Dinosaurs & Prehistoric Life · Unit 8
The Great Extinction
The asteroid, the volcanoes and who survived
The end-Cretaceous extinction is the best-understood mass extinction in the record, and it is still argued about, because an asteroid and a volcanic province arrived close enough together to be hard to separate.
The unit covers the Chicxulub impact, the Deccan volcanism, the evidence preserved in the rock layer, and the question of who survived and why.
This unit breaks down into 18 short steps and 109 questions, starting at difficulty 2 and building to 3. Below you can see exactly what it covers, how the path is structured, and worked examples with explanations.
- Steps
- 18
- Questions
- 109
- Difficulty
- 2-3
What this unit covers
- The Evidence in the Rocks
- Who Survived
- The Asteroid Impact
- Volcanoes and Climate
- The Chicxulub Crater
Where this fits
Follows The Age of Dinosaurs. Leads into After the Dinosaurs.
Where people slip
Non-avian dinosaurs died out; dinosaurs did not. Birds are dinosaurs and came through, which is why the qualifier matters.
How the unit is structured
The Great Extinction runs as 18 short steps that unlock in order. 13 are practice rounds and 5 are challenge rounds that pull together everything before them. Questions start at difficulty 2 and climb to 3 as you progress.
Challenge rounds
Example questions
30 real questions from this unit, with the answer and the reason behind it, grouped by what they practise. There are 109 in the unit altogether.
The Asteroid Impact
- Fact or fibLevel 2
1. The impact set off huge waves and fires as well as darkness.
Answer: True
True. Tsunamis, wildfires and earthquakes followed the strike.
- Fill the blankLevel 2
2. The cold, dark period after the impact is often called an impact ____.
- wintercorrect
- summer
- harvest
- holiday
An impact winter chilled the whole planet.
- Guess the numberLevel 2
3. How many millions of years ago did the great extinction happen?
Answer: 66 million years
It happened about 66 million years ago.
- Multiple choiceLevel 2
4. About how wide was the asteroid that ended the age of dinosaurs?
- About ten kilometrescorrect
- About ten metres
- About one thousand kilometres
- About one centimetre
Estimates put it at roughly ten to twelve kilometres across.
- True or falseLevel 2
5. The impact threw enormous amounts of dust and gas into the sky.
Answer: True
True, and that material blocked sunlight around the world.
- Choose all that applyLevel 3
6. Which immediate effects followed the impact? Pick all that apply.
- Massive earthquakescorrect
- Giant tsunamiscorrect
- A pulse of heat from falling debriscorrect
- A worldwide snowfall of ash within seconds
Earthquakes, tsunamis and thermal pulses all struck within hours.
The Chicxulub Crater
- Fact or fibLevel 2
7. The Yucatan rocks at the impact site were rich in sulphur, which made the aftermath worse.
Answer: True
True. Vaporised sulphur created a cooling haze around the world.
- Fill the blankLevel 2
8. The Chicxulub crater lies partly under the ____ and partly under land.
- seacorrect
- desert
- ice sheet
- volcano
Half of it lies beneath the Gulf of Mexico.
- Multiple choiceLevel 2
9. How wide is the Chicxulub crater?
- About 180 kilometrescorrect
- About 2 kilometres
- About 20 metres
- About 5000 kilometres
It is roughly 180 kilometres across, one of the largest known on Earth.
- True or falseLevel 2
10. The crater is buried and cannot be seen on the surface today.
Answer: True
True. It is hidden under later rock and sediment.
- Type the answerLevel 2
11. What is the name of the buried crater in Mexico linked to the extinction?
Answer: Chicxulub
Chicxulub is named after a nearby village.
- Choose all that applyLevel 3
12. Which techniques confirmed Chicxulub as the impact site? Pick all that apply.
- Geophysical surveyscorrect
- Drill cores from the cratercorrect
- Matching debris in boundary layerscorrect
- Eyewitness accounts
Geophysical surveys, drill cores and matching boundary debris all contributed.
The Evidence in the Rocks
- Build the sentenceLevel 2
13. Build a sentence about the extinction.
Answer: An asteroid struck Earth long ago
An asteroid struck Earth sixty-six million years ago.
- Choose all that applyLevel 2
14. Which clues at the boundary point to an impact? Pick all that apply.
- Iridiumcorrect
- Shocked quartzcorrect
- Tiny glass beadscorrect
- Fossil footprints
Iridium, shocked quartz and tiny glass beads all indicate a violent impact.
