نتایج جستجو برای: fossilization

تعداد نتایج: 247  

Journal: :Proceedings. Biological sciences 2010
Maria McNamara Patrick J Orr Stuart L Kearns Luis Alcalá Pere Anadón Enrique Peñalver-Mollá

The very labile (decay-prone), non-biomineralized, tissues of organisms are rarely fossilized. Occurrences thereof are invaluable supplements to a body fossil record dominated by biomineralized tissues, which alone are extremely unrepresentative of diversity in modern and ancient ecosystems. Fossil examples of extremely labile tissues (e.g. muscle) that exhibit a high degree of morphological fi...

2013
Jessica R. Creveling David T. Johnston Simon W. Poulton Benjamin Kotrc Christian März Daniel P. Schrag Andrew H. Knoll

The fossilization of organic remains and shell material by calcium phosphate minerals provides an illuminating, but time-bounded, window into Ediacaran–Cambrian animal evolution. For reasons that remain unknown, phosphatic fossil preservation declined signifi cantly through Cambrian Series 2. Here, we investigate the phosphorus (P) sources for phosphatic Cambrian carbonates, presenting sediment...

Journal: :American journal of botany 2001
R J Burnham N C Pitman K R Johnson P Wilf

Leaf margin characters are strong predictors of mean annual temperature (MAT) in modern plant communities and widely used tools for reconstructing paleoclimates from fossil floras. However, the frequency of nonentire-margined species may vary dramatically between different habitats of the same forest. In this paper we explore the potential for this habitat variation to introduce error into temp...

2017
Jesus Lozano-Fernandez Mario dos Reis Philip C.J. Donoghue Davide Pisani

Establishing an accurate timescale for the history of life is crucial to understand evolutionary processes. For this purpose, relaxed molecular clock models implemented in a Bayesian MCMC framework are generally used. However, these methods are time consuming. RelTime, a non-Bayesian method implementing a fast, ad hoc, algorithm for relative dating, was developed to overcome the computational i...

2000
Robert S. Nowak Robin J. Tausch

p s t m w t n p a g e r t A procedure to calculate probability limits for the inference that the absence of a taxon from a woodrat (Neotoma) midden implies bsence from the paleolandscape uses paired samples of modern egetation communities and paired samples of paleocommunities. ssumptions are: (1) each member of a sample pair is an indeendent measure of the same vegetation assemblage; (2) behav...

2015
ZHE KANG

-With the rapid development of Internet, the complexity of the network and control difficulty has increased dramatically. For the problem of fossilization network is more and more prominent, SDN (software defined network) arises at the historic moment. Due to SDN controller centralized control and the characteristics of shunt on SDN network equipment, this paper puts forward that part of nodes ...

2007
Virginia Yip

A certain group of English verbs, the ergatives, is consistently mis-passivized in Chinese-speakers' interlanguage. Comparison of the ergative construction in Chinese and English shows that they share similar properties. However, this does not seem to facilitate learning of the target English construction. Furthermore, the passive ergatives are not attributable to exemplification in either the ...

Journal: :Philosophical transactions of the Royal Society of London. Series B, Biological sciences 2015
Gregory D Edgecombe Xiaoya Ma Nicholas J Strausfeld

Extant panarthropods (euarthropods, onychophorans and tardigrades) are hallmarked by stunning morphological and taxonomic diversity, but their central nervous systems (CNS) are relatively conserved. The timing of divergences of the ground pattern CNS organization of the major panarthropod clades has been poorly constrained because of a scarcity of data from their early fossil record. Although t...

Journal: :Evolution & development 2008
Neil J Gostling Ceri-Wyn Thomas Jenny M Greenwood Xiping Dong Stefan Bengtson Elizabeth C Raff Rudolf A Raff Bernard M Degnan Marco Stampanoni Philip C J Donoghue

Experimental analyses of decay in a tunicate deuterostome and three lophotrochozoans indicate that the controls on decay and preservation of embryos, identified previously based on echinoids, are more generally applicable. Four stages of decay are identified regardless of the environment of death and decay. Embryos decay rapidly in oxic and anoxic conditions, although the gross morphology of em...

2018
Alba Sánchez-García Enrique Peñalver Xavier Delclòs Michael S Engel

Among the many challenges in paleobiology is the inference and reconstruction of behaviors that rarely, if ever, leave a physical trace on the environment that is suitable for fossilization. Of particular significance are those behaviors tied to mating and courtship, individual interactions critical for species integrity and continuance, as well as those for dispersal, permitting the taxon to e...

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