New paleontological finds are changing the prevailing beliefs about pterosaurs - and the most bizarre animals that have ever flown over the earth.
Pterosaur and Pterodactyl are two names for outlandish flying creatures; the first of them in translation from Greek means "wing lizard", the second - "flying finger".
For the first time the remains of such an animal were found in the 18th century. Since then, scientists have described more than 200 species of winged lizards, but the common idea of these dragons, which reigned in the skies of the Mesozoic era for more than 160 million years, remains the same.
We invariably imagine them as clumsy, but very dangerous flying reptiles with a long beak and leathery wings, pacing on their hind legs like penguins.
Take, for example, the 1966 film A Million Years BC, in which a piercing purple pterosaur takes the heroine Raequel Welch to her nest to feed her cubs (spoiler alert: the beauty in a bikini escaped). Has anything changed in 50 years? Not at all: in Jurassic World, filmed in 2015, pterosaurs still carry more of their own weight into the skies. (Just in case, let's clarify: the last pterosaurs became extinct 66 million years ago, that is, an eternity before humans appeared on Earth.)
The sheer amount of recent fossil evidence suggests that pterosaurs came in all shapes and sizes, and varied widely in behavior. Hundreds of pterosaur species lived simultaneously, occupying different ecological niches, like today's birds. Among them were giant monsters, such as Quetzalcoatl (Quetzalcoatlus northropi), one of the largest flying creatures known today: standing on all fours, he could rival the growth of a giraffe, and in a wingspan of 10.5 meters. But there were also pterosaurs the size of a sparrow: they sat on branches in ancient forests and, most likely, caught insects.
One of the most curious finds is the fossilized pterosaur eggs. By scanning the best preserved ones, scientists saw the embryos under the shell and were able to learn about how they developed. One egg was even found in the oviduct of a female Darwinopterus, who lived in China, and next to it - another, which apparently squeezed out under the weight of volcanic ash that covered the animal. Mrs T (that was the name of this female) became the first pterosaur, whose gender was accurately determined. There was no crest on her skull. Perhaps such outgrowths adorned only the heads of males, as they adorn the males of some modern species of birds - nature gave them a large, brightly colored crest to attract individuals of the opposite sex.
After all these finds, pterosaurs seem to have become closer to us, but everything is not enough for scientists. And on the way to Big Bend National Park in southwest Texas, paleontologist Dave Martill of the University of Portsmouth shares with me work plans: first, meet and admire a rattlesnake; second, find the whole skull of quetzalcoatl. The chances of fulfilling the first point of the program are immeasurably higher.
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The most important thing for a pterosaur expert is to be optimistic. Imagining that on such and such a day you will go there and find at least something related to them is like buying a lottery ticket and immediately start planning what you will spend your winnings on. Pterosaur fossils are extremely rare because their bones were hollow and thin. As for quetzalcoatl, we know about it thanks to just a few fragments found in Big Bend Park in the 1970s.
The hollow, ultralight bones of pterosaurs were good for flight, but are rarely preserved as intact as these Anhanguera remains. In most cases, they are crushed, "as if a roller had driven over them."
Martill and his colleague Nizar Ibrahim spent three days searching for fossil bones in the beds of dry rivers in the park. They walked up and down the Pterodactyl Ridge (what a promising name!), Now and then checking the maps compiled by the discoverer of this lizard. They delved into all the nuances of geological strata ("Look at these manifestations of Milankovitch cycles!" - exclaimed Martill, meaning that periodic changes in the shape of the Earth's orbit and the inclination of its axis, as established by the Serbian astronomer Milutin Milankovic at the beginning of the 20th century, affect the climate planet, and this is reflected in the cyclical structure of sedimentary deposits). Climbing the ridge of sandstone, from which it seemed impossible to get off, Martill only dropped: “Where ours did not disappear! ", Jumped down and remained unharmed.
However, the researchers did not have a chance to either meet a rattlesnake, or even find a fragment of a pterosaur bone. In consolation, they came across the thigh bone of a giant dinosaur, most likely a sauropod. But they are not interested in dinosaurs.
Leaving the national park, paleontologists are developing a plan for a new search for quetzalcoatl - they really want to know more about this amazing lizard, in which everything is unusual: both size, and appearance, and behavior - this can be judged by the few remaining fossils from it.
In some parts of the fossil of the Zheholopter from China, subtle prints of hairs or down have been preserved. (For the first time, such integumentary structures were discovered by Soviet paleontologists in the Jurassic pterosaur.) Photo: INSTITUTE OF VERTEBRATE PALEONTOLOGY AND PALEOANTHROPOLOGY, BEIJING
The concept of pterosaurs has changed a lot - even in terms of their appearance and behavior. This is partly explained by the fact that until very recently, scientists had to build their conclusions on an extremely small number of samples.
