Until 15 years ago, Grimaldi’s work focused on current insect research. But her encounter with amber from the Dominican Republic turned her investigations around. He has worked in the site located in Lebanon, belonging to the Hauterivian Cretaceous -between 116 and 120 million years ago- and now focuses his attention on that of New Jersey, from the upper Turonian Cretaceous, 80 to 90 million years ago- of the that contributions of scientific interest are being obtained. The discovery in Álava of a site from the Lower Cretaceous period, specifically from the Upper Aptian and Middle Albian – from 114 to 112 million years ago – has caught his attention. We found Grimaldi in Vitoria-Gastéiz, at the World Congress on Amber Inclusions held there. During the interview Grimaldi suffered from a strong aphonia, played an unusual game with a ring that, on his little finger of his right hand, is set with a large piece of amber. Inside, a very particular fly he investigated, Valeseguya disjuncta, a species in which an unsuccessful attempt was made to find traces of DNA, stopped his flight.
–Does the possibility of entering a world that existed millions of years ago awaken you any emotion?
-It is truly impressive. The state of conservation of the specimens makes it appear that they are alive. It’s like they are doing something.
–It seems that the pieces with organic inclusions are the ones that most interest scientists …
-Not much less. There are many more things within amber that are of interest. For example, inclusions with gases or liquids, which can provide information about the conditions in which that amber was formed in the past.
–Could it even be known what kind of atmosphere dinosaurs breathed?
-Sincerely I dont know. This is a matter about which there is great controversy. The only way to reach a conclusion is to study the air or water bubbles contained in amber from all over the world. So far these inclusions have been very little investigated. It is still not possible to be sure that there is a paleoatmosphere in these bubbles. Perhaps in the future we can have reliable data that need not be spectacular or positive. Perhaps we will discover that there is no interest in these traces of air or water. There are researchers who consider that the permeability of amber may have allowed the exchange of gases with the outside; they are of the opinion that there are no original bubbles, not because they contain no atmosphere, but because it has not been shown to be pure. There are many bubbles with a high CO2 content and not even the most risky would dare to assure that this was the primitive atmosphere. The composition may be due to chemical reactions with the amber that has produced gas evolution. Amber is an organic substance and therefore has carbon, so it seems logical that, due to chemical reactions, carbon dioxide is produced.
–With what it does solve unknowns is with the study of inclusions of insects, crustaceans, plants or feathers. Are they the best testimonies of what the fauna of the planet was?
-Because of its characteristics, amber provides a bias to the study of the fauna it collects. Animals that have fossilized in rock sediments, for example lakes, are very different from those that have fossilized in resin. While the former are usually large animals, the latter are small in size; But to know the prehistoric fauna it is necessary to have a global vision of all the sedimentation and fossilization media. The British Robert May carried out a work in the 80s that shows that 90% of the organisms that are known today are less than one centimeter in size, so amber should have been the best system to trap the vast majority of the fauna of the past. The large animals found are more spectacular, but much less numerous.
–What can the discovery of a new deposit contribute at this point? Have not enough answers been obtained with the material already studied?
-There are two issues: first is the fact that when the animals are well preserved in amber, very delicate details can be studied, such as wings, hair or eyes, which allow a high degree of comparison with current specimens. Second, it is one thing that there is a lot of amber and another that the vast majority of what can contribute something to the knowledge of prehistoric biology comes from less than a dozen places in the world. Most of the relatively modern amber comes from the Baltic and the Dominican Republic. But ancient amber, those dating from the Cretaceous, with a significant number of biological inclusions, are only found in Lebanon, New Jersey (United States), Canada, Siberia (Russia) and now Álava (Spain). The rest of the ancient amber deposits have little or no inclusions.
– Is it therefore expected that the Peñacerrada site will contribute to clearing up unknowns about the fauna of the past?
-The most significant data of this site is its time, the lower Cretaceous -between 107 and 116 million years before-, since most of the known Cretaceous amber belong to the upper period, between 65 and 95 million years ago. Precisely because of its age, it can provide a lot of information about the transition of fauna from the Jurassic – between 135 and 205 million years ago – to other periods of life on the planet.
–Some modern insects have been found to possess compounds, such as elastin, arthropodin, and resilin, whose properties could have high-tech applications. Would it be possible to find biomolecules in primitive insects and imitate them?
-We can say metaphorically that the jury is assembled, but has not yet given its verdict. That is, there is no unanimity and certainty that DNA exists in insects preserved in amber, only indirect evidence. I have to say that I don’t believe the reports of amber bacteria because their DNA has been found to be highly fragmented. Various experiments have been done in this regard. DNA was obtained from a Dominican amber bee of the genus Proplebella and the data confirmed that it was genetic material but not from this hymenoptera, with which the chances of contamination, possibly human, were very high. Other laboratories have tried to repeat these experiments under conditions of stricter asepsis and the results have been negative. In 1992, my team studied termites of the genus Mastotermes, from Dominican amber, and we also found DNA that seemed to match what was expected of these individuals; Mastotermes exist today. But the problem is that those experiments were also impossible to repeat. Therefore, it is difficult to decide whether the results are good or bad; they are rather ambiguous. What is clear is that the preservation of internal tissues in amber is exceptional and that it is very difficult to explain this preservation with a simple mineral replacement of the tissue by any type of inorganic substance. It is evident that something organic must be inside the insects, since the amino acids are conserved, which indirectly leads to the conclusion that perhaps the nucleotics that make up the DNA may also be conserved.
–You have recently announced new discoveries in the American field in New Jersey. Which are?
-Although this site has been known since ancient times, now there are surprises. We have found the presence of Mantids (mantis) and some mosquitoes from the Culicoides group, which are those with a very long trunk, which was not foreseeable that they would appear there. These specimens are also missing links in current groups. Without going any further, the relationship between mantises and cockroaches is suspected, but you have to go a long way in time to find intermediate individuals like these that we have now found. They are mantises that do not have raptor front legs like the current ones, but rather have similarities with cockroaches. The further we go back in time through the study of deposits such as New Jersey – from 80 to 90 million years old – the more we can delay the age of certain groups, such as Estecomirman ants, which are the medium oldest ants in the fossil record. On the other hand, research has discovered that, in the past, there were animals that had different geographic distributions than they do today. We have found mantises in Cretaceous New Jersey, related to mantises that now live in Africa.
–But these New Jersey bugs weren’t the only surprising discoveries you’ve made …
-Two years ago we found a curious specimen in Dominican amber and, although there are some specimens in Baltic amber, I am very proud of the first one. It is a small insectivorous mammal of which part of the skeleton is preserved and that lived 18 to 29 million years ago. The greatest scientific significance of the discovery is its biogeographic significance compared to what we know now.
–Are there any more surprises awaiting us about the Cretaceous?
-Yes. Very surprising discoveries may still appear. For example, flowers. In the amber of New Jersey they have appeared, and at the moment, they are the oldest discoveries in the world.
–How could it be possible to create accumulations of pieces of amber the size of a fist, spread over expanses as immense as occurs in the Baltic or even Álava deposit, which, although not comparable in size, is also surprising?
-There are 2 hypotheses studied. One, which explains the massive production of resin by trees, especially conifers, to protect themselves from diseases or from the attack of beetles, fungi, etc. Another, more catastrophic, considers the possibility that the damage caused to the trees by natural phenomena such as storms or hurricanes, made them manufacture large amounts of resin with which to heal their wounds.
Coral Larrosa
This interview was published in December 1998, in number 211 of VERY Interesting.
