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题目材料：
According to one current hypothesis, the typical evolutionary history of a species involves a quick origin, followed by a long period of stability of form, or stasis, and then rapid disappearance. The sudden appearance of new species, once attributed to supposed gaps in the fossil record, is thought to represent accurately the histories of species.
There is, however, doubt about some of the scientific evidence for this evolutionary pattern, particularly the extent to which species exhibit stasis. For example, species with a large population are more likely to exhibit relative stasis, but they are also more likely to be found in the fossil record. Moreover, it is invariably only the hard body parts of any organism that are fossilized.Variations over time in soft body parts, in biochemistry, and in behavior largely escape the fossil record; thus, fossil traces preserve only a minute portion of a species' traits. Furthermore,since so few individual organisms leave fossils, the record of a species is likely to understate variation in that species.
There is, however, doubt about some of the scientific evidence for this evolutionary pattern, particularly the extent to which species exhibit stasis. For example, species with a large population are more likely to exhibit relative stasis, but they are also more likely to be found in the fossil record. Moreover, it is invariably only the hard body parts of any organism that are fossilized.Variations over time in soft body parts, in biochemistry, and in behavior largely escape the fossil record; thus, fossil traces preserve only a minute portion of a species' traits. Furthermore,since so few individual organisms leave fossils, the record of a species is likely to understate variation in that species.
以上解析由 考满分老师提供。
