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May 21, 2007 · Marine Mammal Diversity. Living groups of marine mammals vary greatly in their diversity. Rice (1998; Table 1 therein) reports that living Cetacea include 83 species in 39 genera; living Pinnipedia include 36 species in 21 genera; and Recent Sirenia include 5 species in 3 genera. Since then, several new species of cetaceans have been described ...
- Mark D. Uhen
- 144
- 2007
- 21 May 2007
- Bob Strauss
- Fish and Sharks. Between 500 and 400 million years ago, vertebrate life on earth was dominated by prehistoric fish. With their bilaterally symmetric body plans, V-shaped muscles, and notochords (protected nerve chords) running down the lengths of their bodies, ocean dwellers like Pikaia and Myllokunmingia established the template for later vertebrate evolution It also didn't hurt that the heads of these fish were distinct from their tails, another surprisingly basic innovation that arose during the Cambrian period.
- Tetrapods. The proverbial "fish out of water," tetrapods were the first vertebrate animals to climb out of the sea and colonize dry (or at least swampy) land, a key evolutionary transition that occurred somewhere between 400 and 350 million years ago, during the Devonian period.
- Amphibians. During the Carboniferous period, dating from about 360 to 300 million years ago, terrestrial vertebrate life on earth was dominated by prehistoric amphibians.
- Terrestrial Reptiles. About 320 million years ago, give or take a few million years, the first true reptiles evolved from amphibians. With their scaly skin and semi-permeable eggs, these ancestral reptiles were free to leave rivers, lakes, and oceans behind and venture deep into dry land.
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
People also ask
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The return to the sea: The evolution of marine mammals. : : : 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! Each lineage shows shared as well as unique evolutionary solutions to the challenges of ...
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
The first seabirds evolved in the Cretaceous period, and modern seabird families emerged in the Paleogene. Seabirds generally live longer, breed later and have fewer young than other birds, but they invest a great deal of time in their young.
Nov 15, 2019 · Abstract. Early Cetacea are classified as Archaeoceti (six families), and their fossils reveal the morphological and functional evolution of early, terrestrial Artiodactyla to fully aquatic Cetacea over 15 million years during the Eocene (~52 Mya). The evolution of modern Cetacea (Neoceti: Mysticeti and Odontoceti) began in the late Eocene (~37 ...
