Here's why:
* Cheetahs are the fastest land animals on Earth, reaching speeds of up to 70 mph (112 km/h) in short bursts.
* Gallimimus, while a large and fast dinosaur, likely reached speeds of around 40 mph (64 km/h) based on estimations from its bone structure.
So, even though Gallimimus was a very fast dinosaur, it couldn't keep up with the incredible speed of a cheetah.