In the Mesozoic gliding

In Mesozoic gliding Chinese scholars found that the earliest known fossil mammals will fly

www.thebeijingnews.com · 2006-12-18 9: 18: 24 ·

Source: Beijing News

1.25 billion years ago, Earth, Ocean, dinosaur acts as a leader in the animal world, sky pterodactyl you share dinosaur hegemony.

This time, bird has just expanded its wings, at this time, a delicate mammals have begun to try flying fun.

14 December "nature" magazine cover story reported by a unique fossil mammals, it is the earliest known flying mammals, are all flying mammals and dinosaurs in the only contemporaries.

Scientists will this new species is named "ancient flying beasts".

Zhang Zong up to draw another Zhang Xiang animal recovery plan

Flying squirrels in shape, size and flying animal is very close, but they are unrelated

Flying animal fossils.

Picture of a skull and mandible, left is right hind limbs flying beasts, kidney-shaped shadows is a wing membrane

Flying animal skulls recovery plan.

It's teeth have incisor teeth, molar, canine teeth molar, respectively, there are three small tip pen rack.

Dialectical

It is not a pterodactyl

We all know, the dinosaurs are Mesozoic "Earth overlord".

After entering the Cenozoic mammals has replaced the hegemony of the dinosaurs. However, the ascent of man but mammals from 2.2 billion years ago, measured from the Triassic of late, the ascent of man's 2/3 of the time in the Mesozoic era. Mammalian origin and early evolution has always been a study of Paleontology.

Early this year, the Chinese Academy of Sciences and paleoanthropology researcher Wang Xiao-Lin in the areas inspected ningcheng County, Inner Mongolia, China, found a Mesozoic fossils.

According to the specimen shown in dental characteristics, Wang Xiao Lin preliminary judgment this is a mammal. Researchers may soon discoveredthat there are large areas of fossil wing membrane. A new idea have shaken Wang Xiao Lin initial judgement: this may be a pterodactyl.

In order to ascertain the truth of this fossil, researchers from two aspects at the same time, while those with pterodactyl phylogenetic aspects of feature, mutatis mutandis, with the characteristics of mammalian teeth.

Specimen showing the animal's body side having large wing membrane.

However it's teeth tooth column but according to the "front incisor teeth — England — — molar molars" arranging sequential disaggregated. Arguably, a dinosaur mouth no matter how long the teeth, tooth shape are the same, no Division of the teeth, and therefore cannot chew, paleontologists and put this as "with teeth". And mammals, with each Division of the "special-shaped teeth". However, wing feature film but pterodactyl, City area had previously found pterosaur fossils, not to mention the fact that Germany has unearthed an overly long "-shaped teeth" pterodactyl.

So what exactly is new fossil pterosaur or mammals? as fossil intensive restoration work, the researchers found the final answer: from the bone structure and soft tissue characteristics, this animal is not a pterosaur specimens, which belongs to mammals.

Obviously, this is a completely different with the pterodactyl, long winged film mammal!

"specimen kept relatively intact, just a crack in the middle. But we also give a sample of x-rays. "Ancient ancient vertebrates and the Chinese Academy of Sciences Institute of Wang Qing said that the classification of species without any problems. The Institute's mengjin, Hu Yaoming, Li Kui, Wang Xiao Lin and Wang Yuan ching and others of the group then completed the fossils of related research.

Habits

Glide to escape

Newly discovered species is named "ancient flying beasts".

Its body length 12 to 14 cm, weighs about 70 g, size and small flying squirrels. Xiang beast head back bone structure display, suitable for living in a tree, a tree-dwelling animals. It has both a specialized teeth structure and size of the moderate wing of the film. Wing membranes covered with hair, limbs and tail. Wang Qing explained that "wing membrane, is the connection between the Forelegs and hind skin membrane. Flying beasts of wing membrane is relatively large, lightweight body. With this coating, you can assume it has the ability to glide. ”

Researchers according to the flying beasts of the mandible and the forelegs than columns, some against modern mammals can glide for varieties, such as flying squirrels, wu wu and bag and found their proportion relatively close.

On the body size, almost animal, a difference of mandibular and body ratio. This ratio shows that the beast of aspectual character flying its distraction coating for gliding. Wang Qing explained that "If you can't, it's not going to generate so much buoyancy. This is distinct from the third beast James sharp-toothed mammal of a feature. ”

According to the physical characteristics of the beast James, researchers determine its habits and the world's few remaining will be gliding way flying mammal closer.

