The unique mammalian characteristics are :
- hairs, pinna and mammary glands
- hairs, pinna and indirect development
- pinna, monocondylic skull and mammary glands
- hairs, tympanic membrane and mammary glands
Answer
(1) hairs, pinna and mammary glands
Solution
Hair on the skin, external ears (pinnae) and milk-producing mammary glands are found only in mammals.
(2) Mammals show direct development, not indirect development.
(3) Mammals have a dicondylic skull (amphibians also dicondylic; reptiles and birds monocondylic).
(4) A tympanic membrane is also present in amphibians, reptiles and birds.
Answer: (1)