Q Mass Extinctions in the Marine Fossil Record David M. Raup and J. John Sepkoski, Jr.Authors Info & Affiliations Abstract A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background extinction rates appear to have declined since Cambrian time, which is consistent with the prediction that optimization of fitness should increase through evolutionary time. Q 地球史上5次大的集群灭绝事件最早是由美国芝加哥大学古生物学家大卫·骆普（David Raup）和杰克·塞科斯基（(Jack Sepkoski）1982年发布在《科学》杂志上的论文所认定的。 第一次大灭绝：奥陶纪—志留纪灭绝事件 绝灭指数排名：3 时间：奥陶纪晚期或奥陶纪与志留纪 过渡时期（4.50~4.40亿年前） 可能原因：全球进入“冰河世纪” 特点：地球史上第一次物种灭绝事件 结果：约27%的科与57%的属灭种 奥陶纪是古生代的第二纪，开始于距今5亿年，约延续了6500万年。“奥陶”一词由英国地质学家拉普沃思于1879年提出，取自古奥陶部族（Ordovices）的居住地名。 灭绝发生于奥陶纪末期或奥陶纪与志留纪过渡时期，约85%的物种灭亡。古生物学家认为这次物种灭绝是由全球气候变冷造成的。撒哈拉所在的陆地曾经位于南极，当陆地汇集在极点附近时，容易造成厚的积冰。大片的冰川使洋流和大气环流变冷，整个地球的温度下降，冰川锁住水，海平面大幅降低，原先丰富的沿海生态系统遭到破坏。 第二次大灭绝：长达2000万年的泥盆纪后期大灭绝 绝灭指数排名：5 时间：泥盆纪后期（3.75~3.60亿年前） 原因：灭绝事件持续近2000万年， 根源难辨 特点：海洋生物遭重创 结果：约19%的科、50%的属灭绝 泥盆纪是古生代第四纪，约开始于4.05亿年前，持续约5000万年。泥盆纪迎来了脊椎动物的飞速发展，鱼类繁盛，各种类别的鱼都有出现，故泥盆纪被称为“鱼类的时代”。 这次大灭绝事件主要是海洋生物的灭绝，陆生生物受影响不显著。由于灭绝持续了近2000万年，且期间有多次灭绝高峰期，其根源很难辨识。 可能的生物学原因一说为地球进入卡鲁冰河时期所致。还有研究认为，泥盆纪陆生植物进化出发达的根系深入地表土之下数米，加速了陆地岩石土壤的风化，大量铁等元素释放进入地表水，造成了水系的富营养化大暴发，导致了海底缺氧事件。此外，海洋表层的繁盛的有机物的沉降，使得全球碳循环中大气层的二氧化碳大量进入海底沉积层，也加强了地球冷化。 UQ
MMitchell 发表于 2025-04-23 07:54 The Great Oxidation Event.
Q The Great Oxidation Event, a period of rapid increase in atmospheric oxygen, led to the extinction of many anaerobic (oxygen-intolerant) organisms, marking one of the earliest mass extinction events on Earth. While it's difficult to pinpoint specific animals, the event likely wiped out most of the microbial life that thrived in the absence of oxygen. Elaboration: Anaerobic Life: Before the Great Oxidation Event, Earth's atmosphere had very little oxygen, and life was largely anaerobic. These organisms relied on alternative energy sources and were toxic to oxygen. Oxygen's Toxicity: As oxygen levels rose due to cyanobacteria producing it as a byproduct of photosynthesis, it became toxic to many of these anaerobic organisms. Mass Extinction: This shift in atmospheric conditions caused a massive die-off of anaerobic bacteria and other early life forms, marking a significant extinction event. Evolution of Aerobic Life: While many organisms perished, the event paved the way for the evolution of aerobic metabolism, where organisms can use oxygen to generate energy. Difficulties in Specific Identification: Due to the age and nature of the evidence, it's challenging to identify the specific types of organisms that perished in this event. The impact was likely widespread, affecting many microbial lineages. Not a "Great Dying" event: While the Great Oxidation Event resulted in a significant loss of life, it is not typically included in lists of "Great Extinctions" because it occurred before the Phanerozoic eon, which marks the period when life became more complex and visible through the fossil record. UQ
Abstract A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background extinction rates appear to have declined since Cambrian time, which is consistent with the prediction that optimization of fitness should increase through evolutionary time.
