Mongolia may need to rustle up some more glass cases for its first dinosaur museum after US authorities announced Friday they will hand back a large new collection of stolen fossils.

At a ceremony on Monday, officials had turned over the nearly complete skeleton of a 70-million-year-old Tyrannosaurus bataar, a cousin of the fearsome Tyrannosaurus rex.

It had been found in the Gobi desert and illegally sold at auction for $1.05 million in the United States last year, before authorities intervened.

Now, the federal prosecutor's office in Manhattan says that a herd of other prehistoric remains is due to be surrendered.

These include two more Tyrannosaurus bataars, a Hadrosaur, at least six Oviraptor skeletons, and fossils including several Gallimimus skeletons.

Mongolia's minister of culture, sport and tourism, Oyungerel Tsedevdamba, said this week her country is planning to build a Central Dinosaur Museum of Mongolia and that the T-bataar bones repatriated Monday will be the "first exhibit."