Wounded Teeth Dragon

Dinosaurs of the Late Cretaceous

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Traodontosaurus survives late Cretaceous About 75 million years ago to 65 million years ago, it was originally named for its sharp teeth. At first, people thought it was a lizard, and then regarded it as a dull looking dinosaur. Later, after combining its bones, they found that previous knowledge and understanding were almost all wrong. In terms of the proportion of body and brain, Traodontosaurus had the largest brain among dinosaurs, and its sensory organs were very developed, so it was considered to be the most intelligent dinosaur.

Wounded Teeth Dragon was created by Joseph Leidy (Joseph Leidy) was named in 1856. The original spelling is Troödon 。 In 1876, H E. Sauvage officially revised the spelling.

Chinese scientific name: Wounded Teeth Dragon
Latin name: troodon
circles: Animal kingdom
door: Chordate
Outline: Sauropsida

order: Saurischia
Suborder: Theropoda
section: Sargassosauridae
genus: Traodontosaurus
Distribution area: North America

catalog

eleven Evolving adults
twelve times
thirteen Sargassosauridae

Basic information

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Dinosaur name: Traodontosaurus

Wounded Teeth Dragon hatching eggs.

Other names: Rodent dragon, old name Stenonychosaurus (Stenonychosaurus) saw tooth dragon

Latin First Name: troodon

Pronunciation: TRO-uh-don

Name meaning: the most lethal tooth

Restoration diagram

Dinosaur body length: 2m long

The wounded tooth dragon is a relative of birds.

Dinosaur weight: 50 kg

Dinosaur food: carnivorous

Living years: Cretaceous advanced

Living place: Canada, the United States, China

Dinosaur species: Saurischia ， Xu Gu Long Bird like?

Classification dispute: Traodontosaurus is a small theropods 。 It once caused great confusion and thought it was Ornithiales The only carnivorous dinosaur, but now it is known that it is actually a sauropod dinosaur. Recently, scientists found that Stenonychosaurus Our dinosaur should be called Traodontosaurus. Paleontologists believe that Traodontosaurus belonged to Dendroctosaurus 。

Mode: T. Formosus is famous for the wounded tooth dragon^[1]

Restoration drawing of damaged tooth dragon

name

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Wounded Teeth Dragon was created by Joseph Leidy (Joseph Leidy) was named in 1856. The original spelling is Troödon 。 In 1876, H E. Sauvage officially revised the spelling.

The first fossil tooth of Traodontosaurus, painted by Joseph Leddy

The teeth of Traodontosaurus were initially classified by Ledi into the suborder Lizards. But in 1901, Franz Nopcsa reclassified Traodontosaurus to Bambusaceae; Bambusoideae has been the concentration place of most carnivorous dinosaurs for a long time in history. In 1924, Gilmore proposed that these teeth should belong to the raptor of herbivorous pachycephalosaurus, and raptor was actually a secondary synonym of the wounded tooth dragon; Sargassosauridae The similarity between teeth and those of herbivorous dinosaurs has led many paleontologists to believe that these animals are Omnivorous animal 。 In 1945, Charles Mortram Sternberg (Charles Mortram Sternberg) rejected the possibility that Traodontosaurus belonged to Pachycephalosaurus, because these teeth had many similarities with the teeth of carnivorous dinosaurs.

The first specimen of Traodontosaurus was not a tooth, but a Leptognathosaurus fossil named by Sternberg in 1932. The Leptognathosaurus fossil was found in Alberta, consisting of a foot, a hand fragment, and some tail vertebrae. The obvious feature of these fossils is the enlarged toe claw on the second toe, which is considered to be the feature of Hypodactylus. Sternberg initially classified Micrognathosaurus in the family Phantosauridae. In 1951, Sternberg hypothesized that because Micrognathus had very special feet and Traodontosaurus had a unique tooth, they might be close relatives. Unfortunately, there were not enough specimens for comparison at that time to test this hypothesis.

