Actor Nicolas Cage is involved in a legal dispute so grandiose that it could very well be the plotline of an upcoming sequel to his "National Treasure" franchise. After learning that a dinosaur skull he previously purchased was in fact illegally smuggled, he agreed to return the fossil to the Mongolian government, reported Reuters.

Preet Bharara, a U.S. attorney based in Manhattan, filed a civil forfeiture complaint to have the rare skull returned and repatriated back to Mongolia and, while Cage was not named in the lawsuit, his publicist Alex Schack confirmed that Cage is the owner of the dinosaur skull.

The Oscar-winning actor purchased a Tyrannosaurus bataar skull in 2007 from the I.M. Chait gallery in Beverly Hills, according to USA Today. He outbid fellow Hollywood actor Leonardo DiCaprio for the fossil and even received a certificate of authenticity at the time of purchase.

The I.M. Chait gallery had unknowingly purchased the illegally smuggled skeleton from paleontologist Erick Prokopi, according to Reuters. Prokopi was convicted of smuggling and selling illegal fossils in June 2014. U.S. authorities contacted Cage the following month.

"At no time did Prokopi believe that it was illegal for a private individual to purchase or own fossils of Mongolian origin," stated Prokopi's sentencing documents, as reported by Forbes. "In short, his crimes relate to his failure to comply with export and import regulations."

In Mongolia, it has been a crime to export dinosaur fossils since 1924. Both Cage and the gallery have not been accused of any wrongdoing.

The Tyrannosaurus bataar is a relative of the Tyrannosaurus rex. It was a carnivorous dinosaur that lived about 70 million years ago and its bones have only been discovered in Mongolia.