题型分类：简化句子题

原文分析：本题型要从长难句的内容和逻辑上进行分析。句中没有太明显的逻辑标识词，主要是定语从句部分。从句子主干信息抓起，第一个逗号前表达信息是在1972年两位古生物学家用相反的论点挑战了世俗的结论；an opposing viewpoint 和 the punctuated equilibrium hypothesis 是同位语结构。which 之后是定语从句，表达 the punctuated equilibrium hypothesis 的理论内容，它假设了物种演变为新的物种是在相对突然的爆发中发生的，并非通过长时间的过渡时期。

选项分析：

D选项“The punctuated equilibrium hypothesis, in opposition to gradualism,”对应原句的前半部分“In 1972 paleontologists Stephen Jay Gould and Niles Eldredge challenged conventional wisdom with an opposing viewpoint, the punctuated equilibrium hypothesis,”；“holds that transitions from one species to another occur in comparatively sudden bursts.”对应原句后半部分“which posits that species give rise to new species in relatively sudden bursts, without a lengthy transition period.”主干信息和逻辑都符合。

A选项中“gradualism, which holds that species evolve in relatively sudden bursts of brief duration.” which 后面应该是 The punctuated equilibrium hypothesis 的内容，与原文描述不符。

B选项说“The punctuated equilibrium hypothesis developed by Stephen Jay Gould and Niles Eldredge was challenged in 1972.” 按照原句，被挑战的应该是 gradualism，与原文描述不符。

C选项说“cannot occur without a lengthy transition period”，与原文描述不符。