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

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Mean shell length of a model oyster species by rock layer (model data)

   layer	age (million years ago)	mean shell length (mm)
   1	10	18
   2	7	24
   3	4	30
   4	1	36

2. 1.

   Ari reads a model fossil series for an oyster species. What was the average rate of change from the oldest layer to the youngest layer?

   • 18 mm per million years
   • 6 mm per million years
   • 2 mm per million years
   • 0.5 mm per million years

3. Mean leaf length of a model shrub species by rock layer (model data)

   layer	age (million years ago)	mean leaf length (mm)
   1	14	30
   2	11	30
   3	8	30
   4	5	30
   5	4.5	42

4. 2.

   Esme reads a model fossil series for a shrub. For how many million years did the leaf length stay at 30 mm, from layer 1 to layer 4?

   • 5 million years
   • 0.5 million years
   • 14 million years
   • 9 million years

5. Mean shell width of two model snail species (model data)

   age (million years ago)	species A (mm)	species B (mm)
   8	10	10
   6	12	10
   4	14	10
   2	16	24

6. 3.

   Jun compares two model fossil series. Which statement fits both species?

   • Both change in small steady steps, since evolution is slow and steady
   • Species B stopped evolving, since its flat stretch shows it cannot change
   • Species A changed in steady steps, while B held steady and then changed
   • Species B changed in a moment, with no time passing between layers 3 and 4

7. Mean trait values of two model species (model data)

   age (million years ago)	species X (mm)	species Y (mm)
   9	15	12
   7	18	12
   5	21	12
   3	24	12
   1	27	30

8. 4.

   Luz reads two model fossil series. Which conclusion do the two series support?

   • Species Y changed overnight, so gradual change cannot happen
   • Gradual change is the rule, so the jump in species Y must be a mistake
   • Gradual change does not happen, since species Y shows a quick jump
   • Both patterns can happen, so a quick change does not rule out gradual change

9. The five mass extinctions (real data from Biology 2e Table 47.2)

   mass extinction	time (million years ago)
   end-Ordovician	450–440
   Late Devonian	375–360
   end-Permian	251
   end-Triassic	205
   end-Cretaceous (K–Pg)	65.5

10. 5.

    Milo reads the table of the five mass extinctions. How many million years passed between the end-Permian and the end-Cretaceous?

    • 139.5 million years
    • 316.5 million years
    • 46 million years
    • 185.5 million years

11. Recovery after two mass extinctions (real data from Biology 2e)

    mass extinction	what recovered	time to recover (million years)
    end-Permian	land animals with four limbs (tetrapods)	30
    end-Cretaceous	biodiversity	about 10

12. 6.

    Noah reads two recovery times. About how many times as long was the end-Permian recovery as the end-Cretaceous recovery?

    • About 20 times as long
    • About 3 times as long
    • About one third as long
    • About 40 times as long

13. Share of species that became extinct at the end-Permian (real data from Biology 2e)

    group	share that became extinct (percent)
    marine species	96
    land species	70

14. 7.

    Pia applies the end-Permian shares to a model sample of 200 marine species. About how many became extinct?

    • About 200 species, since life on Earth ended
    • About 192 species
    • About 8 species
    • About 96 species

15. Model fossil counts below and above a layer where the climate changed (model data)

    species	below the layer	above the layer
    A	120	340
    B	80	0
    C	0	55

16. 8.

    Ren compares fossil counts below and above a layer where the climate changed. Which statement fits the counts?

    • Species B became extinct, so no life was left in the layer above it
    • Species A and B became extinct, and species C grew in number
    • Species C grew in number, and species A is a new species
    • Species A grew in number, B became extinct, and C is a new species

17. Species on a model island, each in a different habitat, since one founder species arrived (model data)

    time (million years ago)	species on the island
    3	1
    2	3
    1	5
    0	7

18. 9.

    Tala reads a model island table. What is the pattern called, and how many species formed per million years on average?

    • Mass extinction, losing 2 species per million years
    • Adaptive radiation, adding 2 species per million years
    • Adaptive radiation, adding 7 species per million years
    • Stasis, adding 2 species per million years

19. Background extinction rate and a model group (rate from Biology 2e, model group)

    quantity	value
    background rate	about 1 extinction per million species per year
    species in the model group	2.5 million
    time	2 years

20. 10.

    Zee uses the background rate on a model group. About how many species in the group would become extinct in 2 years?

    • About 2 species
    • About 1.25 species
    • About 2.5 species
    • About 5 species