Morphometric analysis of Eocene nummulitids in western and central Cuba: taxonomy, biostratigraphy and evolutionary trends
Author
Torres-Silva, Ana. I.
Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria;
Author
Eder, Wolfgang
Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria;
Author
Hohenegger, Johann
Department of Palaeontology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria;
Author
Briguglio, Antonino
Dipartimento di Scienze della, Terra dell’Ambiente e della Vita, Universita ́ degli Studi di Genova, Corso Europa, 26, I- 16132 Genova, Italy
text
Journal of Systematic Palaeontology
2018
2018-04-13
17
7
557
595
http://dx.doi.org/10.1080/14772019.2018.1446462
journal article
10.1080/14772019.2018.1446462
1478-0941
PMC6474738
31057335
10883523
Nummulites striatoreticulatus
Rutten, 1928
(
Fig. 15A–M
)
1928
Nummulites striatoreticulatus
Rutten
: 1068, pl. 1, figs 41–50, F–J.
1941
Camerina vanderstoki
(Rutten & Vermunt)
; Cole: 28, pl. 8, figs 5, 8.
1942
Camerina vanderstoki
(Rutten & Vermunt)
; Cole: 27, pl. 8, fig. 10.
1958
Camerina striatoreticulata
(Rutten)
; Cole: 265, pl. 32, figs 6–8.
1974
Nummulites
(
Nummulites
)
striatoreticulatus
Rutten
; Frost & Langenheim: 74, pl. 11, figs 1–14, pl. 13, figs 1, 13.
1993
Nummulites striatoreticulatus
Rutten
; Robinson & Wright: 331, pl. 30, fig. 5, pl. 30, fig. 6.
Material.
Sixty-one well-preserved megalospheric specimens comprising 15 equatorial sections from Entronque de Herradura (98LC-2); 12 equatorial and nine axial sections from Loma Candelaria (98LC-1); seven equatorial sections from Loma El Santo (CA-215); and nine equatorial and nine axial sections from (E-126).
Figure 14.
Distribution of larger benthic foraminifera (LBF) in the Loma Viǵıa section, central Cuba.
Figure 15.
Nummulites striatoreticulatus
Rutten.
A
–C,
Entronque de Herradura;
A,
98LC-2-686;
B,
98LC-2-687;
C,
98LC-2-1a.
D–F,
Loma Candelaria;
D,
98LC-1-660;
E,
98LC-1-630;
F,
98LC-1-806.
G–K,
La Esperanza;
G,
E-126-474;
H,
E-126-466;
I,
E-126-458;
J,
E-126-470, gaps in the septa between adjacent alar prolongations of the chambers;
K,
E-126-459;
L, M,
Loma El Santo;
L,
CA-215- 865;
M,
CA-215- 65.
A, B, E, F, H, I, L
and
M
are A forms in equatorial section;
C, D, G
and
J
are A forms in axial section.
Table 2.
Characters and attributes (means and standard deviations, SD, in mm) for
Nummulites
and comparisons with
Palaeonummulites
and
Operculinoides
.
Symbol key: ++, strong positive differences with <1% error probability; +, differences with <5% error probability; 0, no significant differences; ――, strong negative differences with <1% error probability.
Nummulites
|
Mean |
SD |
Operculinoides
|
Palaeonummulites
|
First chamber length |
448.7 |
220.50 |
0 |
++ |
Proloculus nominal diameter |
334.2 |
152.84 |
++ |
++ |
Deuteroloculus ratio |
0.999 |
0.1297 |
―― |
0 |
Initial marginal radius |
355.9 |
143.51 |
++ |
++ |
Marginal radius increase |
0.062 |
0.0081 |
―― |
0 |
Spiral chamber height increase |
3.8 |
1.47 |
++ |
++ |
Initial spiral chamber height |
111.0 |
58.49 |
++ |
++ |
Backbend angle |
0.164 |
0.0513 |
―― |
+ |
Initial chamber length |
246.6 |
125.21 |
0 |
++ |
Chamber length increase |
0.009 |
0.0065 |
―― |
0 |
Perimeter ratio |
1.101 |
0.0595 |
―― |
0 |
Description.
External features.
The test is planispiral involute, inflated, biconvex with a lenticular contour and a diameter in the A form ranging from 1.7 to 8.5 mm. Surface smooth with radial septal traces forming distinctly raised lines radiating from the centre to the periphery.
Internal features.
