Faxinalipterus

In 2010 paleontologists Jose Bonaparte, César Schultz, and Marina Soares described a tiny pterosaur from the 220-million-year-old Caturrita Formation of Rio Grande do Sul, Brazil. This pterosaur, named Faxinalipterus minima, is known from an incomplete left arm and shoulder, the right humerus, most of the left leg and part of the right leg. In addition to the limb bones, the authors referred a tooth-bearing bone from the upper-jaw. 

There are no hand or finger bones in the specimen, therefore the arm bones don't preserve the long wing-finger that characterizes pterosaurs. The original discovery team determined that Faxinalipterus was a pterosaur because the humerus has a distinctive shape at the shoulder that is seen in other pterosaurs, and the bones are hollow. The humerus is only 18 mm (¾ inch) long, indicating that in life it would have been the size of a sparrow with a wingspan under 25 cm (10 inches). 

Faxinalipterus lived in a terrestrial environment rather than the coastal environments that many other Triassic pterosaurs are found. The teeth on the referred skull bone are recurved cones that are only about one millimeter long. The shape of the teeth and its small size makes it likely that Faxinalipterus was an insectivore. 

Bonaparte and colleagues considered Faxinalipterus to be the earliest and most primative pterosaur. Unlike all other known pterosaurs, the tibia and fibula of Faxinalipterus are unfused, suggesting it diverged before all other known pterosaurs. The earliest known pterosaurs were small, had short necks, short wings, and long tails, often with vanes at the tips, so it's likely Faxinalipterus was similar. Not all authors agree that Faxinalipterus represents a pterosaur, with Alexander Kellner suggesting it might be a close relative of pterosaurs and dinosaurs, and Fabio Della Vecchia was unable to identify what kind of vertebrate it represents.