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A rigorous test for the evolution of marine mammals would use many more species and more characters. But the general result holds: mammals made the transition to water at least three times: in pinnipeds (seals and walruses), in whales, and also in sirenians (dugongs and manatees).
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May 21, 2007 · Evolutionary highlights are presented, focusing on changes affecting the sensory systems, locomotion, breathing, feeding, and reproduction in Cetacea, Sirenia, Desmostylia, and Pinnipedia. Aquatic adaptations are specifically cited, supported by data from morphological and geochemical studies.
- Mark D. Uhen
- 144
- 2007
- 21 May 2007
Apr 16, 2009 · Abstract. 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
Meet Pakicetus, a goat-sized, four-legged creature that scientists recognise as one of the first cetaceans (the group of marine animals that includes dolphins and whales). How Pakicetus ' descendants evolved into whales is one of the most intriguing evolutionary journeys known to science.
Oct 18, 2012 · I particularly appreciated the paleoecology section, as it showed how the evolution of marine mammals was deeply intertwined with the past positions of the continents, evolution of Earth’s oceans, and with other oceanographic factors like temperature, salinity, and productivity.
- Mark D. Uhen
- muhen@gmu.edu
- 2013
Nov 15, 2019 · Convergent morphological adaptations for an aquatic life (e.g., fusiform body shape, flukes and flippers) evolved separately in the three taxonomic orders of extant marine mammals (Artiodactyla [infraorder Cetacea], Carnivora [clade Pinnipedia and sea otters], and Sirenia).
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May 21, 2007 · First published: 21 May 2007. https://doi.org/10.1002/ar.20545. Citations: 144. Read the full text. PDF. Tools. 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.
