After analyzing experimental samples from Patagonia, scientists came to the conclusion that the diversity of local insects after the Chicxulub catastrophe was restored only four million years later, which is much faster than in other parts of our planet, which were located closer to the point of impact of the asteroid.
A new way to estimate the rate of recovery of the planet's biosphere after the fall of a large asteroid 66 million years ago was proposed by an international group of researchers who calculated that leaf-eating insects, like the plant world, took many millions of years to return to their former diversity.
The authors of the new work, published in the journal Nature Ecology & Evolution, turned to the Patagonian sediments of the turn of the Cretaceous and Paleogene. It is believed that at this time an asteroid with a diameter of about 10 kilometers collapsed to Earth, which led to a colossal impact with a force of about 100 million megatons. Presumably, this caused long-term volcanic eruptions, which for a long time destabilized the planet's climate and led to a powerful volcanic winter reigning on Earth and the extinction of animals.
Paleontologists have been looking for places where not quite complete extinction (the so-called refuges or reserves) has occurred for several decades. It was found that the area of such a shelter could be Patagonia, Australia and New Zealand, where the consequences of the impact were most benign. The restoration of marine organisms in the waters near these areas has occurred over hundreds of thousands of years, and some plants in Australia and Patagonia even survived the Cretaceous extinction.
A general assessment of the situation after the impact was made thanks to a special technique for determining the traces of leaf-eating insects, which make up the largest animal part of the terrestrial food pyramid in terms of biomass. At the same time, thanks to traces of their nutrition on fossil leaves, one can distinguish one species from another. The analysis of three and a half thousand samples from ancient Patagonia convinced scientists that this kind of insects that survived the Cretaceous catastrophe were not there at all. Moreover, these non-organisms did not appear even hundreds of thousands of years after this event. Over time, insect diversity gradually begins to recover and in just 4 million years after the impact of the meteorite, the level of diversity that existed in the period after the extinction of the dinosaurs was achieved.
According to the researchers, this is a fairly good result against the background of previously studied areas. For example, in the territory of North America, which is more close to the epicenter of the explosion, such a recovery in the number of herbivorous insect species took 8 million years. And yet, even such a rapid recovery as in Patagonia does not mean that the region has not been severely affected by the disaster: there is no sign of a reserve for terrestrial animals, including insects, there.
