damage by dragging造句

• They retained aquatic, fry-like tadpoles, a system still seen in transitional animal had legs and both lungs and gills, but could never have survived on land : its limbs and its wrist and ankle joints were too weak to bear its weight; its ribs were too short to prevent its lungs from being squeezed flat by its weight; its fish-like tail fin would have been damaged by dragging on the ground.
• However, in 1987, nearly complete fossils of " Acanthostega " from about showed that this Late Devonian transitional animal had legs and both lungs and gills, but could never have survived on land : its limbs and its wrist and ankle joints were too weak to bear its weight; its ribs were too short to prevent its lungs from being squeezed flat by its weight; its fish-like tail fin would have been damaged by dragging on the ground.