Mammuthus columbi, the Columbian mammoth, used to be common in America, but went extinct about 10,000 years ago. The specimen found south of Dallas is estimated to be 20,000 - 40,000 years old. Illustration by Karen Carr/Perot Museum of Nature and Science hide caption

itoggle caption Illustration by Karen Carr/Perot Museum of Nature and Science

Yes, indeed, cows can leap. Here, Regina Mayer jumps with her cow Luna — yes, Luna — over a hurdle in southern Germany, in 2011. Kerstin Joensson/AP hide caption

itoggle caption Kerstin Joensson/AP

Workers at the National Geographic Museum in Washington grind the rough edges off a life-size replica of a spinosaurus skeleton. Mike Hettwer/National Geographic hide caption

itoggle caption Mike Hettwer/National Geographic

Visitors watch an orca performance at SeaWorld in San Diego this year. The company has seen attendance slip in the year since the release of a documentary film critical of the company's captive whale program. Mike Blake/Reuters/Landov hide caption

itoggle caption Mike Blake/Reuters/Landov

To refrigerate or not to refrigerate? It boils down to bacteria, aesthetics and how much energy you're willing to use. Robert S. Donovan; Flickr / Alex Barth; Flickr hide caption

itoggle caption Robert S. Donovan; Flickr / Alex Barth; Flickr