The rare Tyrannosaurus bataar — standing 8 feet (2.4 meters) tall and 24 feet (7.3 m) long — is to be auctioned Sunday (May 20) by Heritage Auctions.
An email to LiveScience late on Friday afternoon claimed the Mongolian President Elbegdorj Tsakhia was raising concerns that the specimen was actually his country's property. The email contained a note signed by Mark Norell, a vertebrate paleontologist at the American Museum of Natural History in New York City.
"There is no legal mechanism (nor has there been for over 50 years) to remove vertebrate fossil material from Mongolia. These specimens are the patrimony of the Mongolian people and should be in a museum in Mongolia," the letter reads.
Norell confirmed that the letter was his.
The auction house stands by their collection, saying the items legally entered the United States.
"There is nothing from Mongolia that is legal. It's not that I am against the commercial trade of fossils, it's just different countries have different laws," Norell told LiveScience, adding that Heritage Auctions avoids giving the specific locality for the origin of the fossil in their catalog of natural history items to be auctioned.