Elephants (Elephantidae) are a family in the order Proboscidea in the class Mammalia. They were once classified along with other thick skinned animals in a now invalid order, Pachydermata. There are three living species: the African Bush Elephant, the African Forest Elephant (until recently known collectively as the African Elephant), and the Asian Elephant (also known as the Indian Elephant). Other species have become extinct since the last ice age, which ended about 10,000 years ago, the Mammoth being the most well-known of these. Elephants are mammals, and the largest land animals alive today. The elephant's gestation period is 22 months, the longest of any land animal. At birth it is common for an elephant calf to weigh 120 kilograms (265 lb). An elephant may live as long as 70 years, sometimes longer. The largest elephant ever recorded was shot in Angola in 1956. This male weighed about 12,000 kg (26,400 lb), with a shoulder height of 4.2 m (13.8 ft), a metre (3 ft 4 in) taller than the average male African elephant. The smallest elephants, about the size of a calf or a large pig, were a prehistoric species that lived on the island of Crete during the Pleistocene epoch. Elephants are symbols of wisdom in Asian cultures, and are famed for their memory and high intelligence, and are thought to be on par with cetaceans. Aristotle once said the elephant was "the beast which passeth all others in wit and mind."