Toward the Origin of Whales: Eocene Cetacea from Pakistan

走向鲸鱼的起源：来自巴基斯坦的始新世鲸类

• 批准号: 9526686
• 负责人: Johannes Thewissen
• 金额: $ 19万
• 依托单位: Northeast Ohio Medical University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-15 至 2000-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526686&HistoricalAwards=false
• 关键词: Toward; Origin; Whales; Eocene; Cetacea

Thewissen 9526686 This project investigates the transition of cetaceans (whales, dolphins, porpoises) from terrestrial quadrupeds to obligate marine swimmers. This transition is one of the few paleontologically documented examples of macroevolutionary change in mammals. The project will interpret patterns of macroevolutionary change in two systems that underwent pervasive modifications, locomotion and hearing, and evaluate its paleoecological context. Hypotheses.-- Seven hypotheses will be tested. Two of these make predictions about changes in the modes of locomotion in early cetaceans. Three hypotheses make predictions about evolution and function of the cetacean middle and inner ear. Another two hypotheses address the physical environment under which this transition took place, making prediction about paleoecology. New fossil material will be collected from freshwater and shallow marine sediments of the Kuldana and Kohat Formations of Northern Pakistan, the only area where the earliest and most plesiomorphic cetaceans are found. This material will allow testing of the hypotheses. Kuldana/Kohat cetaceans lived across a variety of depositional environments in what is now a structurally complex area, requiring detailed geological study. Sedimentological study will elucidate the physical setting of the transition. Related, ongoing work includes analyses of modern cetacean ear development and function, and an analysis of physiological constraints, based on stable oxygen isotopes. Significance.-- Cetacean origins is one of the best documented examples of land-water transitions among vertebrates, and showcases several form-function complexes that underwent pervasive change. Cetacean swimming evolved from quadrupedal paddling to dorsoventral oscillation of the broadened tail, and the Kuldana cetaceans display intermediate modes. The ears of cetacean ancestors were tuned to mid-frequency airborne sounds, whereas modern cetaceans hear underwater high- (odontocete) or low- (mys ticete) sounds. The position of the Kuldana cetaceans is unclear, but their auditory morphology is different from their terrestrial sister group and modern cetaceans. Fossil morphologies interpreted in an established phylogenetic context and against a background provided by modern aquatic mammals elucidates these evolutionary patterns. Studying the sedimentology of the rocks that document these morphological patterns clarifies the ecological setting of the land-to-water transition. This study is of broader significance for the higher phylogeny of mammals. It will provide morphological data to test phylogenies of the affinities of sperm whales (odotocete paraphyly) and the relationship of cetaceans to artiodactys (artiodactyl paraphyly). These phylogenetic hypotheses were proposed on the basis of molecular data, and are greatly disputed by morphologists. Studies of faunal evolution have suggested that Indo-Pakistan contacted Asia in the Cretaceous. Geological data dispute this claim. This study will provide a critical test for the Eocene paleontological data.

Wwissen 9526686该项目调查了鲸类（鲸鱼，海豚，海豚）的过渡，从陆地四足动物到义务海洋游泳者。 这种过渡是哺乳动物中宏观进化变化的少数古生物学作品的例子之一。 该项目将解释两种经过普遍修改，运动和听力并评估其古生态环境的系统中宏观进化变化的模式。 假设 - 将检验七个假设。 其中两个对鲸类早期运动模式的变化做出了预测。 三个假设对鲸类中耳和内耳的进化和功能进行了预测。 另外两个假设解决了这种过渡的物理环境，对古生态学进行了预测。 新的化石材料将从巴基斯坦北部北部北部和浅水陆地沉积物中收集，这是唯一发现最早，最易植物的鲸类动物的唯一地区。 该材料将允许测试假设。 Kuldana/Kohat Cetaceans在现在的结构复杂区域中生活在各种沉积环境中，需要详细的地质研究。 沉积学研究将阐明过渡的物理环境。 相关的，正在进行的工作包括对现代鲸类耳朵发育和功能的分析，以及基于稳定的氧同位素的生理约束分析。 意义。-鲸类起源是脊椎动物中土地水过渡的最佳示例之一，并展示了经历了普遍变化的几种形式功能复合物。 周年游泳从四足动划桨演变为宽阔的尾巴的背腹倾斜，库尔达纳鲸鱼显示了中间模式。 鲸类祖先的耳朵被调整为中频的空中声音，而现代的鲸类会听到水下高（odoncocete）或低 - （mys ticete）的声音。 kuldana鲸类动物的位置尚不清楚，但是它们的听觉形态与他们的陆地姐妹组和现代鲸类动物不同。 在既定的系统发育环境中解释的化石形态，在现代水生哺乳动物提供的背景下阐明了这些进化模式。 研究记录这些形态学模式的岩石的沉积学阐明了土地到水过渡的生态环境。 这项研究对于较高的哺乳动物系统发育具有更广泛的意义。 它将提供形态学数据，以测试晶石鲸亲和力的系统发育（Odotocete paraphyly）和鲸类与Artiodactys（Artiodactyl paraphyly）的关系。 这些系统发育假设是基于分子数据提出的，形态学家极大地争议。 对动物的进化研究表明，印度 - 巴基斯坦在白垩纪与亚洲接触。 地质数据争议这一主张。 这项研究将为始新世古生物学数据提供重要的测试。