نتایج جستجو برای: plant fossils

تعداد نتایج: 407293  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1391

in this work, a novel and fast method for direct analysis of volatile compounds (davc) of medicinal plants has been developed by holding a filament from different parts of a plant in the gc injection port. the extraction and analysis of volatile components of a small amount of plant were carried out in one-step without any sample preparation. after optimization of temperature, extraction time a...

2001
Christophe Plomion Grégoire Leprovost

Wood is the most important natural and endlessly renewable source of energy and therefore has a major future role as an environmentally cost-effective alternative to burning fossils fuels. The major role of wood is not only the provision of energy but also the provision of energy-sufficient material for our buildings and many other products. In addition, developing wood cells represent one of t...

Journal: :Trends in ecology & evolution 2007
Philip C J Donoghue Michael J Benton

A great tradition in macroevolution and systematics has been the ritual squabbling between palaeontologists and molecular biologists. But, because both sides were talking past each other, they could never agree. Practitioners in both fields should play to their strengths and work together: palaeontologists can provide minimum constraints on branching points in the Tree of Life with considerable...

2015
Bin Sun Yu-Fei Wang Cheng-Sen Li Jian Yang Jin-Feng Li Ye-Liang Li Tao Deng Shi-Qi Wang Min Zhao Robert A. Spicer David K. Ferguson Rakesh C. Mehrotra

The area and elevation of the Tibetan Plateau over time has directly affected Asia's topography, the characteristics of the Asian monsoon, and modified global climate, but in ways that are poorly understood. Charting the uplift history is crucial for understanding the mechanisms that link elevation and climate irrespective of time and place. While some palaeoelevation data are available for sou...

Journal: :Proceedings. Biological sciences 2007
M A Wills

Biologists routinely compare inferences about the order of evolutionary branching (phylogeny) with the order in which groups appear in the fossil record (stratigraphy). Where they conflict, ghost ranges are inferred: intervals of geological time where a fossil lineage should exist, but for which there is no direct evidence. The presence of very numerous and/or extensive ghost ranges is often be...

Journal: :Systematic biology 1999
F Lutzoni F K Barker

of randomly distributed fossil horizons. Paleobiology 20:459–469. MAXWELL, W. D., AND M. J. BENTON. 1990. Historical tests of the absolute completeness of the fossil record of tetrapods. Paleobiology 16:322–335. NORELL, M. A., AND M. J. NOVACEK. 1992a. Congruence between superpositional and phylogenetic patterns: Comparing cladistic patterns with fossil records. Cladistics 8:319–337. NORELL, M....

Journal: :The American naturalist 2006
Robert E Ricklefs Andrea E Schwarzbach Susanne S Renner

The contribution of nonecological factors to global patterns in diversity is evident when species richness differs between regions with similar habitats and geographic area. Mangrove environments in the Eastern Hemisphere harbor six times as many species of trees and shrubs as similar environments in the New World. Genetic divergence of mangrove lineages from terrestrial relatives, in combinati...

2007
Habib G. Khosroshahi Trevor J. Ponman Laurence R. Jones

Using Chandra X-ray observations and optical imaging and spectroscopy of a flux-limited sample of 5 fossil groups, supplemented by additional systems from the literature, we provide the first detailed study of the scaling properties of fossils compared to normal groups and clusters. Fossil groups are dominated by a single giant elliptical galaxy at the centre of an extended bright X-ray halo. I...

Journal: :Anais da Academia Brasileira de Ciencias 2007
Jorge O Calvo Juan D Porfiri Bernardo J González-Riga Alexander W A Kellner

A unique site at the northern area of Patagonia (Neuquén, Argentina) reveals a terrestrial ecosystem preserved in a detail never reported before in a Late Cretaceous deposit. An extraordinary diversity and abundance of fossils was found concentrated in a 0.5 m horizon in the same quarry, including a new titanosaur sauropod, Futalognkosaurus dukei n.gen., n.sp, which is the most complete giant d...

Journal: :Proceedings. Biological sciences 2009
Torsten Wappler Ellen D Currano Peter Wilf Jes Rust Conrad C Labandeira

Insect herbivores are considered vulnerable to extinctions of their plant hosts. Previous studies of insect-damaged fossil leaves in the US Western Interior showed major plant and insect herbivore extinction at the Cretaceous-Palaeogene (K-T) boundary. Further, the regional plant-insect system remained depressed or ecologically unbalanced throughout the Palaeocene. Whereas Cretaceous floras had...

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