Cetartiodactyls Fossil range: late Paleocene - Recent
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Infraclass: Eutheria Superorder: Laurasiatheria (unranked) Cetartiodactyla
Orders
Order: Cetacea Suborders: Suina Tylopoda Ruminantia Family: Hippopotamidae

Humpback Whale breaching.

Pod of hippopotamuses, Luangwa Valley, Zambia.

Cetartiodactyla is the superorder 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 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. The Paleocene, early dawn of the recent, is a geologic epoch that lasted from 65. ... Download high resolution version (2587x1709, 1092 KB) Wikipedia does not have an article with this exact name. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Orders[1] Bobolestes Eomaia Maelestes Montanalestes Murtoilestes Prokennalestes Placentalia Superorder Xenarthra: Cingulata (Armadillos) Pilosa (Sloths, True Anteaters) Superorder Afrotheria: Afrosoricida (Tenrecs, etc. ... Laurasiatheria is a proposed clade with the rank of cohort or super-order, of the Epitheria infraclass of the Placentalia (living) or Eutheria (Placentals and their extinct ancestors) subclass of Mammals, based on molecular and DNA research It is a sister group to Euarchontoglires. ... Suborders Mysticeti Odontoceti Archaeoceti (extinct) (see text for families) The order Cetacea (IPA: , L. cetus, whale) includes whales, dolphins and porpoises. ... Families  Suidae  Tayassuidae  Hippopotamidae The Suina contains the earliest and most archaic Artiodactyla. ... Species  Lama glama  Lama pacos  Lama guanicoe  Vicugna vicugna  Camelus dromedarius  Camelus bactrianus The four llamas and two camels are camelids: members of the biological family Camelidae, the only family in the suborder Tylopoda. ... Families  Tragulidae  Moschidae  Cervidae  Giraffidae  Antilocapridae  Bovidae The biological suborder Ruminantia includes many of the well-known large grazing or browsing mammals: among them cattle, goats, sheep, deer, and antelope. ... Genera Hippopotamus Phanourios Hexaprotodon Archaeopotamus Choeropsis Saotherium Hippopotami (colloquially also Hippopotamuses) are the members of the family Hippopotamidae. ... Image File history File links humpback whale breaching File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links humpback whale breaching File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Binomial name Megaptera novaeangliae Borowski, 1781 Humpback Whale range The Humpback Whale, Megaptera novaeangliae, is a baleen whale. ... Image File history File links Download high resolution version (2160x1440, 435 KB)Cara was here hehehe! File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (2160x1440, 435 KB)Cara was here hehehe! File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Binomial name Linnaeus, 1758[2] Range map[1] The hippopotamus (Hippopotamus amphibius), from the Greek ‘ιπποπόταμος (hippopotamos, hippos meaning horse and potamos meaning river), often shortened to hippo, is a large, mostly plant-eating African mammal, one of only two extant species in the family Hippopotamidae (the other being the Pygmy... This article is about the animal. ... Genera See article below. ... Families Antilocapridae Bovidae Camelidae Cervidae Giraffidae Hippopotamidae Moschidae Suidae Tayassuidae Tragulidae Leptochoeridae † Chaeropotamidae † Dichobunidae † Cebochoeridae † Entelodontidae † Anoplotheriidae † Anthracotheriidae † Cainotheriidae † Agriochoeridae † Merycoidodontidae † Leptomerycidae † Protoceratidae † Xiphodontidae † Amphimerycidae † Helohyidae † Gelocidae † Merycodontidae † Dromomerycidae † Raoellidae † Choeropotamidae † Sanitheriidae † The even-toed ungulates form the mammal order Artiodactyla. ... Suborders Mysticeti Odontoceti Archaeoceti (extinct) (see text for families) The order Cetacea (IPA: , L. cetus, whale) includes whales, dolphins and porpoises. ... Families Suidae Hippopotamidae Tayassuidae Camelidae Tragulidae Moschidae Cervidae Giraffidae Antilocapridae Bovidae The even-toed ungulates form the mammal order Artiodactyla. ... Binomial name Linnaeus, 1758[2] Range map[1] The hippopotamus (Hippopotamus amphibius), from the Greek ‘ιπποπόταμος (hippopotamos, hippos meaning horse and potamos meaning river), often shortened to hippo, is a large, mostly plant-eating African mammal, one of only two extant species in the family Hippopotamidae (the other being the Pygmy... A clade is a term belonging to the discipline of cladistics. ...

