Difference between revisions of "Subembryonic chamberlets"

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(Created page with "File:Fig 41.jpg|thumb|<font size="2">'''Fig. 1.''' Embryonic apparatus. '''A:''' ''Discocyclina'', stereograph after Ferràndez (1999), modified. Schema, not to scale. '''B:...")
 
 
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*''according to Hottinger (2006):''
 
*''according to Hottinger (2006):''
 
'''SUBEMBRYONIC CHAMBERLETS''' - chamberlets that are produced in a mono- or plurilocular third stage in the growth of [[megalospheric]] embryos of agglutinated conical [[foraminifera]]. They are located below the [[proloculus]] in the cone axis and are subdivided by structural elements of uncertain, probably exoskeletal origin.  
 
'''SUBEMBRYONIC CHAMBERLETS''' - chamberlets that are produced in a mono- or plurilocular third stage in the growth of [[megalospheric]] embryos of agglutinated conical [[foraminifera]]. They are located below the [[proloculus]] in the cone axis and are subdivided by structural elements of uncertain, probably exoskeletal origin.  
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''Remarks:'' J. Hofker Jr (1963, p. 211, fig. 14) interpreted the life habit of an orbitolinid as face upward, i.e. the cone apex downward, buried in the sediment. Therefore, he called the third growth-stage in Orbitolina s.str. "epiembryonic". The confusion up-down is complicated by a supposed error in the legend of fig. 2 in J. Hofker Jr (1966), where deuteroconch and epiembryonic chambers are reversed by comparison with his 1963 paper. Today, all foraminifera with an extensive apertural face covered by numerous apertures live with their apertural face towards the substrate. Undoubtedly, the same is true for conical foraminifera in general. The term epiembryonic is therefore to be avoided. Douglas (1960) did not distinguish between sub- and periembryonic chambers, both representing the third growth stage.  
 
''Remarks:'' J. Hofker Jr (1963, p. 211, fig. 14) interpreted the life habit of an orbitolinid as face upward, i.e. the cone apex downward, buried in the sediment. Therefore, he called the third growth-stage in Orbitolina s.str. "epiembryonic". The confusion up-down is complicated by a supposed error in the legend of fig. 2 in J. Hofker Jr (1966), where deuteroconch and epiembryonic chambers are reversed by comparison with his 1963 paper. Today, all foraminifera with an extensive apertural face covered by numerous apertures live with their apertural face towards the substrate. Undoubtedly, the same is true for conical foraminifera in general. The term epiembryonic is therefore to be avoided. Douglas (1960) did not distinguish between sub- and periembryonic chambers, both representing the third growth stage.  
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==References==
 
==References==
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Douglas (1960), The foraminiferal genus Orbitolina in North America, Geological Survey Professional Paper, Washington, 333, 52 p. + 14 pls.
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Ferràndez I Cañadell (1999), Morfoestructura i paleobiologia dels Ortofragmínidos de la Mesogea (Discocyclinidae i Orbitocyclinidae, Foraminifera), Arxius de les Seccions de Ciències, Barcelona, (Secció de Ciències i Tecnologia), CXXI, 339 p.
 
Ferràndez I Cañadell (1999), Morfoestructura i paleobiologia dels Ortofragmínidos de la Mesogea (Discocyclinidae i Orbitocyclinidae, Foraminifera), Arxius de les Seccions de Ciències, Barcelona, (Secció de Ciències i Tecnologia), CXXI, 339 p.
  
 
Hofker (1963), Studies on the genus Orbitolina (Foraminiferida), Leidse Geologische Mededelingen, Leiden, vol. 29, p. 181–253 + 23 pls.
 
Hofker (1963), Studies on the genus Orbitolina (Foraminiferida), Leidse Geologische Mededelingen, Leiden, vol. 29, p. 181–253 + 23 pls.
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Hofker (1966),  Studies on the family Orbitolinae,  Palaeontographica, Stuttgart, (Abteilung A), Band 126, Lieferung 1-2, p. 1-34 + 10 pls.
  
 
Hottinger (1967), Foraminifères imperforés du Mésozoïque marocain, Notes et Mémoires du Service géologique, Rabat, N° 209, p. 5-168
 
Hottinger (1967), Foraminifères imperforés du Mésozoïque marocain, Notes et Mémoires du Service géologique, Rabat, N° 209, p. 5-168

Latest revision as of 14:19, 10 May 2019