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Genus of reptiles (fossil). Tyrannosaurus (lat. Tyrannosaurus) is a genus of tyrannosaurids of the late Cretaceous period that lived in North America. It is the most famous dinosaur thanks to numerous works.

Tyrannosaurus (lat. Tyrannosaurus) is a genus of tyrannosaurids of the late Cretaceous period that lived in North America. It is the most famous dinosaur thanks to numerous works.

The first fossilized bones, including a lower jaw (AMNH 5866), were discovered in Wyoming in 1900 by an expedition from the American Museum of Natural History led by Barnum Brown. 

Tyrannosaurus Rex was first described in 1905, it was so impressive and huge that even then scientists noted that it was larger than the 9-meter (30 feet) Megalosaurus and Allosaurus - the largest carnivorous dinosaurs of that time. According to the first discovered fossils, scientists assumed that the tyrannosaurus reached from 8 to 11 meters and was obviously the largest carnivorous dinosaur in the world. Time passed and in 1990 the most complete and even larger tyrannosaurus was found, nicknamed "Sue". Sue was truly gigantic, estimated to be between 12.3 and 12.8 meters (40-44 feet) long, 4 meters (13 feet) high, and weighing between 6 and 9 tons. Thus, the maximum size estimate for Tyrannosaurus rex is 12 to 13 meters (39 to 44 ft) long and up to 9 tons in weight.


But there are some fragmentary isolated fossils that were larger than Sue's. In 2000, Jack Horner described the lower leg bone of one of the largest tyrannosaurus rex, proportionally reaching up to 14.1 meters in length, this animal was nicknamed Celeste or C.rex (specimen MOR 1126). There are also two other Tyrannosaurus rex bone fossils: UCMP 137538 (foot bone) and UCMP 118742 (upper jaw anterior). Molina-Perez and Larramendi estimated that UCMP 137538 is 12.3 meters long and weighs 8.5 tons. True, they believe that Sue is 12 meters long and weighs 8.3 tons. However, research by Phil Curry found that comparisons of individual bones in different individuals have different proportions and cannot be used to reliably calculate overall length. Gregory Pohl estimated that UCMP 118742 is 13.6 meters long and weighs 12 tons. But he said that the length of the upper jaw of UCMP 118742 is 29% longer than the upper jaw of AMNH 5027, however, this is not true. The upper jaw of UCMP 118742 is only 14% longer than the upper jaw of AMNH 5027 (that is, it reaches a length of 810 mm).

Mortimer (on Theropod Database) estimated UCMP 118742 to be 12.1 - 12.4 meters long, as opposed to Sue's 12.8 meters. Molina-Perez and Larramendi estimated that UCMP 118742 is only 10.4 meters long. And the weight is 5.7 tons. In a press release dated April 7, 2006, Montana State University (Boseman) announced that it has the largest skull of a tyrannosaurus rex. Fossil MOR 008 (shattered skull) is possibly the largest T. rex skull discovered in the 1960s and only recently reconstructed. The skull reached a length of 1.53 meters, its maximum estimate is almost 10 cm more than Sue's skull at 141 cm. However, subsequent estimates have cast doubt on the correctness of this reconstruction, according to other researchers, the skull reached no more than 1, 37 meters, and the total body length reached no more than 11.5 meters.

Giant finds The "Scotty" specimen (RSM P2523.8) was discovered in August 1991 by Robert Gebhardt, a school principal who accompanied paleontologists from the Saskatchewan Museum on a future expedition to southwest Saskatchewan, Canada. Excavations began only in June 1994 and took place in two stages, the first ended in 1995, and the second from 2000-2003, when even more bones were found. The extremely rigid rock matrix surrounding the fossil, combined with the size of the specimen, led to a long period of processing of the fossil and a delay in subsequent study. Although some limb bone measurements have been mentioned in previous publications (Larson, 2008a; Benson and Campione, 2014), specimen RSM P2523.8 has never been formally described. The "Scotty" fossils were first on display at the T. rex Research Center in Eastend in 2015. In 2019, Walter Scott Persons and Phillip Currie published "The Oldest and Exceptionally Large Adult Species of Tyrannosaurus rex" where they described the extremely large, approximately 65% ​​skeleton of Tyrannosaurus Rex RSM P2523.8. Numerous studies involving measurements of the skull, hips, and limbs indicate that specimen RSM P2523.8 was a very large specimen with an estimated body mass greater than all other known specimens of tyrannosaurs and members of all other giant terrestrial theropods.

Analysis of bone damage showed that this Tyrannosaurus rex lived an unusually long and cruel life, at the time of death he was at least 28 years old. Its body weight has been estimated at around 8870 kg, surpassing the other Tyrannosaurus rex's maximum weight of 8460 kg. As an extreme example of ontogenetic maturity, this finding supports the hypothesis that dinosaurs could grow to be larger than the known specimens.