The embryonic apparatus is bilocular, proportionally small for the test size. Subspherical proloculus ranging from 0.12 to 0.40 mm followed by a reniform deuteroconch about 0.10 to 0.56 mm in diameter. Spiral exhibits a weaker marginal radius increase, producing numerous whorls. There are many simple chambers that are more or less equidimensional in the equatorial plane. In some specimens, chambers in the outer whorls can be up to 2 times as long as high. Chambers are divided by septa gently bent inwards (weak backbend angle), and supplementary passages can be present as a result of gaps in the septa between adjacent alar prolongations of the chambers. The well-developed marginal cord, with a fanshaped cluster of coarse canals, forms the chamber apex. Pillars visible in axial section usually do not reach the surface of the test.
Characters and attributes (means and standard deviations) for
Nummulites striatoreticulatus
and comparison to
Palaeonummulites trinitatensis
,
Operculinoides floridensis
(tightly coiled) and
O. floridensis
are given in
Table 3
.
Occurrences.
Early middle Eocene, P11/12, lower part of Loma Candela Formation; late middle Eocene to late Eocene, NP 16/17, upper part of Loma Candela
Table 3.
Characters and attributes (means and standard deviations, SD, in mm) for
Nummulites striatoreticulatus
and comparisons with
Palaeonummulites trinitatensis
,
Operculinoides floridensis
(tightly coiled),
O. floridensis
(loosely coiled) and
O. soldadensis
.
Symbol key: ++, strong positive differences with <1% error probability; +, differences with <5% error probability; 0, no significant differences; -, negative differences with <5% error probability; ――, strong negative differences with <1% error probability.
N. striatoreticulatus
|
Mean |
SD |
O. floridensis
(tightly coiled)
|
O. floridensis
(loosely coiled)
|
O. soldadensis
|
P. trinitatensis
|
First chamber length |
454.7 |
221.33 |
0 |
―― |
++ |
++ |
Proloculus nominal diameter |
335.0 |
151.10 |
++ |
++ |
++ |
++ |
Deuteroloculus ratio |
1.003 |
0.1318 |
0 |
- |
―― |
0 |
Initial marginal radius |
360.2 |
144.63 |
++ |
0 |
++ |
++ |
Marginal radius increase |
0.062 |
0.0080 |
―― |
―― |
―― |
―― |
Spiral chamber height increase |
3.8 |
1.45 |
0 |
0 |
++ |
++ |
Initial spiral chamber height |
112.9 |
59.18 |
+ |
0 |
++ |
++ |
Backbend angle |
0.167 |
0.0527 |
―― |
―― |
―― |
―― |
Initial chamber length |
253.2 |
131.05 |
0 |
―― |
++ |
++ |
Chamber length increase |
0.009 |
0.0064 |
―― |
―― |
―― |
0 |
Perimeter ratio |
1.102 |
0.0591 |
―― |
―― |
―― |
―― |
Figure 16.
Operculinoides floridensis
(Heilprin)
.
A–C,
Loma Candelaria;
A,
98LC-1-651;
B,
98LC-1-667;
C,
98LC-1-815.
D, E,
Loma Viǵıa;
D,
CA-216-F3-16;
E,
CA-216-D1a.
F,
Loma El Santo, CA-215-852.
G,
Loma Jabaco, LM-52-759.
H,
Angelita Quarry, 98MT-1.
A–D, F
and
G
are A forms in equatorial section;
E
and
F
are A forms in axial section.
Formation; late middle Eocene,
CNE
13/ NP 16, Arroyo Blanco Formation; late Eocene, Jicotea Formation.
Remarks.
Nummulites striatoreticulatus
is one of the most widely recognized species of
Nummulites
in the Caribbean. It is distinguished from
N. macgillavry
by the much smaller diameter of the proloculus. In random sections, the range of morphological variation of the species
P. trinitatensis
overlaps with
N. striatoreticulatus
and it is difficult to distinguish between these two species.
Nummulites striatoreticulatus
is rare in the latest Eocene. It is almost absent in the Loma Viǵıa and Jabaco localities and sparsely present (
two specimens
) in the Norona section. These localities represent optimum conditions for orbitoids, with enormous numbers of microspheres and megalospheres of
Lepidocyclina chaperi
and
L. pustulosa
.
Amphistegina cubensis
is less abundant and might replace
N. striatoreticulatus
.
Stratigraphical and geographical distribution.
Middle Eocene to late Eocece (Lutetian to Priabonian);
Cuba
,
Mexico
,
Curacao
, Florida,
Trinidad
,
Costa Rica
, French Lesser Antilles, Panaḿa,
Jamaica
and St. Bartheleḿey.