The tallest dinosaur to have ever existed is the Sauroposeidon.

Sauroposeidon is a genus of sauropod dinosaur that lived during the Late Cretaceous period, approximately 110 to 105 million years ago. While our knowledge of Sauroposeidon is limited due to incomplete fossil remains, its estimated size suggests it was one of the tallest dinosaurs ever known.

Based on the fragmentary fossils discovered, scientists estimate that Sauroposeidon reached heights of around 18 to 20 meters (60 to 65 feet). Its incredible height was primarily attributed to its long neck, which allowed it to reach vegetation that was high above the ground. This immense stature enabled Sauroposeidon to access food sources that were inaccessible to other herbivorous dinosaurs.

Sauroposeidon belonged to the group of sauropod dinosaurs, characterized by their long necks, small heads, and massive bodies. It likely had a slender build and a lightweight skeletal structure, which would have allowed for more efficient movement despite its towering height.