Many Worlds of April. Saga of the Jurassic period. Sauropods

The late Jurassic Period is renowned for the emergence of sauropod dinosaurs. They were the classic long-necked and long-tailed dinosaurs, and the largest grew to more than 40 metres in length and probably weighed up to 100 tonnes. Much of their apparent bulk was due to internal, air-filled sacs that passed through their huge bones, allowing them to grow even bigger.
In order to process the vast amount of plant matter consumed, it is thought that sauropods may have had large stones in their stomachs, called gastroliths, to help them digest tough vegetation. Much of the evidence on the diet of dinosaurs comes from the study of their fossilised dung, called coprolites, or taking data from fossilised trackways.
Palaeontologists used to believe that sauropods were amphibious as it wasn’t thought possible that sauropods could support their vast weight without the buoyancy aid of water. Today, we are confident that sauropods had pillar-like legs that were akin to a modern elephant’s, able to support their own body weight. After studying fossil tracks and skeletal remains, it was also concluded that giant sauropods walked with their tails held aloft, not dragging along the ground as previously thought.