Edmonton palaeontologist solves pterosaur pelvis puzzle
'Bizarre' specimen shows winged creatures likely spent more time on the ground
Two years after the unearthing of a puzzling fossil in southern Alberta, an Edmonton paleontologist has finally identified the mysterious bone, showing in the process that the winged reptile it belonged to rarely got off the ground.
The pelvis bone, discovered by a group of University of Alberta researchers in a sandstone bone bed near Steveville in Dinosaur Provincial Park, turned out to belong to a pterosaur, an order of reptiles best known for the ability to fly.
Pterosaur bones are notoriously rare because the fossils are so fragile few remain intact. When found, they are either highly fragmented or severely eroded.
"It confused us for a long time, because it's such an unusual bone," said Greg Funston, a University of Alberta PhD student in paleontology. "At every turn we would come up with an idea of what it could have been and then some feature would tell us it was something else.
"It took a long time to figure out but it was very rewarding because it ended up being be something really unique ... It was less frustrating than it was fascinating."
Puzzled over bizarre specimen
For months, Funston puzzled over the bizarre specimen trying to identify the species of animal and body part the bone belonged to.
He initially thought the bone might belong to either a theropod dinosaur or a prehistoric bird, but nothing matched.
Finally, after detailed imagining, painstaking measurements and insight from his PhD supervisor, world-renowned paleontologist Phil Currie, Funston identified the bone as a pelvis belonging to an azhdarchid, making Funston's fossil the first its kind to be found in North America.
This family of oddly proportioned pterosaurs had gigantic heads, long necks, and short wings.
Funston's azhdarchid roamed the earth during the Late Cretaceous period and likely had a wingspan of between three and seven metres.
'The smoking gun was the hind limb'
However the features of the pelvic bone Funston identified, such as muscle scarring, suggests his giant reptile actually spent more time walking.
"By looking at their biomechanics, we can tell these animals were probably spending a considerable portion of their time on the ground," he said.
"The smoking gun was the hind limb. We typically find a lot of wing and vertebral bones of these animals, so finding a pelvis became important for understanding whether these animals were spending time on the ground."
Unlike its flying ancestors, these pterosaurs likely adapted to land travel to accommodate larger bodies but also to improve their access to prey, Funston speculates.
Sticking close to the ground or "land stalking" would have made hunting easier for these strange creatures.
The fossil is rare direct evidence that these creatures were land-bound, something that was only a hypothesis until now, he said.
"It helps confirm some ideas that have been out there," Funston said. "They were spending less time in the sky and more time on the ground.
"It was a different lifestyle than their ancestors had, and it also tells us about the animals in that region."
"The first pterosaur pelvic material from the Dinosaur Park Formation (Campanian) and implications for azhdarchid locomotion" appears in Facets, a new open-access journal from Canadian Science Publishing.
"When we think of that region, the Dinosaur Park area, we think of the major predators as the raptor dinosaurs and the tyrannosaurs, but we also have to consider that these giant flying reptiles were there as well."
"Having direct evidence of that ... I think it will help stimulate more thought on that ecosystem and how these animals were living."