- Multiple choiceLevel 2
15. What unusual metal is found in a thin clay layer worldwide at the extinction boundary?
- Iridiumcorrect
- Iron
- Gold
- Aluminium
Iridium is rare in Earth's crust but common in asteroids.
- Put in orderLevel 2
16. Put the discovery of the impact story in order.
Answer: A strange iridium layer is found -> An asteroid impact is proposed -> A buried crater is identified -> The crater is drilled and studied
Iridium was found first, then the idea proposed, then the crater identified.
- True or falseLevel 2
17. Grains of quartz shattered by enormous pressure are also found at the boundary.
Answer: True
True. Shocked quartz forms in impacts and nuclear blasts, not ordinary volcanism.
- Fact or fibLevel 3
18. The asteroid hypothesis was widely resisted at first before the evidence became overwhelming.
Answer: True
True. It took a decade and the crater's identification to convince most researchers.
Volcanoes and Climate
- Choose all that applyLevel 2
19. Which effects can huge volcanic eruptions have? Pick all that apply.
- Cooling from sulphur particlescorrect
- Warming from carbon dioxidecorrect
- Acid rain and ocean acidificationcorrect
- Increasing Earth's gravity
They release gases that cool, warm and acidify, damaging ecosystems.
- Fact or fibLevel 2
20. Most scientists now think the asteroid impact was the main cause of the extinction.
Answer: True
True, though many accept volcanism made conditions worse.
- Multiple choiceLevel 2
21. What are the Deccan Traps?
- Vast layers of volcanic rock in Indiacorrect
- A kind of dinosaur trap
- A group of islands
- A mountain range in Peru
They are huge layers of volcanic rock in India, left by eruptions around the end of the Cretaceous.
- True or falseLevel 2
22. Volcanic gases can change the climate by both warming and cooling the planet.
Answer: True
True. Carbon dioxide warms while sulphur particles cool.
- Type the answerLevel 2
23. In which country are the Deccan Traps?
Answer: India
They cover a huge area of western India.
- Choose all that applyLevel 3
24. Which gases from volcanism affect climate? Pick all that apply.
- Carbon dioxidecorrect
- Sulphur dioxidecorrect
- Chlorine compoundscorrect
- Helium
Carbon dioxide, sulphur dioxide and chlorine compounds all matter.
Who Survived
- Choose all that applyLevel 2
25. Which groups survived the extinction? Pick all that apply.
- Birdscorrect
- Mammalscorrect
- Crocodilianscorrect
- Mosasaurs
Birds, mammals, crocodilians and turtles all made it through.
- Fact or fibLevel 2
26. After the dinosaurs disappeared, mammals grew larger and more varied.
Answer: True
True. Empty ecosystems gave them room to expand.
- Multiple choiceLevel 2
27. Which dinosaurs survived the extinction?
- Birdscorrect
- Tyrannosaurs
- Sauropods
- None at all
Only the birds, which are dinosaurs, made it through.
- Sort into groupsLevel 2
28. Sort each group by whether it survived the extinction.
Answer: Birds = Survived; Mammals = Survived; Pterosaurs = Died out; Ammonites = Died out
The extinction was selective, not random.
- True or falseLevel 2
29. Crocodiles and turtles both survived the extinction.
Answer: True
True. Freshwater animals did comparatively well.
- Type the answerLevel 2
30. Which living animals are the direct descendants of dinosaurs?
Answer: birds
Birds carry the dinosaur line into the present.
Where these questions come from. Each unit starts as a plan of the concepts it should cover and the difficulty it should span. Questions are written against that plan with AI assistance, then checked by a validator that rejects anything without a single defensible answer, an explanation, or plausible wrong options. How we write questions sets out the whole process, and corrections are fixed in the bank and reach the site and the app the same day.
How you practise
This unit mixes 10 different question formats, so you are recalling and applying rather than recognising the same layout every time.
- Build the sentence
- Choose all that apply
- Fact or fib
- Fill the blank
- Guess the number
- Multiple choice
- Put in order
- Sort into groups
- True or false
- Type the answer
Practise The Great Extinction
109 questions across 18 steps. Start with step one and crawl at your own pace.
Play this unitRead about The Great Extinction
Explainers from our blog on what this unit covers. Each one ends with real questions from the bank.
- What Killed the Dinosaurs?The asteroid impact, the crater it left, what happened in the months afterwards, and why birds survived when almost nothing else did.August 28, 2026 · 6 min read
- What Was the Permian Extinction? The Day Life Nearly EndedAbout 252 million years ago most species on Earth vanished in the worst extinction known. What caused it, how long recovery took, and what it says about carbon.September 9, 2026 · 4 min read
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