File:Extinction Intensity(in Chinese).jpg
Extinction_Intensity(in_Chinese).jpg (577 × 428 pixels, file size: 74 KB, MIME type: image/jpeg)
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DescriptionExtinction Intensity(in Chinese).jpg |
此幅图表显示了各个时期在属的层面上物种的灭绝强度,即一个时期灭绝的物种的属的数量占该时期物种总属量的比重。图表数据来源于罗德与穆勒(2005年补充材料),并依据Sepkoski所著《海洋动物化石汇编》(Compendium of Marine Fossil Animal Genera)(2002年)制表。图中黄线表示一个用以指向物种灭绝长期趋势的三次多项式。需要注意这些数据并不能代表各个时期的所有物种,而仅仅局限于海洋动物,这是因为海洋环境使得海洋物种更易于得到完整的保存,成为留存至今的化石。 图中显示了5次较大规模的物种灭绝事件,使用较大字体标出;另外还有多次较小的物种灭绝事件,使用较小字体标出。发生在寒武纪时期的两次物种灭绝事件(即德雷斯巴奇阶灭绝事件和波托米阶灭绝事件)中灭绝物种占总物种数的比重相当惊人,但是由于缺乏留存下来的化石而不为人熟知。许多科学家主张中二叠世灭绝事件应该是一个更大规模的灭绝事件的构成部分;而在报告中,该时期物种灭绝的数量往往与二叠纪灭绝事件的数据向混杂。如图所示,晚泥盆纪灭绝事件事实上包括了三起独立的灭绝事件,总跨度达4,000万年。这些数据都只是统计至“属”的层面上,可以预料到,(当统计至更低层级时)灭绝强度比之图表更高。 统计数据中,许多灭绝事件在时间上似乎都被拉长了。在某些案例中这是由古生物学上的人为影响造成的,被称为西格诺-利普斯效应(Signor-Lipps effect)。简单的说,采样不足会造成一个物种被误认为在其真正灭绝之前就已消失。这将导致一个过程较短的灭绝事件的时间维度被拉长了。所以,当统计一个灭绝事件的灭绝量时,往往会包括多个独立的灭绝事件及其间的灭绝低谷期。这可以解释为何诸多统计得出的灭绝强度比之事实上的灭绝强度要高20-30%。 |
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Source | Originally from en.wikipedia; description page is/was here. | |||||
Author | This figure was originally created by Dragons flight and then altered by johnbobyray | |||||
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current | 10:33, 26 April 2009 | 577 × 428 (74 KB) | Johnbobyray (talk | contribs) | {{Information |Description=此幅图表显示了各个时期在属的层面上物种的灭绝强度,即一个时期灭绝的物种的属的数量占该时期物种总属量的比重。图表数据来源于罗德与穆勒(2005年补充材料),并� |
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File change date and time | 18:12, 26 April 2009 |
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