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About 50 million years ago
- Cetaceans (whales, dolphins, and porpoises) are an order of mammals that originated about 50 million years ago in the Eocene epoch.
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May 21, 2007 · Before exploring how the anatomical changes for life in water came about, one must know how marine mammals are related to one another, and particularly to their terrestrial relatives. A brief introduction to the phylogeny of each group of marine mammals is presented here, based on the latest studies using both morphological and molecular data.
- Mark D. Uhen
- 144
- 2007
- 21 May 2007
Apr 16, 2009 · Around 34 million years ago, the first representatives of the modern groups of whales, odontocetes and mysticetes are found. It is now generally assumed that odontocetes and mysticetes (together called Neoceti) arose from a common Eocene cetacean ancestor and are thus monophyletic.
- J. G. M. Thewissen, Lisa Noelle Cooper, Lisa Noelle Cooper, John C. George, Sunil Bajpai
- 2009
Those of us who study the history of marine mammals can describe the circumstances, the evolutionary pathways, the rela-tionships, and even some of the behaviors of these early representatives of the clades of marine mammals, but we have difficulty with the question of why.
Mar 21, 2012 · When did scientists first propose that marine mammals evolved from land-living mammals? What findings led to this conclusion?
Due to Erwin’s research, it is now known that the first animal evolved during the Ediacaran and not the Cambrian like previously thought. By studying Permian fossils, Erwin has also contributed to our understanding of why the Permian Extinction—the largest extinction in Earth’s history—came to be.
Feb 1, 2019 · Mammals evolved on land around 160 million years ago. Each taxonomic marine mammal group evolved from a different group of land mammals, whose ancestors separately ventured back into the ocean environment.
Marine mammals were first hunted by aboriginal peoples for food and other resources. Many were also the target for commercial industry, leading to a sharp decline in all populations of exploited species, such as whales and seals.
