Dr Karl: What were pterodactyls?
IUSED TO THINK pterodactyls were two-legged flying dinosaurs. Yes, they could fly, but they were not dinosaurs and they had four legs.
Pterodactyls were part of a larger group called pterosaurs – literally “flying reptiles”. Although they existed at the same time as dinosaurs, about 200–66 million years ago (mya), pterosaurs were a completely different group.
They were widespread across Earth, with at least 110 known species in more than 85 genera.
Pterosaurs did not have feathers. Instead, their wings were flexible membranes of muscle, skin and related tissues. This membrane stretched from the ankles, up along the sides of the rather short pterosaur body and out to the wing tips.
Some of them – notably Quetzalcoatlus spp. – were the largest creatures ever to fly, with wingspans of 10m and more – bigger than a modern-day F-16 fighter aircraft. That’s three times bigger than today’s largest flying animals – the wandering albatross and the Andean condor.
Some pterosaur species had a torso that made up only onequarter of their body length.
The remainder was a very long neck and even longer head. To potential prey, they were the flying jaws of death.
Some of the pterosaurs weighed 250kg, making them the heaviest creatures ever to fly. There’s always, of course, been one big mystery: how did they take off or launch into flight, when they were that heavy? And we have finally worked it out. First, they had a very strong, but very light, skeleton. Second, their membrane wings gave more lift than wings with feathers.
And finally, they had lots of haunch, or launch, power. Having four limbs – two short, powerful hind legs and two long front legs that unfolded into wings – gave them more than double the power of a twolegged animal trying to launch.
They would crouch, bending their hind legs, which they’d straighten to vault upwards, then continue with their front legs to add a catapult action, before finally lifting off – all 250kg of them.
Anyway, in the Great Extinction 66mya, why did all the pterosaurs die out, when the birds did not? Nobody knows – yet.
DR KARL is a prolific broadcaster, author and Julius Sumner Miller fellow in the School of Physics at the University of Sydney. His latest book, Dr Karl’s Random Road Trip Through Science, comes with pop-up holograms and is published by HarperCollins Publishers
Australia. Follow him on Twitter at @DoctorKarl