natural resources (oil, gas, minerals, fresh water, fish and, if the subarctic is included, forest) to which modern technology and the economic opening up of Russia have given significant new opportunities. The interest of the tourism industry is also on the increase. The Arctic contains some of the last and most extensive continuous wilderness areas in the world, and its significance in preserving biodiversity and genotypes is considerable. The increasing presence of humans fragments vital habitats. The Arctic is particularly susceptible to the abrasion of groundcover and to the disturbance of the rare breeding grounds of the animals that are characteristic to the region. The Arctic also holds 1/5 of the Earth's water supply. Paleontology During the Cretaceous time period, the Arctic still had seasonal snows, though only a light dusting and not enough to permanently hinder plant growth. Animals such as the Chasmosaurus, Hypacrosaurus, Troodon, and Edmontosaurus may have all migrated north to take advantage of the summer growing season, and migrated south to warmer climes when winter came. A similar situation may also have been found amongst dinosaurs that lived in Antarctic regions, such as the Muttaburrasaurus of Australia. However, others claim that dinosaurs lived year-round at very high latitudes, such as near the Colville River, which is now at about 70° N but at the time (70 million years ago) was 10° further north. Indigenous population The earliest inhabitants of North America's central and eastern Arctic are referred to as the Arctic small tool tradition (AST) and existed c. 2500 BCE. AST consisted of several Paleo-Eskimo cultures, including the Independence cultures and Pre-Dorset culture. The Dorset culture (Inuktitut: Tuniit or Tunit) refers to the next inhabitants of central and eastern Arctic. The Dorset culture evolved because of technological and economic changes during the period of 1050–550 BCE. With the exception of the Quebec/Labrador peninsula, the Dorset culture vanished around 1500 CE. Supported by genetic testing, evidence shows that descendants of the Dorset culture, known as the Sadlermiut, survived in Aivilik, Southampton and Coats Islands, until the beginning of the 20th century. The Dorset/Thule culture transition dates around the ninth–10th centuries CE. Scientists theorize that there may have been cross-contact of the two cultures with sharing of technology, such as fashioning harpoon heads, or the Thule may have found Dorset remnants and adapted their ways with the predecessor culture. Others believe the Thule displaced the Dorset. By 1300