Complex sentence: A guard opens the cargo hold, accidentally releasing the "T. rex", which escapes into the city and goes on a rampage; it turns out the crew revived the animal after it stopped breathing, only to realise they couldn't keep it under control.
Split into simpler sentences: A guard opens the cargo hold, accidentally releasing the "T. rex", which escapes into the city and goes on a rampage. It turns out the crew revived the animal after it stopped breathing, only to realize they couldn't keep it under control.