CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia (Turborotalia) archeocompressa Blow 1979

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> G -> Globorotalia (Turborotalia) -> Globorotalia (Turborotalia) archeocompressa
Other pages this level: G. (Turborotalia) acostaensis pseudopima, G. (Turborotalia) acostaensis tegillata, G. (Turborotalia) akersi, G. (Turborotalia) archeocompressa, G. (Turborotalia) bauerensis, G. (Turborotalia) cifellii, G. (Turborotalia) exserta, G. (Turborotalia) galapagosensis, G. (Turborotalia) griffinae, G. (Turborotalia) hansbollii, G. (Turborotalia) humerosa praehumerosa, G. (Turborotalia) incisa, G. (Turborotalia) longiapertura, G. (Turborotalia) mendacis, G. (Turborotalia) nkbrowni, G. (Turborotalia) oceanica, G. (Turborotalia) palpebra, G. (Turborotalia) parkerae, G. (Turborotalia) peripheroacuta> >>

Globorotalia (Turborotalia) archeocompressa

Citation: Globorotalia (Turborotalia) archeocompressa Blow 1979
Rank: Species
Type locality: Zone P , DSDP Hole 47.2/11/5: 148-150 cm
Type age (chronostrat): Lowermost Paleocene basal Danian Zone P.a ( Glohororatia ( Turbororalia) longiapertura partial-range zone): ranges u p t o Lower Paleocene, lower Danian , top of Zone P.1a ( Globorotalia ( Turborotalia) pseudobulloides / Glo_borotalia ( Turborotalia) archeocompressa concurrent-range zone).
Type specimens: Holotype:PM PF 63595 Paratype:PM PF 63594
Type repository: London, UK; NHM

Linked specimens: London, UK; NHM (PM PF 63595) London, UK; NHM (63594)

Current identification/main database link: Globanomalina archeocompressa (Blow 1979)


Original Description
The very small test consists of about 11-12 chambers coiled in a low, lax trochospire with 5 1/2 chambers visible in the final convolution of the test. In dorsal aspect, the chambers are almost hemispherical with inflated dorsal surfaces and depressed, sensibly radially disposed, intercameral sutures; the chambers are almost equidimensional with the tangential length only very slightly greater than the radial breadth. The inflation of the dorsal surfaces of the last convolution of chambers is such that the initial spire of chambers is depressed below the level of the later chamber surfaces. In equatorial profile, the test is moderately lobulate but is almost circular in overall outline. In axial-apertural profile, the test appears biconcave because of the depression of the initial spire below the level of the dorsal surfaces of the later chambers. The test is also seen in the axial-apertural view to have a rounded peripheral marginal outline and the later chambers, at least, appear subglobular with little or no differentiation in the degree of inflation for the ventral and dorsal surfaces of the chambers. In ventral aspect, the chambers appear subglobular but with quite deeply depressed, but not sharply incised, intercameral sutures which are radially disposed. The umbilicus is open but is shallow with no clearly marked umbilical shoulders to the surrounding convolution of chambers. The aperture is interiomarginal and extends from the shallow umbilicus to very nearly to the peripheral margin. The aperture is bordered by a well-marked flange-like lip and is a low, only slightly arched, opening. The wall is very finely perforate and the mural-pores do not open into distinct pore-pits, neither are they densely arranged. In optical appearance, the finely and sparsely perforate wall combined with the absence of pore-pits and inter-pore ridges gives the test a smooth, almost polished appearance which is characteristic of the G. (T.) compressa (sl) lineage.

Size: Maximum diameter of holotype) 0.139 mm as measured by electron-beam sensor.

Extra details from original publication

This very small taxon appears to range in size from ca. 0.125 mm to 0.20 mm in maximum dimensions with the largest size being recorded for the paratype figured on pl. 68, fig. 5. which is shown in axial-apertural view and which has 6 complete  chambers visible in 
the final  convolution  of  the test as compared  to the 5 I/2 shown by the holotype. The paratype figured on pl. 58, fig. 2, displays a form which  the writer considers as 'primitive' for the chambers are almost globular includ­ing the final chamber combined with a very widely open umbilicus and a very lax coiling-mode. However, in the holotype the coiling is less lax than in this paratype and the final chamber of the holotype displays a slight tendency to become longer tangentially than  radially  broad. This  tendency  for  the  chambers to  become  longer than broad is seen in the representatives of the taxon which show transition towards Globororalia ( Turbororalia) compressa (sensu lato) where the lengthening of the chambers occurs earlier in ontogeny. In this regard  the paratypes figured  on  pl.  56, figs.  I   and  2. are  considered  as 'advanced' and  already  show a  marked  tangential lengthening of the final chambers, but  not, however,any
significant lengthening of the earlier chambers of the last whorl. In these 'advanced' paratypes there is also a tendency  for the earlier 
dorsal  intercameral  sutures to become  less radially disposed and to show slight posterior recurvature. The paratypes figured on pl. 58, figs. 6 and  7, display a typical morphology  of the taxon  and  together  with  the paratypes figured on pl. 64, figs. 5 and 9, and pl. 68, figs. 5 and 6.  show  the  complete  range  of variation which the  writer  associates  with  his  new  taxon.  The  paratype  figured  on pl.  64, fig.  9, shows the  reduction of  the  number  of chambers in  t he  last  whorl  to 4 I/2 which is a feature sometimes associated with  'advanced' forms that show the lengthening of the last chamber referred  to above.

