Gigantism and acromegaly are two disorders with the same disease mechanism and somewhat similar presentations. Even though they have the same disease mechanism, the two have entirely different outcome simply due to the age of onset. Gigantism is the result if the disease mechanism starts in childhood.
Adult Velociraptors grew up to 6.8 feet (2 meters) long, 1.6 feet (0.5 meter) tall at the hip and weighed up to 33 pounds (15 kilograms).
It lived from 98 to 83 million years ago, separating itself from the Velociraptor by roughly 10 million years. You might say it's an ancestor of the actual Velociraptor, even though the original specie of raptor was almost the size of modern chicken and the Achillobator was roughly 1 ft taller than the average person.