Pterosaurs Used Four Legs, Different from Modern Birds

A scientist at the Center for Functional Anatomy and Evolution at the Johns Hopkins University School of Medicine has shown that pterosaurs possessed a fundamentally different body structure from either modern birds or other dinosaurs.

Believed to be descendants of dinosaurs, modern birds have strong wings instead of forelegs and a pair of strong hind legs. These hind legs are used for launching into flight but become useless payload once in the air; thus, a maximum weight function exists for flying birds. However, pterosaurs ("winged lizards") achieved flight even when their bodies were as large as modern giraffes and weighed as much as 500 pounds.

By analyzing their comparative bone structure from fossil records along with modern mathematical models of flight, no solutions could be found that provided flight using just two hind legs to launch. Therefore, pterosaurs must have used all four legs to launch into winged flight with a series of long-jumps. These four limbs were equally adapted to movement on the ground, as the winged surface folded back with pterosaurs essentially walking on their knuckles.

This study appeared in a recent issue of Zitteliana (no website).

Photo: ScienceDaily