An artists rendition of Quetzalcoatlus northropi, a kind of pterosaur and the biggest flying animal that ever survived on Earth. Quetzalcoatlus stood about 12 feet tall and walked with a special gait due to the fact that of its huge 20-foot wings, which touched the ground when folded. Credit: Artwork courtesy of James Kuether
70 million-year-old fossils expose special strolling habits of this huge, heron-like pterosaur.
Take a look around any wetland today and youre most likely to see 3-foot-tall egrets or 4-foot-tall herons wading in the shallows in stealthy search of fish, crustaceans or pests.
70 million years earlier, along the Rio Grande River in Texas, a more impressive and scarier creature stalked the marshes: the 12-foot-tall pterosaur known as Quetzalcoatlus. With a 37- to 40-foot wingspan, it was the largest flying animal that ever lived on Earth.
Unlike the serpent god, Quetzalcoatlus had no plumes: Its body, consisting of wings of skin and fibers of keratin, was covered with hair, as in all pterosaurs. To understand how the Quetzalcoatlus pterosaurs behaved, Padian and coworkers controlled casts of bones from about a lots smaller and more total pterosaur fossil skeletons, consisting of those of the types Quetzalcoatlus lawsoni, which is newly-named after Lawson in one of the accompanying documents. Despite 2 centuries of reconstructing pterosaurs like bats, there is no evidence for this view: Bats are unique and very different from birds and pterosaurs.”
Research study of the bones reveals that the pterosaur could not have utilized the wings for propulsion. Padian admits that questions about Quetzalcoatlus and pterosaurs, in general, still stay, such as the shape of the wing membranes and where they were connected to the body.
In six papers published this week as a Memoir by the Society of Vertebrate Paleontology, scientists and an artist supply the most total picture yet of this dinosaur relative, the biggest example of which is represented by simply a single set of fossilized bones gathered in the late 1970s from Big Bend National Park. The papers describe the pterosaurs geological and environmental setting throughout the Upper Cretaceous, its anatomy and taxonomic position, and how it moved on the ground and in the air.
How can an animal walk with wings so long that they touch the ground when folded? And how does an animal whose wings cover 40 feet, yet whose legs are only 6 feet high at the hip, launch itself into the air?
A sketch of the bones of Quetzalcoatlus northropi. When walking, the animal had a special gait unlike any other, and noticeably various from that of the vampire bat. Credit: Drawing by John Conway
” This ancient flying reptile is famous, although the majority of the public conception of the animal is artistic, not scientific,” said Padian, who co-edited the essay. “This is the first real take a look at the totality of the largest animal ever to fly, as far as we understand. The outcomes are innovative for the study of pterosaurs– the first animals, after pests, ever to develop powered flight.”
The original Quetzalcoatlus fossils were discovered by Douglas Lawson, who at the time was a 22-year-old studying for a masters degree in geology at the University of Texas, Austin, and later on ended up being a doctoral trainee at UC Berkeley. The fossil pterosaur– which he called after the Aztec flying serpent god– consisted of a partial wing that indicated a size similar to that of some planes and was at least 50% larger than the wings of the largest recognized bird, an extinct and much bigger relative of living condors and a descendent of the dinosaurs.
Unlike the serpent god, Quetzalcoatlus had no feathers: Its body, consisting of wings of skin and fibers of keratin, was covered with hair, as in all pterosaurs. Like dinosaurs, it was likely warm- blooded and active. It had lost its tail, most likely to improve its maneuverability, and its 6-foot neck and 4-foot crested skull suggest a stork on steroids.
Wann Langston, for several years a manager of UT Austins Vertebrate Paleontology Laboratory, welcomed many colleagues, consisting of Padian, to deal with the fossils, but was not able to release a complete description of the animal prior to his death in 2013.
At the request of the lab, Padian teamed up with engineer and amateur paleontologist James Cunningham and London artist John Conway– all long time colleagues of Langston– to take a look at the fossilized bones of Lawsons discover, Quetzalcoatlus northropi, and compare them with more many specimens of a smaller Quetzalcoatlus types in order to much better understand feeding, flying, walking and launch habits. Langston is listed as a fourth co-author of the paper.
” Jim and John and I concerned the job with extremely different concepts,” Padian said, “but we didnt put a single declaration in our paper unless all 3 of us settled on it.”
Having fun with the bones
To understand how the Quetzalcoatlus pterosaurs behaved, Padian and associates manipulated casts of bones from about a dozen smaller and more total pterosaur fossil skeletons, consisting of those of the types Quetzalcoatlus lawsoni, which is newly-named after Lawson in among the accompanying documents. The Q. lawsoni fossils were found in the very same Javelina Formation in West Texas around the time the bigger Q. northropi was excavated. The smaller specimens are half the size of the bigger one Lawson initially found, but they include about 300 fossilized bone bits. The larger animal, nevertheless, is understood only from a couple of wing bones: a humerus and an ulna from the arm and lower arm, respectively.
The image that Padian, Cunningham and Conway paint is of an animal similar to egrets and herons in how it feeds and launches itself into the air, like condors and vultures in how it skyrockets, however, due to the fact that of its enormous wings, unlike any other known animal in how it strolls.
The wings worked basically like those of birds and other dinosaurs, to which pterosaurs are most carefully associated. In spite of 2 centuries of reconstructing pterosaurs like bats, there is no evidence for this view: Bats are very different and unique from pterosaurs and birds.”
