People take pictures with their mobile phone of a scale model of a dinosaur displayed in front of La Sapienza University headquarters in Rome April 10, 2015. The realistic reproductions of dinosaurs are part of the “Dinosaurs in the flesh, science and art bring to life the rulers of a lost world” exhibition. (Photo by Alessandro Bianchi/Reuters)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

Mercedes Formula One driver Lewis Hamilton of Britain sprays champagne at a grid girl as he celebrates his victory on the podium after the Chinese F1 Grand Prix at the Shanghai International Circuit, April 12, 2015. (Photo by Carlos Barria/Reuters)

Cheng Chen (R), a 27-year-old worker at a state-owned enterprise, poses for a photograph with his nephew who is wearing his home-made Iron Man armour, in Xuzhou, Jiangsu province April 13, 2015. It cost Cheng about 500 yuan ($81 USD) to make the armour, which weighs about 4 kilograms, with plastic boards and LED lights, local media reported. (Photo by Reuters/Stringer)

Models at the Sophia Webster presentation during London Fashion Week Spring Summer 2015 on September 14, 2014 in London, England. (Photo by Anthony Harvey/Getty Images)

A dachshund portraying a racehorse, trots down Duval Street in Key West, Florida, December 31, 2014. About 175 dachshunds and other dogs participated in the event that preludes four warm-weather takeoffs on New York City's Times Square ball drop. (Photo by Steve Panariello/Reuters/Florida Keys News Bureau)

The Mercedes-Benz F015 Luxury in Motion autonomous concept car is shown on stage during the 2015 International Consumer Electronics Show (CES) in Las Vegas, Nevada January 5, 2015. (Photo by Steve Marcus/Reuters)

A Pakistani farmer guides his bulls as he competes in a traditional bull race in Khunda village in the northwestern district of Attock, some 80 kilometers from Islamabad on January 3, 2015. Tens of thousands of people gather whenever there is a bull race held in Pakistan which are usually the highlight of festivals organized in rural areas of the Asian country, and attract lots of spectators due to their thrilling nature. The traditional competition attracts landlords and farmers from all around the province where the race is held, and they all bring their fastest and strongest bulls in hopes of gaining a reputation. (Photo by Aamir Qureshi/AFP Photo)