Article by: Adam Manning
Edited by: Harry T. Jones and J. D. Dixon
Here at Darwin’s Door, we have already discussed the evolution of flight in insects, pterosaurs, birds, and bats, but gliding may have been much more common. Many different groups of modern animals have gliding membranes, even including the flying paradise snake. So, were gliders common in the prehistoric world too, and why has this mode of locomotion been so prevalent?
The earliest fossil evidence of gliding among vertebrates dates back to the Late Permian reptiles Coelurosauravus jaekeli and Rautiania alexandri. These were small diapsid reptiles with independent, elongated, rod-like bones along each side of their body, which supported their gliding membranes. They also had a series of hollow cavities in their bones to make them lighter, allowing them to glide further.
Gliding animals continue to appear in the subsequent periods of the Triassic and Jurassic. This included more gliding reptiles, such as Longisquama insignis, that glided on highly modified scales resembling feathers, and Kuehneosuchus latissimus, which glided on a membrane supported by independent rib bones, like Coelurosauravus. Gliding also appeared in new groups of animals. The Thoracopteridae were a group of fish from the Late Triassic that exhibited over-water gliding, using modified pectoral fins.
There was also the Late Triassic gliding pterosaur Sharovipteryx mirabilis, whose triangle-shaped gliding membrane stretched across only its hind limbs – a unique morphology among pterosaurs. In the Jurassic Period, we find the first instances of gliding mammals: Volaticotherium antiquum from northeast China, an arboreal insectivore with an elongated tail and limbs. A patagium (a gliding membrane made of skin) stretched between its limbs and was covered in dense hair. There was also Arboroharamiya allinhopsoni, which had a similar gliding morphology to Volaticotherium.
Many gliding reptiles have been found from the Early Cretaceous of China. Xianglong was a small lizard, again with a gliding membrane supported by independent and elongated rib-like bones. It was likely a prey item of dinosaurs like Microraptor gui and Sinornithosaurus. Both of these dinosaurs famously glided via feathers on all four limbs. The colours of Microraptor and Sinornithosaurus have even been worked out (see our article on fossil colours), with studies revealing Sinornithosaurus was covered in a mixture of blacks and russets, and Microraptor was iridescent black, like a modern raven. Furthermore, it has been suggested that Sinornithosaurus was venomous, injecting venom into its prey along grooves in its teeth.
So why is gliding such a common form of locomotion over so many different animal lineages? One of the biggest reasons for this is the environment they live in. Many of the prehistoric animals listed above and gliding animals alive today are all arboreal, meaning they live in trees. Therefore, they evolved gliding as a means of transportation from tree to tree. This is more energy-efficient than having to climb down each tree to get to the next one, and it provides more safety from predators as well. However, this doesn’t explain the evolution of gliding in animals like Thoracopteridae, where over-water gliding was more energy-inefficient than swimming. This highlights the other main benefit of gliding, by giving a new form of locomotion to use to escape from predators, like modern gliding fish escaping from dolphins.
Gliding is a fascinating evolutionary trait because it is so common in so many vertebrates, and shows how animals with similar problems will often develop the same solutions to overcome them.
 Examples of living gliding vertebrates. A) Polypedates dennysi, the Chinese flying frog. B) Glaucomys volans, the Southern flying squirrel. C) Chrysopelea paradisi, the Flying paradise snake. D) Glaucomys volans, the Sugar glider, a marsupial. Figure created by Manning, 2020. Images: D. Gordon E. Robertson; Kim Taylor; The Daily Conversation; Remon Knaap.
 Left: A reconstruction of Coelurosauravus jaekeli, with the left-wing folded and the right-wing spread. Right: A nearly complete fossil of Coelurosauravus jaekeli. Figure compiled by Manning, 2020, using Frey, Sues, and Munk, 1997. Click Here.
 A. Fossil of the Thoracopteridae Potanichthys xingyiensis, a fish that could glide over water. B. Reconstruction of the gliding membrane of Sharovipteryx mirabilis. Adapted from Dyke, et al., 2006 and Xu, et al., 2013.
Information References and Further Sources
 Bishop, K. L. (2006). ‘The relationship between 3-D kinematics and gliding performance in the southern flying squirrel, Glaucomys volans’, Journal of Experimental Biology, 209, pp. 689-701. Accessed 18th June 2020. Click Here.