Like bats and birds and even human beings, the forelimbs of pterosaurs have three sections: the arm or humerus, from the shoulder socket to the elbow; the lower arm, including the radius and ulna; and the wrist and hand bones. However unlike birds and bats, the leading edge of the external part of the pterosaur wing is formed by a huge wing-finger.
” Its like having a ski pole extended from the base of your fingers and angled 90 degrees external,” Padian said.
Quetzalcoatlus was bipedal, that is, it walked on two legs. Since its forelimb bones are so lengthened, its wings could not avoid touching the ground when folded. This four-point stance suggested to some that the pterosaurs walked like a vampire bat, which uses its forelimbs to move itself forward on the ground. Research study of the bones reveals that the pterosaur could not have used the wings for propulsion. When grounded, they might only move their wings forward or to the side.
” Once you put the forelimbs on the ground in these pterodactyls, you cant rotate the forelimb back to press the animal forward like any practical quadruped since theres a bone in the way in the shoulder,” Padian stated.
That does not imply they were awkward.
” To prevent tripping, the animal first raised its left arm, then advanced its left leg in a full step, then it positioned the hand on the ground,” he said. “The procedure was duplicated with the best limb: The best arm lifted, the best leg advanced and emplaced the ideal foot, and then the right-hand man came down. It seems a troublesome process to us, but the animal might carry out the gait quickly and quickly.”
This fits perfectly with trackways of walking pterosaurs discovered in Southern France in the 1990s, Padian said.
Powerful legs offer a jump-start
Nevertheless, due to the fact that its legs were shorter than its wings, taking off was not as easy as flapping to produce lift.
In the smaller specimens, youre looking at a 9-foot wing thats most likely flexed to a bit under 8 feet on each side. If youre running along, you can only depress the wings about 40 degrees below the horizontal before they struck the ground. Preferably, you d like to get a deeper stroke, and because these wings are so big, you cant move them really rapidly, so a much faster stroke will not work.
Rather, pterosaurs likely utilized their strong rear legs to jump up, and after that, once the ground clearance equated to the wing length, started to flap. Herons and egrets do the same, though they are significantly smaller sized than Quetzalcoatlus.
” If they might jump two times their hip height, to 8 feet, the wings would be able to clear the ground, and they might perform a much deeper flight stroke,” Padian stated. “This might be the very best choice for taking off, though it depends upon adequate power from the legs.”
He said that the forelimbs might have assisted push the creature off the ground in the way of vampire bats, but this would have required remarkable strength of the extensor muscles of the forearm, which seems unlikely.
Offered its habitat– inland marshes and open fields, much different from the West Texas desert today– the pterosaurs most likely feeding technique would look like that of todays herons and egrets, which are waders and stalkers with a different diet plan. They sift the mud for worms, crabs and clams, however likewise snatch up small fish, insects, snakes and lizards.
” Some people stated it was a carrion feeder, some individuals stated it flew over the water and plucked fish like a pelican. Those things dont work,” he said. And if you look at a heron or egrets jaws, theyre the same– good for plucking lizards and other little game, but definitely not carcass-scavenging.
Quetzalcoatlus could have been as competent at stalking victim from the air as from land.
” This animal might raise its head and neck vertically, so as to swallow the small victim it took with its jaws. It could reduce the terrific head far below the horizontal, so if it were cruising above dry land, it may have been able to swoop down and pluck an unsuspecting animal,” Padian said. “Walking about on land, it could move its head and neck to an arc of 180 degrees, capable of complete vision all around it.”
Almost 40 years back, Padian teamed up with paleontologist Jean-Michel Mazin, who had actually found the pterosaur trackways in France, to explain the landing strategies of pterosaurs.
” The animal had to flap its wings to stall and slow its descent. And after that it lands with its back feet and takes a little hop,” Padian said. “And then it puts down its front feet, then it presumes a four-legged posture, straightens itself out and leaves.”
The groups comprehensive reconstruction of the anatomy and habits of Quetzalcoatlus was possible thanks to the exceptional condition of the fossils, which were protected in almost their original three-dimensional shape, he stated. This is unusual for fossil animals and specifically for pterosaurs, which have very thin bones that are generally crushed.
Padian admits that concerns about Quetzalcoatlus and pterosaurs, in basic, still remain, such as the shape of the wing membranes and where they were connected to the body. He pointed out that the legs were organized like those of birds and other dinosaurs, with the knees pointed forward, and that they put one foot in front of the other when strolling. They could not have angled the legs sideways, nevertheless, like bats, which have unique hip joints that permit this.
Because of this, pterosaur legs would have been ineffective for extending the wings, which recommends that the wings were connected to the body just. Pterosaurs most likely resembled birds in flight, with their legs tucked underneath.
All of the information will be online for the world to read and review, thanks to Nathan Myhrvold, previous chief technology officer of Microsoft Corp., who funded the various teams to prepare the essays and spent for open access. The essay was coedited by Matthew Brown, director of UT Austins Vertebrate Paleontology Collections at the Jackson School of Geosciences.
” Its really amazing to get together all these individuals who have been involved with studying (Quetzalcoatlus) over the years, all these various aspects, from the history of discovery to the ancient environment of the animal to the research study of what its anatomy resembled and how numerous type of animals there were and how it flew and walked and removed, and so on,” Padian said. “To put all these things in a single set of papers in an essay is type of one-stop-shopping for this animal. And were really pleased to be able to make it open gain access to, thanks to Nathan.”