About 200 million years ago, in the area of present-day Argentina, a group of rat dragons all died in a few square meters of land. suicide? The cause of death has remained unsolved.
Perhaps, this group of "rat dragons" died of a great plague, some kind of plague rampant in Argentina, overnight, the "rat dragons" were all infected with the plague and never survived.
01 Discovery: Of all the dinosaur fossils, "Rat Dragon" is the most special one
It wasn't until 1977 that these fossils of "rat dragons" from Argentina were discovered. This formation contains the egg nests, eggshells and fossils of newly hatched larvae of "Rat Dragon", more than 100 eggs have been found in the nest, and 69 skeleton fossils, including not only individuals of the same age, but also different ages, all in 1 square kilometer and 3 meters thick rock.
These fossils contain 5 cub fossils, one tail skeleton has not been found, and these cub fossils are only about 20 centimeters long, equivalent to the size of a mouse.
In 2007, paleontologists found more fossils in the Colorado Formation where "rat dragons" were once found, including at least 14 juvenile "rat dragon" fossils.
"Rat dragon", listen to the name to know that it is a very small dinosaur, paleontologists once mistakenly thought that "rat dragon" is the smallest dinosaur. But with the deepening of research, we know that "rat dragons" grow up longer than lions
So far, more than 700 dinosaur fossils have been unearthed on the earth, including the "king of dinosaurs" Tyrannosaurus rex and the "tallest dinosaur" brachiosaurus. Among all the dinosaur fossils, "rat dragon" is the most special one, why do you say so, see the breakdown below.
02 Appearance: When young, the body length is only 20 cm, 60 grams, only the size of a mouse
" Ratosaurus " was a herbivorous dinosaur that lived in the early Jurassic period , belonging to the order Sauropodidae , Sauropod suborder , " Plateosaurus " , and " Leptosaurus " . As the name suggests, this is a dinosaur that is very small like a mouse.
In its infancy, the proportion of the "rat dragon" was exaggerated, and when this dinosaur first hatched, it was only about 20 centimeters long and weighed about 60 grams, almost the size of a mouse. However, at this time, the "rat dragon", the head and eyes are very large, and it is very incompatible with the whole body.
After adulthood, the proportion of the head and eyes of the adult "rat dragon" to the body is much smaller, the nose begins to become more pointed, with a long neck and tail, and the thick long tail always swings from side to side when running.
The "rat dragon" is 2-3 meters long, the largest body length is about 5 meters, the weight is about 1000 kg, and among the 774 known dinosaurs, the "rat dragon" ranks 457th. However, compared to dinosaurs with a length of less than 1 meter, such as Yaolong and Linglong, the skeleton length of "Rat Dragon" is much smaller than them. It can be seen that the "rat dragon" is still the smallest bone length dinosaur found so far.
"Ratosaurus" has the characteristics of typical plant-eating dinosaurs, its teeth are leaf-shaped, the stomach chamber is small, at the same time, it also has the obvious characteristics of sauropods: a small head, but the neck is very long, the forelimbs and hindlimbs are 5 finger claws, cylindrical, forelimbs are thicker than the hindlimbs.
03 Walking: When I was young, I walked on all fours, and when I grew up, I began to walk upright on 2 legs
Experts from the Royal Veterinary College in the United Kingdom said that humans may be the only animals left in the world today to transition from crawling on 4 legs to walking on 2 feet.
This shift must be rare if it happens in animals, and scientists have tried to find similar behaviors in existing animals, but so far they haven't found them.
However, in ancient times, there were very few animals that underwent a transition from crawling to upright walking with age. Fossils show that this is the case with "rat dragons". In addition, several dinosaurs, including Plesiosaurus, Iguanodon, Psittacosaurus, Oakosaurus and Plesiosaurus, also changed their movement patterns with age. But most pronosaurs spent their entire lives walking on 4 legs, supporting their massive bodies.
When it first hatched, the center of gravity of the "rat dragon" body leaned forward, and the center of gravity was located in the middle of the back and the front of the legs, which meant that it had to stand with 4 limbs to maintain the balance of the body, otherwise, it would fall down without taking a few steps.
However, when the "rat dragon" grows to a 3-meter-long adult body, its body center of gravity will change as it grows, and its center of gravity will gradually move backwards, and the center of gravity will be close to the hips and legs, which makes them start to walk upright on 2 legs.
A study by stephen, a paleontologist in Melbourne, Australia, suggests that these adult dinosaurs became bipeds mainly because their tails played a large role, and their tail muscles became thicker and thicker as they grew, causing the center of gravity to move backwards.
epilogue
For "rat dragon", because of the limited number of fossils unearthed, there are still many questions that remain unanswered: why does it like to eat hard plants such as cycads and conifers? Born less than 60 grams, why can it grow to 1 ton after the age of 8?
Xuelinggu Nature Lab/Production
References: Friends of Science Magazine, Science Bulletin Journal, Communication Biology, Science Grand View Garden Magazine