This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)

A dog walks past a handmade replica of Lamborghini Diablo outside a garage rented by Wang Yu and Li Lintao on the outskirts of Beijing, August 21, 2014. Chinese race car enthusiasts Wang Yu and Li Lintao, both in their 30s, have finished designing and making two replicas of the Lamborghini Diablo, which can reach the top speed of 310km/h, and are currently working on a replica of the T-Rex motorcycle. They spent approximately 5 million yuan (around USD 811,899) to buy parts and hire workers, and about 6 years to assemble them with the knowledge they gained from studying mechanology for nearly a decade abroad. Wang and Li went popular after showing their first handmade replica of Lamborghini Diablo at the Beijing International Automobile Exhibition in 2012, and sold their second Lamborghini replica to Alibaba as a collection. (Photo by Petar Kujundzic/Reuters)

Cars pass a tank position close to the Russian border near the Ukrainian city of Kharkiv March 24, 2014. U.S. President Barack Obama sought support from European allies and China on Monday to isolate Russia over its seizure of Crimea, and Ukraine told its remaining troops to leave the region after Russian forces overran one of Kiev's last bases there. (Photo by Dmitry Neymyrok/Reuters)

In Mumbai, the windows of new high-rise apartment blocks, old low-rise residential buildings and shantytown shacks portray the disparity in living conditions and incomes in the Indian city. Rents for a place to live range from more than $2,000 to less than $5 a month. Here: Windows and doors of an old residential building are pictured in central Mumbai October 10, 2014. The cost for buying a residential apartment in Mumbai close to the city centre ranges from 12,000 Indian rupees ($ 200) per square feet to 112,552 Indian rupees ($ 1800) per square feet. (Photo by Danish Siddiqui/Reuters)

Performers take part in a rain soaked Notting Hill Carnival on August 25th, 2014 in London, England. Despite the bad weather over 1 million visitors are expected to attend the two-day event which is the largest of its kind in Europe. The event has taken place on the West London streets every August Bank Holiday weekend since 1964. (Photo by Mary Turner/Getty Images)

An employee walks near a rotary dredge which works on the coal face of the Borodinsky opencast colliery, near the Siberian town of Borodino, east of Krasnoyarsk, December 9, 2014. The Borodinsky colliery, 9 km (5.6 miles) long and more than 100 meters (328 feet) deep, annually produces more than 20 million tons of coal and is considered to be the biggest opencast coal mine in Russia, according to official representatives. (Photo by Ilya Naymushin/Reuters)

Tibetan boys dressed in traditional attire take part during a function organised by the Tibetan Refugee Community in Nepal,commemorating the 25th Anniversary of the Nobel Peace Prize conferment to exiled Tibetan spiritual leader Dalai Lama and the 66th International Human Rights Day in Kathmandu December 10, 2014. Nepal ceased issuing refugee papers to Tibetans in 1989 and recognizes Tibet to be a part of China. (Photo by Navesh Chitrakar/Reuters)

Rescuers search for survivors in the rubble of a collapsed residential building in Makongeni estate in Nairobi December 17, 2014. Three more bodies were recovered on Wednesday night from the building that collapsed in Makongeni estate in Nairobi, raising the death toll to four, Kenya Red Cross has reported. The residential building whose sixth floor was still under construction had allegedly not been cleared for occupation by the Nairobi City County and its owner has been missing since it collapsed. A search and rescue and rescue operation is ongoing for the unknown number of people still trapped under the rubble, Kenya Red Cross also reported. (Photo by Thomas Mukoya/Reuters)