Difference between revisions of "Beam"
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[[File:Fig 45.jpg|thumb|<font size="2">'''Fig. 2.''' Alveolar exoskeleton and polygonal network. | [[File:Fig 45.jpg|thumb|<font size="2">'''Fig. 2.''' Alveolar exoskeleton and polygonal network. | ||
'''A-C:''' simple alveolar layer in ''Everticyclammina virguliana'' (Koechlin), Mechra Klila, Northeastern Morocco, Uppermost Jurassic. '''A:''' stereograph, schematic, not to scale. '''B:''' tangential section. Note the large size of the alveoles in a postseptal position. '''C:''' para-equatorial, non-centered section showing septa and the basal coat at the bottom of the chamber, resembling a basal layer. '''E-G:''' polygonal network in ''Spirocyclinidae''. '''E:''' ''Choffatella tingitana'' Hottinger, megalospheric generation, in tangential section near to the equatorial plane. Note the clear differentiation of beams and rafters. '''D:''' stereograph of spirocyclinid polygonal network. Note the curved pigeon holes in preseptal position which in axial section might be mistaken for foramina. '''F-G:''' extension of beams into a corrugated sheet that replaces endoskeletal pillars in ''Hottingertidae''. '''F:''' stereograph representing a part of an axial section. Not to scale. '''G:''' ''Alveosepta powersi'' (Redmond), Northeastern Morocco, Upper Jurassic. Equatorial section of megalospheric specimen. | '''A-C:''' simple alveolar layer in ''Everticyclammina virguliana'' (Koechlin), Mechra Klila, Northeastern Morocco, Uppermost Jurassic. '''A:''' stereograph, schematic, not to scale. '''B:''' tangential section. Note the large size of the alveoles in a postseptal position. '''C:''' para-equatorial, non-centered section showing septa and the basal coat at the bottom of the chamber, resembling a basal layer. '''E-G:''' polygonal network in ''Spirocyclinidae''. '''E:''' ''Choffatella tingitana'' Hottinger, megalospheric generation, in tangential section near to the equatorial plane. Note the clear differentiation of beams and rafters. '''D:''' stereograph of spirocyclinid polygonal network. Note the curved pigeon holes in preseptal position which in axial section might be mistaken for foramina. '''F-G:''' extension of beams into a corrugated sheet that replaces endoskeletal pillars in ''Hottingertidae''. '''F:''' stereograph representing a part of an axial section. Not to scale. '''G:''' ''Alveosepta powersi'' (Redmond), Northeastern Morocco, Upper Jurassic. Equatorial section of megalospheric specimen. | ||
| − | '''alv:''' alveoles; '''b:''' [[beam]]; '''bl:''' [[basal layer]]; '''corr:''' corrugated median extension of beams; '''f:''' [[foramen]]; '''ph:''' pigeon holes; '''s:''' [[septum]]; '''sf:''' supplementary foramina; '''sph:''' [[sphaeroconch]]; '''ssut:''' [[septal suture]]. Arrows: direction of growth. After Hottinger, 1967.; (Hottinger, 2006; fig. 45 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]] | + | '''alv:''' alveoles; '''b:''' [[beam]]; '''bl:''' [[basal layer]]; '''corr:''' corrugated median extension of beams; '''f:''' [[foramen]]; '''ph:''' pigeon holes; '''s:''' [[septum]]; '''sf:''' supplementary foramina; '''sph:''' [[sphaeroconch]]; '''ssut:''' [[septal suture]]. '''Arrows:''' direction of growth. After Hottinger, 1967.; (Hottinger, 2006; fig. 45 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]] |
[[File:Fig 19.gif|thumb|<font size="2">'''Fig. 3.''' Henson's "subepidermal partitions" (1948, text-figs. 6-7). | [[File:Fig 19.gif|thumb|<font size="2">'''Fig. 3.''' Henson's "subepidermal partitions" (1948, text-figs. 6-7). | ||
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==Definition== | ==Definition== | ||
*''according to Hottinger (2006):'' | *''according to Hottinger (2006):'' | ||
| − | '''BEAM''' - an [[exoskeletal]] main partition of the chamber lumen, perpendicular to the chamber septum and to the lateral chamber wall. In discoidal shells often separated from an [[endoskeleton]] by an empty space in the chamber ([[annular passage]]). May fuse with endoskeletal elements such as [[septula]], particularly in verbeekinids, orbitolinids and cuneolinids. May occur as unique exoskeletal element (Orbitopsella, Fig. 1) or in combination with minor, shorter exoskeletal elements producing a subepidermal polygonal network (Spirocyclinidae, Fig. 2). | + | '''BEAM''' - an [[exoskeletal]] main partition of the chamber lumen, perpendicular to the chamber septum and to the lateral chamber wall. In discoidal shells often separated from an [[endoskeleton]] by an empty space in the chamber ([[annular passage]]). May fuse with endoskeletal elements such as [[septula]], particularly in verbeekinids, orbitolinids and cuneolinids. May occur as unique exoskeletal element (Orbitopsella, Fig. 1.) or in combination with minor, shorter exoskeletal elements producing a subepidermal polygonal network (Spirocyclinidae, Fig. 2.). |
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* [[septula]] | * [[septula]] | ||
==References== | ==References== | ||
| − | Hottinger (2006), [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Illustrated glossary of terms used in foraminiferal research]. [http://paleopolis.rediris.es/cg/uk-index.html Carnets de Géologie], [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Memoir 2], ISSN 1634-0744 | + | Davies (1930), The genus Dictyoconus and its allies: a review of the group, together with a description of three new species from the lower Eocene beds of northern Baluchistan, Transactions of the Royal Society of Edinburgh, vol. 56, p. 485-505. |
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| + | Davies (1939), An early Dictyoconus and the genus Orbitolina: their contemporaneity, structural distinction and respective natural allies, Transactions of the Royal Society of Edinburgh, vol. 59, p. 773-790. | ||
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| + | Henson(1948), Larger imperforate Foraminifera of south-western Asia, Families Lituolidae, Orbitolinidae and Meandrosipinidae, British Museum (Natural History), London, 127 p. + 16 pls. | ||
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| + | Hottinger (1967), Foraminifères imperforés du Mésozoïque marocain. Notes et Mémoires du Service géologique, Rabat, N° 209, p. 5-168 | ||
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| + | Hottinger (1978), Comparative anatomy of elementary shell structures in selected larger Foraminifera, In: Hedley R.H. & Adams C.G. (eds.), Foraminifera. Volume 3.- Academic Press, London, p. 203-266. | ||
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| + | Hottinger (2006), [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Illustrated glossary of terms used in foraminiferal research]. [http://paleopolis.rediris.es/cg/uk-index.html Carnets de Géologie], [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Memoir 2], ISSN 1634-0744 | ||
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| + | Silvestri (1932), Foraminiferi del Cretaceo della Somalia, Paleontographica Italica, Pisa, vol. XXXII (1931, Nuova Serie, vol. II), p. 143-204. | ||
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