Amniota Tetrapoda Choanata Sarcopterygii Osteichthyes Gnathostomata Vertebrata
Figure 4 Craniate phylogeny. The extant agnathans (hagfish and lamprey) form two successive sister groups to the gnathos-tomes. Within the Gnathostomata there is a basal division between bony fishes (Osteichthyes) and cartilaginous fishes (Chondrichthyes). Within the clade of bony fishes there is a division between lobe-finned fishes (Sarcopterygii) and ray-finned fishes (Actinopterygii). Coelacanths (Actinistia) and lungfishes (Dipnoi) are successive sister taxa to the Tetrapoda, which include all terrestrial vertebrates. See text for further discussion.
Figure 6 Phylogeny of extant mammals. The living mono-tremes (platypus and echidnas) and marsupials are successive sister taxa to the living placental mammals. Four major clades comprise Placentalia. The Afrotheria and Xenarthra have southern hemisphere origins, in Africa and South America, respectively. The clades Euarchontoglires and Laurasiatheria have northern hemisphere origins. Afrotheria includes elephants, manatees, golden moles, and aardvarks. Xenarthra comprises anteaters, sloths, and armadillos. Euarchontoglires includes primates and rodents. Laurasiatheria includes artiodac-tyls, perissodactyls, cetaceans, bats, and carnivores. The Afrotheria and Laurasiatheria comprise two independent parallel radiations of similar morphologies, ranging from mole-like forms to ant-eating forms. See text for further discussion.
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