April 17, 2009 -- New experiments on one of the planet's most adaptable reptiles, alligators, are lending clues to how dinosaurs took over the world. The first dinosaurs appeared along with the ancestors of alligators around 230 million years ago, in a tough environment for air breathers. Oxygen in Earth's atmosphere had bottomed out at 12 percent, only about half of today's 21 percent concentration. Dinosaurs evolved into huge multi-ton lizards and then died out. But alligators survived almost unchanged from their ancient form, despite fluctuations in oxygen -- with concentrations as high as 23 percent -- while the dinosaurs were still alive. "We know alligators are doing something right," Tomasz Owerkowicz of the university of California-Irvine said. "They survived hypoxia and hyperoxia (low and high oxygen), they have been around a very long time, and they are all over the world. A lot of other vertebrates wouldn't have made it." Related Content:
To figure out how they do it -- and how dinosaurs' bodies may have adapted to initially low, then increasing oxygen levels -- Owerkowicz and group of researchers incubated three separate groups of alligator eggs, exposing them to environments containing 12 percent, 21 percent, and 30 percent oxygen. When the eggs hatched, baby alligators in the low-oxygen environments were born with bellies distended by an excess of egg yolk. Normal and high-oxygen hatchlings had normal bellies. The differences were even more pronounced after three months of growth. Oxygen-starved alligators had enlarged lungs and hearts, but overall they didn't grow as long or as heavy as the other two groups. Owerkowicz believes this is because animals in the low-oxygen environment have to dedicate larger amounts of their metabolic energy to breathing enough oxygen to function. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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