新的罗纪早期四足动物组合约束了罗纪-罗纪四足动物灭绝事件
Science (New York, N.Y.)
|August 28, 1987
概括
最早的罗纪四足动物化石组合揭示了大多数罗纪-罗纪灭绝发生在赫塔尼亚时代之前. 这种模式表明,在特里亚斯纪-罗纪边界发生了全球灭绝事件,可能与马尼库阿根撞击有关.
科学领域:
- 古生物学的古生物学
- 地质时间学 (Geochronology)
- 灭绝事件研究 灭绝事件研究
背景情况:
- 三亚纪-罗纪灭绝事件标志着一个重要的生物周转.
- 以前的研究表明,在罗纪-罗纪边界发生了全球灭绝.
- 四足动物灭绝的确切时间和持续时间仍在争论中.
研究的目的:
- 重新评估三叠纪-罗纪四足动物灭绝事件的持续时间.
- 为了确定Fundy盆地最早的罗纪四足动物组合的精确年龄.
- 为了调查四足动物家族消失和引入的模式,跨越了三叠纪-罗纪的边界.
主要方法:
- 确定相关的最早的拉纪四足动物组合的发现和分析.
- 使用花粉和子的平流图相关性.
- 化石集合的放射测量和地化学测年.
- 动物构成与特里亚斯纪晚期和罗纪纪录的比较分析.
主要成果:
- 芬迪盆地组合代表了一个早期的赫坦格纪 (最早的罗纪) 时代.
- 该组合包括多种多样的四足动物:类似哺乳动物的爬行动物,恐龙,鱼类,虫类和鱼类.
- 所有构成家族都是从早期的地层中知道的,在这个最早的罗纪组合中没有新家族出现.
- 典型的三叠纪形式不存在,这表明灭绝发生在早期赫坦格纪之前.
结论:
- 大多数特里亚斯纪-罗纪四足动物的灭绝发生在赫坦格纪早期之前,没有引入新的家族.
- 这种模式支持在罗纪-罗纪边界发生的全球灭绝事件,与海洋无脊椎动物研究一致.
- 马尼库阿根撞击事件,大致可以追溯到三叠纪-罗纪边界,是灭绝的潜在因果因素.
相关概念视频
01:07Speciation Rates
Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
02:31Habitat Fragmentation
Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land conversion, as well as slower geological processes leading to changes in the physical environment, are the two leading causes of habitat fragmentation. The fragmentation process typically follows the same steps: perforation, dissection, fragmentation, shrinkage, and attrition.
02:16Genetics of Speciation
Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.The genetics of speciation involves the different traits or isolating mechanisms preventing gene exchange, leading to reproductive isolation. Reproductive isolation can be due to reproductive barriers that have effects either before or after the formation of a zygote. Pre-zygotic mechanisms prevent fertilization from occurring, and post-zygotic mechanisms...
02:35What is Evolutionary History?
Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.Phylogenetic trees illustrate the evolutionary relationships among these organisms. Scientists infer organisms’ common ancestry by evaluating shared morphological and genetic characteristics. Together, the fossil...
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
01:54Convergent Evolution
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.The structures that arise from convergent evolution are called analogous structures. They are similar in function even if they are dissimilar in structure. Further, structures can be analogous while also...