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The skeletons of Pakicetus show that whales did not derive directly from mesonychians. Instead, they are artiodactyls that began to take to the water soon after artiodactyls split from mesonychians. Archaeocetes retained aspects of their mesonychian ancestry (such as the triangular teeth) which modern artiodactyls, and modern whales, have lost.
Pakicetus (meaning 'whale from Pakistan') is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to Indian Subcontinent during the Ypresian (early Eocene) period, about 50 million years ago. [2]
The large teeth of the raptorial sperm whales either evolved once in the group with a basilosaurid-like common ancestor, or independently in Livyatan. The large temporal fossa in the skull of raptorial sperm whales is thought to a plesiomorphic feature, that is, a trait inherited from a common ancestor.
This green turtle is about to break the surface for air at Kona, Hawaii. A flipper is a broad, flattened limb adapted for aquatic locomotion. It refers to the fully webbed, swimming appendages of aquatic vertebrates that are not fish. In animals with two flippers, such as whales, the flipper refers solely to the forelimbs.
Fewer than 400 individual North Atlantic right whales remain in the wild, and their numbers continue to decline. ... As many whales begin to leave their protected zones in search of warmer waters ...
Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene 1] Representing the earliest cetacean radiation , they include the initial amphibious stages in cetacean evolution , thus are the ancestors of both modern cetacean suborders ...
Baleen whales - a group that includes the blue whale, the largest animal in Earth's history - use a larynx, or voice box, anatomically modified to enable underwater vocalization, researchers said ...
Eerie and fascinating, whale songs are one of the most mysterious sounds reverberating through the ocean. Now, researchers say they know how the leviathans vocalize. Mystery of whale song ...