Attributes | Values |
---|
rdf:type
| |
Description
| - Conulariids are fossils of the presumed polyps of an extinct scyphozoan cnidarian group. Their cone-shaped skeletons normally show perfect tetraradial symmetry. However, in the Ordovician species Metaconularia anomala (Barrande 1867) from Drabov (Czech Republic), tetraradial symmetry is compromised in three ways: (1) the skeleton often shows torsion; (2) the four sides may vary in width at the same level within one individual; and (3) one side may be deleted to give a triradial skeleton. Almost 2000 specimens were studied in museum collections. About 56% of analysed specimens are twisted in an anticlockwise direction (sinistral) when viewed from the apex towards the aperture, 28% show no torsion, 1% exhibit clockwise torsion (dextral) and the remaining 15% cannot be classified. Maximum measured torsion rate was 1.5 degrees/mm. A significant negative correlation between torsion rate and length suggests that more highly torted individuals may have survived less well. Almost 5% of individuals show loss of one side for at least part of their lengths. Although many individuals have four sides of equal width, in a significant proportion the sides are of unequal width, up to a maximum/minimum side width ratio of 2 (i.e. widest face twice the width of the narrowest). In the absence of a satisfactory taphonomic model to explain the asymmetries, they are regarded as mirroring asymmetries in the living conulariids, with the strong preference for sinistral torsion interpreted as an example of a fixed asymmetry that was genetically controlled and heritable. It is speculated that the signalling protein Nodal as well as Hox-like genes were involved in controlling the asymmetries described in M. anomala.
- Conulariids are fossils of the presumed polyps of an extinct scyphozoan cnidarian group. Their cone-shaped skeletons normally show perfect tetraradial symmetry. However, in the Ordovician species Metaconularia anomala (Barrande 1867) from Drabov (Czech Republic), tetraradial symmetry is compromised in three ways: (1) the skeleton often shows torsion; (2) the four sides may vary in width at the same level within one individual; and (3) one side may be deleted to give a triradial skeleton. Almost 2000 specimens were studied in museum collections. About 56% of analysed specimens are twisted in an anticlockwise direction (sinistral) when viewed from the apex towards the aperture, 28% show no torsion, 1% exhibit clockwise torsion (dextral) and the remaining 15% cannot be classified. Maximum measured torsion rate was 1.5 degrees/mm. A significant negative correlation between torsion rate and length suggests that more highly torted individuals may have survived less well. Almost 5% of individuals show loss of one side for at least part of their lengths. Although many individuals have four sides of equal width, in a significant proportion the sides are of unequal width, up to a maximum/minimum side width ratio of 2 (i.e. widest face twice the width of the narrowest). In the absence of a satisfactory taphonomic model to explain the asymmetries, they are regarded as mirroring asymmetries in the living conulariids, with the strong preference for sinistral torsion interpreted as an example of a fixed asymmetry that was genetically controlled and heritable. It is speculated that the signalling protein Nodal as well as Hox-like genes were involved in controlling the asymmetries described in M. anomala. (en)
|
Title
| - Asymmetry in an Ordovician conulariid cnidarian
- Asymmetry in an Ordovician conulariid cnidarian (en)
|
skos:prefLabel
| - Asymmetry in an Ordovician conulariid cnidarian
- Asymmetry in an Ordovician conulariid cnidarian (en)
|
skos:notation
| - RIV/00023272:_____/12:#0001819!RIV13-MK0-00023272
|
http://linked.open...avai/predkladatel
| |
http://linked.open...avai/riv/aktivita
| |
http://linked.open...avai/riv/aktivity
| |
http://linked.open...iv/cisloPeriodika
| |
http://linked.open...vai/riv/dodaniDat
| |
http://linked.open...aciTvurceVysledku
| |
http://linked.open.../riv/druhVysledku
| |
http://linked.open...iv/duvernostUdaju
| |
http://linked.open...titaPredkladatele
| |
http://linked.open...dnocenehoVysledku
| |
http://linked.open...ai/riv/idVysledku
| - RIV/00023272:_____/12:#0001819
|
http://linked.open...riv/jazykVysledku
| |
http://linked.open.../riv/klicovaSlova
| - Symmetry; Scyphozoa; Patterns; Anatomy (en)
|
http://linked.open.../riv/klicoveSlovo
| |
http://linked.open...odStatuVydavatele
| - US - Spojené státy americké
|
http://linked.open...ontrolniKodProRIV
| |
http://linked.open...i/riv/nazevZdroje
| |
http://linked.open...in/vavai/riv/obor
| |
http://linked.open...ichTvurcuVysledku
| |
http://linked.open...cetTvurcuVysledku
| |
http://linked.open...vavai/riv/projekt
| |
http://linked.open...UplatneniVysledku
| |
http://linked.open...v/svazekPeriodika
| |
http://linked.open...iv/tvurceVysledku
| - Sendino, Consuelo
- Zágoršek, Kamil
- Taylor, Paul D.
|
http://linked.open...ain/vavai/riv/wos
| |
issn
| |
number of pages
| |
http://bibframe.org/vocab/doi
| - 10.1111/j.1502-3931.2011.00302.x
|
is http://linked.open...avai/riv/vysledek
of | |