Simplify the following text for a Grade 4 native English-speaking person.
Original: The Saurornithoides runs up to the dead Charonosaurus , but before it can start feeding it too collapses and expires from inhaling the poisonous gas , leaving this entire region of Mongolia devoid of any animals .
Simplified: The Troodon runs up to the dead Charonosaurus . Then it too dies from inhaling the poisonous gas .