 Bishop, K. L. (2007). ‘Aerodynamic force generation, performance and control of body orientation during gliding in sugar gliders (Petaurus breviceps)’, Journal of Experimental Biology, 210, pp. 2593-2606. Accessed 18th June 2020. Click Here.
 Chatterjee, S., and Templin, R. J. (2007). ‘Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui’, Proceedings of the National Academy of Sciences of the United States of America, 104 (5), pp. 1576-1580. Accessed 18th June 2020. Click Here.
 Dyke, G. J., Nudds, R. L., and Rayner, J. M. V. (2006). ‘Flight of Sharovipteryx mirabilis: the world’s first delta‐winged glider’, Journal of Evolutionary Biology, 19 (4), pp. 1040-1043. Accessed 18th June 2020. Click Here.
 Frey, E., Sues, H.-D., and Munk, W. (1997). ‘Gliding Mechanism in the Late Permian Reptile Coelurosauravus’, Science, 275 (5305), pp. 1450-1452. Accessed 18th June 2020. Click Here.
 Gong, E., Martin, L. D., Burnham, D. A., and Falk, A. R. (2010). ‘The birdlike raptor Sinornithosaurus was venomous’, Proceedings of the National Academy of Sciences of the United States of America, 107 (2), pp. 766-768. Accessed 18th June 2020. Click Here.
 Han, G., Mao, F., Bi, S., Wang, Y., and Meng, J. (2017). ‘A Jurassic gliding euharamiyidan mammal with an ear of five auditory bones’, Nature, 551, pp. 451-456. Accessed 18th June 2020. Click Here.
 Li, Q., Gao, K-Q., Meng, Q., Clarke, J. A., Shawkey, M. D., D’Alba, L., Pei, R., Ellison, M., Norell, M. A., and Vinther, J. (2012). ‘Reconstruction of Microraptor and the Evolution of Iridescent Plumage’, Science, 335 (6073), pp. 1215-1219. Accessed 18th June 2020. Click Here.
 McCay, M. G. (2001). ‘Aerodynamic Stability and Maneuverability of the Gliding Frog Polypedates dennysi’, Journal of Experimental Biology, 204, pp. 2817-2826. Accessed 18th June 2020. Click Here.
 Meng, J., Hu, Y., Wang, Y., Wang, X., and Li, C. (2006). ‘A Mesozoic gliding mammal from northeastern China’, Nature, 444, pp. 889-893. Accessed 18th June 2020. Click Here.
 Li, P-P., Gao, K-Q., Hou, L-H., and Xu, X. (2007). ‘A gliding lizard from the Early Cretaceous of China’, Proceedings of the National Academy of Sciences of the United States of America, 104 (13), pp. 5507-5509. Accessed 18th June 2020. Click Here.
 Reisz, R. R., and Sues, H-D. (2000). ‘The ‘feathers’ of Longisquama’, Nature, 408, pp. 428. Accessed 18th June 2020. Click Here.
 Socha, J. J., O’Dempsey, T., and LaBarbera, M. (2005). ‘A 3-D kinematic analysis of gliding in a flying snake, Chrysopelea paradisi’, Journal of Experimental Biology, 208, pp. 1817-1833. Accessed 18th June 2020. Click Here.
 Stein, K., Palmer, C., Gill, P. G., and Benton, M. J. (2008). ‘The Aerodynamics of the British Late Triassic Kuehneosauridae’, Palaeontology, 51 (4), pp. 967-981. Accessed 18th June 2020. Click Here.
 Xu, G-H., Zhao, L-J., Gao, K-Q., and Wu, F-X. (2013). ‘A new stem-neopterygian fish from the Middle Triassic of China shows the earliest over-water gliding strategy of the vertebrates’, Proceedings of the Royal Society B: Biological Sciences, 208 (1750), p. 20122261. Accessed 18th June 2020. Click Here.
 Xu, G-H., Zhao, L-J., and Shen, C-C. (2015). ‘A Middle Triassic thoracopterid from China highlights the evolutionary origin of overwater gliding in early ray-finned fishes’, Biology Letters, 11 (1), p. 20140960. Accessed 18th June 2020. Click Here.
 Zhang, F., Kearns, S. L., Orr, P. J., Benton, M. J., Zhou, Z., Johnson, D., Xu, X., and Wang, X. (2010). ‘Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds’, Nature, 463, pp. 1075-1078. Accessed 18th June 2020. Click Here.