Simplify the following text for a Grade 12 native English-speaking person.
Original: Oviraptor lived in the late Cretaceous period , during the late Campanian stage about 75 million years ago ; only one definitive specimen is known ( with associated eggs ) , from the Djadokhta Formation of Mongolia , though a possible second specimen ( also with eggs ) comes from the northeast region of Inner Mongolia , China , in an area called Bayan Mandahu .
Simplified: Oviraptor lived in the Upper Cretaceous period , about 75 million years ago . Only one definite specimen is known ( with associated eggs ) , from Mongolia , though a possible second specimen ( also with eggs ) comes from the northeast region of Inner Mongolia , China .