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- Most agree that Physeteridae (sperm whales) and Ziphiidae (beaked whales) are among the earliest of living groups to branch off within the odontocete clade after the split of Odontoceti and Mysticeti, which appears to have occurred at or perhaps just before the Eocene/Oligocene boundary (Fordyce, 2002).
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May 21, 2007 · 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. This review presents a brief introduction to the phylogeny of each group of marine mammals, based on the latest studies using both morphological and molecular data.
- Mark D. Uhen
- 144
- 2007
- 21 May 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 · March 21, 2012. All cetaceans, including whales, dolphins, and porpoises, are descendants of land-living mammals. How did these terrestrial ancestors morph over millions of years into the...
Hippos likely evolved from a group of anthracotheres about 15 million years ago, the first whales evolved over 50 million years ago, and the ancestors of both these groups were terrestrial. These first whales, such as Pakicetus, were typical land animals. They had long skulls and large teeth that could be used for eating meat.
Oct 18, 2012 · University of California Press, Berkeley, CA. 2012. 205 pp., $49.95 (cloth), $25.62 (Kindle). ISBN 9780520270572. 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. In this volume geared towards non-specialists (one might ...
- Mark D. Uhen
- muhen@gmu.edu
- 2013
Dec 1, 2010 · There was no straight-line march of terrestrial mammals leading up to fully aquatic whales, but an evolutionary riot of amphibious cetaceans that walked and swam along rivers, estuaries and the...
Nov 15, 2019 · However, another hypothesis is that Odobenidae first evolved in the North Pacific and then dispersed into the Arctic Ocean and North Atlantic during an interglacial event in the Pliocene or Pleistocene.
