jura creta

CHAPTER 5

MESOZOIC

JURASSIC - CRETACEOUSForaminifers

Sabudia

Suborder TEXTULARIINA Delage and Herouard, 1896Superfamily ATAXOPHRAGMIACEA Schwager ,1877

Family CUNEOLINIDAE Saidova, 1981

Genus Sabudia

Test a high cone with flattened base; Small initial trochospiral stage of three to four subglobular chambers; Followed by later biserial stage, biserial chambers partially subdivided by

numerous vertical subepidermal partitions that arise perpendicular to the septa, Secondary horizontal partitions also present in later chambers of large individuals,

the ensemble of inner partitions resulting in a subepidermal network of chamberlets that open at the test interior;

Wall of embryonal trochospire double, with inner microgranular layer and outer hyaline layer;

Wall of biserial stage agglutinated, imperforate; Aperture an interiomarginal slit. Early Cretaceous (Late Hauterivian Aptian)

Genus Cuneolina

Cuneolina

Test free, compressed conical to flabelliform; Early trochospire of about five chambers followed

by very broad and low biserially arranged chambers; Commonly compressed parallel to the the plane of biseriality; Interior subdivided into nearly rectangular cahamberlets

by radial parttions arising perpendicular to the outer; Wall agglutinated, imperforate, with reticulate subepidermal layer; Aperture a row of pores at the base of the septal face.


Family CUNEOLINIDAE Saidova, 1981

Suborder TEXTULARIINA Delage and Herouard, 1896Superfamily LOFTUSIACEA Brady ,1884

Family MESOENDOTHYRIDAE Voloshinova, 1958

Test enrolled; Early stage streptospiral, later becoming nearly planispiral; Involute, periphery broadly rounded; Wall microgranular, agglutinated carbonate grains, with outer imperforate layer,

inner alveolar layer; Aperture interiomarginal slit. Middle Triassic (Ladinian) Late Jurassic (Early Kimmeridgian).

Mesoendothyra

Genus Mesoendothyra


Family CYCLAMMINIDAE Marie, 1941

Genus Choffatella

Test planispirally enrolled, compressed, partially evolute, whorls enlarging rapidly; Chambers numerous, later chambers tendency to uncoil; Wall exoskeleton with well-developed subepidermal network; No pillars; Aperture a single areal row of large opennigs extending up the apertural face

in the plane of coiling. Late Jurassic (Oxfordian) Late Cretaceous (Cenomanian)

Genus Evertycyclammina

Test planispirally enrolled and involute; Lenticular to slightly compressed, later with a slight tendency to uncoil; Wall agglutinated, alveolar, septa short and not alveolar; Aperture a short vertical areal slit.

Late Jurassic (Late Oxfordian) Late Cretaceous (Cenomanian).



Test planispirally enrolled, and involute at least in early stage; Later uncoiling; Subspherical to flattened; Wall coarsely agglutinated, with coarse subepidermal network (alveolar); Septa thick and massive, perforated by large openings; Aperture areal, cribrate, covering the apertural face..

Early Jurassic Late Cretaceous (Coniacian).

Genus Pseudocyclammina



Genus Anchispirocyclina

Test enrolled, planispiral to slightly asymetrical, large flattened and commonly slightly undulating discoid microspheric tests;

Early stage close coiled, later flaring, spreading, and peneropline to reniformor circular in outline;

Chambers broad, low, strongly arcuate in the early stage, later may become completely cyclic, periphery roundede to subacute;

Wall microgranular to finelyagglutinated or may include occasionally large grains of smaller foraminifers, imperforate outer layer underlain by a reticulate choffateloid subepidermal network of rafters and beams

Narrow chambers not subdivided inward from the reticulate zone but leave a narrow open canal

Chambers near the median plane occupied by an irregular labrynthic structure produced by an irregular pillars or buttresses

Aperture cribrate, scattered over theapertural face. Late Jurassic (Early Kimmerdigian) Early Cretaceous (Early Valanginian).


Family SPIROCYCLINIDAE Munier-Chalmas,1887

Genus Anchispirocyclina





Genus Haurania

Test free, elongate conical; Early chambers planispiral coil followed by elongate uncoiled

and rectilinear stage; about a central column with chambers; Wall finely agglutinated, with imperforate epidermal layer, radial

exoskeletal septula or beams are perpendicular to the septa and outer wall but unrelated to the apertural openings present in the early stage, beams bifurcating inward in later chambers and accompanied by rafters that parallel the septa, forming a coarse alveolar network in the lower part of the chamber and becoming finer in the upper part, endoskeletal pillars in the central region of the test are continuous in successive chambers;

Aperture cribrate, a series of openings in a circular area of the terminal face.

