Answer:
- Even though fossils from more than 200,000 different species have been found, the fossil record remains incomplete.
- Fossilization has occurred at multiple times during the prehistory of the earth.
Explanation:
The age of fossils can be determined through several methods, the most common of which is radiometric dating, which establishes how old a fossil is by comparing the radioactive isotopes within it and measuring how much they have decayed over time. Also, during fossilization, hard tissue such as bones and teeth is more likely to get fossilized than soft tissue such as skin or organs, which rapidly degrade after a living organism dies. And while the seabed might hold some fossils, it is very difficult to reach them, while the immense crush depth might have ruined already existing fossils.
The true options here are two: even though fossils from more than 200,000 different species have been found, the fossil record remains incomplete. This happens because fossilization has been a random process, and the only fossilized remains that have made it to this day are those of species that happened to die under the precise circumstances that allowed their remains to be fossilized, and from these, those lucky enough to have been unearthed by palenthologists. This is why the human fossil record still remains incomplete, with several important gaps in the evolutionary process of human beings. Also, fossilization has occurred at multiple times during the prehistory of the Earth. It hasn't been a one off event, but it's been an ongoing process ever since the appearance of life on Earth.
