fly

There is no conclusion about the flight mode, wing movement mode and take-off mode of pterosaurs in paleontology. In 2008, Kewen Sato, a researcher at the University of Tokyo in Japan, thought that pterosaurs could not fly. Kevin Sato conducted a special study in the Croze Islands in the South Indian Ocean to test the flying ability of large seabirds. He attached the No.3 battery-sized accelerometer to the wings of 28 birds of five different species, including the world's largest albatross. According to Sato Kewen's calculation, when there is no wind, a bird weighing more than 40 kilograms can't flap its wings fast enough to fly. The albatross weighs 22 kilograms and can still fly. According to this benchmark, it is impossible for large pterosaurs to soar high in the sky. However, the research report pointed out that when comparing these two flying animals, we must also consider their differences in anatomical structure, physiology and environment. In the book Attitude, Movement and Paleoecology of Pterosaur, it is considered that the oxygen content in the atmosphere was high in the late Cretaceous, and pterosaurs could fly in this environment [34]. However, both of them speculated that pterodactyls flew in a bird-like way, and the size of some giant pterodactyls could not be included in the calculation (for example, pterodactylidae, pterodactylidae). Darren Naish, on the other hand, thinks that the difference of atmospheric composition between Mesozoic and modern times is not the reason why large pterosaurs can fly.

Paleontologists Mark Wheaton and Mike Habib of Portsmouth University and Johns Hopkins University put forward the hypothesis that pterosaurs took off. Pterosaur will put its body in a ready state when it takes off, then push its body forward with the strength of its limbs at the same time, and then fly with its wings, similar to the catapult ejection method. When pterosaurs fly in the sky, the speed can reach 120 kilometers per hour, and they can fly several kilometers at a time.

1985, the Smithsonian Institution entrusted aviation engineer Paul McGrady to test the flight mode of pterosaurs. He made a model of Fengshen Pterosaur with the size of 1/2, tested it many times with the ejection device, and made the process into an IMAX movie "On the Wing". However, there are some physiological structural errors in this model, such as vertical and horizontal control rudders installed at the tail to help the model take off, but the pterodactyl tail does not have these redundant tissues. In addition, because the tail of the model is too long, it is impossible to truly present the influence of pterosaur's center of gravity distribution on flight.

Airbags and respiratory system

In 2009, a study showed that pterosaur's skeleton had a space filled with air, and there should be an air bag inside, similar to the respiratory system of modern birds, which could make pterosaurs breathe more effectively, lose weight and help pterosaurs fly.

nervous system

Because the skulls of pterodactyls are very fragile, it is very difficult to study their skulls. But in 2003, Lawrence Witmer of Ohio University and others used X-ray computed tomography to scan the brains of Rhamphorhynchus muensteri and Anhanguera santanae, and established 3D images of the brains of these two species, and found that the cerebellum of these two species had huge lobules. Pills are used to integrate information from joints, muscles, skin and balance organs.

Pterosaur's pompoms account for 7.5% of its brain capacity, which is larger than other vertebrates. The villi of birds are larger than those of other animals, but only account for 1%~2% of the brain.

The pompoms transmit nerve signals, which make the eye muscles produce tiny automatic movements. This makes the animal retina produce a stable image. Pterosaurs may have big pompoms because of their huge wings, which means they have a lot of sensory information to process.

Ground motion

Pterosaur's buttock fossa was slightly upward, and the femoral head was moderately bent inward, indicating that Pterosaur had a semi-upright gait. When they fly, their thighs may be lifted parallel to their bodies, similar to modern gliding lizards.

In the past, paleontologists had a great debate about whether pterosaurs were quadruped or bipedal on the ground. In the1980s, paleontologist Kevin Padian pointed out that small pterosaurs, such as Liang Long, had long hind legs, and they might walk and run on the ground in a bipedal way besides flying, just like the modern roadrunner. At present, a large number of pterosaur footprint fossils have been found, showing the obvious footprints of four toes on the hind legs and three toes on the forelimbs. It can be confirmed that pterosaurs moved on the ground in a quadruped way. The larger pterodactyl had smaller hind legs and larger front half. It is generally believed that they use their limbs when moving on the ground. According to the pterosaur footprint fossils found so far, it can be found that they are wading or looking for food, but no footprint fossils have been found to prove that they are flying or gliding.

