A new method to prepare clean cuticular membrane from fossil leaves with thin and fragile cuticles  

作　　者：WANG Li1,2 & LENG Qin1,3 1 State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China 2 Graduate School of Chinese Academy of Sciences,Beijing 100049,China 3 Department of Science and Technology,Bryant University,Smithfield RI 02917,USA 

出　　处：《Science China Earth Sciences》2011年第2期223-227,共5页中国科学（地球科学英文版）

基　　金：supported by CAS/SAFEA International Partnership Program for Creative Research Teams,the Pilot Project of Knowledge Innovation of CAS (Grant No. KZCX2-YW-105);National Basic Research Program of China (Grant No. 2006CB806400);National Natural Science Foundation of China (Grant Nos. 40402002,40872011)

摘　　要：Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to ＂strengthen＂ the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.Leaf cuticle analysis has long been a powerful tool for fossil plant identification,systematics,and palaeoclimatological recon-struction.In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with suffi-cient size a critical technique in palaeoclimatological research.However,for plants with originally thin and fragile cuticles,e.g.,most deciduous plants,conventional techniques sometimes fail to obtain cuticular membranes with sufficient size,or sometimes unable to recover any.This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeoclimatological research.Here,we describe a new method using clear nail polish as a medium to "strengthen" the originally thin and fragile cuticles prior to maceration procedures.We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature.Metasequoia,with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living representative,M.glyptostroboides,as a comparative reference,has been widely used as a model genus for the study of evolution of plants,palaeoclimatological reconstruction,and plant adaptation to climate changes.But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process.The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.

关 键 词：fossil leaf cuticle METASEQUOIA new method thin and fragile cuticle SEM observation stomatal frequency CO2 

分 类 号：Q914[天文地球—古生物学与地层学]