The  specimens  referred   to  as  Globorotalia  ( Turborotalia)  cf.  archeocompressa ( Blow, 1979, op. cit., pl..64. figs. 2, 3 and 6) have a ventral aspect just like the forms referred to archeocompressa without qualification but, instead of showing a dorsal initial spire depressed below the level of the dorsal surtaces of the later chambers, the initial spire stands at the same level, or slightly above the level, of the dorsal surfaces of the last convolution of chambers. This feature may be due to a  slight ,  purely phenotypic, irregularity of the
trochospire but it may represent a very primitive con­dition and is noted  for the sake of completeness of the record  of these
stratigraphi­cally very early turborotaliids.

In summary. the differences between archeocompressa  Blow,  1979 and  G!obororalia ( Turbororalia)  compressa  planocompressa  Shutskaya  ( 1965,   Voprosy   Mikropal., no. 9. p.  1 80.  pl.  I . fig. 6, given  as  Globorota!ia planocompressa  planocompressa) may be  stated  as  follows.  Shutskaya 's  taxon  possesses  tangentially  longer chambers , an  almost  flay  dorsal  side  and  a  smaller  but  deeper,  umbilicus  than  the  forms referred   to  archeocompressa;  these  differences  are  also  accompanied   by  an   overall
increase in test size.

 
Morozova figured two forms as Globigerina (Eoglobigerina) theodosica and Globi­gerina  (Eoglobigerina) taurica (  see catalogue  sheets)  but  unfortunately  the  holotypic illustrations  are  not  adequate  for  taxonomic differentiation  and   sure  identification. However,  it  is  a  possibility  that   the  new  taxon  described   here  as  archeocompressa
 may be closely related to raurica Morozova , 1961, and the form described here as cf archeocompressa (Blow. 1979, loc. cir .) may be closely related to rheodosica Moroz­ova, 1961. However, the synonymy must await the redescription of Morozova's type by Russian colleagues. At least for biostratigraphic, taxonomic and descriptive pur­poses the writer feels just ified in describing as a new taxon the
forms herein ascribed to  archeocompressa. especially as other forms such as longiaperrura Blow, 1979, planocompressa Shutskaya , or  even  one  of  the  numbered  types described  herein, might equally be related  to  Morozova's taxa.  Furthermore. it is not  clear what 
the differences are between  taurica and rheodosica and  whether or not the second  taxon is a synonym of the first. The solution to these problems can only be forthcoming after redescription and comparative diagnoses of Morozova's types with the forms described in this work.



 
  

 

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G LO BOROTA LI A (TU R BOR OTA LI A) A RC H EOCO M PR ESSA  Blow.  1979


may be closely rela ted to raurica Morozova . 1961. and t he form described here as cf archeocompressa (Blow. 1979, loc. cir .) may be closely related to rheodosica Moroz­ ova, 196 1. H owever. t he synonym y m ust awa it t he redescription of M orozova's type by R ussia n colleagues. At least for bi ost ratigra phic, taxonomic a nd descript ive pu r­ poses t he writer feels ju st ified i n describing as a new ta xon t he for ms herei n ascribed
t o  archeocompressa. especially as ot her forms such as / ongiaperrura Blow, 1979, planoc ompressa Sh u tskaya , or  even  one  of  t he  n u m bered  types descri bed  he rein, m ight eq ua lly be related  to  Morozova's ta xa.  Fu rt hermore. it  is not  clear what  t he d ifferences are bet ween  taurica a nd rheodosica and  whet her or not the second  ta xon is a syn on y m of t he fi rst. The solu tion t o t hese pro blem s ca n on ly be fort hcom in g after redescription and compara tive d iagn oses of M orozova's types with t he forms described i n t h is work."

"

References:

Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs


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Globorotalia (Turborotalia) archeocompressa compiled by the pforams@mikrotax project team viewed: 25-10-2020

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