Aerodynamics seldom scale well. The challenges large birds have in getting airborne today have left palaeontologists puzzled as to how much larger animals managed it in the past. Now a set of four simultaneous papers has shed some insights on Quetzalcoatlus northropi, probably the largest pterosaur that ever lived and therefore the largest creature ever to take to the skies, and how it actually got airborne (spoiler: it involves a rather large jump).
Soaring over the now North American skies, with a 10-12 meters (33-40 feet) wingspan, Q. northropi was larger than some light aircraft, proving the claim that everything is bigger in Texas was true even in the Cretaceous. It didn’t have the power of a modern engine to provide it with thrust, however, leading to questions of whether it was capable of flight at all. Scientists from several fields have addressed this, assisted with insights from a smaller relative Q. lawsoni, described for the first time in one of the papers, and named after the scientist who described the genus decades ago.
To get airborne Quetzalcoatlus would have needed to jump its hip height into the air so its wings could start flapping. That would be impressive enough for the smaller Q. lawsoni, but for Q. northropi it means a jump of almost 2.5 meters (8. 2 feet). Few creatures could manage that today, even without the giant wings to weigh them down.
“Pterosaurs have huge breastbones, which is where the flight muscles attach, so there is no doubt that they were terrific flyers," Professor Kevin Padian of the University of California, Berkeley, who co-edited the papers, said in a statement.
Landing probably wasn’t graceful either. "The animal had to flap its wings to stall and slow its descent before it lands with its back feet and takes a little hop," Padian told the Natural History Museum, London. "Then it puts down its front feet, assumes a four-legged posture, straightens itself out and walks away."
The papers were published together in the Journal of Vertebrate Paleontology, having been submitted around four years ago but held back until all were ready for publication. Q. lawsoni’s announcement has been coming for much longer. The first Quetzalcoatlus description included the observation the dozen giant bones were accompanied by many smaller but similar ones. The presence of a smaller, more numerous, species, was suspected, but the possibility of high mortality among adolescent Quetzalcoatlus was also considered. It’s only now the existence of two members of the genus has been confirmed.
Quetzalcoatlus has been proposed to be a carrion eater, like modern-day condors, but the papers reject this, as its beak was too delicate. Instead, the closest modern counterpart is probably the heron, snatching fish and small reptiles from the surface of the water, as well as invertebrates from the muddy bottom.
One paper describes the ecosystem in which Quetzalcoatlus lived. The area was dotted with shallow alkaline lakes surrounded by palms with subtropical forest on higher ground. It proposes Q. lawsoni, whose wingspan reached 5.5 meters (18 feet) appears to have been common here, and may have fed on bivalves and mollusks, which fossils suggest were similarly abundant. The paper suggests its giant cousin “May have had a more solitary lifestyle and preferred riparian habitats.”
A third, more distantly related pterosaur, Wellnhopterus brevirostris, also occupied the same ecosystem. The relationships between these and other pterosaur species are described in another paper.
Extraordinary as it may seem that an animal facing such difficulties in landing and taking off could survive, Quetzalcoatlus thrived for millions of years, only being wiped out by the impact that ended the Cretaceous.
"These ancient flying reptiles are legendary, although most of the public conception of the animal is artistic, not scientific,” Padian said. Twenty-four countries have put it on their postage stamps, for example. However; "This is the first real look at the entirety of the largest animal ever to fly, as far as we know.”