求助，gwd上一篇文章我怎么都找不出观点

这个是第22套里的第3篇阅读，我看了7分钟，才把第一题做出来。

有没有人指点下这种文章该怎么分析好呢？ 我看来看去都没看出观点在哪？

The dry mountain ranges of the

Western united states contain rocks

Dating back 440 to 510 million years,

Line to the Ordovician period, and teeming

1)        with evidence of tropical marine life.

This rock record provides clues about

One of the most significant radiations

(periods when existing life-forms gave

rise to variations that would eventually)

10) evolve into entirely new species) in the

history of marine invertebrates. During

this radiation the number of marine

biological families increased greatly,

and these families included species

15) that would dominate the marine ecosys-

tems of the area for the next 215 million

years. Although the radiation span-

ned tens of millions of years, major

changes in many species occurred

20) during a geologically short time span

within the radiation and, furthermore,

appear to have occurred worldwide,

suggesting that external events were

major factors in the radiation. And , in

25) fact, there is evidence of major eco-

logical and geological changes during

this period: the sea level droopped

drastically and mountain ranges were

formed, in this instance, rather than

30) leading to large-scale extinctions,

these kinds of environmental changes

may have resulted in an enriched pat-

tem of habitats and nutrients, which in

turn gave rise to the Ordovician radi-

35) ation, However, the actual relationship

between these environmental factors

and the diversification of life forms is

not yet fully understood

The dry mountain ranges of the        (开篇给出一个事实teeming

Western united states contain rocks      with evidence of tropical marine life)

Dating back 440 to 510 million years,

1)  to the Ordovician period, and teeming

          with evidence of tropical marine life.     

This rock record provides clues about    (接下来讲该事实的意义即证明了
            

One of the most significant radiations
                    有一个radiations,在此期间

(periods when existing life-forms gave     marine invertebrates evolve

rise to variations that would eventually     into entirely new species

10) evolve into entirely new species) in the

history of marine invertebrates. During

this radiation the number of marine

biological families increased greatly,

and these families included species

15) that would dominate the marine ecosys-

tems of the area for the next 215 million

years. Although the radiation span-        (转折递进, 有可能考细节题)

ned tens of millions of years, major(说明了evolve过程的特点greatly, quickly

changes in many species occurred
                 and     worldwide,)

20) during a geologically short time span

within the radiation and, furthermore,
            

appear to have occurred worldwide,

suggesting that external events were       (这些特点又进一步证明了external

major factors in the radiation. And, in     event是radiation形成的原因)

25) fact, there is evidence
                of major eco-

logical and geological changes during

this period: the sea level droopped

drastically and mountain ranges were

formed, in this instance, rather than
            

30) leading to large-scale extinctions,

these kinds of environmental changes

may have resulted in an enriched pat-

tem of habitats and nutrients, which in  (呼应上文, 得出结论造山运动极大的丰

turn gave rise to the Ordovician radi-   富了物种)

35) ation,
                However, the actual relationship

between these environmental factors

and the diversification of life forms is

not yet fully understood (结尾让步,以示严谨)

 有题目吗. 有时候通过题目可以了解文章的意图, 像这种自然科学的文章 结论就是观点