MORPHOLOGIC EVOLUTION AND DISPARITY IN CAMBRIAN ECHINODERMS

Cladograms predict the order in which fossil taxa appeared and, thus, make predictions about general patterns in the stratigraphic record. Inconsistencies between cladistic predictions and the observed stratigraphic record reflect either inadequate sampling of a clade's species, incomplete estimates of stratigraphic ranges, or homoplasy producing an incorrect phylogenetic hypothesis. A method presented in this paper attempts to separate the effects of homoplasy from the effects of inadequate sampling. Sampling densities of individual species are used to calculate confidence intervals on their stratigraphic ranges. The method uses these confidence intervals to test the order of branching predicted by a cladogram. The Lophospiridae (“Archaeogastropoda”) of the Ordovician provide a useful test group because the clade has a good fossil record and it produced species over a long time. Confidence intervals reject several cladistic hypotheses that postulate improbable “ghost lineages.” Other hypotheses are acceptable only with explicit ancestor-descendant relationships. The accepted cladogram is the shortest one that stratigraphic data cannot reject. The results caution against evaluating phylogenetic hypotheses of fossil taxa without considering both stratigraphic data and the possible presence of ancestral species, as both factors can affect interpretations of a clade's evolutionary dynamics and its patterns of morphologic evolution.

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Mathematical modelling of shallow flows: Closure models drawn from grain-scale mechanics of sediment transport and flow hydrodynamicsThis paper is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007).

Canadian Journal of Civil Engineering ◽

10.1139/l09-033 ◽

2009 ◽

Vol 36 (10) ◽

pp. 1605-1621 ◽

Cited By ~ 14

Author(s):

Rui M. L. Ferreira ◽

Mário J. Franca ◽

João G. A. B. Leal ◽

António H. Cardoso

Keyword(s):

Sediment Transport ◽

Mathematical Modelling ◽

Conceptual Models ◽

Numerical Solutions ◽

Shear Stresses ◽

Shallow Flows ◽

River Modelling ◽

Morphologic Evolution ◽

Sediment Mixtures ◽

Selection Of

Mathematical modelling of river processes is, nowadays, a key element in river engineering and planning. River modelling tools should rest on conceptual models drawn from mechanics of sediment transport, river mechanics, and river hydrodynamics. The objectives of the present work are (i) to describe conceptual models of sediment transport, deduced from grain-scale mechanics of sediment transport and turbulent flow hydrodynamics, and (ii) to present solutions to specific river morphology problems. The conceptual models described are applicable to the morphologic evolution of rivers subjected to the transport of poorly sorted sediment mixtures at low shear stresses and to geomorphic flows featuring intense sediment transport at high shear stresses. In common, these applications share the fact that sediment transport and flow resistance depend, essentially, on grain-scale phenomena. The idealized flow structures are presented and discussed. Numerical solutions for equilibrium and nonequilibrium sediment transport are presented and compared with laboratory and field data.

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Mass-movement, geologic structure and morphologic evolution of the Pizzotto–Greci slope (Calabria, Italy)

Geomorphology ◽

10.1016/s0169-555x(99)00051-3 ◽

1999 ◽

Vol 30 (1-2) ◽

pp. 147-163 ◽

Cited By ~ 24

Author(s):

Marino Sorriso-Valvo ◽

Giovanni Gullà ◽

Loredana Antronico ◽

Carlo Tansi ◽

Maria Amelio

Keyword(s):

Mass Movement ◽

Geologic Structure ◽

Morphologic Evolution

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Techniques, Tools and Methods to Determine Coastal Landscape Morphologic Evolution & Management for ‘Coasts in Crisis’ in ‘The State of Kuwait’

International Journal of Environmental Science and Development ◽

10.7763/ijesd.2010.v1.59 ◽

2010 ◽

pp. 302-306

Author(s):

Saji Baby

Keyword(s):

The State ◽

Coastal Landscape ◽

Morphologic Evolution ◽

The State Of Kuwait ◽

Tools And Methods

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Phylogeny and morphologic evolution of the Ordovician Camerata (Class Crinoidea, Phylum Echinodermata)

Journal of Paleontology ◽

10.1017/jpa.2016.137 ◽

2017 ◽

Vol 91 (4) ◽

pp. 815-828 ◽

Cited By ~ 23

Author(s):

Selina R. Cole

Keyword(s):

Phylogenetic Analysis ◽

Phylogenetic Relationships ◽

Evolutionary History ◽

Phylogenetic Analyses ◽

Major Group ◽

Higher Taxa ◽

Morphologic Evolution ◽

Phylogenetic Framework ◽

Selection For

AbstractThe subclass Camerata (Crinoidea, Echinodermata) is a major group of Paleozoic crinoids that represents an early divergence in the evolutionary history and morphologic diversification of class Crinoidea, yet phylogenetic relationships among early camerates remain unresolved. This study conducted a series of quantitative phylogenetic analyses using parsimony methods to infer relationships of all well-preserved Ordovician camerate genera (52 taxa), establish the branching sequence of early camerates, and test the monophyly of traditionally recognized higher taxa, including orders Monobathrida and Diplobathrida. The first phylogenetic analysis identified a suitable outroup for rooting the Ordovician camerate tree and assessed affinities of the atypical dicyclic family Reteocrinidae. The second analysis inferred the phylogeny of all well-preserved Ordovician camerate genera. Inferred phylogenies confirm: (1) the Tremadocian genera Cnemecrinus and Eknomocrinus are sister to the Camerata; (2) as historically defined, orders Monobathrida and Diplobathrida do not represent monophyletic groups; (3) with minimal revision, Monobathrida and Diplobathrida can be re-diagnosed to represent monophyletic clades; (4) family Reteocrinidae is more closely related to camerates than to other crinoid groups currently recognized at the subclass level; and (5) several genera in subclass Camerata represent stem taxa that cannot be classified as either true monobathrids or true diplobathrids. The clade containing Monobathrida and Diplobathrida, as recognized herein, is termed Eucamerata to distinguish its constituent taxa from more basally positioned taxa, termed stem eucamerates. The results of this study provide a phylogenetic framework for revising camerate classification, elucidating patterns of morphologic evolution, and informing outgroup selection for future phylogenetic analyses of post-Ordovician camerates.

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