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UPSC Prelims 2011 · Environment · Species Watch
From the point of view of the evolution of living organisms, which one of the following is the correct sequence of evolution?
- (a) Otter - Tortoise – Shark
- (b) Shark - Tortoise - Otter
- (c) Tortoise - Shark - Otter
- (d) Shark - Otter - Tortoise
Show the answer and explanation
Answer: (b) Shark - Tortoise - Otter
Shark (fish) evolved first, then tortoise (reptile), then otter (mammal).
The idea
Animals with backbones appeared in a fixed order: first in water, then on land. Place each animal in its group and the order follows.
Fish → shark → Amphibians → Reptiles → tortoise → Birds and mammals → otter
Why the others are wrong
(a) The reverse order.
(c) Puts the reptile before the fish.
(d) Puts the mammal before the reptile.
Also know
The otter is a mammal that has gone back to water, but its group still came last. India has three otters: the smooth-coated, the Eurasian and the small-clawed.
🔒 Vertebrate order: fish → amphibians → reptiles → birds / mammals.