We have fantasized a lot in recent decades about extincting species of the past. And specifically, dinosaurs. Since the publication of the novel Jurassic Park by Michael Crichton, in which these animals were cloned from DNA extracted from amber, we have not stopped dreaming of bringing extinct species back to life. But beyond the novels and their film adaptations, is this viable? How realistic is it?
Could we extract dinosaur DNA as proposed in Jurassic Park? Its scientists manage to clone dinosaurs using their DNA, preserved inside mosquitoes that had fed on the blood of dinosaurs, and then had been trapped in resin, which, over millions of years, had fossilized into amber. Is this a real possibility?
When the bark of a tree is damaged, the resin is released, which hardens when it comes into contact with the air. It is a sticky substance that, as it flows down trunks or branches, can trap leaves, flowers, pollen grains, spores, invertebrates and even small vertebrates. And if this resin remains buried, it can fossilize. And the fossils preserved in amber are a wonder, both for our eyes and for the paleontologists who study them. However, despite the fact that it may seem that these small animals, and especially the insects, are perfectly preserved, only their surface is. Most of its organic matter has disappeared, and what remains of it will have fossilized like the resin that surrounds it. Of course, this type of conservation allows us to study the external anatomy of insects trapped in amber as if they were current.
Are there mosquitoes trapped in amber? And why are they so old? Well, the truth is that the oldest known mosquitoes date from the Upper Cretaceous. So far, three species of mosquitoes have been described from the Cretaceous. Two of them, Burmaculex antiquus and Priscoculex burmanicus, have been found in Burmese amber from Myanmar, dating from the first stage of the Late Cretaceous, which we call the Cenomanian, and which would be around 99 million years old. This amber has revealed true paleontological treasures, but it is controversial, since it is extracted from a politically unstable area, and the purchase of this amber fuels the civil war in this area. This problem is so great that even paleontological societies have spoken out against the acquisition and study of specimens extracted from these sites. The other known Cretaceous mosquito is Paleoculicis minutus and has been found in amber from Alberta, Canada, from the Campanian floor, around 79 million years ago (again in the Late Cretaceous).
Other hematophagous insects -which feed on blood- have also been found in amber. This is the case of ticks, such as Deinocroton draculi, also found in the controversial Burmese amber and of the same age. This tick also appeared clinging to a dinosaur feather inside its amber capsule. Other ticks, the oldest until now, have been found in Spain, specifically in the cave of El Soplao, 80 kilometers from Santander. Its age, 105 million years, within the Albian floor, the last of the Lower Cretaceous.
Suppose that one of these insects had bitten a dinosaur, was trapped in resin, and this was preserved as amber, and part of the organic matter inside the mosquito was preserved, it would not be likely to find remains of biomolecules from the dinosaur. Why? Because when insects feed on blood, they digest it. And in his digestive apparatus his enzymes would have been put to digest the blood of the dinosaur. So it is highly unlikely that any large fragments of dinosaur DNA were preserved. It would be more likely to find fragments of the DNA and other biomolecules of the insect itself.
Is all lost? No way to find dinosaur DNA? Well, not entirely. Traces of protein have been found in dinosaur bones for years. These findings led to the birth of a new discipline, Molecular Paleontology. And not only proteins have been detected…
The latest bombshell in this history of Molecular Paleontology was published in 2020, in an article headed by the paleontologist Alida Bailleul, in which the presence, in dinosaur bone, of proteins, chromosome-like structures and even chemical DNA markers is described. .
Does that mean we’ve finally found dinosaur DNA? Yes and no. If this finding is confirmed, we would have found traces of what was DNA, but most likely they are tiny fragments of molecules “made into mush” impossible to extract, much less sequence. So far, only their presence has been detected. But something is something.
However, if we are learning anything from the latest discoveries, it is that the fossil record is much more complex and wonderful than we ever imagined.
References:
Poinar, G.O. et al. 2000. Paleoculicis minutus (Diptera: Culicidae) n. gen., n. sp., from Cretaceous Canadian amber with a summary of described fossil mosquitoes. Acta Geologica Hispanica, 35: 119–128.
Peñalver, E. et al. 2017. Ticks parasitised feathered dinosaurs as revealed by Cretaceous amber assemblages. Nature Communications, 8 (1924): 13 págs. doi 10.1038/s41467-017-01550-z
Bailleul, A.M. et al. 2020. Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage. National Science Review, 0: 1–8.
