Complex sentence: While it is out grazing with its parents, it wanders off and is almost killed by a "Tyrannosaurus rex", but the parents hear its cries and knock the "Tyrannosaurus" over with their strong tails.
Split into simpler sentences: While it is out grazing with its parents, it wanders off and is almost killed by a "Tyrannosaurus rex". But the parents hear its cries and knock the "Tyrannosaurus" over with their strong tails.