Boundary: animals in the animal kingdom
Door: Chordata, Chordata.
Class: Reptiles, Reptiles
Objective: Sciatica.
Branch:? Tyrannosaurus rex
Genus:? dinosaur
Type species: Strong, afraid of dragons.
Torosron
Proportional reference between strong dragon and human beings
Although dinosaurs were very large for today's predators, they were not the largest Tyrannosaurus species. Adult dinosaurs can reach 8-9 meters in length and the average weight is estimated to be about 2.5 tons.
Afraid of the dragon has a huge skull, about 1 meter long. The structure of the skull is particularly strong, for example, the nasal bones on the nose and mouth heal each other to increase strength, while the big hole in the skull can reduce weight. The skull of Afraid of the Dragon Head is unique in that the surface of the maxilla is uneven, and the lacrimal bone, retroorbital bone and zygomatic bone around the eyes are obviously raised. The eye socket is rectangular, between the round shape of the gorgon and the keyhole shape of Tyrannosaurus Rex.
Adult dinosaurs had about 60 teeth, and each tooth was very long. The cross section of a tooth is oval, not short. The teeth in the front of the maxilla are D-shaped, which is very common in Tyrannosaurus rex.
Dinosaur skeleton model
Tyrannosaurus rex is similar to other Tyrannosaurus rex families, with a heavy head supported by an S-shaped neck. Its forelimbs are very short, with only two fingers, but in Tyrannosaurus rex, its forelimbs have the longest ratio to its body. Afraid of dragons with two huge hind legs and four toes, the first toe is an anti-claw, so it can't land. Dinosaurs have a long and heavy tail, which can balance the head and chest and make the center of gravity in the buttocks.
taxonomy system
Among Tyrannosaurus rex, Tyrannosaurus rex, Tyrannosaurus rex and Diptera belong to Tyrannosaurus subfamily. The species of Tyrannosaurus rex is closely related to Tyrannosaurus rex, but it is not similar to Albertosaurus. It is characterized by a strong body, a large proportion of skull and bones, and a long femur.
Tyrannosaurus rex is usually regarded as a close relative of Tyrannosaurus rex or a direct ancestor of Tyrannosaurus rex. Gregory S. Paul once classified Tyrannosaurus rex as Tyrannosaurus rex, but this classification is generally not accepted.
Many scholars believe that Tyrannosaurus Rex and Tyrannosaurus Rex are sister taxonomic units and even belong to the same genus. Tyrannosaurus Rex is the basic species of this evolutionary branch. Phil Currie and others put forward different theories. Cladocera and Tyrannosaurus rex, two Asian genera, formed an evolutionary branch, and Tyrannosaurus rex was closer to this evolutionary branch and farther away from Tyrannosaurus rex. Only by studying and describing all dinosaur species can we get a clear classification relationship of dinosaurs.
Discovery and naming
At present, there are two effective species: Toros and Hornari. These fossils were found in Alberta, Canada, while other fossils found in Alberta, Montana and New Mexico have not been formally studied and named. If these unnamed species are included, Tyrannosaurus rex is the most diverse genus among Tyrannosaurus rex.
The type specimen (number CMN 8506) of dinosaurs is some bones, including skull, cervical vertebra, spine, sacrum, anterior1/coccyx, shoulders, forelimbs, pelvis and femur. These fossils were discovered by Charles Robert Jeffrey Sternberg in 192 1 year. At first, he thought that these fossils belonged to a new kind of snake-haired female monster. However, it was not until 1970 that these specimens were completely described by Dale Russell and a new genus was established. The scientific names of dinosaurs are "δασπλητO-" (meaning "fear") and "σ α υ ο?" (meaning "lizard"). The name torosus means "strong" or "strong" in Latin.
D. horneri's head recovery map.
Unnamed species
Over the years, two or three more species have been classified as Dactylogyrus, but so far, they have not been officially described or named. Although they may not be the same species, they are temporarily listed as "D.SP", but this does not mean that they belong to the same species.
