POWRE: Locomotor Transition in Fossile Sirenia

POWRE：Sirenia 化石中的运动转变

• 批准号: 9805793
• 负责人: Emily Buchholtz
• 金额: $ 1.5万
• 依托单位: Wellesley College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2002-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9805793&HistoricalAwards=false
• 关键词: POWRE; Locomotor; Transition; Fossile; Sirenia

9805793BuchholtzSoon after the origin of the Order Sirenia in the Eocene, ancestral members of the group began the transition from terrestrial to obligate aquatic habits. Among functional systems transformed during the transition was locomotion. Ancestral members were terrestrial quadrupeds with paraxial oscillatory movements of the limbs; living descendants are aquatic axial oscillators. The goals of this project are:1) to document the locomotor style of individual transitional fossil taxa, 2) to reconstruct the sequence of locomotor styles in Sirenia based on current understanding of the phylogenetic history of the group, and 3) to compare the trajectory of the sirenian transition with that of an independent transition to axial undulation in the Order Cetacea, the subject of previous analysis.Prediction of locomotor style will be based on analysis of the vertebral column. Regional variation of the column is a powerful but underutilized tool for analysis of segmental neural supply, body regionalization, and postcranial mobility. Paleoneorological methods developed during a study of marine Carnivora, and functional/morphological methods developed in the study of cetacean locomotor style will be used, adapted, and augmented for this project. These techniques have been useful in the determination of size and innervation territory of limbs, the presence/absence of a fluke and peduncle, the degree of cervical shortening, the regions of prefluke stabilization, and the extent of anatomical (and functional) deviation from ancestral (terrestrial) patterns of vertebral regionalization.Specimens of fossil Sirenia with significant postcranial material have been identified. The necessity of examination of original specimens and the distribution of their repositories require that the principal investigator travel for data collection, but analysis of data can occur at her home institution.Data analysis will include determination of fossil swimming styles and placement of those styles in phylogenetic context. It will also include a comparison of the inferred Sirenian transition with that already predicted for Cetacea. In cetacean history, axial undulation of the vertebral column preceded limb loss, and first served to propel enlarged hind feet that served as the propulsive surface. Hind limbs were progressively reduced in size after they were replaced by the wide torso, and finally by the fluke as the dominant propulsive surface. Origin of a peduncle postdated the fluke, and was accompanied first by elongation and finally by the secondary stabilization of the lumbos.The comparison of two independent and broadly contemporary terrestrial/aquatic transitions from terrestrial paraxial to aquatic axial locomotion in taxa of different ancestry and lifestyle offers a test case for an examination of sequence and constraint in evolutionary transitions.

9805793布赫霍尔茨始新世海妖目（Sirenia）起源后不久，该群体的祖先成员开始从陆生向专性水生习性过渡。 在这一转变过程中，功能系统发生了变化，其中之一就是运动。 祖先的成员是陆地四足动物与傍轴振荡运动的四肢;生活的后代是水生轴振荡器。 本项目的目标是：1）记录个体过渡化石分类群的运动方式，2）根据目前对该群体系统发育历史的理解重建Sirenia的运动方式序列，3）将Sirenia过渡的轨迹与先前分析的主题鲸目中独立过渡到轴向波动的轨迹进行比较。运动方式的预测将基于脊柱的分析。 脊柱的区域变化是一个强大的，但未充分利用的工具，节段性神经供应，身体区域化和颅后活动的分析。 在海洋食肉动物的研究过程中开发的古生物学方法，以及在鲸目动物运动风格的研究中开发的功能/形态学方法，将用于该项目，调整和增强。 这些技术已被用于确定的大小和神经支配领域的四肢，存在/不存在的一个侥幸和梗，颈椎缩短的程度，地区的prefluke稳定，以及程度的解剖（和功能）偏离祖先（陆地）模式的脊椎regionalization. Species化石Sirenia具有显着的postcranial材料已被确定。 原始标本的检查和他们的存储库的分布的必要性，要求首席研究员旅行的数据收集，但数据分析可以发生在她的家乡institution.Data分析将包括化石游泳风格和这些风格在系统发育背景下的位置的确定。 它还将包括一个比较推断的塞雷纳过渡与已经预测的鲸类。 在鲸类的历史中，脊柱的轴向波动先于肢体的丧失，并首先用于推进作为推进表面的扩大的后足。 后肢逐渐缩小后，他们取代了广泛的躯干，最后由作为主导推进表面的吸虫。 起源的一个花序梗落后的侥幸，并伴随着第一次延长，最后由二次稳定的lumbos.The比较两个独立的和广泛的当代陆地/水生过渡从陆地近轴水生轴向运动的类群不同的祖先和生活方式提供了一个测试的情况下，检查序列和约束的进化转型。