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The resurrection of dinosaurs

  Not long ago, some scientists claimed that they found dinosaur bone fossils with blood vessels, protein and DNA. is this real? Also, why do scientists almost no longer mention the method of resurrecting dinosaurs with dinosaur blood sucked by mosquitoes?
Can DNA be preserved for tens of millions of years?

  Scientists in the first part of “Jurassic Park” introduced that they obtained dinosaur DNA in this way: They found mosquitoes preserved in amber, and the last meal of this mosquito was dinosaur blood. Scientists extracted the dinosaur blood from the mosquito’s belly, and they obtained a relatively complete dinosaur DNA.
  Some people may have wondered when watching this movie clip, can dinosaur blood really be preserved for so long? Scientists have similar questions, but they are more detailed. What they wonder is, can dinosaur DNA really be preserved for that long? But because the mosquito amber fossils in “Jurassic Park” are extremely rare, scientists can only find another way to find the answer.
  They found copal resin containing insects in various stages from 60 years ago to 10,000 years ago. Copal resin can be regarded as a semi-finished product of amber, which has not yet become fossilized, while amber is pine resin that has become fossilized. Scientists extracted the insects from copal fat and sequenced their DNA to find out how long the DNA can be stored.
  If the DNA of these insects can be measured, it means that the DNA can be stored in the resin for at least 60 to 10,000 years; if the DNA cannot be measured, it means that the DNA has not been stored in the resin for that long. Scientists can almost give up looking for mosquitoes containing dinosaur blood. The results of the experiment showed that even for a 60-year-old copal, scientists only found 535 nucleotides in it, and the sequence of 535 nucleotides did not match in the gene bank. In other words, the DNA of the insects in the copal is no longer complete, and even the DNA fragments are not left.
  However, scientists still did not give up searching for dinosaur DNA, because dinosaur DNA may be preserved in the form of bone fossils. It’s just that the existence of DNA in the bone fossils is just a hypothesis, and it needs evidence to prove it. Scientists have found it. At present, the bone fossil with a complete genome is a 700,000-year-old horse bone found in frozen soil. At this time, the question seems to be how long the DNA in the fossil bones can be preserved. Can DNA really be preserved for tens of millions of years?
  In 2020, molecular paleontologist Mary Schweitzer published a paper. The paper mentioned that she had discovered cartilage containing collagen from the skull fossil of a baby hadrosaur 75 million years ago, and it may have preserved complete dinosaur DNA.
Discovery and controversy

  Because it took too long to distinguish between ordinary bones and cartilage with the naked eye, how did Mary tell that there is cartilage in the fossils of baby hadrosaurs? In the first step, she cut the skull fossil into thin slices. Then put the slices in an acid solution to dissolve inorganic substances such as bones.
  In the second step, she injected the collagen-containing liquid into the body of the experimental mouse to make the mouse immune response to these foreign substances. Next, Mary extracted the antibodies produced by the immune response from the mouse. Finally, Mary drops the antibody into the solution of the baby hadrosaur skull slice, using the specific reaction of the antibody. If the antibody reacts, it means that the slice contains collagen. The results showed that the antibody did react, and this collagen only exists in cartilage. Therefore, Mary believes that the skull fossil contains cartilage.
  Later, on the basis of this research, Mary used an electron microscope to discover the material structure of suspected blood vessels, red blood cells and bone cells in the same kind of thin slices. The reason why these organic matter can be stored for so long is that Mary’s explanation is that since the baby hadrosa was just born, its skull and cartilage have not been separated. This creates a closed environment for the organic matter inside. The organic matter cannot be lost outward, and other bacteria or fungi cannot invade.

  Other scientists successfully repeated Mary’s experiment with other fossils. This is undoubtedly a great encouragement. At the same time, doubts will not be absent.
  First, the questioning scientist believes that the antibody test method is not completely reliable. Antibodies can also bind to minerals such as calcium phosphate. In addition, because the flake solution is exposed to bacteria, although bacteria cannot produce collagen, fungi can. Therefore, the collagen in the solution may not be dinosaurs, but produced by fungi in the laboratory or in the process of fossil excavation.
  Secondly, the vacuum environment in the process of fossil formation can also make bone minerals produce structures similar to blood vessels, red blood cells and bone cells. Therefore, what Mary observed with an electron microscope may not be blood vessels, red blood cells, and bone cells. As for the fact that Mary’s experiment can be repeated, the questioning scientist believes that this is because other colleagues are using more polluted fossils, and it is not surprising that antibodies reacted accordingly.
A dead end, or “another village in the dark”?

  In order to resolve the dispute, American paleontologist Evan Seta started from scratch and used scientific procedures to verify.
  Canada’s Dinosaur Provincial Park is a paradise for paleontologists, and many dinosaur fossils were unearthed here. Paleontologists have discovered 35 types of dinosaur fossils in Dinosaur Provincial Park. Evan’s verification will begin here.
  Come to the excavation site of dinosaur fossils. Before entering the scene, Evan had already worn a mask and blue gloves. This is not because there is a virus at the scene, but Evan is trying to avoid the fossils being contaminated by his saliva, hand dander or carried microorganisms. What he excavated was a fossil of a triceratops.
  Bringing the “fresh” fossils to the laboratory, Evan re-run Mary’s experiment. But this experiment could not be repeated, and the antibody did not respond. Even with other methods, Evan failed to find collagen in the fossil. Evan and his colleagues found the DNA of 46 bacteria and other microorganisms in the fossil. Experimental results show that collagen and cartilage are unlikely to be stored for tens of millions of years.
  The reason why Mary and her colleagues detected collagen is probably a false alarm caused by modern collagen-like substances produced by microorganisms that have invaded fossils. The blood vessels, blood cells and bone cells they observed with electron microscopes may also be the products of microorganisms.
  Evan also used a very creative method to test whether fossils can preserve collagen or cartilage. He reproduced the formation of fossils in the laboratory. Because fossils are formed under high temperature and high pressure, Evan and his colleagues mixed the corpses of chickens or lizards into clay and processed them under high temperature and pressure to press them into cakes to make artificial fossils. Then, Evan inspected the artificial fossils. Experiments have proved that among the artificial fossils, only bones and melanin are preserved, and almost all other materials such as collagen and cartilage are lost. Therefore, it is unlikely that organic matter may still exist in the naturally formed dinosaur bone fossils.
  So, is the dream of resurrecting dinosaurs once again stuck in a dead end? Although Evan falsified Mary’s experiment, Evan also discovered that a long necked dragon dinosaur egg containing a short amino acid sequence was 80 million years ago. Perhaps because of the closed system created by the eggshell, the protein in it disappears more slowly, and some amino acids have been preserved to the present.
  Using short amino acid sequences, scientists may be able to spell out a complete dinosaur protein like a jigsaw puzzle. let us wait and see.

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