نتایج جستجو برای: trilobite

تعداد نتایج: 345  

Journal: :Quarterly Journal of the Geological Society 1873

2015
Russell Hart William C. Stwalley

We observe long-range “trilobite-like” states of ultracold 85Rb2 molecules in which a novel form of chemical bonding occurs: an ultracold ground state atom is bound by the attraction of the Rydberg electron, with its Rydberg electronic wavefunction in np Rydberg atomic levels with n = 7-12 [1]. Unlike earlier work by others at much higher n formed by photoassociation, our observations involve b...

2003
Jan Bergström Hou Xian-Guang

Reconsideration of the position of trilobite-like arthropods leads to an idea of the last shared ancestor of known (eu)arthropods. The ancestry and morphological evolution is traced back from this form to a hypothetical ciliated and pseudosegmented slug-like ancestor. Evolution logically passed through a lobopodian stage. Extant onychophorans, Cambrian xenusians, and perhaps anomalocaridids wit...

Journal: :Arthropod structure & development 2010
Bruce S Lieberman Talia S Karim

Trilobites are a highly diverse group of extinct arthropods that persisted for nearly 300 million years. During that time, there was a profusion of morphological form, and they occupied a plethora of marine habitats. Their diversity, relative abundance, and complex morphology make them excellent candidates for phylogenetic analysis, and partly as a consequence they have been the subject of many...

Journal: :Biology letters 2013
Javier Ortega-Hernández Jorge Esteve Nicholas J Butterfield

Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most probably as a defence mechanism against adverse environmental conditions or predators. Although most trilobites could enrol at least partially, there is uncertainty about whether olenellids-among the most phylogenetically and stratigraphically basal representatives-could perform this behaviour becau...

2008
Curtis R. Congreve Bruce S. Lieberman

Cladistic parsimony analysis of the trilobite family Homalonotidae Chapman 1980 produced a hypothesis of relatedness for the group. The family consists of three monophyletic subfamilies, one containing Trimerus Green 1832, Platycoryphe Foerste 1919, and Brongniartella Reed 1918; one containing Plaesiacomia Hawle and Corda 1847 and Colpocoryphe Novák in Perer 1918; and one containing Eohomalonot...

2006
RUSSELL S. SHAPIRO STANLEY M. AWRAMIK

The distinctive, branched thrombolite, Favosamaceria cooperi new group and form, is found widely in the Great Basin, USA, where it is restricted to the Late Cambrian Saukia trilobite Zone. This thrombolite is distinguished by a hedgerow, mazelike organization of ridges similar to garden walls (maceriae) in plan view, branching of ridges into daughter ridges and columns, the polymorphic nature o...

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