Such changes are all but invisible over the short time scale of modern observations, and, it is argued, they are usually obscured by innumerable gaps in the imperfect fossil record.

这些变化在现代观测短时间范围内几乎是看不见的，而且，有人认为，这些变化常常被不完善的化石记录中的无数空白所掩盖。