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

合作研究：晚泥盆世四足形鱼和四足动物的起源。纳特。SCI。费城，耳--尼尔·H·舒宾，0544093，大学芝加哥，EAR-0544656摘要随着泥盆纪的结束，在3.85亿到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，以及陆地植物群落的细化。PIS在加拿大北极(埃尔斯米尔岛、努纳武特领地)和宾夕法尼亚州正在进行的工作为理解这些极其重要的事件提供了新的证据。例如，埃尔斯米尔岛上的一个新发现的地点包括许多铰接鱼，它们是已知的四肢动物最接近的近亲之一。此外，在宾夕法尼亚州卡茨基尔组进行了12年的实地研究，发现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、环境环境和时代是PI建议研究最早的四足动物及其瓣鳍鱼类前体的演化，以及晚泥盆世生境的发展的基础，晚泥盆世栖息地是晚泥盆世进化创新的熔炉。由于已经有了大量的收藏品和更多实地发现的巨大潜力，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，供全球分布，4)对早期四肢动物及其近亲的描述和进化分析，5)对硬骨鱼类骨骼结构的功能分析，这将有助于理解鱼-四足动物转变的生物学意义，以及6)评估与四足动物起源相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.