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What was the cause and what evidence exists of the KT mass extinction event?
The Chicxulub crater at the northwestern point of the Yucatán Peninsula was formed by the impact of an asteroid 66 million years ago. The cloud of dust and carbon gases that resulted is thought by some scientists to have caused the extinction of the dinosaurs.
What pieces of evidence support the existence of the K PG asteroid?
The impact hypothesis, also known as the Alvarez hypothesis, was bolstered by the discovery of the 180 km (112 mi) Chicxulub crater in the Gulf of Mexico’s Yucatán Peninsula in the early 1990s, which provided conclusive evidence that the K–Pg boundary clay represented debris from an asteroid impact.
How did the KT asteroid cause mass extinction?
Paul explains, ‘The asteroid hit at high velocity and effectively vaporised. It made a huge crater, so in the immediate area there was total devastation. A huge blast wave and heatwave went out and it threw vast amounts of material up into the atmosphere. ‘It sent soot travelling all around the world.
What evidence supports the impact hypothesis for the end Cretaceous extinction?
A mass extinction occurs when at least 60 percent of species are wiped out within 1 million years. What evidence supports the impact hypothesis for the end-Cretaceous extinction? Sedimentary rocks from the K-Pg boundary layer contain large amounts of iridium.
What is the K-T boundary layer evidence of?
The K-T boundary separates the age of reptiles and the age of mammals, which was first recognized over one hundred years ago by geologists who realized that there was a dramatic change in the types of fossils deposited on either side of this boundary.
What evidence is there that an asteroid struck Earth at the end of the Cretaceous Period?
The evidence for the impact was first discovered by Walter Alvarez and colleagues. They found that rocks laid down precisely at the K-T boundary contain extraordinary amounts of the metal iridium (Figure 18.1). It doesn’t seem to matter whether the boundary rocks were laid down on land or under the sea.
What evidence is there that an asteroid struck Earth at the end of the Cretaceous period?
How long did the KT extinction last?
However, the group at MIT improved they way they collect and analyze these mineral isotopes in the lab—their radiometric dating of the uranium and lead in the zircons show that the extinction event spanned 60,000 years, plus or minus 48,000 years.
What evidence did Luis Alvarez use to propose his hypothesis that an asteroid hit the Earth 65 Mya?
What evidence did Luis Alvarez use to propose his hypothesis that an asteroid hit the earth 65 mya? The element, Iridium, mainly found in asteroids, was discovered in large amounts in the clay.
When was the asteroid theory accepted as the leading cause of dinosaur extinction?
In March 2010, an international panel of scientists endorsed the asteroid hypothesis, specifically the Chicxulub impact, as being the cause of the extinction. A team of 41 scientists reviewed 20 years of scientific literature and in so doing also ruled out other theories such as massive volcanism.
What evidence do geologists use to identify a meteorite impact as the cause of the extinction of the dinosaurs?
Ranging in size from large chunks to tiny beads, impact ejecta are common at or near the Cretaceous/Tertiary (KT) boundary, the geological layer that defines the dinosaur extinction. These crystals, often called “shocked quartz,” show a distinctive pattern of fracturing caused by high-energy impacts or explosions.
What is the evidence for the asteroid?
Evidence For the Asteroid Impact Theory High levels of iridium, a mineral which is rare on Earth but common in asteroids. Iridium is much more common in rocks from the Cretaceous Period than it is in rocks from any other time. A lot of ejecta, small pieces of rock thrown up by big collisions.
What evidence supports the asteroid impact hypothesis?
To test the hypothesis that an asteroid impact caused the K-T mass extinction, key evidence included impact ejecta, tsunami debris, and careful gravitational field measurements.
How did birds survive the dinosaur killing asteroid?
The combination of bigger brains, small size, their ability to eat a wider palate of foods, and their ability to fly ultimately may have helped birds survive the last mass extinction.
What evidence supports the Alvarez hypothesis?
The evidence for the Alvarez impact hypothesis is supported by chondritic meteorites and asteroids which contain a much higher iridium concentration than the Earth’s crust.
What was the critical piece of evidence that supported the dinosaur killing asteroid hypothesis?
In the case of the K-T mass extinction, the critical piece of evidence was finding the impact crater.
How can the evidence for the KT extinction be obtained?
The evidence for the KT extinction can be obtained by comparing the fossils found at the end of the Cretaceous period to that at the beginning of the Tertiary period. The point between the Cretaceous (K) and the Tertiary (T) period is known as the KT boundary.
Did an asteroid hit Earth at the K–Pg boundary?
As iridium remains abundant in most asteroids and comets, the Alvarez team suggested that an asteroid struck the Earth at the time of the K–Pg boundary. There were earlier speculations on the possibility of an impact event, but this was the first hard evidence.
How is evidence for the Tertiary extinction obtained?
Sometimes the remains of the dead organisms are preserved as fossils. The evidence for the KT extinction can be obtained by comparing the fossils found at the end of the Cretaceous period to that at the beginning of the Tertiary period. The point between the Cretaceous (K) and the Tertiary (T) period is known as the KT boundary.
Did an asteroid really kill the dinosaurs?
Most paleontologists now agree that an asteroid did hit the Earth at approximately the end of the Cretaceous, but there was still an ongoing dispute for some time on whether the impact was the sole cause of the extinctions. There is evidence that dinosaurs had been in decline for up to 50 million years already due to changing environmental factors.