Question

Differentiate between Vestigial organ and atavistic organ.

Answer 1

Aspect	Vestigial Organ	Atavistic Organ
Definition	Organs that are non-functional in the present organism but were functional in their ancestors.	Sudden reappearance of an ancestral structure that had disappeared or greatly reduced.
Functional Status	Non-functional or reduced in function in the current organism.	May reappear with partial or full ancestral function.
Occurrence	Present as remnants or reduced organs in the organism.	Appears occasionally or suddenly as a reversion trait.
Example	Human vermiform appendix, coccyx, rudimentary wings in kiwi and ostrich, eyes of some burrowing animals.	Rudimentary tail in newborn human babies, additional mammae, large canines, power of moving pinna.