Home Shop Freebies Info DolphinHut
Dolphin Info  
Sponsored Links
Sign up for the Dolphin Hut Newsletter. Your email will not be shared with other parties.

Dolphin Evolution

Basic Dolphin Evolution
All dolphins, whales, and porpoises are related. Fossil evidence from the early Eocene epoch, indicate that the early dolphins or Protocetidae were already aquatic 45 to 50 million years ago. However, they bore little resemblance to the dolphins and whales we know today.

Fossil Records
Fossil dolphins can be traced through time by the changes in their teeth. About 30 million years ago the early dolphins split into the two main divisions known today: the toothed whales, and the baleen whales. Delphie, the group from which modern dolphins arose, began to appear in the early Miocene about 25 million years ago.

Physical Structure
Because the dolphins evolutionary line diverged some 50 million years ago, their physical structure had time to develop independently from terrestrial mammals. For instance, the fossil record indicates that there was a stage when the animals were amphibious. However, this record also shows that once the early dolphins decided to be aquatic, it didn't take long for the bones of the hind limbs to disappear altogether.

The obvious streamlining of a dolphin's bodies caused by living in water has produced several other modifications to the animal's physiology. The thickened body and raised head has caused the vertebrae of the cetacean neck to become fused. Instead of the major blood supply to the brain running up the outside of the neck, as in land animals, it passes through an artery within the fused vertebrae. This insures a constant supply of blood when the dolphin dives to extreme depths in the ocean. (Dolphins and man...equals?)

What are cetaceans?
Cetaceans is a collective term for whales, dolphins, and porpoises. It contains two suborders Mysticeti and Odontoceti. The baleen whales are members of the Mysticeti suborder, while the toothed whales, dolphins and porpoises make up the Odontoceti suborder. Within these two suborders contain eighty-one known species, separated into thirteen different families. (Cetacea)

Dolphins are mammals, not fish. They are warm-blooded like man, and give birth to one baby or calf at a time.


Dolphin Info:  
» Dolphin Facts  
» Dolphin Body  
» Dolphin Species  
» Dolphin Behavior  
» Communicating  
» Dolphin Diet  
» Eating Methods  
» Dolphin Evolution  
» Breathing  
» Dolphin Intelligence  
» Dolphin Interacting  
» Pink Dolphin  
» Body Language  
» Sleeping  
» Social Behavior  
» Vocalizing  
» Dolphins & Whales