While the earth is about 4.54 billion years old and the first life dates to at least 3.5 billion years ago, the first primates did not appear until around 50-55 million years ago. But by 50 million years ago, dinosaurs were extinct from the Earth. Continental fragments collided, pushing up mountain ranges still existing today. The collision of Africa into Europe gave rise to the Alps in Europe, and the collision of India into Asia formed the Himalaya. Birds and mammals began to expand in number and diversity. Genetic studies show that primates diverged from other mammals about 85 million years ago, in the Late Cretaceous period, and the earliest fossils appear in the Paleocene, around 55 million years ago. Within the Hominoidea (apes) superfamily, the Hominidae family diverged from the Hylobatidae (gibbon) family some 15–20 million years ago; African great apes (subfamily Homininae) diverged from orangutans (Ponginae) about 14 million years ago; the Hominini tribe (humans, Australopithecines and other extinct biped genera, and chimpanzee) parted from the Gorillini tribe (gorillas) between 9 million years ago and 8 million years ago; and, in turn, the subtribes Hominina (humans and biped ancestors) and Panina (chimps) separated about 7.5 million years ago to 5.6 million years ago and humans are around 200,000 years ago.