Why is said that pterodactyls were too heavy to fly?

The new research claims that the ancient reptiles, which could grow to the size of small aeroplanes, were too heavy to fly - even with their massive wings. The problem, according ... The 'dinosaur' popularly known as a pterodactyl is actually called a reptile called a pterosaur, which is Greek for flying lizard. read more

It's never really been said that pterosaurs as an order were too heavy to fly, although some workers from decades ago have suggested they were only gliders. This is no longer believed to be the case by pterosaurologists, who generally claim the animals to have been active, dynamic fliers. read more

But now it seems pterodactyls, the terror of the prehistoric skies, may have struggled to get off the ground. The new research claims that the ancient reptiles, which could grow to the size of small aeroplanes, were too heavy to fly - even with their massive wings. read more

It was not a pterodactyl but gives an idea of an early forerunner of pterodactyls. From there it is but a short hop to powered flight, enabling the animals to stay airborne longer, and thus we get the pterosaurs (of which Pterodactyl is just one genus). read more