GMAT
One of the earliest known birds with a beak and contour feathers, Confuciusornis sanctus, had large clawlike "thumbs" on its wings, which probably helped them climb up to a launching position for flight.
One of the earliest known birds with a beak and contour feathers, Confuciusornis sanctus, had large clawlike "thumbs" on its wings, probably to help it climb up to a launching position for flight.
题目基本信息