Reconstruction model of Traodontosaurus, London Natural History Museum

In 1969, Dale Russell (Dale Russell) narrated a more complete skeleton of fine claw keel; The scientific theoretical basis for the evolution of Micrognathus into a fictional creature similar to humans, "Dinosaur like Man", comes from this research. Micrognathus became a famous theropod dinosaur in the 1980s, and their brain and feet are described in more detail. In 1987, Phil Currie reexamined the known Sargassosauridae Fossils, he reclassified Leptognathosaurus as a synonym for the beautiful wounded tooth dragon. This change has been widely accepted by other paleontologists. Therefore, in recent scientific literature, all specimens previously known as Leptognathos are now called Traodontosaurus.^[2]

features

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Traodontosaurus is a small dinosaur with a length of about 2 meters, a height of 1 meter and a weight of 60 kilograms. Traodontosaurus had very slender limbs, indicating that they could run quickly. Traodontosaurus had long arms that could be folded back like birds, while its hands had thumbs that could make relative movements. They have large retractable sickle shaped claws on their second toe, which may rise when running.

Because of these characteristics, scientists believe that Traodontosaurus belonged to Maniraptor 。 Traodontosaurus has large eyes, indicating that it may have nocturnal activities and may feed on nocturnal mammals; And the eye direction is slightly forward, so that the wounded tooth dragon has Depth perception 。 In fact, the eyes of Traodontosaurus were more forward than most other dinosaurs, which showed that Traodontosaurus had better depth perception than other dinosaurs. They are light Cranium The brain sacs of some dinosaurs are similar to those of ostriches. Compared with the body, the head of Traodontosaurus was one of the largest dinosaurs. Therefore, Traodontosaurus is considered to be one of the most intelligent dinosaurs. The dinosaur eggs of Traodontosaurus were once found in the egg nest.^[3]

distribution

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The fossil of Traodontosaurus was found in Montana Of Judith River Formation And Haierhe Formation and Two Medicine Formation 、 Alberta Of Horseshoe Canyon Formation , and Alaska North Slope area. There is also some evidence that Traodontosaurus often lives in cold regions. It seems that it is particularly prosperous in northern regions and in cold periods, such as early Maastrichtian 。^[4]

These fossils came from places thousands of kilometers away, and appeared millions of years after the separation of continents. It seems impossible to represent the same species of Traodontosaurus. However, further research and more fossils are needed to understand how many species of Traodontosaurus exist.

nest

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Skeleton diagram

Between 1978 and 1984, John Horner John Horner and his colleague Bob Makela excavated in the Montana Mountains and found three dinosaur nest remains, including a nest of neatly arranged Troodon eggs. Traodontosaurus laid its eggs in the wet soil at the bottom of a newly dried up lake or marsh, and it could easily insert them into the soil by the downward creeping force of the fallopian tube. While those living in China Cretaceous Traodontosaurus chose the sandy land near the water as the spawning place. They first dug a hole on the ground with their claws, then squatted down to make their bodies upright or semi upright, and laid their eggs into the soft sand in the egg pit. Then carefully bury the eggs with sand. They also hatch eggs.^[5]

wisdom

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Traodontosaurus, one of the most intelligent and strong dinosaurs, is a carnivore that can slow down the evolution of mammals for millions of years! Compared with the size of brain, it has the largest brain in dinosaurs. This may indicate that they are the smartest group in the late Cretaceous. Some scientists even think that it may be similar to the IQ of ostrich, which will be smarter than any living reptile. Kangaroo's IQ is about 0.7. The IQ of the wounded tooth dragon is as high as 5.3! Boy, it's really high intelligence. Traodontosaurus may be similar to the intelligence of birds today. Today's birds are extremely smart: the smartest birds can train to make jokes and even imitate human language. Canadian paleozoologist Dale Russell It is assumed that if there had been no catastrophe 65 million years ago, the close relative of Velociraptor, Bendrosaurus, would have evolved into an animal instead of humans - "Dinosaur Man", and become the master of the earth. This was once popular“ Anthropophobic theory ”。^[6]

relationship

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Sargassosauridae Dinosaurs play an important role in finding the origin of birds, because they have many common physiological characteristics in early birds. The complete specimen of WDCDML001 recently found in the Morison Formation of the Late Jurassic belongs to the Traodontidae family and is close to the age of Archaeopteryx. This important Jurassic Traodontosaurus fossil confirms that the appearance time of the more evolved claptophobic dinosaurs is very close to the appearance time of birds, and the more basic near birds should have evolved in an earlier period. This discovery invalidates the time contradiction in the evolution of dinosaurs and birds, but a few people still hold this time contradiction in evolution.

classification

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The ratio of wounded tooth dragon to human