Pterosaurs differed, frankly, very strange anatomy. It may seem that they were poorly adapted for life on earth or in the air. Once it was even thought that wing lizards crawled on their belly, or imagined them walking on their hind legs with long forelegs stretched forward like a zombie and dragging behind like a cloak with folded wings. Later, on the basis of fossil traces, it was established that pterosaurs moved on four limbs, but there was still no clarity in exactly how and where they put their wings. And they doubted their flying abilities so much that they considered them incapable of getting off the ground, except by throwing themselves down the cliff.
"It is quite common to see individuals with a head and neck three or even four times the length of the body," says biophysicist Michael Habib of the Natural History Museum of Los Angeles County. Even scientifically trained artists are often mistaken when portraying them. “They take the bird as a model, just add webbed wings and a crest to it,” says Michael. "However, the body proportions of the pterosaurs were not at all avian."
Khabib decided to revise the prevailing ideas about the biomechanics of pterosaurs using, firstly, a mathematical approach and, secondly, the practical knowledge of vertebrate anatomy, which he acquired in his other work, namely in the laboratory of the medical school of the University of Southern California. Like most scientists, Michael believes that the first pterosaurs, around 230 million years ago, evolved from light, slender reptiles that were well-suited for running and jumping. The ability to jump - to grab a flying insect or to dodge a predator's teeth - has evolved into the ability, as Habib put it, "to jump and hover in the air."
At first, pterosaurs probably only hovered, and then, tens of millions of years before birds (and even more so before bats), they became the first vertebrates to master flapping flight.
Using equations used in aircraft engineering, Habib and his colleagues refuted the cliff jumping hypothesis. In addition, they proved that if pterosaurs took off from an upright position, standing on their hind legs, then in large species, the thigh bones would break from overload. Four-limb takeoff is more practical.
“You need to jump up, leaning on the front limbs, like a high jumper - on his pole,” explains Habib. To take off from the water, pterosaurs used wings in the manner of oars in rowing: they pushed them off the surface. And again, like rowers, they had large, well-developed shoulders, which were often combined with strikingly small legs to minimize drag in flight.
The wing of a pterosaur was a membrane stretched from shoulder to ankle; and it was stretched by an extremely long flying (fourth) finger, which forms the leading edge of the wing. Samples from Brazil and Germany show that the membrane was pierced by fine muscles and blood vessels. Protein strands "stitching" it gave additional rigidity to the septum. Scientists now believe that pterosaurs could slightly alter the wing profile depending on flight conditions, by contracting muscles or turning the ankles inward or outward.
Changing the angle of inclination of the ossified tendon on the wrist - the pteroid, may have served the same purpose as the slat reversal in large modern aircraft - to increase lift at low speeds.
In addition, in pterosaurs, more muscles and a greater proportion of body weight were involved in ensuring flight than in birds. And in their brains, like in birds (and even better), the frontal and visual lobes, the cerebellum and the labyrinth were developed: such a brain could quickly respond to changes in the situation in flight and transmit signals to numerous muscles that regulate the tension of the membrane.
Thanks to the work of Habib and his colleagues, pterosaurs are no longer a winged misunderstanding, but skillful aviators. Many species seem to have been adapted for slow but very long flight over long distances; they could hover over the ocean using weak warm updrafts (thermals). There were also such species that Khabib calls super flyers: for example, the albatross-like Nyctosaurus, whose wingspan reached almost three meters, gliding qualities, especially the distance that he flew for each meter of descent, were quite comparable with the characteristics modern sports glider.
“Okay, everything is clear with wings,” one paleontologist began once after Khabib's lecture. - But what about the heads? “Quetzalcoatl, for example, could have a skull three meters long, while a body less than a meter. And the Nykosaurus had a long "mast" sticking out of a huge skull, to which a crest was probably attached.
Answering the question, Michael spoke about the brain of pterosaurs, the mass of which, like in birds, only slightly weighed the huge head, talked about bones that were hollow, also like in birds, and even lighter. The thickness of the bone walls sometimes did not exceed a millimeter, while the bone tissue was formed by numerous crossed layers, which gave strength to the bones (like in multi-layer plywood). And from the inside, the cavities for greater rigidity were crossed by partitions. All this allowed pterosaurs to achieve large body sizes without significant weight gain.
The skulls decorated with ridges and gaping mouths were so huge that Khabib, looking at them, developed the “Scary Gray Wolf hypothesis”: “If you have a big mouth, then you can swallow more. And the protruding crest could attract females. " Well, returning to the question of that paleontologist, pterosaurs, according to Michael, were "huge flying killer heads."
