Blockbuster news! Scientists have found well-preserved chondrocytes in fossils of 125 million-year-old cephalopods in the Rehe biota in northeastern China. The nuclei of these cells also hold filamentous chromatin, which is the carrier that preserves DNA.
Above: Restoration of a dragon with tail feathers from the Rehe biota
At the same time, the DNA fragments with genetic information store all the information about the race, blood type, gestation, growth, apoptosis and other processes of life. This means that it is entirely possible that we can resurrect the dinosaurs with this. Sound exciting? But in practice, it can be said that it is difficult, after all, this is not the first time that dinosaur DNA has been discovered.
In fact, as early as the 90s of the last century, Chinese scientists have obtained the gene fragment of dinosaurs for the first time from a 65 million-year-old dinosaur egg fossil. However, if you want to reproduce a complete dinosaur, you must obtain complete genetic data. This DNA is easier to find in the "softer parts" of animals, such as organs, blood vessels, nerves, muscles, and fat. But these soft parts are long gone, either rotting or being eaten by another dinosaur.
Even bones, after burial, decay and decompose and lose their organic matter, which is then replaced by surrounding minerals and gradually petrified. The clues left behind can only tell us the shape and size of the specimen, the time of survival, and some unique characteristics of the animal, but it does not provide us with critical genetic information.
There are also studies that show that the half-life of DNA is 521 years. That is, every 521 years, the chemical bonds between DNA molecules break in half. Year after year, it only takes 6.8 million years for these chemical bonds to be destroyed by time. If you encounter high temperatures, acidic environments, and DNases released by microorganisms, it will inevitably accelerate the rate of DNA decomposition. However, the last dinosaur to die at the end of the Cretaceous Period is more than 65 million years old, and no DNA can last so long. So why can we still find dinosaur DNA this time?
Above: About 65 million years ago, the last dinosaurs walked on Earth.
In the process of burying and petrifying organisms, they often undergo molecular-level replacements, such as silicification – the carbon matter inside is replaced by siliceous matter. In addition, common displacement effects include phosphate, pyrite mineralization, calcification, dolomite petrochemical and so on. The fineness of fossils preserved by mineral substitution of different components is also different, with the highest level of silicification preservation.
Above: The only remaining fossil dinosaur skeleton
Researchers at the Chinese Academy of Sciences took a sample of cartilage from a piece of bone near the joint at the distal end of the tail feather dragon femur. After decalcification and the use of microscopic imaging technology to analyze its microstructure, it was found that after the death of the dinosaur, its chondrocytes underwent silication, and silicification happened to preserve the complete morphology of chondrocytes.
The team then extracted some of the cells and used biochemical methods for staining analysis, so that the nucleus of one of the chondrocytes and the filamentous chromatin were revealed. This suggests that the organic matter in dinosaur bones was not completely "petrified", at least in the chondrocytes there are still organic molecules of the dinosaur itself.
Above: Micrograph of osteochondrocytes of the calf of the tail feather; one of the cells shows a nucleus and filamentous chromatin after staining.
But these are still just fragments of DNA, not enough to replicate dinosaurs. Then we really don't have a chance to resurrect dinosaurs? Don't get discouraged, there are many ways. Most people have heard the saying, "The ancestor of the chicken was a Tyrannosaurus rex," which is really unexpected. However, the reality is that the two do not have a direct inheritance relationship, but they are indeed relatives. Because the ancestors of modern birds are actually hand robbers, they are "cousins" to the Tyrannosaurus family. Therefore, it can be said that they are the descendants of living dinosaurs. Scientists are also planning to find some potential atavistic genes from chickens to make dinosaurs.
The ancestors of chickens (birds) go back further, back to theropod dinosaurs. Until now, they have many common features with their dinosaur ancestors, such as bipedal walking, air bag breathing system and so on. The difference is that the center of gravity of the theropod dinosaurs is behind, and the center of gravity of birds is front. This is because in the process of evolution from theropods to the hand robbers, the long tail gradually shortened, and the tail femoral long muscle also gradually shrunk.
In the process of evolution from the hand robbers to birds, the tail was further shortened and healed into the tail bone, the long tail femur muscles disappeared completely, and the forelimbs and pectoral muscles tended to develop, a series of changes that caused the center of gravity of the birds to move forward when standing. Even now, we can find ancient features such as long tails early in the development of chicken embryos. Such an embryonic development process also gave science the confidence to replicate dinosaurs.
Above: Early embryonic development of chickens
Scientists believe that figuring out why the tail grows from long to short during development and reversing the process of forming a short tail gives you a chance to find the attagen. This may sound incredible, but in 2006, Matthew Harris and John Fallon demonstrated that such experiments were not a fantasy.
Above: Small embryos in a test tube, genetically engineered dinosaurs will also start from here.
While studying the mutant embryos of chickens, Matthew Harris discovered a specimen preserved in a solution of formalin with many tiny teeth in its beak! Although it sounds like a joke, it is not difficult to understand the origin of chickens, after all, they were also the overlords of the earth.
To make sure this wasn't a joke, Matthew Harris added growth factors to a normal embryo to stimulate the manufacture of a protein and see if it happened repeatedly. Unsurprisingly, with the addition of protein and growth factors, the chicken embryos grew tiny teeth similar to crocodile embryos and changed jaws.
Above: Fine teeth have grown in the mutant's beak, which is significantly different from a normal beak.
In addition to teeth, many experimental projects have also studied faces, arms and claws. Scientists believe that once they have completed the study of all parts of the body, it is possible to create a dinosaur-like animal. Of course, it is unlikely now, but as time goes on, the petite and weak chicken will one day be transformed into a mighty dinosaur, and perhaps even brought to the table. If you can't wait to taste dinosaurs, go to the kitchen and stew a chicken!
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