The fossil of the wounded tooth dinosaur is the first group of dinosaurs described Fossil one of. Initially, in about 1856 Siv Leddy (Joseph Leidy) classified these animals into the suborder Lizards; But in 1924, Charles Whitney Gilmore (Charles W. Gilmore) classified them into the order ornithiales of dinosaurs. Until 1945, Charles MortramSternberg identified and classified the Traodontidae into the suborder Zodiacea. Since 1969, Traodontidae and Chirosauridae belong to Hyponychus Evolutionary branch. However, in 1994, Thomas R. HoltzJr established Bullatosauria, which includes the lower order of ornithosaurus and Traodontosauridae, based on the characteristics of enlarged brain, long and low maxillary foramen, etc. The pelvis of Traodontidae also shows that they are more primitive than Chirosauridae. The newly discovered fossils of the original Traodontidae family in China, such as Leptosaurus sinicus and Meilong, show similarities between the Traodontidae family, Chirosauridae, and the primitive bird Archaeopteryx; However, most paleontologists, including Holt, believe that Traodontidae is close to birds, but it is similar to Ornitholestes The classification of Bullatosauria was abandoned due to the long distance. Intensive work by TheropodWorkingGroup members Theropoda Research shows that there are very similar places among the basic Chirosaurus, Traodontosaurus, and Archaeopteryx. These classifications form a near bird evolutionary branch, which was proposed by Novas and Pol. The evolutionary tree proposed by Hwang et al. shows that Archaeopteryx represents a primitive bird branch The Chirosauridae and Dentosauridae are more advanced. This theory raised the possibility of Dendroctosaurus evolving aerodynamic behavior.

Wounded Teeth Dragon

Paleontology

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Restoration diagram

Traodontosaurus was originally considered a predator, mainly feeding on smaller animals, such as invertebrate Or mammals. This argument is based on the wounded tooth dragon Maniraptor Features (such as sickle shaped toe claws on the feet, bird like grasping arms), and good depth perception. However, there is some evidence that Traodontosaurus may be omnivorous or herbivorous. There are broad, U-shaped joint lines in the jaw, similar to the iguana; The iguana is a kind of lizard that has adapted to herbivore. In addition, the teeth of Traodontosaurus were leaf shaped, some with large serrated edges, like herbivorous dinosaurs, and the teeth were short and wide, with wearing surfaces on the side. In 1998, Thomas R. Holtz believed that Traodontosaurus had the same characteristics as omnivorous/herbivorous primates and omnivorous raccoons with its grasping arms, large brain and depth perception.

A 2008 study analyzed the tooth fossils of Traodontosaurus from all over North America and found that the teeth in the northern slope of Alaska were larger than those in the southern area. This shows that Traodontosaurus in Beipo area generally grows to a larger size. The researchers speculate that this is because no Tyrannosaurus rex lives in the northern slope area, so the wounded tooth dragon in this area faces fewer competitors and can grow to a larger size. The study also analyzed the wear pattern of teeth, and believed that Traodontosaurus fed on soft food and could not bite the bones or invertebrate And hard plants. The researchers speculated that Traodontosaurus mainly ate meat.

According to the age identification of fossils, the average age of Traodontosaurus when it died was 3 to 5 years old.

Reproduction

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The egg nest of a wounded tooth dragon is on display in the Rocky Mountain Museum

In 2002, Varriccho et al. described the egg nests of eight wounded tooth dragons found in the Double Madison Group in Montana. These egg nests are in the Rocky Mountain Museum. The first egg nest was discovered by Jack Horner in 1983. Horner found relevant bones the next year, and found part of the bones of the pterodontoid Penzanosaur near the egg nest. Horner therefore described these eggs as the eggs of Penzanosaur. In 1996, Horner and David B. Weishampel re examined the embryos in the eggs, assuming that the eggs belonged to Traodontosaurus, not Penshanosaurus.

In 1997, Varricchio et al. described part of the skeleton of another adult Traodontosaurus, which may be hatching eggs with at least five eggs in its womb. Varricchio et al. also described one of the egg nests mentioned above. The egg nest is saucer shaped, with the inner diameter of about 100 cm. The wall of the nest surrounds the egg on the inner side. Other more complete egg nests have 16 to 24 eggs. These eggs are elongated teardrop shaped, with a sharp lower end, the lower half inserted into the sedimentary layer, and the upper half inclined towards the center. There is no evidence of plant material in the egg nest.

