Scientists separate dinosaurs into two groups based on the shape of their skeletons. The most common group had hips similar to modern lizards and these included both the plant-eaters (called sauropods) and meat-eaters (called theropods). The other group had hips similar to modern birds and include ornithopods. However, for most people, shape and pattern of life are also what matter. The sauropods (meaning ‘lizard foot’) are what people think of as the classic long-necked, plant-eaters.

Sauropods are among the oldest dinosaurs and they appeared in Triassic time. They were very successful and were common throughout the world in Jurassic times. Some of the most common are Apatosaurus (previously called Brontosaurus), Brachiosaurus and Diplodocus. You may very well find a skeleton of one of these giants in a museum, but it is unlikely it will be complete because they were simply too big to allow all of the skeleton to remain in place.

Sauropods are not as easy to tell apart as other dinosaurs. They all had small heads, long necks, great barrel bodies and long balancing tails. The tails of some were quite thin and may have been used in defence. You would not want to receive a whiplash from a 20m-long tail. Some probably stood on their hind legs, at least for part of the time. Many were able to arch their necks up high, while others, like Diplodocus, probably could not. We can tell the difference by looking at the neck bones. Some can be bent more than others. In general, sauropods kept their heads level with their body. Sauroposeidon, however, could crane its neck and might have been able to reach up to 18m (four times as tall as a giraffe), and if it were alive today could easily have looked in at a third-storey window.

On the other hand, if some were alive today, they would need the roads reinforced. Argentinosaurus weighed up to 100 tonnes and Bruhathkayosaurus may have weighed 200 tonnes. (For comparison, an elephant weighs 10 tonnes.) From tip to toe, Supersaurus was 40m long and Amphicoelias (the world’s longest ever animal) may have been 60m long. Even the smallest were 6 m long. Sauropods had teeth for chewing tough plants and must have had a giant stomach for digesting them. They laid eggs and had feet with five toes. Some had plates which have mostly been thought of as armour plates.