Fast and slow change, and extinction, in the fossil record

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Mean shell width of a model snail species by rock layer (model data)

   layer	age (million years ago)	mean shell width (mm)
   1	10	12
   2	8	14
   3	6	16
   4	4	18
   5	2	20

2. 1.

   Ari reads a model fossil series for a snail species. What was the mean shell width in the layer that is 6 million years old?

   • 6 mm, from layer 3
   • 18 mm, from layer 4
   • 14 mm, from layer 2
   • 16 mm, from layer 3
3. 2.

   Bo reads a model graph of clam shell length through rock layers. What was the mean shell length 6 million years after the oldest layer?

   • 30 mm
   • 20 mm
   • 6 mm
   • 50 mm

4. Mean leaf length of a model plant species by rock layer (model data)

   layer	age (million years ago)	mean leaf length (mm)
   1	12	40
   2	9	44
   3	6	48
   4	3	52

5. 3.

   Esme reads a model fossil series for a plant species. How many million years separate the oldest layer from the youngest layer?

   • 9 million years
   • 12 million years
   • 3 million years
   • 15 million years

6. Mean shell height of a model mussel species by rock layer (model data)

   layer	age (million years ago)	mean shell height (mm)
   1	10	30
   2	8	33
   3	6	36
   4	4	39
   5	2	42

7. 4.

   Jun reads a model fossil series for a mussel species. Which pattern of change does the series show?

   • Stasis: the height stays the same through the series
   • Extinction: the species is missing from the later layers
   • Gradual: small steady steps from layer to layer
   • Punctuated: long flat stretches with one quick jump

8. Mean beak length of a model bird species by rock layer (model data)

   layer	age (million years ago)	mean beak length (mm)
   1	8	14
   2	6	14
   3	4	14
   4	3.5	22
   5	1.5	22

9. 5.

   Kira reads a model fossil series for a bird species. Which pattern fits the series?

   • Punctuated: the beak changed in a single moment, with no time passing
   • Stasis: the beak length stays the same through the series
   • Punctuated: long stasis, then a quick change, then stasis again
   • Gradual: small steady steps through the whole series

10. Recovery after three mass extinctions (real data from Biology 2e)

    mass extinction	what recovered	time to recover (million years)
    end-Ordovician	biodiversity	5 to 20, depending on location
    end-Permian	land animals with four limbs (tetrapods)	30
    end-Cretaceous	biodiversity	about 10

11. 6.

    Noah reads recovery times after three mass extinctions. Which statement fits the table?

    • After the end-Permian, life ended for 30 million years before it began again
    • Diversity recovered after each one, in about 5 to 30 million years
    • The three recoveries took the same 10 million years
    • The end-Cretaceous took longest to recover, about 65 million years

12. Notes on the end-Cretaceous mass extinction (real data from Biology 2e)

    topic	note
    when	about 65 million years ago
    cause scientists understand best	an asteroid impact off the coast of the Yucatán Peninsula
    dinosaurs	most became extinct, but one theropod line continued as birds
    recovery of biodiversity	on the order of 10 million years

13. 7.

    Pia reads notes on the end-Cretaceous mass extinction. What do the notes say about the dinosaurs?

    • They became extinct and left no descendants, so birds come from another group
    • Most became extinct, and one theropod line continued as birds
    • One theropod line became extinct, and the other lines continued as birds
    • They were not affected, and other groups became extinct

14. Word card (definition from Biology 2e)

    word	where it is used
    punctuated equilibrium	a model of how quickly species change in the fossil record

15. 8.

    Ren reads a word card. Which meaning fits punctuated equilibrium?

    • A species that stays fixed for good and cannot evolve again later
    • A new species that appears at once, with no time passing
    • Change in small steady steps through the whole history
    • Long stretches of little change, broken by quick changes
16. 9.

    Tala reads a word card about dinosaurs. What does the card say about birds?

    • Birds descend from a theropod line of dinosaurs
    • Birds became extinct along with most dinosaurs
    • Birds come from another group, because dinosaurs left no descendants
    • Birds are a kind of theropod that became extinct
17. 10.

    Zee reads a word card. Which meaning fits mass extinction?

    • One species becoming extinct at the usual background rate, in a quiet year
    • A period when species became extinct at a rate far above usual
    • A time when life ended everywhere and nothing recovered after it
    • A slow, steady loss of one species over a very long time span