Introduction to Quetzalcoatlus northropi Pterosaurs have been known for more than two centuries. A pterosaur fossil was found between 1767 and 1784 in the Solnhofen limestone quarry that would later yield the famous fossil bird Archaeopteryx. The exquisitely preserved pterosaur skeleton soon began to intrigue the natural historian Baron Georg- es Cuvier, who was the first to realize that the long fourth finger supported the membrane of a wing. The scientific description of Pterodactylus antiquus by Cuvier (1801) was the first pterosaur species to be named and described. Over the centuries of further research it became clear this was only one species of a highly successful group of flying animals with a membrane wing supported on a single digit. Many species also often had a large and bizarre skull and crest. Although they dominated the skies for hun- dreds of millions of years, ranging from the Late Triassic to the end of the Cretaceous, they are now completely extinct. The first pterosaurs discovered were relatively small but many new discoveries gradually increased the known size of pterosaurs. By the late 1960s various Pteranodon specimens were approaching 7 metres wing span. Since the largest flying animals today have wing spans in the 3 metre range it was recog- nised that these animals seemed too large to fly, prompting a great deal of debate. In the early 1970s Douglas Lawson and his col- leagues discovered the remains of several large pter- osaurs in the Maastrichtian sediments of the Late Cretaceous of North America, placing their age at approximately 68 million years old. One of these fossils was the humerus bone of a gigantic wing that far surpassed the size of any pterosaur wing found previously. Lawson (1975) named the pterosaur Quet- zalcoatlus northropi. Most recent studies estimate that its wing span was in the 10 to 11 metre range. The fossil evidence seems to indicate that Quetzal- coatlus northropi were spread over a huge area. Fossils Abstract The envisaged flying ability of the gigantic Quetzalcoatlus northropi pterosaur has produced ongoing debate since its first discovery, mainly because aeronautical calculations show it is too large to produce continuous powered flight in our gravity. This problem has encouraged a number of authors to suggest that continuous powered flight might be possible in a reduced gravity. This study quantifies the flying ability of a Quetzal- coatlus northropi in a reduced gravity of 0.62g (6.08 m/s 2 ). The results show that Quetzalcoatlus northropi was capable of producing continuous powered flight in this reduced gravity, allowing its flying ability to be comparable with the largest flying animals of today. Key words: Palaeogravity, Quetzalcoatlus northropi, flying ability. The flying ability of the pterosaur Quetzalcoatlus northropi in a reduced gravity Stephen W. Hurrell email: papers@dinox.org First Published: 16 December 2020 Cite: Hurrell, S.W. (2019). The flying ability of the pterosaur Quetzalcoatlus northropi in a reduced gravity. http://dinox.org/hurrell2020d