From these egg nests, Varricchio et al. proposed several characteristics of the reproduction ability of Traodontosaurus. The reproduction mode of Traodontosaurus seems to be between crocodiles and birds, like Phylogeny The default result of. These are arranged in pairs, indicating that Traodontosaurus may have two birth canals, similar to crocodiles, rather than only one bird. Crocodiles produce more eggs, which are smaller than the adult body; Birds have fewer eggs than their bodies. The volume ratio of Traodontosaurus ranked in the middle, with an egg weighing about 0.5kg and an adult weighing 50kg. This proportion is 10 times that of reptiles of the same size, but the weight of two eggs is about 1.1 kg, which is close to that of birds of the same size. Varricchio et al. also found evidence of multiple egg laying. An adult Traodontosaurus may lay two eggs every day or two. One of the egg nests has 22 eggs, while the embryo development in the other egg nest is close, indicating that the hatching mode of these embryos is close. According to the development pattern of these embryos, Traodontosaurus may be able to move soon after hatching, or even just after hatching. The researchers estimated that it would take about 45 to 65 days for an adult to lay eggs, hatch eggs, and be born. Researchers found no evidence of juvenile Traodontosaurus activity in the egg nest, suggesting that they may leave the egg nest just after hatching, just like crocodiles and megapods.

In 2008, Varricchio et al. examined the bone tissue of sample MOR 748 and found that the bone of the sample lacked signs of absorption of bone marrow bone, indicating that the individual was in the process of spawning. This group of scientists also measured the total volume of eggs in the egg nest of Traumatic Teeth Dragon, and the volume ratio of adult Traumatic Teeth Dragon; When comparing the measured proportion with modern birds and crocodiles, it was found that the value of Traodontosaurus was similar to that of male birds that could hatch eggs. According to this result, they speculated that the female Traodontosaurus had no habit of hatching eggs, but the male Traodontosaurus hatched eggs; In addition, they also speculated that Maniraptor It has the same habits as primitive birds.

Evolving adults

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Wounded Teeth Dragon

Dinosaurs may evolve into "Dinosaur people have long believed that dinosaurs are clumsy, cold-blooded animals waiting for extinction. However, with more scientific discoveries emerging recently, for example, archaeologists have found them in both the polar regions of the earth dinosaur fossil Thus forcing scientists to completely change their previous "prejudice" against dinosaurs. U.S.A Minnesota Paleontologist of Science Museum Christie Curry Rogers He said that some dinosaurs had enough ability to adapt to the climate upheaval during the evolution of the earth, which meant that if dinosaurs had not suffered the catastrophe 65 million years ago, they would continue to survive, even through the ice age. Canada University Of Alberta Phil Curry, a paleontologist, said that if the asteroid 65 million years ago had not hit the Earth, he believed that dinosaurs would still be the masters of the Earth. Scientists believe that if human beings can live in the same era as dinosaurs, and humans have no cattle and sheep to graze, they may be able to breed some dinosaurs. But 1.2 meters long and 2.5 kilograms in weight are docile Odysodontosaurus Can become the perfect pet for human beings. Scientists believe that in the era when dinosaurs were on the verge of extinction, the most advanced and intelligent dinosaurs were probably Traodontosaurus. According to Larry Whitmer, a paleontologist at Ohio State University in the United States, Traodontosaurus was "as cunning as a fox". They were very small, walked upright and liked to live in groups. By studying their brain capacity, Whitmer found that they not only have good eyesight, but also have the potential to solve problems. Some scientists believe that Traodontosaurus probably primates Or the development direction of human evolution, "finally evolved intelligent dinosaur man".

