Pterosaurs: dragons of the air
It was established in 1801 that pterosaurs could fly. However, their mode of locomotion on the ground has been controversial.
The French anatomist Baron von Cuvier, who determined that pterosaurs could fly, thought they walked on their hind limbs. Fossil trackways from the Solnhofen Limestone in Germany, which later proved to be from fossil king crabs, gave 19th century palaeontologists the idea that they walked on all four limbs, with the big wing finger folded out of the way over their back. It was only when tracks found in the 1950s in the USA had distinct hand and footprints that they were accepted as quadrupeds. In the 1980s, however, a strong case was made for pterosaurs being bird-like bipeds.
For the next two decades, the most controversial aspect of pterosaur research was their mode of terrestrial locomotion. Now, new evidence from both anatomy and footprints has confirmed that pterosaurs were quadrupedal.
This reconstruction of a pterosaur by French illustrator Eduard Riou for Louis Figuier’s extremely popular 1836 book The World Before the Deluge has become famous as the first depiction of a pterosaur walking on four limbs. The trail of footprints behind this long-tailed Rhamphorhynchus was cited as evidence of quadrupedal walking, but these tracks are now known to be from a king crab.
King crab trail
This trail with a fossil king crab at the end proved that the tracks found in the Solnhofen Limestone were not made by pterosaurs.
Of course, this did not prove that pterosaur did not walk on all fours, but that evidence was a long time coming.
During the 1980s, American researcher Dr Kevin Padian suggested that pterosaurs were bipedal, an idea that is no longer accepted. This reconstruction illustrates a bipedal Dimorphodon.
Drawings courtesy of Dr Mark Witton, University of Portsmouth.
Genuine pterosaur tracks
Pterosaur footprints are known from around the world, but some especially important tracksites in France and South Korea show that pterosaurs did indeed walk on all fours.
These prints from South Korea, named Haenamichnus, are more than 30cm long and are thought to represent a giant azhdarchid, like Quetzalcoatlus.
Footprint images based on Hwang et al 2002
Important tracksites in France and South Korea show that pterosaurs did indeed walk on all fours, with all four limbs underneath the body. Here, Anhanguera and Pterodactylus are shown in what is currently considered to be the natural gait for pterosaurs – on all fours.
Drawing courtesy of Dr Eberhard Frey, Karlsruhe Museum of Natural History Germany.