Flying animal heads smaller, their teeth and limbs and not conducive to capture larger prey. Plus tree-dwelling characteristics, it is likely not predators, most are prey on insects only — unlike most of the Mesozoic mammals. Xiang beast is most likely nocturnal, but it's not like bats, while flying side catch food.

It's gliding ability should be used in the escape.

In order to avoid small dinosaur attacks, it must be sharply glide from tree to tree.

It is this "go to" gliding on the meter, so that mammals in 1.25 million years ago to try a taste of the flight.

Prior to this, a piece from 5100 years of bat fossils provide for human flight history of mammals. Now, that time has been advancing the 7000 years.

Source

Flight

Ability to have their source

Flight can be divided

out gliding, flying, different types, Wang Xiao Lin pointed out that in the current health of mammals, including bats, many species have flight capability. So, these mammals and Mesozoic flying beasts are there between evolutionary up Cap?

Wang Qing pointed out that if from species system, flying beasts and survival of flying mammals are mammals, but "both be gliding or flying, the types of students can fly mammalian origin are not the same.

This point and birds are not the same. ”

Flight of birds is a single origin, whereas mammalian flight is different species, origin of, respectively.

For example, is born a rodent, there are two branches of the animals have the ability to glide: wu mice and squirrels. The two branches of animals glide capability is available separately. While in Australia, there is a kind of marsupials named bag wu. This kind of animal would glide. The most famous flying mammals, bats. All of these flying mammals, its flight capacity does not necessarily, species or between front and back up the contractor relationship.

Of course, the earliest known as currently flying mammals that live in the Mesozoic flying beasts, and they also have no relationship.

In Wang Yuan ching, this is the species depending on the context, the result of an adaptive evolution. He says that researchers see is already has the gliding ability of Xiang beast, but it's hard to imagine flying beasts in the presence of previously or thereafter.

Climbing trees is the premise of the flight.

At Jehol biota, scientists found some early mammalian tree-dwelling, such as the ancestor of the beast. Due to the existing environment, biological competition pressure 1.2 billion years ago here in a tree-dwelling early mammals try to jump from one tree to the next to another tree, this population slowly accustomed to the jump in the branches, and the escape of skills in the body edge long wing membrane to help increase glide distance yourself. This ability is also expanding its search for food.

However, in common with the pterodactyl and birds of the sky competition fierce struggle, the gliding ability Xiang animal and plant species are not strong or crushed, disappear in the long process of animal evolution.

Positioning

The new branch in mammals

Mesozoic mammals, have so far found fossil more limited.

Early Cretaceous mammals mainly when there are five: three sharp-toothed mammal (Triconodonts), on the tooth mammals (Symmetrodonta), number of teeth of mammals (Multituberculata), mammals and true mammals after. This five mammals in the early Cretaceous strata in the West have found.

Researchers in a detailed comparison of morphological characters, even inadvertently found that flying animal does not belong to a known mammalian taxa in any one, but a separate door, represents an unknown new branch of early mammals.

Teeth exposes all of the early mammals.

Wang Qing said the teeth is the scientific community to conduct the Mesozoic mammal species classified the main evidence. Flying animal teeth characteristics, and three sharp teeth mammals are somewhat similar. Three sharp teeth molar on mammals, there are three pen rack of small tip, it is called before and after arranging for three sharp-toothed mammal. Discovery of Western Liaoning rehe belongs to three blaspheme cuspid mammals. Flying animal teeth are arranged in a before and after, but with three sharp-toothed mammal compared to flying beasts of the relatively small number of teeth, there are three molar, lower molar 2, while the third molar tooth tip, mammals are more than four. Flying animal teeth molar of tilt, and three sharp-toothed mammal. In addition, the researchers also found flying beasts of the mandible is called "the back one corner of the sudden" structure, this construct in c sharp-toothed mammal is not in. "A comparative study in detail, we think flying beasts represent a class of its own, but until now, this class only discovered this beast James," Wang Yuan Ching interpretations.

At the same time, the researchers used a 435 characteristics on 58 different classification unit of animal for phylogenetic analysis that flying beasts in the Mesozoic mammal pedigree chart, in an intermediate position.

