Collaborative Research: Late Devonian Tetapodomorph Fishes and the Origin of Tetrapods

合作研究：晚泥盆世四足类鱼类和四足类的起源爱德华B。Daeschler，Acad.自然科学费城，邮编：0544093尼尔·H。Shubin，Univ.芝加哥，芝加哥-0544656摘要泥盆纪末期，即3.85亿至3.6亿年前，生活在淡水栖息地的动植物发生了戏剧性的进化变化。这段时间见证了四肢脊椎动物（四足动物）的起源，与早期四足动物密切相关的鱼类的多样化，以及陆地上植物群落的发展。 PI正在加拿大北极地区（埃尔斯米尔岛，努纳武特地区）和宾夕法尼亚州的工作提供了新的证据，了解这些具有纪念意义的重要事件。例如，在埃尔斯米尔岛的一个新发现的地点包括许多关节鱼，它们是已知的有肢动物的近亲之一。此外，在宾夕法尼亚州的卡茨基尔组进行了12年的野外研究，获得了丰富的晚泥盆世化石，以其分类多样性和脊椎动物，植物和节肢动物的保存质量而闻名。这些北美系统的生物多样性、环境背景和年龄是PI提出的关于最早的四足动物及其叶鳍鱼前体进化的研究的基础，以及晚泥盆世栖息地的发展，这是晚泥盆世进化创新的熔炉。随着大量的收集已经在手，并有很大的潜力进行更多的实地发现，该项目的目标包括：1）额外的野外工作，以发现鱼类-四足动物过渡尖端的关键分类群的新材料，2）勘探可能产生最早的四足动物化石的有希望的地区，3）化石准备，包括塑造和铸造重要的标本，以供世界范围内的分布，4）描述和进化分析早期肢动物和它们的鱼类亲属，5）功能分析elpistostegid鱼类骨骼结构，这将提供一个理解的生物学意义的变化，在鱼类四足动物过渡，（6）评估与四足动物起源有关的地理和环境条件。这项工作将通过在教育和非正式科学学习场所的宣传，以及通过互联网、印刷和广播媒体产生广泛的影响。

Collaborative Research: Late Devonian Tetrapodomorph Fishes and the Origin of TetrapodsEdward B. Daeschler, Acad. Nat. Sci. Philadelphia, EAR-0544093 Neil H. Shubin, Univ. Chicago, EAR-0544656 AbstractTowards the end of the Devonian Period, between 385 and 360 million years ago, there were dramatic evolutionary changes to plants and animals living in freshwater habitats. This time interval witnessed the origin of limbed vertebrates (tetrapods), the diversification of fishes closely related to early tetrapods, and the elaboration of plant communities on land. PIs ongoing work in the Canadian Arctic (Ellesmere Island, Nunavut Territory) and Pennsylvania provide new evidence for understanding these monumentally important events. For example, a newly discovered site on Ellesmere Island includes numerous articulated fish that are one of the closest known relatives of limbed animals. In addition, 12 years of field study in the Catskill Formation in Pennsylvania has yielded abundant Late Devonian fossils notable for their taxonomic diversity and the quality of preservation of the vertebrates, plants, and arthropods. The biological diversity, environmental settings, and age of these North American systems serve as the basis for PIs proposed studies on the evolution of the earliest tetrapods and their lobe-finned fish precursors, and the development of the Late Devonian habitats that were a crucible for the evolutionary innovations in the Late Devonian.With substantial collections already in hand and great potential for additional field discoveries, the goals for this project include: 1) additional fieldwork to discover new material of key taxa at the cusp of the fish-tetrapod transition, 2) exploration of promising areas that may produce the earliest tetrapod fossils, 3) fossil preparation including molding and casting of important specimens for worldwide distribution, 4) description and evolutionary analysis of early limbed animals and their fish relatives, 5) functional analyses of skeletal structures in elpistostegid fishes that will provide an understanding of the biological significance of changes at the fish-tetrapod transition, and 6) assessing the geographic and environmental conditions associated with the origin of tetrapods. This work will have a broad impact through outreach in educational and informal science learning venues, and via internet, print and broadcast media.