Craig Pfister is a professional fossil finder and paleontologist. With the permission of the landowners, he excavates the wide expanses of Montana, his finds are legal and can be sold. Due to the long cold winters, excavations can only be carried out from the end of March to the end of October, the rest of the time is spent on preparing fossils, or on long hikes in search of promising sites. In 2010, on one of these trips, he discovered a part of the pelvic bone sticking out of the ground, Craig immediately realized that it was a tyrannosaurus rex. However, shortly after this incident, he broke his ankle and was hampered by a shoulder injury the following season in 2011. Thus, the excavation of this tyrannosaurus was completed only by October 2012. It took another two years to clean and process 170 bones, resulting in a 50% skeleton with an almost complete skull. The study showed that at the time of death, the individual was 20 years old, it reached 12 meters in length, 3.6 meters in height and weighed about 7 tons.

In the spring of 2015, a "Rees Rex" specimen was discovered in the Hell Creek Formation, northeastern Montana. The skeleton was discovered under a grassy slope in a deep gully. At first, small fragments of broken bone were found on the surface, which led to the excavation of a small outcrop, as the excavation was expanded, scattered tail vertebrae and skull elements were found, which became more and more numerous. In July, an excavation yielded a 30% skeleton (specimen TE-073) and a perfectly preserved T-Rex skull that was 94% complete and is one of the most complete T-Rex skulls ever discovered.

Tyrannosaurus Rex was one of the largest land predators of all time. The most complete specimen, nicknamed "Sue", located at the Field Museum of Natural History, measures 12.3 meters (40 feet) long and up to 3.6 meters (13 feet) high, with mass estimates varying around 8 tons.[6] Osteology guide.jpg

The complete skeleton of a Tyrannosaurus Rex consists of 299 bones, of which 58 are in the skull. The forelimbs are very small and have only two active fingers, the hind limbs are strong and powerful, have three fingers, the tail is long and heavy. The spine consists of 10 cervical, 12 thoracic, five sacral and about 40 tail vertebrae. The neck, like that of other theropods, is S-shaped, but short and thick to support a massive head. Some bones of the skeleton have voids, thus reducing the overall mass of the body without significant loss of strength. The shape of the skull has significant differences compared to theropods from other families: extremely wide at the back, the skull narrows strongly in front, due to which the eyes of the lizard look forward and not to the side, this indicates that the tyrannosaurus had developed binocular vision. The structural features of the skull bones in the tyrannosaurid family make their bite incomparably more powerful than other theropods. Tyrannosaurus rex teeth vary in shape. D-shaped in cross section, the front teeth fit snugly together, they are bent inside the mouth and have small serrations. The location and shape of the front teeth reduce the risk of them being pulled out during biting and tugging. The inner teeth are more banana-shaped than dagger-shaped, more widely spaced, but also have reinforced ridges on the back. The total length (including the root) of the largest tooth found is estimated at 30.5 cm (12 in), the longest of any tyrannosaurus tooth found. There has been a lot of controversy regarding the running speed of Tyrannosaurus Rex, due to the fact that it is not known how much muscle mass the hind limb could carry. Some scientists claim that Tyrannosaurus rex had the largest leg muscles, more than any modern animal that could reach speeds of 40-70 kilometers per hour. However, a 2002 study on theropod locomotion does not support T-Rex speeds faster than 40 km/h. A 2007 study using a computer model of Tyrannosaurus rex running showed a top speed of 29 km/h, comparable to a trained human running short distances of 30 km/h.


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Science X staff
August 23, 2021
Tyrannosaurus rex was not just a huge beast with a big bite, it had nerve sensors in the very tips of its jaw enabling it to better detect--and eat--its prey, a new study published in the peer-reviewed journal Historical Biology today finds.
Science X staff
June 23, 2021
Researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences have discovered a 120-million-year-old partial fossil skeleton of a tiny extinct bird that fits in the palm of the hand and preserves a unique skull with a mix of dinosaurian and bird features.
William Harwood
April 23, 2021
Up to three more flights are planned before Ingenuity's test campaign comes to an end.
Josh K. Elliott
April 16, 2021
Global News
A new study offers the first educated guess at the total number of T. rexes that ever lived, based on biological models.
Marshall, C. R., Latorre, D. V., Wilson, C. J., Frank, T. M., Magoulick, K. M., Zimmt, J. B., Poust, A. W.
April 16, 2021
Estimating the abundance of a species is a common practice for extant species and can reveal many aspects of its ecology, evolution, and threat level. Estimating abundance for species that are extinct, especially those long extinct, is a much trickier endeavor. Marshall et al. used a relationship established between body size and population density in extant species to estimate traits such as density, distribution, total biomass, and species persistence for one of the best-known dinosaurs, Tyrannosaurus rex , revealing previously hidden aspects of its population ecology. Science , this issue p. [284][1] Although much can be deduced from fossils alone, estimating abundance and preservation rates of extinct species requires data from living species. Here, we use the relationship between population density and body mass among living species combined with our substantial knowledge of Tyrannosaurus rex to calculate population variables and preservation rates for postjuvenile T. rex . We estimate that its abundance at any one time was ~20,000 individuals, that it persisted for ~127,000 generations, and that the total number of T. rex that ever lived was ~2.5 billion individuals, with a fossil recovery rate of 1 per ~80 million individuals or 1 per 16,000 individuals where its fossils are most abundant. The uncertainties in these values span more than two orders of magnitude, largely because of the variance in the density-body mass relationship rather than variance in the paleobiological input variables. [1]: /lookup/doi/10.1126/science.abc8300
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