Pakicetus-Squalodon
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Whales and dolphins look like fish. But they are mammals like us and evolved from a family of land mammals, such as Pakicetus, to find a home in the sea. What is amazing is that these swimming mammals look almost exactly like fish, with fins and a tail. That means that the body design for sea creatures has evolved multiple times as some creatures returned to the water for food or to escape predators.
Pakicetus
Year : 55 million years ago
Era : Early Eocene
Classification : Archaeoceti
Habitat : Fossils found in Pakistan
Size : 3.3ft / 1m
Weight : 40lbs / 18kg
Diet : Carnivore
Pakicetus is an extinct mammal that is thought to be the earliest known cetaceans, which is the family that includes whales and dolphins. Not much is known about Pakicetus but it is believed that it may have spent part of its life in water. Pakicetus fossils have shown unusual bone formations of the inner ear that are particular to fossil and modern whales and dolphins. Pakicetus also has some triangular and serrated teeth which are seen in some extinct toothed whales and suggest Pakicetus hunted and ate fish.
Squalodon
Year : 33 million years ago
Era : Middle Oligocene
Classification : Squalodontidae
Habitat : Fossils found in Eastern United States
Diet : Carnivore
Squalodon was a dominant sea hunter during its era, but climate change and evolution of other toothed whales caused them to go extinct. It has triangular serrated teeth similar to its cetacean ancestors but most modern toothed whales have simpler cone shaped teeth. Although it looks much like a dolphin, and fossil skulls show signs that they may have been able to use echolocation like a dolphin, Squalodon is only a cousin of the Dolphin and has no living descendants.
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