Cetartiodactyla - Cetartiodactyla - Wikipedia, the free...

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Cetartiodactyls Fossil range: late Paleocene - Recent A restoration of Pakicetus , an early cetacean Scientific classification Kingdom: Animalia Phylum: Chordata Class: Mammalia Infraclass: Eutheria Superorder: Laurasiatheria (unranked): Cetartiodactyla Clades Tylopoda Artiofabula Suina Cetruminantia Ruminantia Whippomorpha Hippopotamidae Cetacea Humpback Whale breaching. Cetartiodactyla From Wikipedia, the free encyclopedia Cetartiodactyla is the clade to which whales (including dolphins) and even-toed ungulates have currently been placed. The term was coined by merging the name for the two orders, Cetacea and Artiodactyla, into a single word. The term Cetartiodactyla is most commonly used to describe the classification that whales evolved from within the artiodactyls. Under this definition their closest living land relative is thought to be the hippopotamus. The clade formed by uniting whales and hippos is called Whippomorpha or Cetancodonta. Alternatively, the term Cetartiodactyla is used to denote a clade where Cetacea and Artiodactyla are sister groups, but where Cetacea did not actually evolve from within the Artiodactyla. Under this definition, all artiodactyls, including hippos, are more closely related to one another than any are to the whales. Whales evolved from land mammals and appear to form a monophyletic group. The notion that all whales evolved from a single ancestor is not in dispute. The most widely accepted hypothesis before the 1990s was that the closest relatives to whales was the fossil group Mesonychia. These were hooved, predominantly carnivorous, mammals that are known only from fossils. Few modern authorities still consider mesonychids to be more closely related to whales than artiodactyls. Instead, they are usually considered to be the closest relative of the Cetartiodactyla as a whole. Contents 1 Kin to hippos 2 A clade apart 3 See also 4 References Kin to hippos The idea that whales evolved from within the Artiodactyla was based on analysis of DNA sequences. In the initial molecular analyses, whales were shown to be more closely related to ruminants (such as cattle Page 1 of 4 Cetartiodactyla - Wikipedia, the free encyclopedia 9/10/2009 http://en.wikipedia.org/wiki/Cetartiodactyla
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Pod of hippopotamuses, Luangwa Valley, Zambia. and deer) than ruminants are to pigs. In order for the order name to reflect a real evolutionary unit, the term Cetartiodactyla was coined. Later molecular analyses included a wider sampling of artiodactyls and produced a more complete tale. Hippos were determined to be the closest relative of whales, ruminants were related to a whale/hippo clade, and pigs were more distant. In addition to producing the controversial whale/hippo clade, these analyses suggested that hippos and pigs were not closely related. This had been a popular taxonomic hypothesis (Suiformes) based on similarities in morphological (physical) characteristics. In addition to DNA and protein sequences, researchers tracked the movement of transposons called
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This note was uploaded on 05/31/2011 for the course BIO 2108 taught by Professor Ammons during the Spring '11 term at Georgia Southern University .

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Cetartiodactyla - Cetartiodactyla - Wikipedia, the free...

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