报告人：Alida Mehiti Marie Bailleul
报告题目: Skeletal tissues: a window into the lives of extinct dinosaurs and birds
内容概况：Paleohistology is the study of fossil tissues, such as bone or cartilage, under the microscope. This sub-discipline of paleontology has had a tremendous impact our current understanding of dinosaurian and avian growth, but it is now starting to show new trends. For example, it has been essentially used on limb bones since the 1970’s, but recently it has been applied to dinosaur skull bones as well. Here, I will discuss the fact that histology is underestimated in paleontology, and show how it can be used to answer a variety of paleobiological questions, not solely revolving around growth or physiology. I propose that, by pairing the recent morphological discoveries of fossils from the Jehol Biota with microscopic examinations (i.e., histology, microCT-scanning, or synchrotron technology), we can shed light on a whole new set of biological questions related to avian and paravian evolution. To demonstrate this, I will specifically show how specific skeletal tissues can be used to answer questions related to 1) cranial kinesis; 2) the evolution and homology of ‘avian’ skeletal structures, and 3) the evolution of avian soft-tissues at the cellular and chemical level.
First, I will demonstrate how two skeletal tissues can be used to make inferences of cranial kinesis in living birds, and by analogy, in fossil birds as well: secondary articular cartilage for kinetic, synovial joints, and chondroid bone, for flexion zones. Second, I will explain how histology can resolve problems related to homology, by identifying different tissue types, modes of tissue formation and developmental processes. This method can be used to shed light on the evolution of the sternum, or the pygostyle for example. Lastly, I will introduce a newly developed histochemical method for fossil tissues that I recently learnt and used on well-preserved dinosaur cartilage from Montana. I propose to use this method for the first time on preserved soft-tissues, to shed light on early avian soft-tissue evolution at the fine, histochemical level.
These old and new techniques have the potential to be applied to other extinct groups as well, to bring new understanding to other important evolutionary transitions in vertebrate paleontology at IVPP.