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- Cetaceans (whales, dolphins and porpoises) and sirenians (manatees and dugongs) emerged during the Eocene epoch 7, 8, 9, 10 through diversification from the Cetartiodactyla and Afrotheria, respectively. Pinnipeds (seals, sea lions and walruses) emerged approximately 20 million years later during the Miocene from within the Carnivora 7, 8.
www.nature.com › articles › ngConvergent evolution of the genomes of marine mammals - Nature
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May 21, 2007 · It is also interesting to note that the clades of marine mammals seem to have originated at two discrete times, Cetacea and Sirenia during the early Eocene, and Desmostylia and Pinnipedia during the Oligocene.
- Mark D. Uhen
- 2007
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.
- J. G. M. Thewissen, Lisa Noelle Cooper, Lisa Noelle Cooper, John C. George, Sunil Bajpai
- 2009
Mar 21, 2012 · The earliest whales are known from India and Pakistan from around 52.5 million years ago, during the early Eocene. How long did it take for this land mammal to morph into the whales and...
Figure 1. Harbor seal, walrus, dugong, and right whale) The first mammals were certainly terrestrial. There is good evidence that mammals evolved from reptile-like ancestor. Therefore at some point there was a transition from terrestrial environment to an aquatic lifestyle in this group of species. How did that occur?
Oct 18, 2012 · Mark D. Uhen. 350 Accesses. Explore all metrics. Annalisa Berta leads readers through a vast range of topics regarding the evolution of marine mammals in Return to the Sea: The Life and Evolutionary Times of Marine Mammals.
- Mark D. Uhen
- muhen@gmu.edu
- 2013
Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC. ABSTRACT. The fossil record demonstrates that mammals re-entered the marine realm on at least seven separate occasions. Five of these clades are still extant, whereas two are extinct.
A review of the broad outlines of what we know about the evolution of marine mammals from their fossil record, and then a focus on three discrete case studies that highlight important ecological transitions and evolutionary transformations that have occurred over the past 50 million years.