Question

Plants and animals that die under certain conditions, such as being rapidly buried by sediment, are more likely to be preserved as fossils. The endangered Chisos agave plant is found only in the grasslands of Big Bend National Park. The table below shows the cause of death for Chisos agave plants over one year.

Chisos Agave Plants

Cause of Plant Death Number of Plants Was fossilization possible?
Consumed by animals 70 No
Burned by wildfire 129 No
Trampled/killed by trail and road maintenance 75 No
Buried by mud due to flooding of the Rio Grande river 7 Yes
Died of unknown causes, evidence of decayed material was present 38 No

Which of the following statements uses the data above to provide evidence to explain why most organisms that lived in the past were never fossilized?
A.
Very few of the plants died under conditions where a fossil might form.
B.
More of the plants were burned by wildfire than were consumed by animals.
C.
Plants killed by human activity were more likely to be preserved artificially by scientists.
D.
Plants consumed by animals were more likely to be preserved as fossils.

Answer 1

A.

Only a tiny fraction of deaths (7 out of 319, ≈2.2%) occurred under conditions that could lead to fossilization (rapid burial). The rest died in ways that prevent preservation, so most organisms are never fossilized.