Q 地球史上5次大的集群灭绝事件最早是由美国芝加哥大学古生物学家大卫·骆普（David Raup）和杰克·塞科斯基（(Jack Sepkoski）1982年发布在《科学》杂志上的论文所认定的。
第一次大灭绝： 奥陶纪—志留纪灭绝事件 绝灭指数排名：3 时间：奥陶纪晚期或奥陶纪与志留纪 过渡时期（4.50~4.40亿年前） 可能原因：全球进入“冰河世纪” 特点：地球史上第一次物种灭绝事件 结果：约27%的科与57%的属灭种 奥陶纪是古生代的第二纪，开始于距今5亿年，约延续了6500万年。“奥陶”一词由英国地质学家拉普沃思于1879年提出，取自古奥陶部族（Ordovices）的居住地名。 灭绝发生于奥陶纪末期或奥陶纪与志留纪过渡时期，约85%的物种灭亡。古生物学家认为这次物种灭绝是由全球气候变冷造成的。撒哈拉所在的陆地曾经位于南极，当陆地汇集在极点附近时，容易造成厚的积冰。大片的冰川使洋流和大气环流变冷，整个地球的温度下降，冰川锁住水，海平面大幅降低，原先丰富的沿海生态系统遭到破坏。
第二次大灭绝： 长达2000万年的泥盆纪后期大灭绝 绝灭指数排名：5 时间：泥盆纪后期（3.75~3.60亿年前） 原因：灭绝事件持续近2000万年， 根源难辨 特点：海洋生物遭重创 结果：约19%的科、50%的属灭绝 泥盆纪是古生代第四纪，约开始于4.05亿年前，持续约5000万年。泥盆纪迎来了脊椎动物的飞速发展，鱼类繁盛，各种类别的鱼都有出现，故泥盆纪被称为“鱼类的时代”。 这次大灭绝事件主要是海洋生物的灭绝，陆生生物受影响不显著。由于灭绝持续了近2000万年，且期间有多次灭绝高峰期，其根源很难辨识。 可能的生物学原因一说为地球进入卡鲁冰河时期所致。还有研究认为，泥盆纪陆生植物进化出发达的根系深入地表土之下数米，加速了陆地岩石土壤的风化，大量铁等元素释放进入地表水，造成了水系的富营养化大暴发，导致了海底缺氧事件。此外，海洋表层的繁盛的有机物的沉降，使得全球碳循环中大气层的二氧化碳大量进入海底沉积层，也加强了地球冷化。 UQ
https://www.science.org/doi/10.1126/science.215.4539.1501
Q 第三次大灭绝： 二叠纪末期创最大规模的物种灭绝 绝灭指数排名：1 时间：二叠纪—三叠纪过渡时期 （2.51亿年前） 可能原因：海平面下降和大陆漂移等 特点：规模最大、涉及生物类群最多、 影响最为深远 结果：约57%的科、83%的属灭绝 二叠纪—三叠纪灭绝事件发生在2.51亿年前的二叠纪—三叠纪过渡时期。这是已知的地质历史上最大规模的物种灭绝事件。许多动物门类整个目或亚目在此次事件中全部灭亡。曾遍布各地的舌羊齿植物群几乎全部绝灭，早古生代繁盛的三叶虫全部消失，蜓类原有40多个属，该世结束时完全消失；菊石有10个科绝灭，腕足类之前有140个属，在该事件后所剩无几。估计地球上有96%的物种灭绝。 这次大灭绝使得占领海洋近3亿年的主要生物从此衰败并消失，让位于新生物种类，生态系统也获得了一次最彻底的更新，为恐龙类等爬行类动物的进化铺平了道路。科学界普遍认为，这一大灭绝是地球历史从古生代向中生代转折的里程碑。其他各次大灭绝所引起的海洋生物种类的下降幅度都不及其1/6，没有使生物演化进程产生如此重大的转折。
第四次大灭绝： 三叠纪末期大灭绝 绝灭指数排名：4 时间：三叠纪—侏罗纪过渡时期 （2.0亿年前） 原因：尚无定论 特点：爬行类动物遭重创 结果：约23%的科与48%的属灭绝 三叠纪是中生代的第一纪，位于二叠纪和侏罗纪之间。始于距今2.5亿年，延续了约5000万年。在此时期，爬行动物和裸子植物崛起，三叠纪末期，估计有76%的物种（其中主要是海洋生物）灭绝，此次灾难并无特别明显的标志，只发现海平面下降之后又上升，出现大面积缺氧的海水。
第五次大灭绝： 白垩纪末期恐龙大灭绝 绝灭指数排名：2 时间：白垩纪晚期（6500万年前） 可能原因：陨石撞击 特点：恐龙灭绝 结果：75%~80%的物种灭绝 在五次大灭绝中，这次大灭绝事件最为著名，因长达1.4亿年之久的恐龙时代在此终结，海洋中的菊石类也一同消失。其最大“贡献”在于消灭了地球上处于霸主地位的恐龙及其同类，为哺乳动物及人类的登场提供了契机。 这次灭绝事件仅次于二叠纪—三叠纪灭绝事件。其成因一般认为是墨西哥尤卡坦半岛的陨石撞击。在白垩纪末期发生的一次或多次陨星雨造成了全球生态系统的崩溃。撞击使大量的气体和灰尘进入大气层，以至于阳光不能穿透，全球温度急剧下降，黑云在相当长的时期内遮天蔽日，植物不能从阳光中获得能量，海洋中的藻类和成片的森林逐渐死亡，食物链的基础环节被破坏，大批的动物因饥饿而死，其中就有恐龙。（赵鲁） UQ
Q The Great Oxidation Event, a period of rapid increase in atmospheric oxygen, led to the extinction of many anaerobic (oxygen-intolerant) organisms, marking one of the earliest mass extinction events on Earth. While it's difficult to pinpoint specific animals, the event likely wiped out most of the microbial life that thrived in the absence of oxygen.
Elaboration: Anaerobic Life: Before the Great Oxidation Event, Earth's atmosphere had very little oxygen, and life was largely anaerobic. These organisms relied on alternative energy sources and were toxic to oxygen. Oxygen's Toxicity: As oxygen levels rose due to cyanobacteria producing it as a byproduct of photosynthesis, it became toxic to many of these anaerobic organisms.
Mass Extinction: This shift in atmospheric conditions caused a massive die-off of anaerobic bacteria and other early life forms, marking a significant extinction event.
Evolution of Aerobic Life: While many organisms perished, the event paved the way for the evolution of aerobic metabolism, where organisms can use oxygen to generate energy.
Difficulties in Specific Identification: Due to the age and nature of the evidence, it's challenging to identify the specific types of organisms that perished in this event. The impact was likely widespread, affecting many microbial lineages.
Not a "Great Dying" event: While the Great Oxidation Event resulted in a significant loss of life, it is not typically included in lists of "Great Extinctions" because it occurred before the Phanerozoic eon, which marks the period when life became more complex and visible through the fossil record.
UQ