The geologic time scale and the great extinctions
Grade 9 Science Worksheet - Challenge Me

Circle the best answer.
Branching tree that narrows, then spreads out again. A classmate says mass extinctions show life on Earth keeps shrinking. Which reply fits the NPS evidence, by Esme's reading?
- Correct; each extinction left fewer groups for good
- Variety stays the same through each extinction
- Correct; variety has dropped since the first extinction
- Variety drops sharply, then bursts of new species rebuild it
Read this first
The Big Five (NPS)
Extinction About when Species lost end-Ordovician 444 million years ago 86% Late Devonian 372 million years ago 75% end-Permian 251.9 million years ago 96% end-Triassic 200 million years ago 80% end-Cretaceous 66 million years ago 76% Why is the end-Cretaceous the extinction scientists tie to an asteroid, by Jun's reading (NPS)?
- Its rocks hold flood basalts from that time
- A huge impact crater of the same age has been found
- Glacier deposits from that time cover much of the poles
- It is the oldest of the Big Five
A student says the end-Permian and end-Cretaceous extinctions had the same cause. Which reply fits NPS, by Kira's reading?
- Yes: both followed glaciations
- Yes: both followed asteroid impacts
- No: an asteroid for the end-Permian, volcanoes for the end-Cretaceous
- No: flood basalts for one, an asteroid for the other
Eras (USGS)
Era Began Ended Paleozoic 541 million years ago 251.9 million years ago Mesozoic 251.9 million years ago 66 million years ago Cenozoic 66 million years ago today The Paleozoic lasted about 289 million years, the Mesozoic about 186 and the Cenozoic 66 so far (USGS). About what share of the last 541 million years is the Cenozoic, by Luz's math?
- About 34%
- About 53%
- About 66%
- About 12%
The Big Five (NPS)
Extinction About when Species lost end-Ordovician 444 million years ago 86% Late Devonian 372 million years ago 75% end-Permian 251.9 million years ago 96% end-Triassic 200 million years ago 80% end-Cretaceous 66 million years ago 76% The end-Ordovician (444) and end-Cretaceous (66 million years ago) are the first and last of the Big Five. On average, about how far apart are the five, by Milo's math?
- About 95 million years
- About 378 million years
- About 76 million years, from dividing by 5
- About 95 thousand years
If Earth's 4,600 million years were a 100-meter track, how far from the finish line would the end-Permian extinction sit, by Noah's math?
- About 5.5 meters
- About 55 meters
- About 5.5 kilometers
- About 0.5 meters
The Big Five (NPS)
Extinction About when Species lost end-Ordovician 444 million years ago 86% Late Devonian 372 million years ago 75% end-Permian 251.9 million years ago 96% end-Triassic 200 million years ago 80% end-Cretaceous 66 million years ago 76% NPS lists several suggested causes for the Late Devonian extinction about 372 million years ago. Which statement fits, by Pia's reading?
- No single cause has strong evidence yet
- Flood basalts are the settled cause
- An asteroid impact is the settled cause
- It is a dating error, and no extinction happened
Four evidence cards, labeled A to D. Which evidence would most strongly support an asteroid cause for an extinction layer, by Ren's reading?
- An iridium layer and a crater of the same age
- Fewer fossils above the layer, by itself
- Glacier deposits just below the layer
- A thick stack of flood basalts of the same age
The Big Five (NPS)
Extinction About when Species lost end-Ordovician 444 million years ago 86% Late Devonian 372 million years ago 75% end-Permian 251.9 million years ago 96% end-Triassic 200 million years ago 80% end-Cretaceous 66 million years ago 76% NPS: the end-Triassic extinctions came over some time, linked to eruptions along rifts as the Atlantic opened. What does this suggest, by Tala's reading?
- Each mass extinction took a single day
- The Atlantic opened in the last million years
- An asteroid opened the Atlantic
- A mass extinction can unfold over a stretch of time
Which summary of the end-Cretaceous fits NPS, by Zee's reading?
- A glaciation, 86% of species lost, then stony corals spread
- An asteroid impact, then variety stayed low
- An asteroid impact, 76% of species lost, then mammals flourished
- Flood basalts, 96% of species lost, then trilobites spread