What caused Cretaceous-Tertiary extinction?
The Cretaceous-Tertiary extinction event, or the K-T event, is the name given to the die-off of the dinosaurs and other species that took place some 65.5 million years ago. For many years, paleontologists believed this event was caused by climate and geological changes that interrupted the dinosaurs’ food supply.
What are two explanations for the mass extinction at the end of the Cretaceous?
The Cretaceous/Paleogene (K/Pg) mass extinction coincided with two major global environmental perturbations: heightened volcanism associated with the Deccan Traps and the Chicxulub asteroid impact (Fig. 1A) (4).
What happened at the Cretaceous-Tertiary boundary?
The Cretaceous–Tertiary extinction event, now called the Cretaceous–Palaeogene extinction event. It may be called the K/T extinction event or K/Pg event for short. This is the famous event which killed the dinosaurs at the end of the Cretaceous period.
What are the 3 theories of dinosaur extinction?
Some of these have dealt with:
- toxic volcanic gases and dust.
- asteroid impact.
- food shortage.
- climate change.
What evidence supports the asteroid impact hypothesis of the Cretaceous Tertiary mass extinction?
Some evidence supporting the impact is the dent and rings that circle the crater which are found submerged underneath the water in the Gulf of Mexico. More supporting evidence is in the form of elevated iridium levels and shocked quarts.
When did the Cretaceous Tertiary mass extinction occur?
66 million years agoCretaceous–Paleogene extinction event / Occurred
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 are major theories explaining the disappearance of the dinosaurs?
Today, paleontologists have discerned that most dinosaur lineages disappeared by about 66 million years ago after intense volcanic activity, climate change and a catastrophic asteroid impact triggered one of the worst mass extinctions in our planet’s history. Many forms of life disappeared.
What is the most widely accepted theory about the extinction of the dinosaurs?
The Alvarez hypothesis
Any fragment of an asteroid that survives landing on Earth becomes known as a meteorite. The Alvarez hypothesis was initially controversial, but it is now the most widely accepted theory for the mass extinction at the end of the Mesozoic Era.
What is the evidence for an impact event at the end Cretaceous and how could this have caused a global mass extinction?
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.
What scientific theories do scientists hold about dinosaur extinction?
For decades, the prevailing theory about the extinction of the dinosaurs was that an asteroid from the belt between Mars and Jupiter slammed into the planet, causing cataclysmic devastation that wiped out most life on the planet.
What are the two major theories to explain the dinosaur extinction?
Luis and Walter Alvarez and others postulated the extinction of the dinosaurs, which had ruled the Earth for about 140 million years, by an asteroid impact and its secondary effects of darkening and cooling of the atmosphere.
What theory explain the extinction of dinosaurs and other plants and animals that ended the Cretaceous Period?
The Alvarez hypothesis was initially controversial, but it is now the most widely accepted theory for the mass extinction at the end of the Mesozoic Era.
What is the hypothesized cause of the Cretaceous Tertiary K-T mass extinction in which many dinosaur lines went extinct describe two major lines of evidence?
Many scientists believe that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of the dinosaurs and many other species near the end of the Cretaceous Period. Follow geologist Jan Smit as he uses samples of Earth’s crust to investigate the K–T extinction.
Which observations finally lead to the hypothesis that an asteroid had hit the Earth at the K-T boundary?
3. What additional observations and findings supported the asteroid-impact hypothesis? Scientists have found glass spherules, shocked quartz, and tektites in the K-T layer. These findings are consistent with a collision or explosion that generated an immense amount of heat and high-energy shock waves.
What evidence supports the impact hypothesis for the end-Cretaceous extinction?
Which observations finally lead to the hypothesis that an asteroid has hit the Earth at the K-T boundary?
What additional observations and findings supported the asteroid-impact hypothesis? Scientists have found glass spherules, shocked quartz, and tektites in the K-T layer. These findings are consistent with a collision or explosion that generated an immense amount of heat and high-energy shock waves.
What evidence is there that the impact of an asteroid on Earth caused the mass extinction at the end of Cretaceous time quizlet?
The first clue that an asteroid had struck earth at around the same time as the mass extinction was the amount of iridium around the K-T boundary. Another clue was that they found that most animals that lived in the cretaceous died when the asteroid crashed and they found bones of animals from the cretaceous.
Which of the following is an evidence of the Cretaceous mass extinction quizlet?
Crater in Yucatan, Mexico that provides evidence of the Cretaceous-Tertiary extinction.
What piece of evidence lead scientists to conclude that the cause of the K-T boundary layer was extraterrestrial in nature?
g. Observing differences in foraminifera fossils above and below the K-T boundary layer. 12A) Which piece of evidence (a-g) lead scientists to conclude that the cause of the K-T boundary layer was extraterrestrial in nature? D, Finding high levels of iridium in the K-T boundary layer.
What caused the Cretaceous-Tertiary mass extinction event?
Other major catastrophes directly caused by the impacts include tsunamis, earthquakes, and possibly increased volcanic activity. All of these devastating events added up to create the results of the Cretaceous-Tertiary Mass Extinction event.
Was there an extraterrestrial impact at the Cretaceous Tertiary boundary?
Other evidence of an extraterrestrial impact from the Cretaceous/Tertiary boundary rocks includes tektites, which are glassy spherules of melt ejected from the crater, and shocked quartz, a form of high pressure quartz only found at other known meteorite impact craters on Earth. The photo below shows tektites from the K/T boundary in Haiti.
Was the Cretaceous biotic crisis caused by extinction from extinction?
the theory of selectivity in species extinction holds good. Volcanic Causes Many palaeontological observations, however, go against an extraterrestrial cause for the Cretaceous biotic crisis. Any impact of extraterrestrial origin should have instantaneous effect on terrestrial life, but evidences show that much of the faunal and
Is there evidence for a massive extinction event near the K-T boundary?
“First evidence for a massive extinction event affecting bees close to the K-T boundary”. PLOS ONE. 8 (10): e76683. Bibcode: 2013PLoSO…876683R. doi: 10.1371/journal.pone.0076683. PMC 3806776. PMID 24194843. ^ a b c d e f Nichols, D. J.; Johnson, K. R. (2008). Plants and the K–T Boundary. Cambridge, England: Cambridge University Press.