The Tyrannosaurus or Tyrannosaurus was the most famous of the ancient dinosaurs, and scientists’ research on them has never stopped. Not long ago, paleontologists published a new study on Tyrannosaurus rex, reconstructing the organism’s growth sequence and uncovering key stages in the growth of Tyrannosaurus rex.
The lead paleontologist, Dr. Thomas D. Carr from Carthage College student who has been working on Tyrannosaurus rex since 2004, initially contained only five Tyrannosaurus rex specimens and fossil number very limit. Based on these fossils, Carr enumerated the characteristics of 84 growth variables for Tyrannosaurus rex. Subsequently, he studied more and more fossils of this organism, and finally obtained 31 specimens, and the growth variable characteristics associated with Tyrannosaurus rex were further explored by him.
Based on the characteristics of the giant growth variables, the team obtained a high-precision growth sequence of Tyrannosaurus Rex and divided the Tyrannosaurus Rex’s life cycle into 21 stages and 6 periods:
Small Juveniles, including 4 stages, aged 0 to 12 years old.
Large Juveniles, consisting of 1 period, is 13 years old.
The third period – Subadults, including 2 periods and the age from 14 to 17 years old.
The fourth period – Young Adults, including 5 stages, aged from 18 to 22 years old.
The fifth period is the adult period (Youth), including 8 stages, from 23 to 27 years old.
Senescent Adults, including 1 period, from 28 years old.
The growth sequence diagram includes the 21 stages of the dinosaurs.
Having obtained the growth sequence, paleontologists undertook further research and discovered that there were two important stages in the development of Tyrannosaurus rex: the sixth stage, which is equivalent to when Tyrannosaurus was 15 years old. During this short year, the skull morphology of Tyrannosaurus rex will change dramatically. The long, narrow skull and lower jaw will become thicker and wider, and the teeth will become thicker, starting to have the features of the skull of an adult Tyrannosaurus. The later stage is the eighth stage, equivalent to when Tyrannosaurus rex was 18 years old. This is the stage where Tyrannosaurus enters adolescence, which is the onset of puberty and will weigh about 3 tons. This weight represents the official transformation of the Tyrannosaurus rex into a giant, powerful super-predator, and their weight will quadruple over the next ten years.
Comparison of the skulls of the adult and immature Tyrannosaurus rex tyrannosaurus.
In the past, paleontologists believed that the larger the size of the dinosaurs, that would mean the higher their age. But in fact, true size is just one of the many traits that change in the growth chain of Tyrannosaurus rex, so the method of evaluating age by body size alone is really unreliable. Because this can easily cause confusion between young but well-developed individuals with adult ones.
In 2019, Canadian paleontologists announced that they had discovered the largest size tyrant ever known, they named it “Scotty”. Research believes that this tyrant could reach 13 meters long and weigh 8.8 tons. Of course, many paleontologists have questioned its true size, because the completeness of this Tyrannosaurus rex was only 65% complete.
It must be said that, because of its enormous size, paleontologists believe that “Scotty” is a very old tyrant, must be over 30 years old. Through analyzing the growth sequence of Tyrannosaurus rex, especially comparing many different traits, Thomas D. Carr’s team argued that there is no absolute relationship between the size of Tyrannosaurus rex and age. . And through analysis, the exact age of “Scotty” in fact is only in the 5th period, between the ages of 23 and 27.
Scotty’s age redetermination demonstrates the advantage of the growth chain in fossil studies. Carr’s team worked on Tyrannosaurus rex, but at the same time they studied another highly controversial Tyrannosaurus, the dwarf tyrannus (Nanotyrannus). The dwarf dinosaur was also found in the Hell Creek strata with two specimens code-coded: CMNH 7541 and BMRP 2002.4.1.
Paleontologists compared the traits collected on fossilized dwarf dinosaurs with the growth sequence of Tyrannosaurus Rex and found that these features were completely consistent, meaning that The dwarf Tyrannosaurus really did not exist, they were just young individuals of the Tyrannosaurus Rex. Specifically for each specimen, CMNH 7541 belongs to an individual Tyrannosaurus Rex around 10 years old, while BMRP 2002.4.1 is slightly older and belongs to a 13 year old individual.
When Carr introduced the growth and development cycle of the Tyrannosaurus rex, he pointed out that growth traits were also an important part of phylogeny. “We found that immature and immature Tyrannosaurus rex exhibited ancestral traits, while adults lost those traits. It is the link between evolution and growth. In a similar way, these traits can be used to simulate individual growth or reproduce population growth.The growth trends of Tyrannosaurus rex can also be compared with dinosaurs another to determine which trends are inherited from the ancestors and which trends develop independently.
In addition, Carr and his team tried to differentiate the sex of the tyrannosaurus by their growth sequence, but after carefully reviewing the data of the different individuals, they could not find a similarity. The evidence can be sexist. This meant that there were no differences in the level of development between the teeth and the bones in the male and female dinosaurs. Therefore, the growth sequence cannot be used to determine the sex of Tyrannosaurus rex.
Right now, the only way we can judge a dinosaur’s sex is the Medullary bone. This structure only exists in the bones of a pregnant tyrant. Its function is to provide calcium for eggshell formation. Bone marrow was found only in the “B-rex” tyrannosaurus fossils, which also shows that this individual is not only female but also in pregnancy.
B-rex femur with a length of 1.15 meters.
A cross-section of the dinosaur’s thigh bone, where MB refers to a bone marrow.
Tyrannosaurus rex’s regeneration of the growth sequence provided new basic information for the study of this famous dinosaur, especially its growth and evolution. Based on the growth sequence, we can use its literature to study Tyrannosaurus rex from different angles and levels, and gain new knowledge about Tyrannosaurus rex.