Question

Which part of the vertebral column is considered as a vestigial tail?

• A. 7 fused sacral vertebrae
• B. 4 fused sacral vertebrae
• C. 7 fused coccygeal vertebrae
• D. 4 fused coccygeal vertebrae

Answer 1

The correct option is D 4 fused coccygeal vertebrae

The structures present in an organism that have lost all or most of their original form and function, in due course of evolution, are known as vestigial organs.

Mammals have tail at some stage of their development. Tail in animals serves the purpose of maintaining balance of the body and helping in movement. As apes and humans emerged from the early ancestral forms, the tail became progressively reduced in structure and function to assist better upright movement.

The vertebral column is divided into five regions which include cervical, thoracic, lumbar, sacrum and coccyx. The cervical, thoracic and lumbar vertebrae are not fused. Five sacral vertebrae are fused forming the sacrum and 4 coccygeal vertebrae fuse to form the vestigial tail. The figure below shows the structure of the coccyx (tailbone) that is formed by the fusion of 4 coccygeal vertebrae.