When did the Indian Ocean take on its present shape?

The Indian Ocean reached its present configuration approximately 36 million years ago.12

Its formation was a complex, multi-stage process resulting from the breakup of the supercontinent Gondwana, which began about 180 million years ago. While the ocean first began to open roughly 140 million years ago, its evolution involved several significant tectonic events, including the northeastward movement of the Indian subcontinent, the separation of Australia from Antarctica, and the eventual collision of India with Eurasia. Despite its initial opening, the majority of the current Indian Ocean basin is less than 80 million years old.132