Species in dinosaur park
When establishing the normal model specimen of Qiang Jian Afraid of Dragons, Russell established the specimen excavated by Barnum Brown in 19 13 as the auxiliary model specimen of Qiang Jian Afraid of Dragons (No.AMNH 5438).
It was once thought to belong to the skull of the gorgon (not AMNH 5434), but was later discovered by the Field Museum of Chicago (No.FMNH PR308) and it belonged to the Fear Dragon at 1999.
This specimen contains a pelvis, a part of hind limbs, and some connected vertebrae, and was found in the upper stratum of Aldman formation in Alberta. This upper layer was later renamed the dinosaur park stratum, belonging to the Late Cambrian, 76-74 million years ago. 19 14, Brown discovered a nearly complete skeleton and skull (No.FMNH PR308) from the same stratum, and was awarded the Field Museum of Natural History in Chicago by the American Museum of Natural History 40 years later.
Bone reconstruction model of FMNH PR308, located at the Field Museum of Natural History in Chicago.
This skull is currently on display at the Field Museum in Chicago and has been classified as "Albertosaurus libratus" for many years. However, before the specimen was reset to Dactylogyrus, it was found that several skull features (including most teeth) were hidden by plaster for many years. Eight specimens were found in dinosaur park 1 * * group, most of which were within the scope of dinosaur provincial park. Philip Cole found some different features on the skulls of dinosaur park specimens, and thought it represented a new dinosaur species. The picture of this new species has been published, but it needs to be formally named and described.
New Mexico species
At 1990, a new specimen of Tyrannosaurus rex (No.Omnh101) was found in the Huntworth section of the Gardeland Formation in New Mexico, including skull fragments, ribs and some hind limbs, and incorporated into the post-curved odontosaurus. The status of the Brachionus retroflexus is a question. Later, many scholars reclassified this specimen, together with some other fossils found in New Mexico, as an unnamed species of African dragon.
Discovery of dragon abuse fossils in New Mexico
A study on 20 10 suggested that this new Mexican species was actually an early Tyrannosaurus rex, which was established as a new genus, Tyrannosaurus rex. At present, the age of the Jiadelan Formation is controversial. Some studies point out that it belongs to the Late Cambrian, while others think it belongs to the early Mester-Richter period.
Double Madison species
1992, Jack Horner and his colleagues published a very preliminary report on the newly discovered Tyrannosaurus dinosaur in the upper layer of the double Madison stratum in Montana, USA. They believe that these new fossils are transitional species from dinosaurs to late Tyrannosaurus rex, and their age is Campania.
In 200 1 year, another partial skeleton was found in the upper layer of the double Madison group, and a young individual fossil of platypus family was preserved in its lower abdomen. This specimen is classified as a dinosaur, but it is not clear which species it is. At least three dinosaur-fearing fossils were found in the double Madison bone bed. None of these specimens have been described in detail, but Cole believes that all the double Madison fossils are the third unnamed species in the genus Dactylogyrus.
Although dinosaur fossils are not as common as other Tyrannosaurus rex, they are enough for paleontologists to study some aspects of their biology. Bifurcation of carina was previously found on a tooth of dinosaur.
A young dinosaur specimen (TMP 94. 143. 1) found in the stratum of dinosaur park has traces of being bitten by other Tyrannosaurus rex. The bite mark has healed, indicating that it survived the incident. An adult dinosaur specimen (TMP 85.62. 1) found in the same stratum also has similar bite marks, indicating that this attack is not limited to young animals. Although these attacks may come from other species, predators often fight and attack within species. At present, this kind of facial attack trace has been found in other Tyrannosaurus rex (such as gorgon and Tyrannosaurus rex) and other theropods (such as Tyrannosaurus China and sauropteryx). Darren Tan Ke and Philip Cole put forward a hypothesis, pointing out that these attacks are intra-species competition, for turf, food resources or dominant groups.
