Since then he has studied rocks and fossils from most parts of the country, including 60 million year old deposits near the Indian Ocean, and 10,000 year old sediments near K-2, the second highest mountain in the world. At that time, Indo-Pakistan had been drifting in isolation in the Indian Ocean for 70 a million year period. The faunas that we study contain some of the oldest representatives of several modern orders of mammals, such as even-toed ungulates.
Fossils collected in Pakistan also help in deciphering the origins of whales.
The most primitive whales, pakicetids, are found here, as well as some very primitive coastal whales, ambulocetids and remingtonocetids. Hans Thewissen uses a toothbrush to clean a fossil at a site in Ganda Kas in Pakistan's Punjab Province.