Footprint fossils show that the pterosaur Norfolk walked in a quadruped way.

Most vertebrates walk on their toes. When you walk, your toes touch the ground and your ankles don't touch the ground. According to the footprint fossils, pterosaurs touched the ground with their feet when walking, which was similar to humans and bears and belonged to plantar animals. Footprint fossils of the pterodactyl family show that at least some pterodactyls walked with upright hind legs instead of extending to the sides of their hind legs.

Traditionally, pterosaurs were clumsy and inconvenient when moving on the ground. However, recent studies have found that at least some pterodactyls (especially pterodactyls) can walk and run smoothly. Compared with other pterodactyls, the forelimbs of Liang Long and pterodactyls are quite long. The arm and metacarpal bones of Chiropteridae are particularly slender, and the proportion of forelimbs is close to that of ungulates who are good at running. Their hind legs are not suitable for high-speed running, but their pace is bigger than other pterosaurs. Diptera insects may not be able to run, but they can walk quickly and effectively.

By comparing the proportions of pterodactyl's hands, feet and body with those of modern birds, scientists can infer the pterodactyl's lifestyle on the surface. Compared with the body shape and hind limbs of the family Polypodiaceae, their feet are quite small, and the length of their feet is 25% to 30% of that of the tibia. This shows that Diptera insects are suitable for walking on dry and hard ground. Pterosaur's claws were longer, 47% of the length of tibia. Filter-feeding pterodactyl (such as pachypteroidea) has very large feet. For example, the foot length of pterodactyl is 69% of tibia, while pterodactyl is 84% of tibia. The large foot/tibia ratio means that they are suitable for walking on soft and muddy ground, similar to modern birds.

hunt for food

Fossil evidence has been found in the past that dinosaurs of Spinosauridae ate pterodactyls. In the July, 2004 issue of Nature, paleontologist Eric Buffto suggested that the broken teeth of Spinosauridae dinosaurs were found on three cervical vertebrae of early Cretaceous pterosaur fossils. Because the joints of these vertebrae are still connected, this pterosaur has not been swallowed and digested.

Diverse

There is almost no direct or indirect evidence about the reproductive behavior of pterosaurs. A pterodactyl egg was found in a quarry in Liaoning Province, China, and many famous feathered dinosaurs were found at the same excavation site. The egg is squashed, but there is no sign of cracking, which means that the egg has a shell, just like today's lizards. The wing membrane of the embryo developed well, indicating that pterosaurs could fly soon after birth.

20 1 1 A fossil of Darwinian pterosaur was discovered. There is an egg fossil between the hind limbs, which is also a soft-skinned egg, like a modern reptile. Modern birds are hard lime eggs. Compared with the mother who laid eggs, this egg fossil is very small. In 2007, a study on the structure and composition of pterosaur eggshells pointed out that they might bury their eggs in the soil, similar to modern crocodiles and turtles. For early pterosaurs, burying eggs in the soil to hatch can reduce the weight of the mother, but it will limit the geographical environment in which pterosaurs live; After the emergence of birds, they will face the competitive living environment and disadvantages of birds. Another possibility is to put eggs under the body until they hatch, similar to some lizards, but most main dragons don't use this method.

At present, several newly hatched young individuals have been found, including pterodactylidae, beak-billed pterodactylidae, comb-jawed pterodactylidae and Dipodactylidae. The bones of these young individuals have been highly hardened and the proportion of wings is close to that of adult individuals. In the early research history of pterosaurs, young individuals and adult individuals were often classified as different species of the same genus. Adult individuals and very young individuals, such as pterodactyl, beak-billed pterodactyl and southern pterodactyl in Brazil, can be found in limestone in Sorenhofen, Germany and marine sediments in Brazil, which can prove that these individuals may fall and drown when jumping over the middle of the lagoon. This also shows that these young individuals have the ability to fly.

