The answer to this question requires another, more subtle question, how can we obtain the DNA needed to complete the cloning process? Scientists are trying to search for it inside amber (a fossilized resin of extinct pine trees, fossilized long ago).
Inside a lot of amber stones there are sucking insects such as mosquitoes and flies, these insects were feeding on the blood of dinosaurs that contain DNA, and here is the sparkle of hope for scientists, as they put a possibility that these organisms retained the DNA of the dinosaurs in their stomachs. However, to what extent can we rely on the DNA preserved in amber? Amber preserves the peel, but it cannot preserve soft tissues well, that is, blood is not kept inside the insect in amber.
At the same time, this does not mean losing hope in the search for the DNA of dinosaurs, as the choices do not end with the insects preserved inside amber, as the remains of blood were found inside ancient fossilized insects that were not found in amber, as one of the research papers referred to a mosquito that lived during the era Eocene 45 million years ago. That is, 20 million years after the extinction of the dinosaurs.
What distinguishes this mosquito - in addition to its great age - is that it was preserved in lake sediments, and its stomach was found to have a red pigment. Upon examination, researchers discovered that this pigment is porphyrins, they are organic compounds derived from hemoglobin (a red protein that carries oxygen throughout the body). Porphyrins are products of the breakdown of hemoglobin. This makes us comfortably knock on the door of hope regarding finding dinosaur DNA in insects, we just need to find insects that lived during this period whose bodies contained some blood residue.
There is blood without DNA!
Finding insects fossilized or preserved in amber inside the remains of blood is very good, but this does not mean the inevitability of the presence of DNA inside them, even if the blood of dinosaurs is found, the chance of recovering these giant reptiles is not guaranteed.
In 2015, a research group was studying fossil bones of a dinosaur that was as old as the Cretaceous. They found red blood cells, which contain nuclei (knowing that the red blood cells of reptiles and birds contain nuclei, which differ from those in mammals and humans known to not contain nuclei). When they examined the red blood cells and compared them to those in the birds, they noticed a similarity in appearance.
During the examination, the researchers divided red blood cells using a concentrated ion beam, like a small knife, to dissect the nuclei and explore whether or not there was DNA present in them. Indeed, they did not find it. This confirms that even if blood or soft tissue is present, this does not necessarily mean the presence of DNA.
An example of this is the dinosaur "Albertosaurus" that lived during the Late Cretaceous period 70 million years ago. It has been observed that although ancient DNA can be recovered from bones or some parts of the body that have not yet fossilized.
But - unfortunately - this ancient DNA is very weak, and it breaks down very quickly, by the action of enzymes secreted by soil microbes, and ultraviolet rays also have a role in this decomposition, in addition to oxygen and water, as they cause the change of DNA from the chemical point of view, then the responsible bonds are broken. When the double strands of DNA hold together, the DNA turns into small pieces and over time nothing remains, in addition to the negative effect of sunlight and water. Therefore, drastic measures should be taken when dealing with these delicate genetic particles.