Oldest Whale Fossils

Archaeocetes

• Archaeocetes are a group of the oldest whale fossils. These fossils differ from modern whales. The teeth of the modern whale are uniform. Ancient whales had a variety of tooth shapes like most land animals. The nostrils of ancient whales were near the tip of their noses unlike today's whales that have blow holes on top of their heads. Ancient whales had hind legs that protruded out of their body. Today's whales have the remnants of hind legs, but these legs do not extend beyond their body.

Pakicetus

• Pakicetus fossils are found in river deltas of modern day Pakistan. Pakicetus was an ancient whale that prospered in the middle Eocene period about 45 million years ago. It weighed about a 100 lbs. and was similar in size to a wolf. These ancient whales had legs and were capable of walking. They also were able to hear much better on land than in the sea. They were carnivorous mammals that waded into the water to eat fish.

Basilosaurus

• Basilosaurus fossils have been found in the United States and in Northern Africa. They lived in the middle and late Eocene period 38 to 55 million years ago. These whales were long and snakelike in appearance, reaching lengths of 70 feet. They had tiny back legs that were not capable of supporting their massive bodies. This was the first ancestor of the modern whale that had a fluke tail. Before this specialization, whales paddled with legs for locomotion.

Mammalodon

• Mammalodon fossils found in Australia are the ancestors of Baleen whales like today's humpback whale and blue whale, both filter feeders. This ancient whale lived 25 million years ago. They had flukes, blow holes and no exterior limbs. These whales did not have teeth but had the baleen adaptation -- a fibrous structure in the mouth used to filter food. Few fossils of baleen have been found because baleen is much less dense than bone. Mammalodon had short baleen plates and was a bottom feeder that was 10 feet in length.