Pangaea, assembled around 335 million years ago, began to fragment in the middle Jurassic — roughly 175 million years ago. The breakup was not a single rupture but a gradual process spanning hundreds of millions of years; the continents are still moving today.

The first major split separated Laurasia in the north (North America, Europe, Asia) from Gondwana in the south (South America, Africa, India, Australia, Antarctica), with the Tethys Sea widening between them. The South Atlantic then began to open around 130 million years ago as the rift between Africa and South America grew into a continuous ocean floor. The North Atlantic opened later, around 80 million years ago. The Indian subcontinent broke from Gondwana and drifted rapidly northward, colliding with Asia approximately 50 million years ago and raising the Himalayas.

The driving force of the breakup is mantle convection: heat flow within Earth's mantle creates rising plumes beneath plates, pushing them apart. Rift valleys forming at divergent boundaries gradually widen into oceans; the East African Rift System today is a snapshot of that process in progress.

The biological consequences were dramatic. Communities that had co-evolved across Pangaea were dispersed to separate landmasses, each of which became an isolated evolutionary laboratory. This process — vicariant speciation — explains why related species on different continents are so similar yet so distinct: comparable climate zones on Africa and South America produced parallel but different faunas. The independent diversification of Australian marsupials is the most striking example of this biological isolation.

Ocean currents, climate, and ocean chemistry were also transformed. New ocean basins produced different circulation patterns; the new latitudinal positions of continents influenced glaciation and regional climate. The breakup of Pangaea is the fundamental biogeographical explanation for the distribution of life we observe today.