托福口语经典文章系列之罕见的化石记录A Rare Fossil Record

所属专题:托福口语  来源:小站教育    要点:托福口语,托福口语范文  
编辑点评: 托福口语的备考和考试当中,考生往往会准备一些模板以方便大家更好的做题,但是在复习的时候一些托福口语的经典题目及答案都是大家很好的复习材料。不知道大家对于些比较好的托福口语高分文章怎么看,小编认为这些资料对于你的托福口语复习非常有帮助。

托福口语备考过程中大家往往会用到一些素材或者模板之类的,其实一些优秀的托福口语范文也是非常不错的。不知道大家在平时的备考过程中收集到了哪些,今天小编在这里为大家整理了托福口语经典文章,希望对大家托福口语提分有帮助。

托福口语必背篇经典文章:罕见的化石记录A Rare Fossil Record
The preservation of embryos and juveniles is a rate occurrence in the fossil record. The tiny, delicate skeletons are usually scattered by scavengers or destroyed by weathering before they can be fossilized. Ichthyosaurs had a higher chance of being preserved than did terrestrial creatures because, as marine animals, they tended to live in environments less subject to erosion. Still, their fossilization required a suite of factors: a slow rate of decay of soft tissues, little scavenging by other animals, a lack of swift currents and waves to jumble and carry away small bones, and fairly rapid burial. Given these factors, some areas have become a treasury of well-preserved ichthyosaur fossils.
The deposits at Holzmaden, Germany, present an interesting case for analysis. The ichthyosaur remains are found in black, bituminous marine shales deposited about 190 million years ago. Over the years, thousands of specimens of marine reptiles, fish and invertebrates have been recovered from these rocks. The quality of preservation is outstanding, but what is even more impressive is the number of ichthyosaur fossils containing preserved embryos. Ichthyosaurs with embryos have been reported from 6 different levels of the shale in a small area around Holzmaden, suggesting that a specific site was used by large numbers of ichthyosaurs repeatedly over time. The embryos are quite advanced in their physical development; their paddles, for example, are already well formed. One specimen is even preserved in the birth canal. In addition, the shale contains the remains of many newborns that are between 20 and 30 inches long.
Why are there so many pregnant females and young at Holzmaden when they are so rare elsewhere? The quality of preservation is almost unmatched and quarry operations have been carried out carefully with an awareness of the value of the fossils. But these factors do not account for the interesting question of how there came to be such a concentration of pregnant ichthyosaurs in a particular place very close to their time of giving birth.
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