GEOLOGY

Detailed explanation-1: -Soft tissue is hard to preserve because it needs to be buried before bacterial decay can occur. This preservation occurs when remains are buried rapidly in an oxygen-free, low-energy sedimentary environment. Since these conditions are uncommon, the preservation of soft tissue rarely happens.

Detailed explanation-2: -When an organism is buried quickly, there is less decay and the better the chance for it to be preserved. The hard parts of organisms, such as bones, shells, and teeth have a better chance of becoming fossils than do softer parts. One reason for this is that scavengers generally do not eat these parts.

Detailed explanation-3: -Fossils also include any preserved trace of life that is typically more than 10 000 years old. Soft body parts decay soon after death, but the hard parts, such as bones, shells and teeth can be replaced by minerals that harden into rock.

Detailed explanation-4: -Nowadays, much of the life that walks, swims, crawls, or slithers has a hard skeleton, and most fossils from the past 400 million years trace those skeletons. But when alive, those creatures are made primarily of soft tissues-brains, muscles, organs, etc.-that often do not get preserved because they decay too quickly.

Detailed explanation-5: -The fossil record is heavily biased towards the preservation of harder parts of organisms, such as shells, teeth, and bones, as the soft-parts such as internal organs, eyes, or even completely soft organisms, such as worms, ordinarily decay away before they can be fossilised.