Perhaps the best description of what this dinosaur might have been like comes from one of the world’s leading palaeontologists Professor Robert Bakker. In his book The Dinosaur Heresies he describes why he believes that T-Rex was a fast and agile hunter. The legs were built for speed with massive muscles capable of propelling T-Rex forward at great speed. The lung and heart cavities were large to enable him to pump the blood and oxygen required by his massive leg muscles. The picture of a group of T-Rex by Frank DeNota gives a vivid portrait of these massive animals.