for National Geographic News
Yaowalak Chaimanee, a government paleontologist, regularly receives scores of tips about new fossil discoveries around Thailand.
But when geologists at Suranaree University of Technology called her last March about an ancient jawbone found in a province three hours from Bangkok, Yaowalak knew the discovery was special.
The fossil belonged to a stegodon, a prehistoric elephant-like animal that was once common in the region. But the location of the findinga rice fieldwas what really intrigued her. Most important fossils in Thailand have been found in caves.
The next morning Yaowalak and her Bangkok-based team from the Thailand Department of Mineral Resources traveled to the site. The scientists soon began unearthing a treasure trove of fossils: skulls of a gavial (a crocodile-like reptile) and a spotted hyena, deer antlers, and a buffalo horn.
"I've never seen such a community of large mammals in one excavation," said Yaowalak, who has since been studying the remains.
The discovery may shed new light on the distribution of prehistoric species, including human ancestors, in the region. The site documents a period when Thailand had a more temperate climate, attracting animals from India and China.
"These southward distribution shifts are important to understand and date, because they may also explain the southward spread of Homo erectus populations and later Homo sapiens," Yaowalak said.
Thailand once had a high diversity of prehistoric fauna, and researchers have unearthed many important fossils, including higher primates, in the country.
Most discoveries in the past have been made in cave deposits. The latest fossils, however, were found at a construction site for a new rice mill.
An abundance of fossils were found deposited in a thin layer of fine gravel and sand mixed with organic matter about 16 feet (5 meters) below the surface.
"The preservation [of the fossils] is exceptional," said Jean-Jacques Jaeger, a professor of paleontology at Montpellier II University in France.
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