Among the main arguments that contradict the primary pin of the last mass extinction in the djinch on the planets, in this case, point to the possible zero impact on the vegetation of that time. Plant species from the end when they had to grow and, with minor exceptions, all effects were measured without problems and noticeable loss of biodiversity species. If the plants, as long as there are not many animals resistant to crop destruction, would eventually die out without any problems, then it could not possibly be as dramatic an event as the proponents of catastrophic rust portray.
As the latest research from North and South America shows, the reality is completely different in this case. In fact, the loss of species diversity of plants at the boundary between the Cretaceous and the Paleogene in the investigated localities is about 50 percent. On the contrary, this clearly shows that it must have been a highly dramatic, catastrophic event in its nature, and at least on a global scale. Last year, a trio of scientists published the results of research on fossil flora from the American Montana and Argentinian Patagonia and significantly changed the view of the extinction of plants 66 million years ago.
The leader of the work, who is Professor of Geological Sciences Peter Wilf from Pennsylvania State University, summarizes the findings as follows: In the literature published so far, the trend is to claim that the Extinction was bad for dinosaurs and other animals, but it was bad for plants, because all the main peila groups. However, research contradicts this claim, because wherever we looked, there was about half of the (plant) species extinct.
In the past, the researches of plant measurements at the end of time were limited to a small and geographically limited sample, which practically came in waves from several locations in the United States of America.
The authors of the new study worked with extensive samples from the distant South American countries of Colombia and Argentina, as well as new locations in the United States of America (in the states of North Dakota, Colorado, and New Mexico). Wilf added that extinctions in the long geological past did not tell us anything, not even the differences in the DNA of any species of plants, and therefore a wide sample of fossils from the time before and after the catastrophe is necessary. And at each of the new localities, more than 50% of plant taxa were lost.
A petrified leaf of a plant named Bisonia niemii. This species, very abundant in the sediments of the Hell Creek Formation, apparently falls into the family of lauropods (Laurales) and some lauropods (Lauraceae). About 1.5 and 2 meters tall, the plant was characterized by its scaly, lobed leaves. It belonged to the latest date, which was seen by the impact of an asteroid 66 million years ago.
Such a large percentage of idiots cannot be confused as a mere mistake or a statistical error, it is a clear proof that even the plants were not spared during the cataclysm at the end. The pitom plants included an incomparable number of species and individuals, not dinosaurs and other animals. Exterminating an entire group of plants is much more difficult than in the case of large animals such as dinosaurs and birds.
However, 66 million years ago, a massive extinction of plant species was followed by a number of evolutionary events that contributed to the formation of the modern world as we know it today. Among other things, the disaster at the end of the year allowed the rise of the dominance of angiosperms and created the modern form of tropical rainforests with their astonishing biodiversity.
Mass extinctions do not only represent the species extinction of many groups of organisms, but also the overall form, composition and functionality of ecosystems. And these changes can be observed even in the investigated locations, which are separated from each other by thousands of kilometers. It is interesting (albeit quite logical) that the impact of the asteroid manifested itself differently in different locations, the course of the disaster was known to differ according to their location. Factors such as distance from the impact or the ability to withstand the darkness and cold brought by the post-impact cold were at issue.
According to Wilf, the main reason for the loss of plants was the drastic change in temperature after the impact, which was particularly severe in tropical regions. In some respects, the end of the world is comparable to the current world, due to human civilization, but that is not our concern now.
Global darkness
Let’s take a look at one new research, which is not related to the previous one, but its introductions lead to the discovery of Peter Wilf and his two colleagues. This is research that has not yet been published, but was presented at the end of 2021 at the American Geophysical Union meeting in New Orleans. The results of an interesting experiment were presented here by geologist Peter Roopnarine from the California Academy of Sciences.
According to his team’s research, the main contributory factor suggested by father and son Alvarez in 1980 could be long-term global darkness. Together with the immediate effects of the impact, such as an extremely strong red wave, infrared radiation or a massive tsunami and an earthquake, it should have been a shock to the biota of that time, and a frost lasting several years. This so-called impact winter could reduce the average temperature at the surface by up to a few degrees Celsius, estimates of about 25 and 40 C.
This in itself represented a terrifying disaster for the vast majority of the species, yet the frost did not have to be the final blow of grace for the dinosaurs and many of their contemporaries. According to Roopnarine, the biggest killer was the darkness, caused by the dense layers of ash and other steeks created by the worldwide vegetation pores after the impact of the asteroid. A large percentage of the world’s plant biomass has been documented for a very long time by the fossil record, but we still do not know how long the effect of the cloudy sky could have lasted.
A large amount of dust, rocks and drops of sulfuric acid were ejected into the atmosphere, which by themselves managed to significantly reduce the amount of sunlight (perhaps not even 50%) on a global scale. Even more important was the enormous volume of soot from the world’s pores, its concentration in the atmosphere could, according to the results, be large enough to actually hinder the process of photosynthesis in many places.
The so-called K-Pg (kda-Paleogn) interface, i.e. the geological boundary between the Mesozoic and Tetizoan eras, on a photograph from the American Colorado. It is often visible due to the dark and black thin layer with a high concentration of the otherwise rare element iridium. The picture shows a treacherous blue car.
According to the scientists, the concentration of soot in the atmosphere in the first weeks and months after the impact was high enough for the shift of sunlight to actually fall below the critical threshold. The team reconstructed a small part of the ecosystem of the Hell Creek Formation, using knowledge of the approximately one hundred species of plants known from that time and a detailed study of geological formations. The plants, originally fossil species from the Hell Creek Formation, were then exposed to conditions of simulated darkness, modeled for the catastrophe at the end of time. The plants of the community were exposed to the conditions of a sleep shift of light for 100 and 700 days, and it was observed how the individual species and the whole community coped with the rise in temperature.
The critical observed value was the rate of 73.3% of the species, determined by researchers for a period of 66 million years. According to the obtained results, the plant community in the ecosystems of the Hell Creek Formation could recover from the darkness after 150 days, i.e. five months. After about 200 days, the pressure on the community reached critical values, and while some species became irreversibly extinct, the dominance of the composition species shifted.
The rate of extinction increased drastically and in the interval between 650 and 700 days (roughly 21 and 23 months), when we reach similar values of loss of species diversity as pi extinction at the end of time (65 and 81%). From this we can cautiously infer that a similar darkness in the ecosystems of the midwest of North America lasted for 2 years.
Of course, these conditions could be very similar in other parts of the world, but in the ecosystems of the famous North American formation, a similar long period of impact darkness can be expected. According to Roopnarine, after the return of the conditions to the pre-impact state, it took about another 40 years, but at least the plant communities could still slowly recover.]Here, Mme gave evidence of the drastic nature of the extinction at the end of time. It can be assumed that in the future we will find out more detailed information about this fascinating and frightening time.
link was created for Vladimr Socha’s dinosaur blog and was edited. The original version including a rich reference index can be found here.
Tags: extinction dinosaurs dark ages
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