An international research team led by Giuseppe Marramà from the Institute of Paleontology at the University of Vienna discovered a new and well-preserved fossil stingray with an exceptional anatomy, which greatly differs ...
Archaeology & Fossils
Oct 02, 2019
1
108
A team of scientists have revealed that after the devastation caused by a mass extinction event on Earth 66 million years ago, the plankton at the base of the ocean ecosystem were disrupted for nearly two million years. It ...
Earth Sciences
Sep 30, 2019
0
186
Figuring out what lies ahead for our species and our planet is one of the most pressing and challenging tasks for climate scientists. While models are very useful, there is nothing quite like Earth's history to reveal details ...
Earth Sciences
Sep 24, 2019
1
28
In the past half-billion years, Earth has been hit again and again by mass extinctions, wiping out most species on the planet. And every time, life recovered and ultimately went on to increase in diversity.
Evolution
Sep 16, 2019
2
375
Late in the prehistoric Silurian Period, around 420 million years ago, a devastating mass extinction event wiped 23 percent of all marine animals from the face of the planet.
Earth Sciences
Aug 30, 2019
26
1131
Earth is seeing an unprecedented loss of species, which some ecologists are calling a sixth mass extinction. In May, a United Nations report warned that 1 million species are threatened by extinction. More recently, 571 plant ...
Plants & Animals
Aug 23, 2019
2
539
In the brain, when neurons fire off electrical signals to their neighbors, this happens through an "all-or-none" response. The signal only happens once conditions in the cell breach a certain threshold.
Earth Sciences
Jul 08, 2019
30
6704
When an asteroid smacked into the Earth 66 million years ago, it triggered mass extinctions all over the planet. The most famous victims were the dinosaurs, but early birds, insects, and other life forms took a hit too. The ...
Evolution
Jun 28, 2019
2
2
Paleontologists are trying to dispel a myth about what life was like when dinosaurs roamed the Earth. The false narrative has wormed its way into books, lectures and even scientific papers about this long-ago era.
Plants & Animals
Jun 21, 2019
0
3
A new study shows how marine life around Antarctica returned after the extinction event that wiped out the dinosaurs.
Archaeology & Fossils
Jun 19, 2019
0
195
An extinction event (also known as: mass extinction; extinction-level event, ELE) is a sharp decrease in the number of species in a relatively short period of time. Mass extinctions affect most major taxonomic groups present at the time — birds, mammals, reptiles, amphibians, fish, invertebrates and other simpler life forms. They may be caused by one or both of:
Over 99% of species that ever lived are now extinct, but extinction occurs at an uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine invertebrates and vertebrates every million years. Marine fossils are mostly used to measure extinction rates because they are more plentiful and cover a longer time span than fossils of land organisms.
Since life began on earth, several major mass extinctions have significantly exceeded the background extinction rate. The most recent, the Cretaceous–Tertiary extinction event, occurred 65 million years ago, and has attracted more attention than all others as it marks the extinction of nearly all dinosaur species, which were the dominant animal class of the period. In the past 540 million years there have been five major events when over 50% of animal species died. There probably were mass extinctions in the Archean and Proterozoic Eons, but before the Phanerozoic there were no animals with hard body parts to leave a significant fossil record.
Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from the threshold chosen for describing an extinction event as "major", and the data chosen to measure past diversity.
This text uses material from Wikipedia, licensed under CC BY-SA
