单项选择题
| It is animals and plants which lived in
or near water whose remains are most likely to be preserved, for one of the
necessary conditions of preservation is quick burial, and it is only in the seas
and rivers, and sometimes lakes, where mud and silt have been continually
deposited, that bodies and the like can be rapidly covered over and
preserved. But even in the most favorable circumstances only a small fraction of the creatures that die are preserved in this way before decay sets in or, even more likely, before scavengers eat them. After all, all living creatures live by feeding on something else, whether it be plant or animal, dead or alive, and it is only by chance that such a fate is avoided. The remains of plants and animals that lived on land are much more rarely preserved, for there is seldom anything to cover them over. When you think of the innumerable birds that one sees flying about, not to mention the equally numerous small animals like field mice and voles which you do not see, it is very rarely that one comes across a dead body, except, of course, on the roads. They decompose and are quickly destroyed by the weather or eaten by some other creatures. |