Fossils reveal a wet, warm 'Shangri-La'-like ecosystem on Tibetan Plateau

Dec. 8 (UPI) -- The Tibetan Plateau once hosted a "Shangri-La"-like ecosystem -- wet, warm and rich in biodiversity -- according to new research.

The ancient ecosystem was revealed by a trove of plant fossils, discovered by a team of scientists in the Bangor Basin in central Tibet.

The Chinese research team, a group of scientists from the Xishuangbanna Tropical Botanical Garden and the Institute of Vertebrate Paleontology, described their discovery this week in the journal PNAS.

"These fossils characterize a luxuriant seasonally wet and warm Shangri-La forest that once occupied a deep central Tibetan valley along the Banggong-Nujiang Suture," lead author Tao Su, forest ecologist at XTBG, said in a news release.

Researchers unearthed the remnants of at least 70 different plant species, including relatives of several modern Asian plant lineages. Several of the plant fossils are the first to be found on the plateau, while several more offer the earliest examples of their taxa on the continent.

The rich fossil assemblage offers a snapshot of a humid subtropical ecosystem during the middle of the Eocene, roughly 47 million years ago.

Until now, paleontological studies on the plateau have been undermined by a lack of clarity on the surface height measurements through time and space.

"These fossils not only record the diverse composition of the ancient Tibetan biota, but also allow us to constrain the middle Eocene land surface height in central Tibet to 1,500 -- plus or minus 900 -- meters, and quantify the prevailing thermal and hydrological regime," said Zhe-Kun Zhou, a professor at XTBG.

Morphological traits in the many leaf fossils recovered at the site allowed researchers to quantify the region's climate and and elevation during the middle Eocene.

According to their calculations, the Shangri-La ecosystem flourished at an elevation of roughly 1500 meters. The forest, which stretched along an east-west valley, was fed by the regular rains of a monsoonal climate.

"In the future, the complex topography of Tibet in the geological past needs to be considered when studying the paleoenvironmental and biodiversity histories on the plateau," said Tao.