Evolution of Whales Alana and Annasimone

Timeline47 million years

ago:- Alligator like

feet- Fed in the water - 4.1 metres long - Forelimbs and hind limbs for

walking- No tail flukes

48 million years ago:

- 1.75 metres long - Nostrils were far

forward - Forelimbs and

hindlimbs function for walking

- No tail flukes

46 million years ago:

- Sea lion figure - Spent some time

on land- 3 metres long

- function for walking and swimming

- Large hind limbs - No tail flukes

37 million years ago: - Completely aquatic

- 4.5 metres long - Nostrils further back

on skull - Forelimbs have become flippers

- Elongation of the trunk

- Reduced hind limbs- Tail flukes

Present day: - Streamlined body - Insultating layer of

blubber - Flippers as fore

limbs - Hind legs are

interbal vestiges - Tail is flattended horixontal flukes

- No external neck - Large head and wide

mouth

34 million years ago: - Completely aquatic - 9-10 metres long

- Teeth reduced - First evidence of baleen for filter

feeding - Nostrils further

back on skull- Elbows immobile

Since whales evolved from land mammals, at first their nostrils were positioned far forward.

At one point, a mutation occurred, producing at least one whale with “nostrils” positioned further back along the snout.

Nostrils Nostrils

This mutation helped that whale thrive in a sea environment by easing the process of surfacing for air.

The mutated whale survived, thrived and reproduced, passing on this favourable characteristic to its offspring.

This mutation became more common among the population

Modern whales are now born with “nostrils” (blowholes) on their backs