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首页> 外文学位 >Ontogeny and phylogeny of Early Cambrian olenelloid trilobites, with emphasis on the late Dyeran Biceratopsidae.
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Ontogeny and phylogeny of Early Cambrian olenelloid trilobites, with emphasis on the late Dyeran Biceratopsidae.

机译：早寒武纪油橄榄三叶虫的个体发育和系统发育，特别是晚代二叠纪双足纲科。

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摘要

Lack of detailed paleobiological information has resulted in disagreement among workers regarding the evolutionary history of Early Cambrian olenelloid trilobites, in terms of the broad relationships among olenelloid taxa and the modes by which particular taxa evolved. This dissertation details the ontogenetic development, intraspecific variability, and evolutionary history of a diverse, monophyletic clade of olenelloids (the Biceratopsidae), and lays the foundations upon which a more complete understanding of olenelloid phylogeny can be built.; The cephalon of all olenelloid species passed through four phases of development during ontogeny, defined by changes in glabellar growth patterns and by the appearance of genal spines. These evolutionarily conserved phases provide a framework within which interspecific comparison of rates and modes of development can be meaningfully conducted.; Detailed comparison of Nephrolenellus geniculatus and its ancestral sister-species N. multinodus throughout their development reveals that the modes by which the ancestral ontogeny was evolutionarily modified were more complex than more traditional investigations would suggest. While less detailed studies would interpret all interspecific differences in terms of an increased rate of development in the descendant (heterochrony), geometric morphometric analyses find evidence of ontogenetic rate accelerations, rate decelerations, modified growth allometries, and deletion of morphological structures. A comprehensive classification of modes by which ontogeny can be evolutionarily modified is presented, recognizing rate modifications, timing modifications, change in location of structures (heterotopy), change in type of structures (heterotypy), change in number of structures (heterometry), and change in growth patterns of structures (allometric repatterning) as discrete classes.; Previous cladistic analyses of the Olenelloidea are shown to have underestimated the degree of intraspecific variability and taphonomic overprint on observed morphology, to have employed inappropriate outgroup taxa, and to have used non-independent characters pertaining to adult morphology. A comprehensive cladistic analysis of the Biceratopsidae (plus many outgroup species), utilizing adult and ontogenetic characters of defendable independence, differs from previous evolutionary hypotheses in terms of clade membership, generic relationships, species relationships, and generic monophyly. A revised classification of the Biceratopsidae, including comprehensive descriptions of all nephrolenelline species, is presented. Four new species are described as Bolbolenellus klondikensis, B. besti, B. inflatus, and Arcuolenellus mccollumi.
机译：缺乏详细的古生物学信息，导致工人之间就早寒武纪油橄榄石三叶虫的进化历史存在分歧，这是因为油橄榄石分类群与特定分类群的进化方式之间存在广泛的关系。本文详细介绍了单核类（Biceratopsidae）的多样性，单系进化枝的个体发育发育，种内变异性和进化史，并为更完整地了解单核系统发育奠定了基础。在个体发育过程中，所有油类物种的头孢菌素都经历了四个发育阶段，这由肾小球生长模式的变化和种棘的出现定义。这些进化上保守的阶段提供了一个框架，在其中可以有意义地进行发展速度和发展方式的种间比较。 Nephrolenellus geniculatus 及其祖先姐妹物种 N的详细比较。 multinodus 在他们的整个发展过程中揭示出，祖先个体发育的进化模式要比传统研究所提出的更为复杂。虽然较少详细的研究会根据后代发育速率的增长（异时）解释所有种间差异，但几何形态分析发现了个体发育速率加速，速率减慢，改良的生长同构异形和形态结构缺失的证据。提供了模式的全面分类，通过该模式可以对进化论进行进化修改，包括速率修改，时序修改，结构位置变化（异型），结构类型变化（异型），结构数量变化（异型）以及作为离散类的结构增长模式的改变（异构重复）。以前对夹竹桃的分类分析表明，低估了观察到的形态上种内变异性和自交系套印的程度，采用了不合适的外群分类群，并使用了与成人形态有关的非独立特征。利用进化枝隶属度，属系关系，物种关系和属系单亲性，利用成年和个体防御性独立的成年和个体发育特征对双足纲科（加上许多外群物种）进行全面的分类分析。提出了修订的双足纲科，包括对所有肾上腺素类的全面描述。四个新物种被描述为：，，和 Arcuolenellus mccollumi 。

著录项

  • 作者

    Webster, Mark.;

  • 作者单位

    University of California, Riverside.;

  • 授予单位 University of California, Riverside.;
  • 学科 Paleontology.; Biology Genetics.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 538 p.
  • 总页数 538
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 古生物学;遗传学;
  • 关键词

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