Uniqueness of habitat. Have high mountains, low deserts, rainforest, dry forest, spiny forest, central highlands, tsingy.
Geology--the great age of the island. Madagascar is not a volcanic island but rather a piece of the continent of Africa that broke loose about 100 mya.
No People. Most significantly, man did not arrive in Madagascar until about 1500 years ago.
- Arrived from Indonesia on boats, not from Africa.
- Extinction of large birds (Aepyornis), and mammals (giant lemurs).