Why are fossils of early life on Earth more rare than fossils of plants and animals from the past few hundred million years?
A) Life was far less abundant prior to a few hundred million years ago.
B) Early organisms lacked skeletons and other hard structures that are most likely to be fossilized.
C) Fossils could not form before there was oxygen in the atmosphere.
D) We find fossils in sedimentary layers, and no sediments were deposited until just a few hundred million years ago.
Question 2
If there are other civilizations at present in the Milky Way Galaxy, which statement is almost undoubtedly true?
A) They are far more technologically advanced than we are.
B) They are anatomically much like us, with two arms, two legs, two eyes, and two ears.
C) They have social structures that are completely different from our own; for example, different types of family units, and so on.
D) For fun, they enjoy buzzing to Earth and temporarily abducting people, showing a clear preference for people located in less-developed rural areas.
Wood first appeared in plants called progymnosperms.
Discovering Fossils 11-30
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