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Unformatted text preview: Geneticist at theTokyo Institute of technology have discovered that hippopotamus DNA has many skeletal structures in common with the dolphin and the order they live in (Cetacea). Pakicetus who lived during the Eocene era (50-60 million years ago) are both species common ancestor The Pakicetus, dolphin and hippopotamus share a common feature family Pakicetids, these animals share a hoofed skeletal structure. A commonality shared are their ear structures. From the ectotympanic bone the auditory bulla is formed. Packitus (common ancestor) description Features The skull structure is unique and is only found in other cetaceans ( Tursiops truncatus). From the ectotympanic bone the auditory bulla is formed. It is significant because dolphins ears were not originally specialized to hear underwater it is an adaptation. That could possibly through evolution change the Hippopotamus structure to fully aquatic as seen in cetaceans whom are older (by 45 million years ( Nature 450 , 1190-1194) Other significant derived similarities between Indohyus and cetaceans include the anteroposterior arrangement of incisors in the jaw, and the high crowns in the posterior premolars. a. originating from the family pakicetids, packitus lived during the Eocene era (50-60 million years ago). Resembling dog features The pakicetids are hoofed mammals that are sometimes classified as the earliest whales.   They lived in the early Eocene , around 53 million years ago. They looked rather like dogs with hoofed feet and long, thick tails. They have been linked to whales by their ears: the structure of the auditory bulla is formed from the ectotympanic bone only. The shape of the ear region in Pakicetus is highly unusual and only resembles the skulls of whales. The feature is diagnostic for cetaceans and is found in no other species. It was initially thought that the ears of cetaceans and is found in no other species....
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- Spring '11