Junchang Lü, one of China's leading paleontologists, greets guests on a busy street in the center of Jinzhou, a major commercial city in the country's northeast, and escorts them through the dimly lit corridor of a seemingly ordinary office building. This is actually the Jinzhou Paleontological Museum. Its director opens the door of a small pantry without windows, and the eyes of those who come open up what would become the main attraction for visitors in any other museum: all the shelves and almost the entire floor are occupied by samples with surprisingly complete, in all the smallest details, the remains of feathered dinosaurs, the most ancient birds and, of course, pterosaurs.
On a large, almost shoulder-length, stone slab, leaning against the wall opposite the door, you can see a large, terrible pterosaur with a wingspan of four meters and tiny chicken hind legs - Zhenyuanopterus. Its elongated head is coiled to the side and seems to consist of only jaws, and the teeth become longer and more and more behind each other as it approaches the beginning of the mouth. “This is to make it convenient to fish while floating on the surface of the water,” explains Lu. Zhenyuanopter is only one of three dozen pterosaur species he has described since 2001 (many are still lying on shelves waiting to be studied).
The skull of the fish-eating Ankhanguera has been preserved in its natural position - to the delight of paleontologists. Photo: NATIONAL MUSEUM OF NATURE AND SCIENCE, TOKYO
The Jinzhou Museum is one of ten such paleontological museums scattered across Liaoning Province, which is home to a treasure trove of pterosaur fossils and one of the regions where the finds have been made that have put China at the forefront of paleontology in recent years.
In addition, Liaoning is the main arena of rivalry, and people from outside compare what is happening here, not entirely justifiably, with the "bone wars" that the pioneers of American paleontology Othniel Charles Marsh and Edward Drinker Kop waged with each other in the 19th century.
The parties to this rivalry are Lu, representing the PRC Academy of Geological Sciences, and Shaolin Wang, whose fossil-filled study is located at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. These pundits, like Marsh and Cope, worked together early in their careers, and then parted ways, and since then they have treated each other with hostility, which, however, is not advertised. “Two tigers cannot get along on the same mountain,” their colleague Shunxing Jiang grins.
Over the fifteen years that have passed since then, Lu and Wang have more than once outstripped each other in the number of discoveries, and a couple of them described more than 50 new species of pterosaurs - almost a quarter of everything that is known today. However, some of these new species will eventually be recognized as synonyms of the former, as is often the case in paleontology. However, the rival parties will have more discoveries in the future. “They would have had to work for ten years all day long to describe everything that they have already dug up,” one of the guests notes with envy. Hearing this, Lü raises his eyebrows in surprise: "I think ten years won't be enough."
The success of Chinese scientists is due not only to competition, but also to the fact that they were in the right place at the right time. China, along with Germany, Brazil, the United States and England, is one of the few countries in the world where 90 percent of all pterosaur fossils have been found. It happened not because pterosaurs lived only in the territories where these countries are now located - fragments of their skeletons are found almost everywhere. It's just that their remains are better preserved here.
This exclusivity is evident in Liaoning Province. At the beginning of the Cretaceous, Lü says, a very diverse community of organisms developed in the local forests and small freshwater lakes - dinosaurs, the first birds, many pterosaurs and insects. Due to the fact that volcanoes erupted in the neighborhood from time to time, many animals died under the ash and fell on the muddy bottom of the lakes. The victims of such disasters were buried very quickly, sometimes even without oxygen access to the remains, their tissues mineralized faster than they had time to decompose, and therefore survived. Paleontologists call such localities Lagerstätte (Lagerstätte in German means "deposit"). And all the same, such finds have to be dissected for months - to cleanse of the breed so that all their features can be seen, including, of course,with all kinds of powerful microscopes.
It's only in places like the Pterosaur Museum in Beipiao or the recent wing lizard exhibit at the Beijing Museum of Natural History that you start to perceive fossils differently - as part of a former great diversity.
For example, Jeholopterus, a pterosaur with a wide frog-like mouth, which, scientists assume, hunted dragonflies and other insects. Here is the Ikrandraco, named after the winged creatures from the Avatar: it probably flew low above the surface of the water and fished for fish using a kind of keel on the lower jaw. Here is a jungaripter (Dsungaripterus) found in North China with a slender, upturned beak, with which it hooked on mollusks and other invertebrates in order to then crush their shells and shells with tuberous teeth.
And all this disappeared at the end of the Cretaceous period, 66 million years ago. What turned out to be wrong with the ultimately extinct pterosaurs? Maybe the animals they hunted disappeared? Or, in the course of evolution, they reached such gigantic proportions that they could not survive a global catastrophe, like the fall of an asteroid, while the small birds survived?
However, when you look at their perfectly preserved remains in a museum, you don't think about that - something amazing happens: it seems that these creatures are ready to free themselves from stone captivity and go in search of their missing fragments in order to soar again above the ground.
