Reconstruction of the giant filter feeder, scooping up a plankton cloud. Aegirocassis benmoulae was one of the biggest arthropods that ever lived. Family members include today's insects, spiders and lobsters. Marianne Collins/ArtofFact hide caption

itoggle caption Marianne Collins/ArtofFact

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

Love your hair. Artists' depictions of a Neanderthal man and woman at the Neanderthal Museum in Mettmann, Germany. Martin Meissner/AP hide caption

itoggle caption Martin Meissner/AP

A family of elephants in Kenya's Maasai Mara game reserve. Tony Karumba/AFP/Getty Images hide caption

itoggle caption Tony Karumba/AFP/Getty Images