Sunday, 10 July 2016
Too Heavy to Fly? Darwin-Defying Design in Huge Pterosaurs
Some pterosaurs were as big as giraffes. With a wingspan of 10–11 metres (32–36 ft.), they seemed to be too large and too heavy to fly.
So, how did they do it?
A recent post in The Conversation suggests that in a way they resembled giant bats, with exquisitely designed features:
“Unlike birds with feathered wings, pterosaurs had a membrane that stretched from the end of an elongated fourth finger to their legs (more similar to a bat than a bird). This membrane had internal structures called actinofibrils to strengthen the wings, and provide structural support. They also had a unique bone in their wrist called the pteroid, which controlled the leading edge of the wing.”
But it seems that like some extinct mosaic-like animals (such as Archaeopteryx and Tiktaalik) and some living mosaics (for instance, the duck-billed platypus and the spiny anteater), they also shared some features with another kind of living animal, viz. the bird:
“Pterosaurs also had a highly specialised respiratory system, similar to that of birds, with air sacs in addition to their lungs. This is a much more effective breathing system, which is important for providing the large amounts of energy needed for flight. Pterosaurs had air sacs in their necks and trunk, and larger creatures also had them in their wings. In many cases, the air sacs invade the bones and hollow them out, making their wing bones extremely thin-walled. This is referred to as skeletal pneumaticity and is another important element contributing to large pterosaurs' ability to fly.”
The take away message from this post is that the pterosaurs were designed for flight.
Darwin-defying top-down design is very evident in these amazing creatures of yesteryear.
Martin-Silverstone, Elizabeth. 2016. Pterosaurs should have been too big to fly – so how did they manage it? The Conversation (30 June).