At present, it is uncertain whether pterosaurs have parental rearing behavior, but according to their flying ability in childhood and the fossils of adults and young individuals in marine sediments, it shows that young individuals are not completely dependent on their parents. Or only after a short period of parenting, when the wings have the ability to fly, young individuals will leave the nest to live. Another possibility is that they only survive the first few days after hatching by the nutrients initially absorbed from the egg yolk, and then start foraging alone without the support of their parents.

Different pterosaur populations have different growth patterns. The early primitive pterodactyl, taking pterodactyl as an example, had an average growth rate of 130% to 173% in the first year of incubation, which was slightly faster than that of modern alligators. When the beak-billed pterosaur reached sexual maturity, its growth rate would be very slow, and then it would take three years to reach its maximum size. Late and advanced pterodactyls, such as odontosaurus, grew into an adult in the first year of hatching. The growth mode of pterodactyl is limited growth, and it will not continue to grow when it reaches full size.

Effective time

20 1 1 year, scientists compared the scleral rings of several pterodactyls, modern birds and reptiles, and obtained their rest and activity time. Chiroptera, Jaw-digging Dragon, Leprechaun Chiroptera belong to diurnal animals, Combed Chiroptera, Southern Chiroptera and Beaked Chiroptera belong to Nocturnal Animals. Pterosaur is an irregular animal, and its foraging and moving behavior is not positively related to day and night, but only takes a short rest. According to the results of this study, the life style of comb-jawed pterodactyl and beak-billed pterodactyl may be similar to that of modern nocturnal seabirds, preying on fish at night; Pterosaur's lifestyle may be similar to that of some suborders. It feeds on small animals that filter water at night. At the same time, comb-jawed pterodactyl, beak-billed pterodactyl and dig-jawed pterodactyl were found in the limestone of Sorenhofen, Germany. They may occupy different niches and have different lifestyles and food sources.

Pterosauria

Latin scientific name: pterosaur

Field: animal kingdom

Phylum: Chordata phylum

Subphylum: Vertebrate subphylum

Class: Reptiles

Subclass: Diptera

Objective: Chiroptera

Definition:

Pterosaur, which means "winged lizard" in Greek, is an evolutionary branch of flying reptiles. Pterosaurs lived from the late Triassic to the late Cretaceous, about 2 10 million years ago to 65.5 million years ago. Pterosaurs were the first vertebrates to fly autonomously. Their wings are composed of skin, muscles and other soft tissues, extending from both sides of the body to the extremely long fourth finger. The jaws of early species were covered with tusks and had long tails; The tails of late species are greatly shortened, while some late species have no teeth. At present, traces of filamentous structures have been found in the bodies and wings of some specimens, indicating that pterosaurs may have evolved hair. Pterosaurs vary greatly in size, ranging from forest pterosaurs of birds to the largest flying animals that have ever appeared on earth, such as Fengshen pterosaurs and Hazgo pterosaurs.

In the mass media and popular books, pterosaurs are often considered dinosaurs, but this is wrong. Dinosaurs refer to some land reptiles, which can adopt upright gait, including sauropods and ornithopods, but excluding pterosaurs, ichthyosaurs, plesiosaurs and black dragon. These Mesozoic flying animals are commonly known as pterodactyl, which means "winged fingers" in Greek. The name comes from pterodactyl and pterodactyl.

Origin of species:

Rhamphorhynchus Meyer, which first appeared in Jurassic, can be taken as a representative. It is about 60cm long with double temporal holes, large orbits and anterior holes. The front of the skull and jaw is slender and has sharp teeth, which may prey on fish; The neck is longer, the rotation is flexible, and the back is shortened; The tail is very long, about twice as long as the recommended anterior spine, and there is an oval membrane at the end of the tail; The humerus of the forelimb is thick, the radius is quite long, the fourth finger is extremely long, forming the main frame of the wing, the fifth finger disappears, and the other fingers degenerate into small shapes; The scapula and beak bone are strong, connecting the sternum and serving as muscles for attaching wings; The hind limbs are small.