body weight for flight, forelimbs of birds are modified.
- Crocodiles are cold blooded, lay eggs and have scale on their body. These characteristics make ’ them reptile.