Double meteorite strike 'caused dinosaur extinction'

Double trouble for dinosaurs: Did more than one meteorite strike cause their demise?
By Howard Falcon-Lang | Aug. 27, 2010 | Science reporter, BBC News

The dinosaurs were wiped out 65 million years ago by at least two meteorite impacts, rather than a single strike, a new study suggests.

Previously, scientists had identified a huge impact crater in the Gulf of Mexico as the event that spelled doom for the dinosaurs.

Now evidence for a second impact in Ukraine has been uncovered.

This raises the possibility that the Earth may have been bombarded by a whole shower of meteorites.

The new findings are published in the journal Geology by a team lead by Professor David Jolley of Aberdeen University.

When first proposed in 1980, the idea that a meteorite impact had killed the dinosaurs proved hugely controversial. Later, the discovery of the Chicxulub Crater in the Gulf of Mexico, US, was hailed as "the smoking gun" that confirmed the theory.

Double trouble

The discovery of a second impact crater suggests that the dinosaurs were driven to extinction by a "double whammy" rather than a single strike.

The Boltysh Crater in Ukraine was first reported in 2002. However, until now it was uncertain exactly how the timing of this event related to the Chicxulub impact.

In the current study, scientists examined the "pollen and spores" of fossil plants in the layers of mud that infilled the crater. They found that immediately after the impact, ferns quickly colonised the devastated landscape.

Ferns have an amazing ability to bounce back after catastrophe. Layers full of fern spores - dubbed "fern spikes" - are considered to be a good "markers" of past impact events.

However, there was an unexpected discovery in store for the scientists.

They located a second "fern spike" in a layer one metre above the first, suggesting another later impact event.

Professor Simon Kelley of the Open University, who was co-author on the study, said: "We interpret this second layer as the aftermath of the Chicxulub impact."

This shows that the Boltysh and Chicxulub impacts did not happen at exactly the same time. They struck several thousand years apart, the length of time between the two "fern spikes".

Uncertain cause

Professor Kelley continued: "It is quite possible that in the future we will find evidence for more impact events."

Rather than being wiped out by a single hit, the researchers think that dinosaurs may have fallen victim to a meteorite shower raining down over thousands of years.

What might have caused this bombardment is highly uncertain.

Professor Monica Grady, a meteorite expert at the Open University who was not involved in the current study, said: "One possibility might be the collison of Near Earth Objects."

Recently, Nasa launched a program dubbed "Spaceguard". It aims to monitor such Near Earth Objects as an early warning system of possible future collisons.

Poll: Large Number Of Texans Doubt The Theory Of Evolution, Believe In Human-Dinosaur Coexistence

*shakes head in disgust* So these people think the Flintstones was a documentary? These are the same people who think the Earth is 6000 yrs old, too. They've no need for science.

Poll: Large Number Of Texans Doubt The Theory Of Evolution, Believe In Human-Dinosaur Coexistence

A new University of Texas/Texas Tribune survey shows just how destructive a politicized right-wing curriculum can be. A large number of Texans polled said they still don’t believe in evolution and are convinced that humans and dinosaurs co-existed:

• 51 percent disagree with the statement, “Human beings, as we know them today, developed from earlier species of animals.”
• 38 percent agree with the statement, “God created human beings pretty much in their present form about 10,000 years ago.”
• 30 percent agree with the statement, “Humans and dinosaurs lived at the same time.” Another 30 percent said they “don’t know” whether the statement is true.

Refusing to believe in evolution is a point of pride for many conservatives, who are also trying to indoctrinate young people with their same misguided views. The right-wing Texas State Board of Education has been reviewing the direction of the state’s social studies curriculum and textbook standards. Some of their changes include adding “causes and key organizations and individuals of the conservative resurgence of the 1980s and 1990s,” “documents that supported Cold War-era Sen. Joseph McCarthy,” and how to “differentiate between legal and illegal immigration.”

In terms of textbook standards, as Texas goes, so goes the nation. The state “is one of the nation’s biggest buyers of textbooks.” Publishers are often “reluctant to produce different versions of the same material,” and therefore create books in line with Texas’ standards. (HT: Daily Kos)