Difference between revisions of "Interseptal pillars"
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− | [[File:Fig | + | [[File:Fig.47E-G.png|thumb|<font size="2">'''Fig. 1.''' Endoskeletal patterns in discoidal shells. |
− | + | Examples: '''E1-2:''' ''Pseudotaberina malabarica'', megalospheric generation, from Iran. Middle Miocene. '''E1:''' oblique-centered section of spiral-involute stage showing radial disposition of pillars. Laterally, there is a layer of short septula. '''E2:''' a transverse section tangential to a septum shows the alternating disposition of the foramina and the pillars. '''F1-2:''' New genus (possibly related to ''Pastrikella'') from the Pyrenean Upper Cretaceous in Northern Spain. The endoskeleton consists only of septula. There is but one median annular preseptal passage and it occupies the total radial extension of the annular chamber. There are only two planes of stolons. '''F1:''' an oblique section at a low angles with respect to the equatorial plane shows the radial disposition of the apertural axes and of the septula. '''F2:''' a transverse section parallel to the shell axis shows that the stolon axes on the two stolon planes are superposed. '''G1-3:''' ''Amphisorus'' from Rottnest Island near Perth, Australia. Recent. '''G1:''' the detail of an equatorial section demonstrates the crosswise-oblique disposition of the pillars on neighboring stolon planes. G2, an equatorial section, demonstrates that pillars are restricted to the equatorial zone of the disc. '''G3:''' a transverse section parallel to the shell axis and tangential to an annular septum shows the disposition of the median foramina and pillars altermating in radial position on successive stolon planes. They are flanked by two annular preseptal passages separating them from a lateral layer of septula subdividing the annular chamber; Abbreviations: '''b:''' beam; '''f:''' foramen; '''pi:''' pillar; '''prp:''' preseptal space; '''ra:''' ramp; '''s:''' septum; '''sl:''' septulum; (Hottinger, 2006; fig. 47); [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]] | |
− | Abbreviations: '''b:''' beam; '''f:''' foramen; '''pi:''' pillar; '''prp:''' preseptal space; '''ra:''' ramp; '''s:''' septum; '''sl:''' septulum; (Hottinger, 2006; fig. | ||
− | [[File:Fig 72.jpg|thumb|<font size="2"> '''Fig. 2.''' The structure of ''Orbitopsella'': a simple [[exoskeleton]] and a pillared [[endoskeleton]] in a discoidal shell: ''Orbitopsella dubari'' Hottinger, Bou Dahar, Eastern Morocco, Middle Lias. Transmitted light micrographs | + | [[File:Fig 72.jpg|thumb|<font size="2"> '''Fig. 2.''' The structure of ''Orbitopsella'': a simple [[exoskeleton]] and a pillared [[endoskeleton]] in a discoidal shell: ''Orbitopsella dubari'' Hottinger, Bou Dahar, Eastern Morocco, Middle Lias. Transmitted light micrographs; '''A:''' oblique section of complete microspheric specimen; '''B:''' oblique section of microspheric specimen. The septa of the thickened margin are cut tangentially and reveal the alternating pattern in the disposition of foramina on the septal face. '''C:''' oblique tangential section of a microspheric specimen at a low angle to the equatorial plane showing a part of the disc with its exoskeleton (restricted to beams). Note the large open spaces, the lateral annular passages (arrows), that separate exoskeleton and endoskeleton. '''D:''' Oblique centered section of megalospheric specimen. Note the structured wall of the embryo, that shows it to be a sphaeroconch. '''E:''' Transverse section (parallel to the axis of coiling) of a megalospheric specimen. The septum in this tangential section reveals the alternating pattern of the apertures. '''F:''' schematic model of structure after Hottinger, 1967; not to scale; '''green''': exoskeleton; '''brown''': endoskeleton'''; a:''' [[aperture]]; '''ap:''' [[annular passage]]; '''b:''' [[beam]]; '''f:''' [[foramen]]; '''p:''' [[pillar]]; '''pr:''' [[sphaeroconch]]; '''s:''' [[septum]]; (Hottinger, 2006; fig. 72 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]] |
− | '''A:''' oblique section of complete microspheric specimen; '''B:''' oblique section of microspheric specimen. The septa of the thickened margin are cut tangentially and reveal the alternating pattern in the disposition of foramina on the septal face. '''C:''' oblique tangential section of a microspheric specimen at a low angle to the equatorial plane showing a part of the disc with its exoskeleton (restricted to beams). Note the large open spaces, the lateral annular passages (arrows), that separate exoskeleton and endoskeleton. '''D:''' Oblique centered section of megalospheric specimen. Note the structured wall of the embryo, that shows it to be a sphaeroconch. '''E:''' Transverse section (parallel to the axis of coiling) of a megalospheric specimen. The septum in this tangential section reveals the alternating pattern of the apertures. '''F:''' schematic model of structure after Hottinger, 1967; not to scale; '''green''': exoskeleton; '''brown''': endoskeleton'''; a:''' [[aperture]]; '''ap:''' [[annular passage]]; '''b:''' [[beam]]; '''f:''' [[foramen]]; '''p:''' [[pillar]]; '''pr:''' [[sphaeroconch]]; '''s:''' [[septum]]; (Hottinger, 2006; fig. 72 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]] | ||
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==Definition== | ==Definition== |