Pleistocene megafauna is the set of large animals that lived on Earth during the Pleistocene epoch. Pleistocene megafauna became extinct during the Quaternary extinction event resulting in substantial changes to ecosystems globally. The role of humans in causing Pleistocene megafaunal extinctions is controversial. Megafauna are any animals with an adult body weight of over . Pleistocene megafauna include the straight-tusked elephant, cave bear (Ursus spelaeus), interglacial rhinoceros (Stephanorhinus), heavy-bodied Asian antelope (Spirocerus), Eurasian hippopotamuses, woolly rhinoceros, mammoths, giant deer, sabre-toothed cat (Homotherium), cave lion, and the leopard in Europe. Paleoecology The last glacial period, commonly referred to as the 'Ice Age', spanned 125,000 to 14,500 years ago and was the most recent glacial period within the current ice age which occurred during the final years of the Pleistocene epoch. The Ice Age reached its peak during the last glacial maximum, when ice sheets commenced advancing from 33,000 years BP and reached their maximum positions 26,500 years BP. Deglaciation commenced in the Northern Hemisphere approximately 19,000 years BP, and in Antarctica approximately 14,500 years BP which is consistent with evidence that this was the primary source for an abrupt rise in the sea level 14,500 years ago. A vast mammoth steppe stretched from the Iberian peninsula across Eurasia and over the Bering land bridge into Alaska and the Yukon where it was stopped by the Wisconsin glaciation. This land bridge existed because more of the planet's water was locked up in glaciation than now and therefore the sea levels were lower. When the sea levels began to rise this bridge was inundated around 11,000 years BP. During the last glacial maximum, the continent of Europe was much colder and drier than it is today, with polar desert in the north and the remainder steppe or tundra. Forest and woodland was almost non-existent, except for isolated pockets in the mountain ranges of southern Europe. The fossil evidence from many continents points to the extinction mainly of large animals at or near the end of the last glaciation. These animals have been termed the Pleistocene megafauna. Scientists frequently define megafauna as the set of animals with an adult body weight of over 45 kg (or 99 lbs). Across Eurasia, the straight-tusked elephant became extinct between 100,000 and 50,000 years BP. The cave bear (Ursus spelaeus), interglacial rhinoceros (Stephanorhinus), heavy-bodied Asian antelope (Spirocerus), and the Eurasian hippopotamuses died out between 50,000 and 16,000 years