Which one of the following characters is not typical of the class Mammalia?
- Thecodont dentition
- Alveolar lungs
- Ten pairs of cranial nerves
- Seven cervical vertebrae
Answer
(3) Ten pairs of cranial nerves
Solution
Mammals have thecodont teeth (set in jaw sockets), alveolar lungs and, almost always, seven cervical vertebrae.
Like reptiles and birds, mammals have twelve pairs of cranial nerves; ten pairs of cranial nerves are found in fishes and amphibians.
∴ 'Ten pairs of cranial nerves' is not typical of mammals.
Answer: (3)