The United States said it will return more than a dozen illegally smuggled dinosaur skeletons, including two Tyrannosaurus bataars that are 70 million years old, to Mongolia. The announcement follows the U.S. Immigration and Customs Enforcement agency’s handing over of a 70 million-year-old T-Rex skeleton to the Mongolian government officials at a ceremony in New York on Monday.

The latest group of skeletons includes at least six fossilized Oviraptors, one Saurolophus Angustirostris skeleton, several Gallimimuses and one restored composite egg nest display piece made of composite dinosaur egg fossils, apart from the two Tyrannosaurus bataars, U.S. officials said on Friday.

The T-Rex skeleton, handed over on Monday was sold at an auction in New York for more than $1 million before it was seized by the Immigration and Customs Enforcement agents. The auction was completed, despite a restricting order from a Texas court at the behest of Mongolian government, prohibiting the auctioning, sale, release, or transfer of the bataar. The United States Attorney’s Office seized the bataar and initiated a forfeiture action.

“Through this investigation, HSI special agents around the country have seized numerous dinosaur skeletons that are pending repatriation to the government of Mongolia. We simply cannot allow the greed of a few looters and schemers to trump the cultural interests of an entire nation,” U.S. Immigration and Customs Enforcement's (ICE) Homeland Security Investigations (HSI) Special Agent-in-Charge James T. Hayes, Jr. said in a statement.

Since 1924, private ownership and export of fossils is banned in Mongolia, whose Gobi Desert is rich in dinosaur fossils. Nevertheless, several fossils are smuggled out of Mongolia to the U.S. and are openly traded in the auctions and trade fairs, Reuters reported.

Mongolian government has announced its decision to open a dinosaur museum to display the fossils and lauded the ICE agency for returning the skeletons.

“The recovery of this treasure trove of dinosaur fossils is the latest significant step in returning missing pieces of the Mongolian people’s history that were literally dug out from under them. One cannot put a price tag on cultural artifacts or overstate the importance of their role in a country’s history, and we are delighted to be moving the process of returning these fossils to Mongolia forward,” Manhattan U.S. Attorney Preet Bharara said in a statement.

Most of the fossils now being handed over were recovered from Eric Prokopi, a fossil preparer and dealer in Gainesville, Florida. Prokopi pleaded guilty to smuggling charges in December. Prokopi faces up to 17 years prison sentence if found guilty.