The earliest and most primitive dinosaurs, however, had smaller hips and less advanced respiratory systems, suggesting their aerobic capacity was lower than in other dinosaurs, birds and mammals.

• 早期那些最原始的恐龙则具有小得多的臀部和欠发达的呼吸系统，说明它们的有氧呼吸能力要比其他的恐龙、鸟类和哺乳动物弱得多。