The word 'mammal' comes from the Latin word 'mamma' for breast. Mammals differ from other vertebrates in two characteristics - they nurse their young and they have hair.

Mammals are believed to have first appeared on earth about 200 million years ago in the Triassic Period.

Wide diversity is seen even within this group. The African elephant goes into labour after a gestation period of 660 days, while the shrew takes only 14 days. Mammalian litter sizes are usually smaller than those of other animals, and while wolves and the wild boar can only have about six young ones at a time; mammals such as the tailless tenrec, at the other end of the spectrum, can have as many as 21!

The cheetah is one of the fastest mammals that can move at speeds of 105 km. per hour. It was last recorded in India in 1947, though stray reports of sightings continued till 1968.

India harbours 7.6 per cent of the world's mammals, classified into several orders and families.

Click here to download the checklist of mammals in India.