Sauropods
The evidence of dinosaur life is fossils found on the bone bed of the double Madison stratum in Montana. There are three dinosaur remains on the bone bed, including a big adult dinosaur, a small baby dragon and another medium-sized dinosaur. At least five hadrosaurs were found in the same place. Geological evidence shows that these remains were not alluvial together by rivers, but were collectively buried in a short time. The remains of hadrosauridae are scattered, and there are many bite marks of Tyrannosaurus rex teeth. It can be seen that dinosaurs ate these hadrosaurs before they died. The cause of death of these animals is still unknown. Philip Cole guessed that the frightened dragons hunted in groups, but he was not sure. Other scientists are skeptical about the evidence of group activities of dinosaurs and other large theropods. Brian Roach and Daniel Brinchmann think that the group lifestyle of dinosaurs is very similar to that of Komodo dragons today. When Komodo dragons compete for food for corpses, they sometimes eat the same kind.
Snake-haired monster dragon
In late Campania North America, the fear of dragons and the gorgon lived in the same area. These are a few examples of the existence of two Tyrannosaurus species. Among today's predators, predators with similar bodies will be divided into different niches for anatomical, behavioral or geographical reasons to limit competition. Some studies try to explain the niche difference between the dragon-fearing and the gorgon.
Duck-billed dinosaur
Dale Russell speculated that the lighter and ordinary gorgon might hunt the prosperous hadrosaurs at that time, while the stronger and rarer dinosaurs specialized in hunting the smaller and better-defended Ceratosaurus. However, the specimen OTM 200 found in the double Madison group preserved the digested duckbill larva fossils in its stomach. Tyrannosainae (such as dinosaurs) has a higher and wider snout and is stronger than Albertosaurinae (such as gorgon) with a lower snout, but the strength of teeth is similar. This shows that they are different in feeding skills or habits. On a skeleton layer, three dinosaurs and at least five hadrosaurs were found.
Other scholars believe that their competition is limited by geographical differences. Unlike other dinosaurs, their distinction seems to have nothing to do with the distance from the coast or the altitude. However, although the living areas partially overlap, the gorgon seems to be more common in the north, while the fear dragon tends to the south. Other dinosaurs had similar geographical distribution. In Campa stage, Duckbill subfamily and Open Angle subfamily flourished in the Double Madison Formation and southwest North America. Thomas Holtz pointed out that this geographical distribution pattern shows that Tyrannosasubfamily, Ceratosaursubfamily and Duckbilled subfamily all have the same niche tendency. He thinks that at the end of Li Xite's master stage, Tyrannosasubfamily (such as Tyrannosaurus Rex), Duckbilled subfamily and Ceratosaursubfamily (such as Triceratops) were widely distributed in western North America, while Albertosaursubfamily and Ceratosaursubfamily were extinct, while Lacey subfamily was rare.
Paleontologist Gregory Millard J. Erickson and his colleagues studied the growth and longevity of Tyrannosaurus Rex. Through bone histological analysis, the age of the dead specimen can be determined. The growth curve can be obtained by drawing the age and body shape of different individuals into charts. Millard J. Erickson pointed out that Tyrannosaurus Rex had been in its infancy for a long time and would grow rapidly in four years. This rapid growth stage will end at sexual maturity and the growth rate will slow down in adulthood. Millard J. Erickson only studied the dinosaur-fearing specimens found in the Double Madison group, but they all had the same growth pattern. Compared with Alberta dragon, it grows faster in the fast-growing period because of its higher weight. The maximum growth rate of fear dragon is180kg per year (assuming the adult weight of fear dragon is1800kg). Some scholars pointed out that dinosaurs should be heavier, but this will only affect the growth rate of dinosaurs, not the overall model.
