Rethinking Dinosaur Extinction

On February 14, a small asteroid known as the Chelyabinsk object hit southwestern Russia. The next day, a 40-meter-long asteroid called 2012 DA14 passed by the earth, coming closer than our own satellites. These recent encounters with large space rocks bring to mind one of the theories of what killed the dinosaurs millions of years ago: an asteroid strike.

Asteroid strike that killed the dinosaurs

A painting by Donald E. Davis that depicts an asteroid crashing into the Yucatan Peninsula in southeast Mexico.

By studying a 110-mile (180-kilometer) wide crater in the Yucatan Peninsula in Mexico, scientists have determined that the asteroid that struck the earth 66 million years ago was 6 miles in diameter. The collision with Earth would have caused wildfires, tsunamis, and particles in the atmosphere. These particles would have blocked the sun, killing the plant-life and causing temperatures to drop significantly. Many scientists believe this series of events led to the demise of dinosaurs.

Dinosaurs dying from volcanic eruptions

Dinosaurs may have been killed by a series of volcanic eruptions in what is now India. Credit: National Science Foundation, Zina Deretsky

But perhaps this wasn’t the only cause of extinction. Many scientists believe that a series of volcanic eruptions that occurred 60-68 millions of years ago in what is now India began killing off the dinosaurs before the asteroid strike. These eruptions would have caused dramatic climate change that would threaten many dinosaur populations.

Learn more about these theories at  National Geographic.

25% of Mammals in Danger of Extinction

Polar bear familyThe International Union for the Conservation of Nature (IUCN), an environmental network of government agencies, non-government organizations, and volunteer scientists, released their latest findings on the status of the world’s mammals.  Their results paint a bleak picture of the future for many animals.

The IUCN estimates that 1 in 4 mammals are at risk for extinction and that 1 in 2 mammal populations is declining.

According to Julia Marton-Lefevre, the director general of the IUCN,

Within our lifetime, hundreds of species could be lost as a result of our own actions, a frightening sign of what is happening to the ecosystems where they live. We must now set clear targets for the future to reverse this trend to ensure that our enduring legacy is not to wipe out many of our closest relatives.

On the bright side, IUCN’s research also shows that many species can recover from the brink of extinction when focused conservation efforts take place.

For more information:

CNN.com: “1 in 4 mammals at risk of extinction, scientists say”
IUCN Red List of Threatened Species Database
IUCN Website