Early Jurassic (Middle Lias) Middle Jurassic (Bathonian)

Genus Nautiloculina

Suborder TEXTULARIINA Delage and Herouard, 1896Superfamily LITUOLACEA de Blainville,1827

Family NAUTILOCULINIDAE Loeblich and Tappan, 1985

Test free, lenticular in form, planispirally enrolled, and involute; globular proloculus followed by numerous small chambers per whorl

that increase gradually in size, interior simple; Wall microagglutinated, no subepidermal network or other exoskeletal

or endoskeletal structures present; Axial region progressively thickened as chambers are added; Aperture equatorial, a low interiomarginal arch. Late Jurassic (Early Malm) Early Cretaceous.


Family TEXTULARIDAE Ehrenberg, 1838

Test biserial, at least in the early stage, later may be reduced to uniserial;

Wall agglutinated; Aperture interomarginal to areal, single or multiple.

Genus Textularia

Test biserial, throughout; Wall agglutinated; Aperture a low arch or slit at the base of the apertural face.

Textularia

Valvulina


Family VALVULINIDAE berthelin, 1880

Test trochospiral in the early stage, later may have an increased number of chambers per whorl, or may become triserial;

Wall agglutinated; Aperture with valvular tooth or flap at least in early stage,

may become multiple and areal in later stage.

Genus Valvulina

Test triserial, triangular in section, sides flattened; Wall agglutinated; Aperture interiomarginal with valvular tooth or flap

Pfenderina

Meyendorfina


Family PFENDERINIDAE Smout and Sugden, 1962

Test trochospiral, later stage may have reduced number of chambers per whorl;

Chamber interior of advanced taxa may be subdivided by vertical or horizontal exoskeletal partitions or both, resulting in a reticulate subepidermal layer

Wall agglutinated. Early Jurassic (Lias) Late Cretaceous (Maastrichtian).

Kurnubia

Pfenderina



Test a high trochospiral; Chambers numerous, surrounding an axial region of thickened shell material; Septa perpendicular to the spiral axis, and oblique to the test axis; Wall micro-agglutinated, imperforate; Aperture consisting of numerous pores in the center of the apertural face. Late Jurassic Late Cretaceous (Cenomanian).

Genus Pfenderina

Kurnubia

Test elongate; Early chambers trochospiral about a central column with chambers; Somewhat inclined to the axis of coiling, later uncoiled, uniserial and

rectilinear, outer part of chambers has a characteristic subepidermal network, central part with endoskeletal pillars that are continuous from chamber to chamber, spaces between pillars later filled secondarily to produce a central column;

Apertural face consists of a plate over the umbilical region with many small apertures interspersed between pillars, where aperturesare secondarrily filled to produce a column.

Early Jurassic (Lias) Late Jurassic (Kimmeridgian)

Genus Kurnubia



AGenus Kurnubia

Suborder TEXTULARIINA Delage and Herouard, 1896

Superfamily ATAXOPHRAGMIACEA Schwager ,1877


A



Test conical, early enrolled stage almost planispiral, later rectilinear, with rapidly enlarging broad and low discoidal chambers;

Chambers subdivided by exoskeletal vertical radial beams that project a short distance inward from the outer wall but lack horizontal rafters, central zone with exoskeletal pillars;

Wall micro-agglutinated; Aperture openings in the septal face between the outer zone and inner pillared

zone, and additional openings are irregularly intercalated between the pillars. Middle Jurassic (Bathonian).

Genus Meyendorfina

Suborder TEXTULARIINA Delage and Herouard, 1896Superfamily CYCLOLINACEA Loeblich and Tappan, 1964

Family ORBITOPSELLIDAE Hottinger and Caus, 1982

Test planispirally coiled in early stage, later peneropliform or cyclic; Chambers numerous; Wall agglutinated, exoskeleton simple, without subepidermal network; Apertures in alternating arrangement. Early Jurassic (Lias) Late Jurassic (Kimmeridgian).

Orbitopsella

Orbitopsella

Genus Orbitopsella

Test planispirally coiled in early stage, later peneropliform or cyclic; Chambers numerous; Wall agglutinated, exoskeleton simple, without subepidermal network; Apertures in alternating arrangement. Early Jurassic (Lias) Late Jurassic (Kimmeridgian).



Genus Labyrinthia (Lituosepta)



Test free, elongate, early planispirally coiled and involute, later uncoiling and rectilinear, slightlycompressed to peneropliform;

Wall agglutinated, simple in structure, imperforate; Endoskeletal pillars extend from chamber floor to roof and also may be

continuous from chamber to chamber; Aperture simple and interomarginal in the early enrolled stage, then areal,

and in the adult stage is areal and multiple over the central part of the apertural face. Early Jurassic (Lias) Late Jurassic (Oxfordian).

Genus Labyrinthia (Lituosepta)



Suborder TEXTULARIINA

Family Orbitolinidae

Orbitolina

jura creta

Documents

late jurassic late oxfordian

alveolar aperture

outer wall

biserial chambers

later chambers tendency

late jurassic oxfordian

later biserial stage

imperforate aperture