Xiang beast than China pointed teeth beast, beast, beaver tail Morgan beast and Shu beast, original mammals more progress, and three sharp-toothed mammal, true mammals and later mammals than flying beasts and the original number. Wang Qing pointed out that this judgment is based on the beast have some flying three sharp-toothed mammal mammals such as progress, such as the total characteristics of the mandibular bone fragments from single form, plantar bone and toes of seeds between success on the bone, these are not the original mammals are also distinguished from Xiang beast more primitive mammalian characteristics. However, more progress on some of the characteristics of the mammals, yet not altogether be flying beasts have, such as the humerus and ulnar joint between the pulleys, talus and calcaneal between superimposition, and a sharp sustentaculum, etc. These characteristics determine the flying beasts and mammals than three sharp-toothed mammal original such as progress.

■ Link

Mesozoic mammal

Mesozoic mammals include three sharp teeth tooth mammal mammals, and many of tooth mammals, mammals and true mammals after five

In a highly individual smaller Central giant fossil animal climbing, researchers found a has not yet been fully Digest of fossil psittacosaurids

Mesozoic era dinosaurs, but mammals have diversified development trend.

Flying animal discoveries further proof of the Mesozoic mammals in morphology, taxonomy and life habits differences well beyond people's understanding of the past.

In recent years, in the early Cretaceous of Western Liaoning China formation found a three-pointed teeth tooth mammal m

ammals, and many tumor after tooth mammals, and true mammal mammals HES mammals complete skeleton, more than for the study of early evolution of mammals and differentiation, and their phylogenetic relationships provide reliable fossil evidence.

In General, individual Mesozoic mammals are very small, such as the ancestor of Jehol beast, beast, beast, China bags are only a few decades.

They shunned by insects, in the shadow of dinosaurs, to compromise.

But early mammals, many big man, three sharp teeth mammals

Climb the beast. Maximum climb animal exceeding 1 m in length and weighs up to 14 kg. Researchers found through analysis of fossils, animals have stout sharp canine teeth and front incisor teeth, molar, developed temporal muscle and masseter muscle. All this shows that they are true carnivorous animals. More surprisingly, researchers in an individual less giant climbing even stomach animal fossils found a has not yet been fully Digest of psittacosaurids bones. This displays the giant climbs to hunt animals may be a living dinosaur. Researchers under joint connected-leg bone, giant climbing beast is prey tearing chunks if swallowed and without chewing. And it's teeth structure has been divided, but it's not clear that it does not have the masticatory function.

This suggests that mammalian chewing function is the beast than climb more progressive mammals evolved.

Mesozoic mammal apart from the physical size of the differences in the way of sports meet also have great variation.

Late in the Cretaceous, mammals has adapted to many different environments.

Of these, rehe beast, Zhang and beast, beast mainly to Gobi desert-dwelling, beaver tail beast you can in the water activities. In addition, in some populations of some generic but also behave differently than the population of motion adaptation. Although in the past in the early Cretaceous fossils found true mammals suggests that true mammals are ground run and type of animal, however, subsequent studies have found that belong to true mammals (placenta class and its near descent) and mammals (bag class and its origin). The oldest known ancestor of the veterinary and animal shows China bags are already adapting to climbing lifestyle, they can be in the ground, trees or bushes. These findings indicate that, during this period early really moving, habits of mammals, there are a lot of differentiation, in order to be able to occupy different ecological space. "This discovery of flying beasts let us see the Mesozoic mammals in occupies the development towards the sky, the sky this environment trends. " Wang Yuan Ching interpretations.

In food, mammals are also showing a diversified trends.

Because individual smaller, Mesozoic mammals common to eat insects.

However, climb the beast is a carnivorous animal. Mammal feeding habits change first dental morphology changes. Giant climbs of the beast is incisor teeth and sharp, mandibular and masseter developed, easy to capture prey. Number of teeth of the Mesozoic mammal is herbivorous mammals. Many variation ensures that they are in the same ecosystem can occupy different niche. This is also the fast development of mammalian gradually, and replace the reptile to become one of the causes of global domination.

This special appreciated: Wang Yuan-Ching (Chinese Academy of Sciences and paleoanthropology research fellow)

Wang Xiao-Lin (Chinese Academy of Sciences and paleoanthropology research fellow)

Special reports/reporter Li Jian-