times

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Wounded Teeth Dragon

Cretaceous (Cretaceous Period, Cretaceous) The last period of the Mesozoic Era. The Cretaceous period is the last period of the Mesozoic era, which began 137 million years ago and ended 65 million years ago, and has experienced 70 million years. Both inorganic and organic communities experienced important changes in the Cretaceous. be located jurassic period Above Cenozoic Below. The Cretaceous is the period when the surface of the earth was most flooded in the Mesozoic era, during which the chalk layer was widely deposited in the northern hemisphere. In 1822, the Belgian scholar J B. J. Omalidaruwa named it Cretaceous system 。 Cretaceous layer It is a very fine and pure powdery limestone, which is a biogenic marine deposit, mainly composed of a kind of calcareous nannoplankton And planktonic foraminifera fossils. During this period, the continents were separated by oceans, and the earth became warm and dry. Flowering plants appeared. At the same time, many new dinosaur species began to appear, including Carnotaurus Such large carnivorous dinosaurs, like Styracosaurus Members of this class of Ankylosaurus and people like lambeosaurus Such herbivores Duckbill 。 Dinosaurs still dominate the land, like airplanes Pterosaur Class, such as Winged Snake Pterosaur Gliding in the sky, huge marine reptiles For example, the sea king dragon rules the shallow sea. But the earliest snakes, moths, bees and many new small mammals also appeared in this period. During the Cretaceous period, the rift between South America and the African continent rapidly opened to form the South Atlantic Ocean, which was widened to about 3000 kilometers by the end of the period. The North Atlantic Rift Valley is located in Greenland And the east side of North America, along with North America Drifting westward, the rift valley is expanding. Tethys Sea Separating Eurasia from Africa, many countries in Central and Southern Europe and the Middle and Near East were in the process of transgression. In Cretaceous, the climate was relatively warm, and there was no evidence of polar ice cover. At that time, most areas had abundant rainfall and humid climate, and offshore and coastal areas formed rich oil, coal, natural gas and oil shale deposits, such as the United States Texas , Mexico Persian Gulf , North Africa and Russia, as well as the Upper Cretaceous in the Songliao Plain of China Daqing Oilfield , many large coalfields of the Lower Cretaceous in Northeast China and Inner Mongolia. In some areas with arid and hot climate, such as the Southwest Lake Group and Yun-mengLakes Water system, with huge thickness of gypsum salt deposit deposits. In addition, in the Cretaceous red beds in Yunnan Copper placer With high grade, large scale and easy mining and smelting, it is a famous copper town in China.

Sargassosauridae

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Wounded Teeth Dragon

Sargassosauridae Dinosaurs are small to medium-sized theropods Dinosaurs, weighing less than 100kg; Compared with other theropod dinosaurs, they have longer hind limbs; Their second toe has a retractable large, curved toe claw, similar to the sickle shaped toe claw of the Chirosauridae. However, the toes and claws of Traodontidae are not as large and curved as those of Chirosauridae; In some cases, these claws will not shrink to the same extent and will not be able to walk away from the ground. Traodontosaurus is unique because of its large brain, which can be compared with modern flightless birds. Their eyes are quite large, moving forward, which shows that they have good stereo vision. The ears of Traodontosaurus are quite unique among theropods. They have an unusually large middle ear space, which shows that they have accurate hearing. Middle ear spatial proximity Tympanic membrane To help detect low frequency sounds. The position of the ears of the wounded tooth dinosaur is not symmetrical, and the ears on both sides of the skull are at different heights. There are only some characteristics owl Only then. The extreme specialization of the ears shows that the Traodontosaurus hunted in a cat owl like manner, using hearing to determine the location of small prey. Although most paleontologists believe that Traodontosaurus dinosaurs are carnivorous predators, the small, rough edged teeth and U-shaped jaws of some species (especially Traodontosaurus) indicate that some species may be carnivorous or herbivorous animals. On the contrary, as few as species such as Byronosaurus It has a large number of needle shaped teeth and is suitable for hunting small animals, such as birds, lizards, and small mammals.

A few fossils of the Traodontosauridae dinosaur, including the specimens of Mytilosaurus and Sinopodosaurus, confirmed that these animals lived in a bird like manner, burying their heads under their forelimbs. These are more like birds Feathered dinosaurs 's skeleton supports Sargassosauridae Dinosaurs were covered with similar birds Feather The theory of. Primitive macaronid dinosaurs completely covered with feathers Jinfengopteryx This theory is further supported by the findings of.

Many egg nests of Traodontosaurus dinosaurs have been found, including embryo Dinosaur eggs. There have been some theories about the reproductive ability of Sargassosauridae. In 1994, Mark Norell and others described part of the skulls of two wounded tooth dinosaurs (IGM100/972 and IGM100/974), both of which were found in Mongolia Degas The Dorcta group is located in an egg nest, where there is one dinosaur egg There are eggs of the egg stealer family in it, so it is determined that it is the egg nest of the egg stealer family. These two skulls were originally described as chirons by Jobel et al Fossil , and then reclassified to Sargassosauridae 。 These two dinosaur skulls of Traodontosaurus were newborn larvae or embryos, with egg shell fragments attached, but they seemed to be egg shells of Lyosaurus. It is puzzling why there are two young wounded tooth dragons in the egg nest of the egg stealing dragon family. The explanations are: they are the prey of the adult egg stealer, they feed on egg stealer larvae, or the wounded tooth dragon has nest parasitism.

Wounded Teeth Dragon

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