The Hypacrosaurus is estimated to have been around 30 feet long, and weighed up to 4.4 tons with neural spines that projected from the top of the vertebrae, the bones that form the spinal column.
The animal is estimated to have been around 9.1 meters (30 feet) long, and to have weighed up to 4.0 tonnes (4.4 tons). The neural spines, which project from the top of the vertebrae, are 5 to 7 times the height of the body of their respective vertebrae in the back, which would have given it a tall back in profile. Vertebrae articulate with each other to give strength and flexibility to the spinal column, and the shape at their back and front aspects determines the range of movement. 
