The five generally recognized mass extinction events, indicated by red arrows al

Question

The five generally recognized mass extinction events, indicated by red arrows along the x-axis, represent peaks in the extinction rate of marine animal families (red line and left vertical axis). These mass extinctions interrupted the overall increase in the number of marine animal families over time (blue line and right vertical axis). 96% of marine animal species became extinct in the Permian mass extinction at the end of the Paleozoic, 252 million years ago. Why does the blue curve show only a 50% drop at that time? Although the extinction rate of 96% was high, the number of species in existence was also very high, so that even after the mass extinction, many species remained. The species that survived the mass extinction diversified very quickly so that the number of families in existence first plummeted but then rapidly increased to 50% of the number before the mass extension. Although 96% of marine animal species became extinct, the extinction rate was far lower for terrestrial species. Families typically contain many species, so the percentage of families that became extinct is lower than the percentage of species that became extinct.

Explanation / Answer

b) those that survived diversified quickly and reached to 50%.

Since survived extinction they would be much fitter to adapt to the current environmental conditions and hence would be able to reproduce faster.

Not 1st option because the graph plotted is for families in general irrespective of which species it belongs to. It is 96% of families of all species put together.

Not 3rd option because only marine families are considered in this study. Terrestrial are nowhere in the picture.

Not 4th option because similar argument done for option 1.

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