1. Reproduction:
* Mammals: Give birth to live young, which are nourished by milk produced by mammary glands.
* Birds: Lay eggs, which are incubated by the parents until hatching.
2. Body Temperature:
* Mammals: Endothermic (warm-blooded). They maintain a relatively constant body temperature regardless of the external environment.
* Birds: Endothermic (warm-blooded). They also maintain a constant body temperature.
3. Skin and Appendages:
* Mammals: Have hair or fur, sweat glands, and typically have four limbs (although some have lost limbs through evolution, like whales).
* Birds: Have feathers, scales on their legs, and wings.
4. Respiration:
* Mammals: Breathe air using lungs.
* Birds: Breathe air using lungs, but their respiratory system is more efficient than that of mammals.
5. Circulation:
* Mammals: Have a four-chambered heart.
* Birds: Also have a four-chambered heart.
6. Skeleton:
* Mammals: Have a flexible skeleton with a well-developed skull.
* Birds: Have a lightweight skeleton with fused bones for flight.
7. Digestive System:
* Mammals: Have a variety of digestive systems adapted to their diets.
* Birds: Have a specialized digestive system with a gizzard for grinding food.
8. Other Distinctions:
* Mammals: Have a wider range of teeth types (incisors, canines, premolars, and molars).
* Birds: Have a beak instead of teeth, which are used for feeding.
* Mammals: Typically have a diaphragm for breathing.
* Birds: Do not have a diaphragm.
In summary: While both mammals and birds are warm-blooded and share some similarities, they have evolved distinct characteristics for their unique lifestyles and environments. This includes differences in reproduction, body coverings, respiratory systems, skeletons, and other features.