Produced by the Population Genetics and Evolution class, Furman University

The Triassic: Pterosaurs
Pterosaurs, flying archoasaurian reptiles, were the first vertebrates to evolve true flight. They were competent in flight and evolutionarily successful, surviving for 140 million years (Hutchinson 1995). Pterosaurs are closely related to dinosaurs, but their true ancestors are unknown, and the poor Triassic fossil record does not help in their identification. However, it has been speculated that they may have been derived from the small archosaur Schleromochlus, due to the similarity of its skull and presumed arboreal nature (even possibly having gliding capabilities). The earliest known pterosaur was Eudimorphodon (unique in their dentition), succeeded by three other Triassic genera, Austriadactylus, Peteinosaurus, and Preondactylus. They were all fairly small, and most likely fed on insects and fish (Orcutt 2005). An elongated fourth digit supported the pterosaur wing. Other flight adaptation included a keeled sternum (for flight muscle attachment), a shortened humerus, and hollow limb and skull bones. Triassic Pterosaurs had tails for balance, although these were lost in more derived forms. Modified epidermal structures served as wing fibers, and may have had a role in thermoregulation. They also had a unique bone, the pteroid bone, which pointed from the wrist to the shoulder to support the wing membrane.

Page by Megan Aprill
Eudimorphodon. Picture from: Wikipedia.com

Dalla Vecchia FM. 2003. A Review of the Triassic Pterosaur Diversity. Accessed on March 23, 2010.

Hutchinson JR. 1995. Vertebrate Flight. University of California Museum of Paleontology (UCMP) Accessed March 23, 2010.

Orcutt JD, 2005. Pterosuar Fossil Record. University of Bristol. Accessed March 23, 2010.