Mamenchisaurus

Most species were 15 to 26 metres (49 to 85 ft) long, possibly up to 35 metres (115 ft). It weighed about 12 tonnes (13 tons).34

Its neck was up to 15 metres (49 ft) long, the longest of any known dinosaur. That is longer than a school bus.54

It was a plant-eater that ate conifers, ferns, cycads and other plants. It swallowed leaves whole and may have used stomach stones to help digest them.4

It lived during the Late Jurassic Period, from about 161 to 145 million years ago. One species lived even later, in the Early Cretaceous.34

Fossils have been found in China, mostly in Sichuan and Xinjiang. The first one was discovered near the Mamenchi River in Sichuan.34

The long neck probably helped it reach leaves high in trees or eat soft plants in wetlands without going into the water. It might also have been used for showing off to mates.45

Yes, Mamenchisaurus was much longer and heavier than T. rex. It could be up to 35 metres (115 ft) long, while T. rex was only about 12 metres (40 ft).3

No, Mamenchisaurus was a sauropod, and no sauropod fossils have ever been found with feathers. It had scaly skin like modern reptiles.3