Powered flight is the ability to use muscles to flap your wings and generate lift. The ancestors of modern birds weren’t the only ones to achieve this feat – other groups of dinosaurs also found weird and wonderful ways to stay aloft.
3 weird and wonderful dinosaurs that could fly
Yi qi
One species that might have flown is Yi qi (‘strange wing’), whose bizarre aerofoils resembled those of bats. While the surface of a bat’s wings feature a membrane of skin (patagium) stretched across its legs and elongated fingers, Yi qi’s membranous wings were supported by its arms and a ‘styliform’ wrist bone unique to the scansoriopterygid dinosaur family. The aerodynamic potential of Yi qi hasn’t been tested, however, and so it may have been a mere glider.
Microraptor
Microraptor (‘tiny thief’) is a dinosaur that was certainly capable of powered flight. It was unusual because it had four wings – two on its arms, two on its legs – with long feathers. While gliding, the crow-sized dinosaur formed an X- shape, arms outstretched and legs slightly splayed.
It occasionally flapped its wings for lift and brought the rear limbs down as an air-brake before landing. The bones of mammals, lizards and fish have been found in Microraptor’s gut, suggesting that – like modern raptors – it might have caught food on the wing.
Rahonavis
Another probable flyer is Rahonavis (‘cloud bird’), from a separate branch of the dromaeosaurid family tree. This was more conventional looking, with two wings, but less is known about its diet and how it flew.
Palaeontologists have predicted the flight potential of numerous dinosaurs from aerodynamics, based on calculations like ‘wing loading’ (the ratio of body mass to wing area).
Besides Microraptor and Rahonavis, several now-extinct birds passed those tests, including relatives of Anchiornis (‘near bird’) and, on a branch leading to modern birds, the well-known Archaeopteryx (‘ancient wing’).
How were some dinosaurs able to fly?
Dromaeosaurids, extinct birds and living avians all belong to a wider group of theropod dinosaurs, the maniraptorans (those with ‘thieving hands’). This raises a question: what enabled this group to evolve flight on at least three separate occasions?
One answer is their respiratory system. In mammals, air reaches the lungs by going in and out of the body along the same route.
By contrast, dinosaurs – including birds – used a one-way system where air flowed around a circuit, not only passing through the lungs but also via multiple air-filled spaces in the limbs, ribs and vertebrae. These balloon-like air sacs gave dinosaurs pneumatic bones, making them lightweight.
When we think of flying dinosaurs, we often think of the iconic pterodactyls. But pterodactyls were not actually dinosaurs – rather flying reptiles that lived during the same period.
