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Ankylosaurs and glyptodont mammals both had spiked tails. [73] The sauropods and giraffes independently evolved long necks. [74] The horned snouts of ceratopsian dinosaurs like Triceratops have also evolved several times in Cenozoic mammals: rhinos, brontotheres, Arsinoitherium, and Uintatherium. [75] Rhynchosaur teeth resemble that of the ...
For instance, descendants of the first reptiles include modern reptiles, mammals and birds; the agnathans have given rise to the jawed vertebrates; the bony fishes have given rise to the land vertebrates; a group of amphibians, the labyrinthodonts, have given rise to the reptiles (traditionally including the mammal-like synapsids), which in ...
Its most dramatic effect is on the zoogeography of mammals, but it also gave an opportunity for reptiles, amphibians, arthropods, weak-flying or flightless birds, and even freshwater fish to migrate. Coastal and marine biota were affected in the opposite manner; the formation of the Central American Isthmus caused what has been termed the Great ...
The tetrapods, including all large- and medium-sized land animals, have been among the best understood animals since earliest times. By Aristotle's time, the basic division between mammals, birds and egg-laying tetrapods (the "herptiles") was well known, and the inclusion of the legless snakes into this group was likewise recognized. [28]
Amphisbaenia / æ m f ɪ s ˈ b iː n i ə / (called amphisbaenians or worm lizards) is a group of typically legless lizards, [2] comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes.
The manatee is unusual among mammals in having just six cervical vertebrae, [12] a number that may be due to mutations in the homeotic genes. [13] All other mammals have seven cervical vertebrae, [14] other than the two-toed and three-toed sloths. Like the horse, the manatee has a simple stomach, but a large cecum, in which it can digest tough ...
Amphibians are in decline worldwide, with 2 out of every 5 species threatened by extinction, according to a paper published Wednesday in the scientific journal Nature.
Both birds and mammals have 4-chambered hearts, which completely separate the flows of oxygenated and de-oxygenated blood. Non-crocodilian reptiles have 3-chambered hearts , which are less efficient because they let the two flows mix and thus send some de-oxygenated blood out to the body instead of to the lungs.