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. Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... In phylogenetics, a group is monophyletic (Greek: of one stem) if all organisms in that group are known to have developed from a common ancestral form, and all descendants of that form are included in the group. ... For the band, see 1990s (band). ... Mesonychids are an extinct order of even-toed carnivorous ungulates (hoofed animals) which looked like wolves, and were scavengers for carrion and hunters of fish. ... This article does not adequately cite its references or sources. ... This article deals with meat-eating animals. ... For other uses, see Fossil (disambiguation). ...

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 and deer) than ruminants are to pigs. In order for the order name to reflect a real evolutionary unit, the term Cetartiodactyla was coined. The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... It has been suggested that this article or section be merged with Ruminantia. ... For general information about the genus, including other species of cattle, see Bos. ... This article is about the ruminant animal. ... For other uses, see Pig (disambiguation). ...

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. The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. ...

In addition to DNA and protein sequences, researchers tracked the movement of transposons called SINEs in the genome (see the method at retrotransposon marker). A transposon is a DNA sequence that will occasionally make a copy of itself and insert that copy into another part of the genome. It is considered highly unlikely that SINEs will insert themselves into the exact same part of a genome by chance. The data indicate that several transposons inserted themselves at the same point in the genomes of whales, ruminants and hippos (sometimes referred to as "pseudoruminants" because although they have four-chambered stomachs like true ruminants, they do not chew the cud). This insertion point is not shared with camels and pigs. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called transposition. ... In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Retrotransposons as cladistic markers The analysis of SINEs – Short INterspersed Elements – LINEs – Long INterspersed Elements – or truncated LTRs – Long Terminal Repeats – as molecular cladistic markers represents a particularly interesting complement to DNA sequence and morphological data. ... For other uses, see Camel (disambiguation). ...

This hypothesis has been tested with DNA sequences from a host of genes: the complete mitochondrial genome (as well as several of its genes independently), beta-casein, kappa-casein, von Willebrand factor, breast cancer 1, recombination activating genes 1 and 2, cannabinoid receptor 1, and several others. These sequence data and the transposons converge on the same conclusion that hippos and whales are more closely related to one another than either is to other artiodactyls. The mitochondrial genome is the genetic material of the mitochondria. ... Von Willebrand factor is a blood glycoprotein of the coagulation system. ... The recombination activating genes encode enzymes that play an important role in the rearrangement and recombination of the genes of immunoglobulin and T cell receptor molecules during the process of VDJ recombination. ... The cannabinoid receptors are a class of receptors under the G-protein coupled receptor superfamily. ...

Sequences analyzed in combined analyses with morphological characters have also produced the same results as sequences alone. Some have argued that the sheer number of characters (one for each nucleotide) in sequences swamps out the effects of morphology. There have been a few morphology-based studies that have suggested (weakly) the same results as the molecular results, but overall most morphological studies have conflicted with the whale/hippo hypothesis of Cetartiodactyla. A nucleotide is a chemical compound that consists of a heterocyclic base, a sugar, and one or more phosphate groups. ...

An important exception is a recent conducted by Boisserie et al. (2005). They examined 80 hard morphological characters of fossil and extant cetartiodactylan taxa. Their results suggest that hippopotamids evolved from within a clade of anthracotheres. That anthracothere/hippopotamid clade appears to be sister to the Cetacea and supports the molecular results. Anthracotherium (coal-animal, so called from the fact of the remains first described having been obtained from the Tertiary lignite-beds of Europe), a genus of extinct artiodactyle ungulate mammals, characterized by having 44 teeth, with five semi-crescentic cusps on the crowns of the upper molars. ...

A clade apart

The morphology and paleontology-based opinion of the relationship of whales to other mammals has also undergone considerable changes since the early 1990s. Fossils such as Rodhocetus, have been discovered that refute the notion that whales are derived from or are closely related to the mesonychids. Many morphologists and paleontologists support the notion of a clade called Cetartiodactyla that unites Cetacea + Artiodactyla. Many are not, however, in support of the hypothesis that Cetacea evolved from within the Artiodactyla. Under this definition, Artiodactyla remains a valid clade since artiodactyls evolved from a common ancestor separate from whales. Cetartiodactyla would represent a grandorder or superorder uniting the two orders. Paleontology, palaeontology or palæontology (from Greek: paleo, ancient; ontos, being; and λόγος, logos, knowledge) is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. ... Rodhocetus is one of several extinct whale genera that possess land mammal characteristics, thus demonstrating the transition from land to sea that whales went through. ... Mesonychids are an extinct order of even-toed carnivorous ungulates (hoofed animals) which looked like wolves, and were scavengers for carrion and hunters of fish. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ...

