In a key piece of evolutionary evidence, palaeontologists have found that two-legged dinosaurs flapped their wings even when they couldn’t fly.
In an attempt to solve the age-old evolutionary question of how flying creatures came to be, new findings made by a team from Tsinghua University in China have shown dinosaurs could have developed flight without even realising it.
Publishing its findings to PLOS Computational Biology, the team created a life-size robotic version of a winged dinosaur called Caudipteryx, the most primitive, non-flying dinosaur known to have had feathered ‘proto-wings’. The bipedal animal weighed approximately 5kg and could run as fast as eight metres per second.
While a gliding type of flight appears to have matured earlier in evolutionary history, increasing evidence suggests that active flapping flight may have arisen without an intermediate gliding phase.
To test this, the team used a mathematical approach called modal effective mass theory to analyse the mechanical effects of running on various parts of Caudipteryx’s body. These calculations revealed that running speeds between about 2.5 to 5.8 metres per second would have created forced vibrations that caused the dinosaur’s wings to flap.
It was when these calculations were tested on the robot dinosaur at different running speeds that it was confirmed the motion caused the dinosaur’s flightless wings to flap. The team even fitted a young ostrich with artificial wings and found that running caused the wings to flap, with longer and larger wings providing a greater lift force.
“Our work shows that the motion of flapping feathered wings was developed passively and naturally as the dinosaur ran on the ground,” said researcher Jing-Shan Zhao. “Although this flapping motion could not lift the dinosaur into the air at that time, the motion of flapping wings may have developed earlier than gliding.”
The latest findings come at a time of great discoveries in palaeontology, including the fossilised remains of a tentacled, spider-like sea creature now named ‘cthulhu’. The creature had 45 tentacle-like tube feet that it used to crawl along the ocean floor and capture food. In terms of size this was no giant, measuring only about the size of a large spider.