Ancient whales: thirsty at sea.Water, water, everywhere but what's a whale to drink? That's the question That's the Question is an American quiz game show on GSN, hosted by game show veteran and former Entertainment Tonight reporter, Bob Goen, which premiered in October 2006. J.G.M. Thewissen posed while studying the earliest chapter in the story of cetaceans. Although modern whales can ingest in·gest tr.v. in·gest·ed, in·gest·ing, in·gests 1. To take into the body by the mouth for digestion or absorption. See Synonyms at eat. 2. seawater seawater Water that makes up the oceans and seas. Seawater is a complex mixture of 96.5% water, 2.5% salts, and small amounts of other substances. Much of the world's magnesium is recovered from seawater, as are large quantities of bromine. , they evolved from four-legged land mammals that needed freshwater to survive. Indeed, the first whales must have lived in freshwater-their fossils are found in deposits from ancient rivers and lakes in Pakistan Pakistan has a number of small and medium lakes located throughout the country: Lake Location Region Area (km²) Ansoo Lake Kaghan Valley NWFP 0.25 Attar Lake Ishkoman and Yasin Valleys Northern Areas 1. . Thewissen, a paleontologist at Northeastern Ohio Universities College of Medicine Northeastern Ohio Universities College Of Medicine (NEOUCOM) is a community-based, state medical school that offers a combined B.S./M.D. program that allows students to graduate with their B.S./M.D. in as few as six or seven years. in Rootstown, and his colleagues wondered when whales developed the ability to drink saltwater. To answer the question, they turned their attention to teeth. As mammals grow, oxygen atoms in the tooth enamel enamel, a siliceous substance fusible upon metal. It may be so compounded as to be transparent or opaque and with or without color, but it is usually employed to add decorative color. It was used to decorate jewelry in ancient Egypt, Greece, and Rome. record information about the type of water the animal drinks. Oxygen typically comes in two isotopes, and saltwater contains a significantly higher ratio of heavy oxygen than freshwater does. The researchers measured the isotopic ratio of oxygen in four ancient whale fossils. The three oldest species showed isotopic signatures An isotopic signature (also isotopic fingerprint) is a ratio of stable or unstable isotopes of particular elements found in an investigated material. The atomic mass of different isotopes affect their chemical kinetic behavior, leading to natural isotope separation processes. similar to those of modern river dolphins, which drink freshwater. The fourth fossil whale, called Indocetus, had a greater proportion of heavy oxygen, like modern whales. Indocetus lived around 48 million years ago, only 4 million years after the earliest known whales. Within that geologically short period, whales must have evolved the specialized kidneys that enable them to drink saltwater, the researchers conclude in the May 30 Nature. "The exciting thing is that this tells you when whales became independent from freshwater," says Thewissen. The earliest whales could not have strayed far from coastlines because they had to return to a river to drink, as manatees do today. One of the fossil whales, Ambulocetus, apparently led such a lifestyle: Its bones come from saltwater deposits, but its teeth show a freshwater isotopic signature. Once whales could survive on seawater, though, they could migrate across oceans and spread around the world, says Thewissen. The fossil record supports this theory. Whales had reached several other continents by the time of Indocetus. |
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