I WONDER - What Group Did The Apatosaurus Belong To?

The video discusses sauropods, a group of large dinosaurs with massive bodies and four pillar-like legs. It highlights the Brachiosaurus and Apatosaurus, also known as Brontosaurus. The Apatosaurus, weighing as much as five elephants, was discovered by American paleontologist Neil Charles Marsh in 1877.

How much did the Apatosaurus weigh compared to elephants?

Who discovered the Apatosaurus and in what year?