The deep-water-research submarine Alvin is launched from Atlantis. Scientists are studying how ecosystems in the Gulf of Mexico may have been affected by the Deepwater Horizon oil spill. Richard Harris/NPR hide caption

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Four of the seven lion cubs (Panthera leo) recently born at the National Zoo in Washington, D.C. Lions boast a special form of sister and brotherly alliance: sisters stay together all their lives in prides, and brothers form coalitions to conquer other prides. Mehgan Murphy/Smithsonian Institution hide caption

itoggle caption Mehgan Murphy/Smithsonian Institution

It's important to talk to your vet about any changes in your dog's behavior or diet, says veterinarian Nicholas Dodman. iStockphoto.com hide caption

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Scientists say the pterosaur, shown here on display at the National Museum of Emerging Science and Innovation in Tokyo, may have been able to fly as high as 15,000 feet for distances up to 12,000 miles at a time. Itsuo Inouye/AP hide caption

itoggle caption Itsuo Inouye/AP

Target (right) and Rufus became heroes when they kept a suicide bomber from taking lives in Afghanistan. A third dog, Sasha, was killed in that attack. Johnny Crawford/Atlanta Journal & Constitution/AP hide caption

itoggle caption Johnny Crawford/Atlanta Journal & Constitution/AP

Wild turkeys cross a street in La Conner, Wash., where the birds have called home since 2004. La Conner's town council recently voted to remove the flock due to sanitation concerns. Marilyn Dunstan/Getty Images hide caption

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Kirk Johnson, chief curator at the Denver Museum of Nature & Science, inspects the Ice Age bison skull. Heather Rousseau/Denver Museum of Nature & Science hide caption

itoggle caption Heather Rousseau/Denver Museum of Nature & Science