Original: They are known as the 'bird-hipped' dinosaurs because of their bird-like hip structure, even though birds actually descended from the 'lizard-hipped' dinosaurs (the saurischians).
Simplified: They are known as the 'bird-hipped' dinosaurs because of their bird-like hip structure, even thouhg bird actually descended from the lizard-hipped' dinosaurs the saurischians.