Millard J. Erickson and others tabulated the specimens of each age group, and sorted out the growth pattern of Alberta dragon. Millard J. Erickson pointed out that the fossil record of young Albertosaurus is very rare, and it is more common for adults who are close to adulthood and fast-growing period. This may be due to the deviation between petrochemical process and fossil excavation. Millard J. Erickson hypothesized that these differences were due to the low mortality rate of young dragons of a certain size, just like some large mammals (such as elephants) today. Because Tyrannosaurus rex surpassed all predators at the same time at the age of two, the mortality rate was very low without prey. Paleontologists don't have enough dinosaur fossils to make a similar analysis, but Millard J. Erickson thinks dinosaurs have a similar growth trend.
At present, dinosaur-fearing fossils are all found in the upper Cretaceous Middle Cambrian to Late Cambrian strata, about 77-74 million years ago. In the middle Cretaceous, western North America was divided into two parts by inland sea, and most of Montana and Alberta were below sea level. During the period when dinosaurs lived, the Silalami orogeny led to the uplift of the Rocky Mountains and the sea lanes retreated eastward and southward. The river flows from the mountain area in the west to the sea channel in the east, and the sediments in it form a vast coastal plain, which becomes the stratum of the double Madison formation of Judith River Group. About 73 million years ago, the sea lanes invaded the west and north again, gradually flooding the dinosaur parks. This new sea area is called the Bearpaw Sea, which forms a marine Bearpaw shale formation, covering the western United States and western Canada.
Dinosaurs lived on the vast flood plain on the west coast of the inland sea in the west. Rivers flow through this land, sometimes flooding and forming new sediments. When the water source is sufficient, a large number of plants and animals can survive, but periodic drought will occur in this area, resulting in a large number of biological deaths, and many bone beds will be formed in Judith River Group and Double Madison Group. There is a similar environment in East Africa today. Periodic volcanic eruptions in the western plain will affect the whole area, resulting in a large number of deaths, but also enrich the soil and contribute to the future plant growth. Scientists also use these volcanic ash to obtain accurate radioactive dating.
The change of sea level has caused many environmental changes in different areas of Judith River Group in different periods, including offshore and inshore marine ecology, coastal wetlands, deltas and lagoons, inland flood plains and so on. Compared with other strata in Judith River Group, Shuangmadison Formation is located in inland high altitude area.
There are good records of vertebrate fossils in Shuangmadison Formation and Judith River Formation, which are caused by abundant fauna, periodic natural disasters and a large number of sedimentary rocks. There are all kinds of freshwater and estuarine fish fossils in these areas, including sharks, rays, sturgeons, finches and other fish. The Judith River Formation also preserves many fossils of aquatic reptiles and amphibians, including frogs, giant salamanders, turtles, E Long and crocodiles. Land reptiles, including Brachionidae, Lycopodidae, Nostoc and Serpentidae.
The flying animals in the sky include: Ceratoptera and Neoptera (such as vertebrates), while the suborder Antiptera lives on the ground. Mammals include: toothed animals, marsupials and real mammals. Besides the above species, there are dinosaurs and other dinosaurs.
In the stratum of Alderman, the strong fear dragon may prey on the hadrosauridae (such as short-crested dragon and sub-crested dragon), small bird-footed dragon (such as mountain dragon), ceratosaurus (such as sharp-horned dragon), thick sauropod, bird-footed dragon, Kamasauropod, and possibly Ankylosaurus. Other carnivorous dinosaurs include: odontidae, egg-stealing dragon, sauropods, and maybe Albertosaurus.
Comparison between Tyrannosaurus Rex and Dinosaur Disease
Dinosaur Park and Double Madison Group are composed of animals similar to Alderman Group, while Dinosaur Park has many kinds of large carnivorous dinosaurs, which do not compete for food sources. The gorgon and dinosaurs live in the upper layers of the dinosaur park and the double Madison group at the same time. The niche of juvenile Tyrannosaurus rex is between adult Tyrannosaurus rex and small theropod, and the weight difference is several times. A dinosaur park team found the tooth bone of a sauropod with teeth marks of juvenile Tyrannosaurus Rex on its surface, which may be left by local fear of dragons.