Sauropods were huge quadrupedal plant eaters. All had extremely long tails and necks. For a long time the necks were thought to be used to reach high-up leaves but later it was discovered that many species could not move their heads far above the hight of their backs. The long tails were mainly used for balance and defence. Overall they have the same sort of general look.
Species appearing in The Land Before Time
Read More at: Sauropod on Wikipedia