An international research team revealed that the organisms that lived in our Arab region and the rest of the African continent faced extreme conditions about 30 million years ago, which led to the extinction of nearly two-thirds of them, but it seems that the matter did not stop only on our continent.
According to the study, published in the journal Nature Communications biology on October 7, that era was characterized by a sharp decline in average temperatures, as ice sheets expanded, sea levels fell, and forests turned into grasslands. This led to the extinction of nearly two-thirds of the living creatures in Europe and Asia at that time.
The researchers used dental topography to examine the change in the diet of these organisms (Hisham Salam)
On the edge of the Oligocene
In his interview with Al Jazeera Net via e-mail, Hisham Salam, Professor of Paleontology at Mansoura University and the American University in Cairo, Egypt, who is the co-researcher from the Egyptian side in this study, said, "This research is a summary of more than two decades in which we examined the change that occurred in the environment during the current era. between the end of the Eocene and the beginning of the Oligocene.
The Eocene refers to a geological epoch that lasted from 56 to 34 million years ago, followed by the Oligocene, a geological epoch that lasted between 34 million and 23 million years ago.
Researchers in this range had assumed earlier that, despite the harsh climate change that occurred at that time, the continent of Africa in particular may have survived by virtue of the equator passing through it, as it makes it the hottest continent, and thus it may not be affected much by low temperatures global temperature.
This assumption was the main reason for questioning the existence of a major extinction that occurred about 30 million years ago, because as temperatures decreased, the animals at risk would have migrated south towards the equator, but according to the new study, the organisms in Africa themselves were affected.
5 types of fossils studied over two decades (Hisham Salam)
genealogical tree
Salam said in a statement to Al Jazeera Net, "To reach these results, we studied groups of 5 types of fossils of organisms that lived in that era, which are two types of monkeys (lemurs and lorises), and two types of rodents (Chileans and echinoderms), and carnivores."
According to the study, data on hundreds of fossils were collected from multiple sites in Africa and the Arabian Peninsula, then the team worked on building a genealogical tree for each of these groups, determining the time of the divergence of new lineages and setting specific time points for the first and last known appearance of each type.
The genealogical tree is simply tracing the lineage of a living being and its connection to another being, and to approximate, we can trace the lineage of a person named Ahmed and another named Ali, to the tenth grandfather for example, then we find that this grandfather was shared between Ahmed and Ali, here we say that there is a branch that has occurred With this grandfather, he created two families;
Ahmed's family and Ali's family.
Hisham Salam added in his statement to Al Jazeera Net, "After building the genealogical trees for each of these groups, we found a significant decline in the branches of the genealogical tree that occurred in the period between the Eocene and the beginning of the Oligocene, which indicates the occurrence of extinction."
On the other hand, the study examined the topography of the teeth of these fossils, that is, their topography, which usually gives an impression of the diet followed by the animal. The climate is so harsh.
Fossil species varied before and after extinction (Hisham Salam)
Life finds a way
But climate change did not last forever. During the Oligocene and with the advent of the Miocene—the next geological period that extends from 23.03 million years ago to 5.332 million years ago—life flourished and diversified again.
According to the study, the fossil species that reappeared later, after the great extinction, are not the same as those found before it.
Rodents and monkeys reappeared after a few million years, but their teeth were different, meaning they were new species with different diets.
The team notes that climate was not only the cause of the extinction that occurred at that stage, as the East African region was subjected to a series of major geological events, such as super volcanic eruptions and basaltic floods that covered vast areas, and at that time also the Arabian Peninsula separated from East Africa And opened the Red Sea and the Gulf of Aden.
In his statement to Al-Jazeera Net, Salam compares what happened in the period between the end of the Eocene era and the beginning of the Oligocene as an "evolutionary bottleneck", as most of the breeds became extinct, but a few of them survived and were able to adapt. Then, over the following millions of years, these remaining strains diversified;
It is the nature of life.
The professor of paleontology points out that climate changes play a key role in refining the tree of life, adding that the human race is not immune from these effects, especially that our planet is currently going through a warming period, and if we do not intervene to act quickly, the same catastrophe may recur.