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Previously the earliest was Eomaia, a crown group mammal from about 125M years ago. It had aquatic adaptations including flattened tail bones and remnants of soft tissue between the toes of the back feet, suggesting that they were webbed. Previously the earliest known semi-aquatic mammaliaforms were from the Eocene, about 110M years later.
Apr 16, 2009 · Cetaceans (whales, dolphins, and porpoises) are an order of mammals that originated about 50 million years ago in the Eocene epoch. Even though all modern cetaceans are obligate aquatic mammals, early cetaceans were amphibious, and their ancestors were terrestrial artiodactyls, similar to small deer. The transition from land to water is documented by a series of intermediate fossils, many of ...
- J. G. M. Thewissen, Lisa Noelle Cooper, Lisa Noelle Cooper, John C. George, Sunil Bajpai
- 2009
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Aquatic mammal. An Amazon river dolphin ( Inia geoffrensis ), a member of the infraorder Cetacea of the order Cetartiodactyla. Aquatic and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water. They include the various marine mammals who dwell in oceans, as well as various freshwater species, such ...
By Katie Pavid. 644. Early ancestors of the ocean's biggest animals once walked on land. Follow their extraordinary journey from shore to sea. Although whales are expert swimmers and perfectly adapted to life underwater, these marine mammals once walked on four legs. Their land-dwelling ancestors lived about 50 million years ago.
Feb 3, 2009 · By Sid Perkins. February 3, 2009 at 9:04 pm. It took early whales a while to fully break free of the land: For at least one species, females came back to shore to give birth, a new study suggests ...
Dec 1, 2010 · Blubber, blowholes and flukes are among the hallmarks of the roughly 80 species of cetaceans (whales, dolphins and porpoises) alive today. But, because they are mammals, we know that they must ...
Mar 21, 2012 · This is an exciting time to study marine mammal evolution as many of the most important discoveries in this field have been made in the last 10-15 years, and there is no reason to expect that pace ...
