The U.S. Immigration and Customs Enforcement's (ICE) Homeland Security Investigations (HSI) agents returned a lot of stolen dinosaur fossils that were taken from Mongolia Tuesday. The fossils originated from six dinosaur species that were smuggled out of the country and eventually seized by agents in New York and Utah.

"Today's ceremony is an excellent demonstration of the cooperation between HSI, our colleagues at the Department of Justice and our foreign counterparts with the Government of Mongolia," said Peter Edge, HSI's executive associate director. "A successful repatriation requires extensive cooperation among all parties involved, which is rewarded by the knowledge that we've returned what rightfully belongs to the people of Mongolia."

Among the fossils returned Tuesday were: an Alioramus skull, Bactrosaurus skeleton, Protoceratops baby skeleton pieces, Troodontid egg bed, Psittacosaurus skeleton and skull and Hadrosaurus skeleton pieces.

The Alioramus skull was the biggest of the fossils and originates from an extremely rare dinosaur that scientists believe lived in the Gobi Desert approximately 66 to 70 million years ago. The rare dinosaur is a relative of the Tyrannosaurs and, as of now, only two specimens have been discovered.

The fossil impounded by agents is described as the most complete Alioramus fossil discovered to date.

The smugglers attempted to retrieve the fossil after having it shipped from France with false papers that identified it as a cheap replica. Afterwards, the shipper submitted forged Mongolian export documents before Mongolia determined that the items were national property in 1924, and the customs agents seized the entire shipment of stolen dinosaur fossils.

Robert Capers, Brooklyn's U.S. attorney, hosted the ceremony surrounding the return of the fossils.

"We are proud of our role in restoring this rich paleontological heritage to the Mongolian people and taking these cultural treasures from the hands of looters and smugglers," he said. "We stand beside the people of Mongolia by disrupting the international trade in smuggled fossils and returning them to their home where they will be studied and treasured."

"Mongolia is home to the world's largest reserve of dinosaur fossils with many discoveries waiting to be made," he added.

Over the past three years, 23 dinosaur fossils were returned to Mongolia from the United States, including the return of a Tarbosaurus bataar fossil that was approximately 70 million years old.