{"title":"渐新世浮游生物有孔虫分类与演化——海洋钻探项目803号点图解修订","authors":"A. Fraass, R. Leckie","doi":"10.2113/gsjfr.51.3.139","DOIUrl":null,"url":null,"abstract":"\n The Oligocene (33.9–23.0 Ma) has historically proven to be a difficult interval to examine with respect to planktic foraminifera; the tendency for many of the taxa to be basically globigerine in shape, with 4 or 5 chambers in the final whorl means differences between species are limited. Recently, an international working group has attempted to clarify the Oligocene planktic foraminiferal taxonomy, with the goal of establishing phylogenetically-consistent generic and species concepts. A relatively expanded and continuous Oligocene section recovered at Ocean Drilling Program Site 803 in the western equatorial Pacific was previously studied by Leckie et al. (1993) using fairly conservative species concepts. Since 1993, foraminiferal biostratigraphic datum age calibrations have changed, and so revised sedimentation rates for the 220-m thick Oligocene sequence are actually more constant than previously thought. As a part of the recent taxonomic revision, this site was reevaluated and numerous additional taxa are recorded at this location. Macroevolutionary rates are calculated from the occurrences, and increased extinction is found within the late Oligocene, counter to the expectations laid out in broader-scale macroevolutionary studies. An effort is made here to describe the diagnostic features, which can be used to distinguish all taxa under a standard binocular microscope. Finally, several figures of scanning electron microscope photomicrographs (from Site 803 and tropical Atlantic Ocean ODP Site 628) depict features used to describe and differentiate important, but difficult or homeomorphic taxa, with the hope that these figures can be used by other workers at the microscope attempting to do Oligocene taxonomy-based studies.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":" ","pages":""},"PeriodicalIF":0.9000,"publicationDate":"2021-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Oligocene Planktic Foraminiferal Taxonomy and Evolution: An Illustrated Revision of Ocean Drilling Program Site 803\",\"authors\":\"A. Fraass, R. 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引用次数: 1
摘要
渐新世(33.9–23.0 Ma)在历史上被证明是一个很难对浮游有孔虫进行检查的时期;许多分类群的形状基本上是球形的,最后轮生有4或5个室,这意味着物种之间的差异是有限的。最近,一个国际工作组试图澄清渐新世浮游有孔虫的分类学,目的是建立系统发育上一致的属和种概念。Leckie et al。(1993)使用相当保守的物种概念。自1993年以来,有孔虫生物地层基准年龄校准发生了变化,因此220米厚渐新世层序的修正沉积速率实际上比以前认为的更恒定。作为最近分类学修订的一部分,对该地点进行了重新评估,并在该地点记录了许多额外的分类群。宏观进化率是根据这些事件计算出来的,在渐新世晚期发现了灭绝的增加,这与更大规模的宏观进化研究中提出的预期相反。本文致力于描述诊断特征,可用于在标准双目显微镜下区分所有分类群。最后,几张扫描电子显微镜显微照片(来自803号地点和热带大西洋ODP 628号地点)描绘了用于描述和区分重要但困难或同源分类群的特征,希望这些照片可以被显微镜下试图进行渐新世分类学研究的其他工作人员使用。
Oligocene Planktic Foraminiferal Taxonomy and Evolution: An Illustrated Revision of Ocean Drilling Program Site 803
The Oligocene (33.9–23.0 Ma) has historically proven to be a difficult interval to examine with respect to planktic foraminifera; the tendency for many of the taxa to be basically globigerine in shape, with 4 or 5 chambers in the final whorl means differences between species are limited. Recently, an international working group has attempted to clarify the Oligocene planktic foraminiferal taxonomy, with the goal of establishing phylogenetically-consistent generic and species concepts. A relatively expanded and continuous Oligocene section recovered at Ocean Drilling Program Site 803 in the western equatorial Pacific was previously studied by Leckie et al. (1993) using fairly conservative species concepts. Since 1993, foraminiferal biostratigraphic datum age calibrations have changed, and so revised sedimentation rates for the 220-m thick Oligocene sequence are actually more constant than previously thought. As a part of the recent taxonomic revision, this site was reevaluated and numerous additional taxa are recorded at this location. Macroevolutionary rates are calculated from the occurrences, and increased extinction is found within the late Oligocene, counter to the expectations laid out in broader-scale macroevolutionary studies. An effort is made here to describe the diagnostic features, which can be used to distinguish all taxa under a standard binocular microscope. Finally, several figures of scanning electron microscope photomicrographs (from Site 803 and tropical Atlantic Ocean ODP Site 628) depict features used to describe and differentiate important, but difficult or homeomorphic taxa, with the hope that these figures can be used by other workers at the microscope attempting to do Oligocene taxonomy-based studies.
期刊介绍:
JFR publishes original papers of international interest dealing with the Foraminifera and allied groups of organisms. Review articles are encouraged.