Original: If this is the case, then the fact that 10 km fragments of the Vesta family and V-type asteroids have survived bombardment until the present indicates that the crater is only about 1 billion years old or younger.
Simplified: If this is the case, then the fact that 10 km fragments of the Vesta family have survived bombardment until the present indicates that the crater is only about 1 billion years old or younger.