A new study has calculated for the first time the number of different sauropod lineages that achieved whopping proportions - 36 of them in a span of about 100 million years bridging the Jurassic and Cretaceous periods.
Sauropods, those familiar plant-eating dinosaurs with long necks, long tails and four pillar-like legs, were the biggest land animals in Earth's history, reaching 100-120 feet (30-36 meters) long and weighing as much as a tractor-trailer.