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现在许多物种灭绝可能消失没有化石痕迹

新闻来源:admin 发布时间:2018-09-24

We judge our planet’;s biological past by using geological evidence –; fossils。 Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past。 But not organisms form fossils, and not all fossils are preserved。 Now, a new study found that many species might be vanishing without a trace, and this could make geologists underestimate previou****tinctions and disruptive events。

Roy Plotnick, professor of earth and environmental sciences at the University of Illinois at Chicago and two colleagues analyzed the “;Red List”; of endangered species, comparing it to the existing fossil record for those species。 Surprisingly, they found that more than 85 percent of the mammal species at high risk of extinction lack a fossil record! In other words, previou****tinctions may have been much more dramatic, but the evidence has since washed away。

Animals least likely to be found as fossils are “;the small, cute and fuzzy ones, like rodents and bats,”; Plotnick said。 “;Body size is an obvious factor —; bigger things tend to leave a fossil record, as do things with larger geographical ranges。”;

In order for fossils to form, empty spaces within an organism (spaces filled with liquid or gas during life) become filled with mineral-rich groundwater。 Minerals precipitate from the groundwater, occupying the empty spaces。 Another fossilization phenomenon is casting –; when the remains of a creature create an external or internal mold around them。 Needless to say, both these processes take specific conditions, and these conditions aren’;t always satisfied。 In fact, they are apparently very rarely satisfied。 This is also the reason why it’;s so hard to find some key fossils, especially of the so-called missing links –; because they might have simply not left any fossils behind (or very few)。

本文源自: 环亚娱乐



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