OG11-21 and 的用法好奇怪啊

21.   Paleontologists believe that fragments of a primate jawbone unearthed in Burma
                and estimated at 40 to 44 million years old provide evidence of a crucial step along the evolutionary path that led to human beings.

(A) at 40 to 44 million years old provide evidence of

(B) as being 40 to 44 million years old provides evidence of

(C) that it is 40 to 44 million years old provides evidence of what was

(D) to be 40 to 44 million years old provide evidence of

(E) as 40 to 44 million years old provides evidence of what was

本题答案D不难，由主谓一致排除B.C.E,estimated 被动接续排掉A，可是我看不懂这个and 前后的并列成分是什么。我觉得Paleontologists believe that fragments（of a primate jawbone unearthed in Burma）(that is )estimated.........原文为什么要用这个and呢，我比较笨，请牛牛解答下，谢谢

哦，懂了谢谢。