The Elements of Evolution (21-13) In the Skies

In the Skies

Besides behemoth land lubbers and their nimbler carnivore cousins, reptiles also took to the air. Pterosaurs were the 1st flying vertebrates. They reigned over the skies 228–66 MYA.

Pterosaurs were neither dinosaurs nor the progenitor of birds. Some were scaly, others furry.

Pterosaurs were able fliers. Their wings were quite unlike those of birds: more like bat wings, in being made of thin membranes stretched between the arms and hind limbs.

Pterosaurs’ hollow bones, respiratory airs sacs, and enlarged brains were reminiscent of avian traits. In these regards, birds were an instance of convergent evolution.

Early pterosaurs had long, trailing tails, and teeth in their beak-like mouths. Later ones, the pterodactyls, were short-tailed, and had no teeth. This was, once again, convergent evolution with only distantly related birds.

Remarkably, pterodactyls were highly precocial and could take wing just after they hatched. Lacking parental care, flaplings were on their own, and so were well stocked with precocious knowledge as well as the ability to fly.

Some of the smaller pterosaurs were covered with fur. That and their doubtless flights in cool air over great distances suggest that pterosaurs were endothermic.