Simplify the following text for a Grade 9 native English-speaking person.
Original: Saurischians ( ` lizard-hipped ' ) are distinguished from the ornithischians ( ` bird-hipped ' ) by retaining the ancestral configuration of bones in the hip .
Simplified: Saurischians ( ` lizard-hipped ' ) and the ornithischians ( ` bird-hipped ' ) have differences in the ways bones in the hip are put together .