The vast majority of phylogenetic analyses based on morphological characters have not uncovered a whale/hippo clade, but show Cetacea and Artiodactyla as distinct from one another. Features of the bones of the astragalus in the ankle region are cited as particular evidence for a monophyletic Artiodactyla. Species See text. ...

Hippo fossils are not observed until the Miocene, but whale ancestors have been dated to the Eocene. The whale/hippo hypothesis imposes a gap of nearly 30 million years where no hippo ancestors are present. Certain anthracotheres have been proposed as hippo ancestors, but this concept has not garnered wide support among paleontologists. The Miocene Epoch is a period of time that extends from about 23. ... hfajhfiudshfas == == == --24. ... Anthracotherium (coal-animal, so called from the fact of the remains first described having been obtained from the Tertiary lignite-beds of Europe), a genus of extinct artiodactyle ungulate mammals, characterized by having 44 teeth, with five semi-crescentic cusps on the crowns of the upper molars. ...

See also

• Evolution of cetaceans

The cetaceans (whales, dolphins and porpoises) are descendants of land-living mammals, and remnants of their terrestrial origins can be found in the fact that they must breathe air from the surface; in the bones of their fins, which look like huge, jointed hands; and in the vertical movement of...

References

Wikispecies has information related to:

Cetartiodactyla

• Boissere, J.-R., F. Lihoreau, and M. Brunet. 2005. The position of Hippopotamidae within Cetartiodactyla. Proceedings of the National Academy of Sciences of the United States of America, 102:1537-1541.
• Gatesy, J. 1997. More support for a Cetacea / Hippopotamidae clade: The blood clotting protein gene g-fibrinogen. Molecular Biology and Evolution, 14:537-543.
• Gatesy, J., C. Hayashi, M. Cronin, and P. Arctander. 1996. Evidence from milk casein genes that cetaceans are close relatives of hippopotamid artiodactyls. Molecular Biology and Evolution, 13:954-963.
• Gatesy, J., C. Mathee. R. DeSalle, and C. Hayashi. 2002. Resolution of a supertree/supermatrix paradox. Systematic Biology, 51:652-664.
• Gatesy, J., M. Milinkovitch, V. Waddell, and M. Stanhope. 1999. Stability of cladistic relationships between Cetacea and higher-level artiodactyl taxa. Systematic Biology, 48:6-20.
• Grauer, D. and D. Higgins. 1994. Molecular evidence for the inclusion of cetaceans within the order Artiodactyla. Molecular Biology and Evolution, 11:357-364.
• Milinkovitch, M. C. and J. G. M. Thewissen. 1997. Even-toed fingerprints on whale ancestry. Nature, 388:622-624.
• Montgelard, C., F. Catzeflis, and E. Douzery. 1997. Phylogenetic relationships among cetartiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12S RNA mitochondrial sequences. Molecular Biology and Evolution, 14:550-559.
• Naylor, G. J. P. and D. C. Adams. 2001. Are the fossil data really at odds with the molecular data? Morphological evidence for Cetartiodactyla phylogeny reexamined. Systematic Biology, 50:444-453.
• O'Leary, M. A. and J. H. Geisler. 1999. The position of Cetacea within Mammalia: phylogenetic analysis of morphological data from extinct and extant taxa. Systematic Biology, 48:455-490.
• Nikaido M, Rooney AP, Okada N (1999) Phylogenetic relationships among cetartiodactyls based on insertions of short and long interpersed elements: Hippopotamuses are the closest extant relatives of whales. Proc Natl Acad Sci U S A 96: 10261–10266.
• Shedlock, A. M., M. C. Milinkovitch, and N. Okada. 2000. SINE evolution, missing data, and the origin of whales. Systematic Biology, 49:808-816.
• Shimamura, M., H. Yasue, K. Ohshima, H. Abe, H. Kato, T. Kishiro, M. Goto, I. Munechika, and N. Okada. 1997. Molecular evidence from retroposons that whales form a clade within even-toed ungulates. Nature, 388:666-670.
• Thewissen, J. G., E. M. Williams, L. J. Roe, and S. T. Hussain. Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature, 413:277-281.