Scientists on Wednesday confirmed the existence of an eighth continent after a nine-week voyage that largely took place in the Pacific Ocean.
Called Zealandia, the continent is mostly submerged in the South Pacific, with the island nation of New Zealand being the most notable landmass.
Scientists, though, believe the entire continent was once much closer to the surface and provided an important route for the migration of animal and plant life about 80 million years ago.
A team of 32 scientists from 12 countries explored Zealandia from a research vessel for more than two months. The return of the scientists was announced by the National Science Foundation (NSF).
"Zealandia, a sunken continent long lost beneath the oceans, is giving up its 60 million-year-old secrets through scientific ocean drilling," said Jamie Allan, program director in the NSF's Division of Ocean Sciences, in a statement.
"This expedition offered insights into Earth's history, ranging from mountain-building in New Zealand to the shifting movements of Earth's tectonic plates to changes in ocean circulation and global climate."
Most of Zealandia is about 1 kilometer (3,280 feet) below the ocean's surface; the researchers believe that the vast majority of the continent, about 93 percent, sunk to the depths of the Pacific Ocean about 23 million years ago. Once part of a landmass that included Antarctica and Australia, the scientists estimate that Zealandia is about 4,920,000 square kilometers (1,900,000 square miles) in size.
Drilling into Zealandia during the research voyage yielded thousands of important fossils that revealed the area was once an important land ecosystem.
"More than 8,000 specimens were studied, and several hundred fossil species were identified," said expedition co-chief scientist Gerald Dickens of Rice University in a statement.
"The discovery of microscopic shells of organisms that lived in warm, shallow seas, and of spores and pollen from land plants, reveal that the geography and climate of Zealandia were dramatically different in the past."