We explain what an extinct species is, what were the mass extinctions in history and examples of extinct and protected species.
What is an extinct species?
When we refer to an extinct species, we refer to one whose last individuals have died, that is, to a species that no longer exists , and of which there are only traces left in the fossil record or in the studies that humanity has made her.
Extinction is a common phenomenon throughout the history of our planet , although it may not seem so. There have been several episodes of mass extinction that have diminished the quantity and diversity of world life , as well as others of smaller size or local area, and isolated cases of species that have become extinct giving their place to others better prepared for use of the resources.
The most famous case of extinct species is that of dinosaurs : lizards of enormous size that ruled the Earth until 65 million years ago, when they became massively extinct; probably as a result of drastic and rapid changes in climate or global temperature, which according to some theories would have been caused by the fall of a huge meteorite .
However, species are still extinct today , especially due to actions and activities of the human species such as massive environmental pollution , selective and uncontrolled hunting and logging, the introduction of foreign species into carefully balanced habitats , etc.
Mass extinctions of history
Throughout the geological history of the planet, life appeared, proliferated and diversified , becoming more complex, but it also perished and became massively extinct. The main events of mass extinction according to the fossil record were five:
- Ordovician-Siluric Extinctions. Occurred 439 million years ago, which ended 85% of the life of the moment.
- Extinction of the Devonian-Carboniferous. Occurred 367 million years ago, which ended 82% of life on the planet.
- Permian-Triassic extinction. The worst of all mass extinctions, occurred 251 million years ago and devastating 96% of the world’s life.
- Extinction of the Triassic-Jurassic. It took place 210 million years ago, as a result of the fragmentation of Pangea , and ended 76% of the life of the moment.
- Cretaceous-Paleogenic extinction. Occurred 65 million years ago, it ended up with 75% of biological genera, especially dinosaurs.
The ecology speaks of threatened species to refer to those that seem likely to become extinct in the near future . That is, those species that classify, within the Red List of threatened species of the NUIC, the groups of Vulnerable Species (VU), Endangered Species (EN) and Critically Endangered Species (CR), according to an order from less risk to greater.
The criteria for assessing the status of a species in this regard are based on the number of mature individuals that the species possesses , as well as the rates of decrease in the number of total individuals (biomass) recorded during the last 10 years or the last 3 generations of individuals.
There is a group of species protected by international ecology organisms, which expressly prohibit their hunting, capture, possession or even the destruction of their habitat , since they are generally species threatened with extinction. This is part of the efforts of numerous conservation organizations that try to prevent the total and definitive disappearance of these animal and plant species, thus defending the legacy of world biodiversity , that is, the variety of animal species that exist on the planet.
Some protected species are the Panda Bear ( Ailuropoda melanoleuca ), the black vulture ( Aegypius monachus ), the Mediterranean seal ( Monachus monachus ) and the Iberian lynx ( Lynx pardinus ).
Examples of extinct animals
Some extinct animals due to their contact with the human species are:
- The Dodo or Dronte bird ( Raphus cucullatus ) , a very docile species of landbird without flight, that inhabited the Mauritius islands, and whose absence of predators made it excessively vulnerable to the arrival of the human species, which hunted it until extinction to late 17th century.
- The Mexican grizzly bear ( Ursus arctos nelsoni ) , a subspecies of brown bear that inhabited the Mexican states of Durango, Chihuahua, Sonora and central Mexico, and whose last specimen was hunted by the US HA Cluff in 1899.
- The Japanese sea lion ( Zalophus japonicus ) , whose habitat was the archipelago of Japan until the bombings of World War II ended the species. The last specimen of the species was captured in 1974.
- The Java tiger ( Panthera tigris probeica ) , a subspecies of tiger from the Indonesian island of Java, which since 1994 is assumed extinct.
- The Baiji dolphin ( Lipotes vexillifer ). also called Chinese river dolphin, he lived in the Yangtze River, thanks to which he was nicknamed the “widow of the Yangtze.” His last copy was sighted in 2007 and in 2008 it was declared extinct.
- The Galapagos tortoise ( Chelonoidis nigra ) , an immense turtle from the Galapagos Islands of Ecuador, capable of living hundreds of years, disappeared with the death in 2012 of “George”, his last known specimen alive.