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May 21, 2007 · Evolution of marine mammals: Back to the sea after 300 million years. Mark D. Uhen. First published: 21 May 2007. https://doi.org/10.1002/ar.20545. Citations: 144. Sections. PDF. Tools. Share. Abstract. The fossil record demonstrates that mammals re-entered the marine realm on at least seven separate occasions.
- Mark D. Uhen
- 144
- 2007
- 21 May 2007
Evolution of Marine Mammals: Back to the Sea After 300 Million Years. MARK D. UHEN* 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.
The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid- Triassic, there were many synapsid species that looked like mammals.
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
Both morphological and molecular data tell us that the ancestors of the marine mammals were terrestrial, and that their various marine lifestyles have evolved independently at least seven times!
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.
Nov 15, 2019 · Since Hb and Mb evolved over 550 million years ago (Pesce et al. 2002 ), increased concentrations of these globins in blood and muscle probably occurred early in ancestral marine mammals as an upregulation of globin expression.
