What are the ansestors of the Pterodactyl?

The term “Pterodactyl” covers a range of species rather than a single creature, and they would not all have had a single immediate common ancestor. However recent discoveries suggest a descent from Nemicolopterus-type creatures.

http://funadvice.com/r/14n4eg777nh

I quote the following observation about a recently discovered Pterodactyl of very small stature: “…
A pterodactyl so small that you could hold it in your hand glided in forest canopies in northeastern China where it feasted on insects 120 million years ago, new fossil remains suggest. Paleontologists discovered the nearly complete skeleton of a toothless mini-pterodactyl, called Nemicolopterus crypticus, in the western part of China’s Liaoning Province. With a wingspan of nearly 10 inches (25 centimeters), this half-pint represents the smallest pterosaur, a group of winged reptiles that shared a common ancestor with dinosaurs and ruled the skies during the Jurassic period (206 million to 144 million years ago) and the subsequent Cretaceous period, which ended 65 million years ago. “The animal is a very young animal, but it’s not a hatchling that just left the egg,” said researcher Alexander Kellner of the Department of Geology and Paleontology at the Museu Nacional/Universidade Federal do Rio de Janeiro. “Therefore it is the smallest pterosaur ever found.” Unlike its fish-eating relatives that lived near the water’s edge, Nemicolopterus sported curved digits on its feet that would have helped the animal grasp tree branches. At that time, the researchers say, this inland environment was covered with gingko, conifers and other trees. The pterosaur’s small size would also have helped it bound across the tree canopy, grabbing insects. Its position in the evolutionary tree of pterosaurs suggests that a lineage of Nemicolopterus-like creatures led to all of the giant pterosaurs, including Quetzalcoatlus, which boasted a wingspan of more than 30 feet (10 meters). …”

from http://funadvice.com/r/14n4eg77918

As far as I am aware, all the creatures loosely referred to as Pterodactyls became extinct with no direct descendants existing today. There are too many differences between the fossils of Pterodactyls and the fossils of early birds to suggest that they could have evolved into birds.

– Best wishes - Majikthise.