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1 CE
Sinonyx - 60 million
Sinonyx was around 5 ft long and almost the size of a modern grey wolf. Morphologists think that the sinonyx was a direct ancestor of Cetacea (whales and dolphins). -
1 CE
Indohyus - 50 million
The indohyus was about the size of a cat but resembled a deer. It belonged to the group called Artiodactyle or also called even-toed ungulates. -
2
Pakicetus - 50 million
The oldest ancestor of whales is believed to be the Pakicetus. A cetacean and quadruped that measured up to 1 to 2 meters long. Unlike whales today, the Pakicetus had artiodactyl ankles used for running. -
3
Water chevrotain - 50 million
A water chevrotain is a herbivore that is native to Africa. It is 80 cm in length and one of the closest living animals to Indohyus, a distant ancestor of whales. It's believed they gravitated towards water sometimes to seek refuge from predators or to eat. -
4
Adaptations - Blubber
The whale's ancestors were land mammals so instead of having blubber like the modern whale they had fur. But as evolution went on they developed thick blubber skin. the blubber acts as insulation to keep the whales warm as well as buoyancy. -
5
Rodhocetus - 46 million
Rodhocetus shows the progression towards modern whales. It got a strong swimming tail, and a more flexible spine for tail movement. It is the earliest mammal known to have mostly used its tail to swim instead of its arms and legs. it could still walk on land but not as effectively as before. -
6
4-legged whale - 42 million
In Peru four-legged whale fossils were discovered of ancestors of the current whale we have today. Finding these fossils supported the hypothesis of westward migration in the northward migration. -
7
Basilosaurus - 35-45 million
This whale was really big at 15 meters or 50 ft long. The serpent-like animal had a very small pelvic girdle and hind limb bones that were too small for them to use on land. The vertebral column has characteristics of whales that have fins. -
7
Durudon - 40 million
The dorudon lived until about 40 million years ago and at the same time as the basilosaurus and might also be an ancestor to whales as well. The creature was fully aquatic and did not have big enough limbs to walk on land. Although they were a lot smaller (4-5 meters). Also, they lacked eco location which modern whales use to day to detect objects. -
8
Mysticetes - 4.5 million
The first mysticete's length was 5 to 9 meters, which is close to the size of a modern-day minke whale. Whales have believed to get so big about 4.5 million years ago. The growth of mysticetes s because of the sudden cooling of the climate from the formation of large ice caps in the northern hemisphere. -
8
Adaptation - Broaden tails horizontally
Cetaceans have flat horizontal tails. While on the other hand, fish have vertical flat tails. The whale's body naturally bends upwards and downwards and not side to side like a normal fish. -
9
Adaptaion - Limbs into flippers
The limbs of the whale's early ancestors were slowly modified over time to help the steer easily through the water. They also use their flippers to slap the surface of the water as a means of communication. A slap can carry on miles away. -
9
Adaptation - Hind limbs disappearing
Fossils that were discovered in the middle east also include the unused hind limbs of the whale's ancestor. Because of their transition from land to the ocean, they didn't have much use for their back limbs. As they evolved they withered away. But, whales today still have vestigial pelvis bones that are a part of their skeleton. -
22
Adaptations - Nostrils on head
Over time the whale's nostrils at a snail's pace moved to the top of their heads. Their nose evolved from the front of their head like a dog to the top. They rise above the surface of the water to breathe. -
23
Adaptation - Eco-location
Humpback whales and other cetaceans have highly developed hearing. Sound travels a lot better in the water than it does if it were just air. So the whales developed and auditory sense that is stronger than their visual senses.