First Record of the Rudist Bivalve Mitrocaprina tschoppi (Palmer) from the Maastrichtian of Jamaica

Abstract

The large plagioptychid rudist bi- valve Mitrocaprina tschoppi (Palmer) is recorded from the Guinea Corn Formation (Late Maastrich- tian) of central Jamaica. This is the first record of this species outside of Cuba. M. tschoppi occurs in rhythm D6 of the Guinea Corn Formation, Macgil- lavryia Bed 1, together with a rudist assemblage including Praebarrettia sparcilirata (Whitfield), Macgillavryia nicholasi (Whitfield), Chiapasella trechmanni Mitchell & Gunter, Plagioptychus zansi Chubb, Titanosarcolites sp.; Titanosarcolites cf. ala- tus Chubb and Antillocaprina cf. occidentalis (Whit- field). The pallial canals of the Jamaican specimens are identical to the Cuban material, but the Jamaican specimens are larger (about one and a half times the size).

Full text

Caribbean Journal of Science, Vol. 40, No. 3, 392-396, 2004
Copyright 2004 College of Arts and Sciences
University of Puerto Rico, Mayagu¨ez
First Record of the Rudist Bivalve
Mitrocaprina tschoppi (Palmer)
from the Maastrichtian of Jamaica
SIMON F. MITCHELL AND GAVIN C. GUNTER.
Department of Geography and Geology, Uni-
versity of the West Indies, Mona, Kingston 7,
Jamaica. Corresponding author: smitchell@
cwjamaica.com
ABSTRACT.—The large plagioptychid rudist bi-
valve Mitrocaprina tschoppi (Palmer) is recorded
from the Guinea Corn Formation (Late Maastrich-
tian) of central Jamaica. This is the first record of this
species outside of Cuba. M. tschoppi occurs in
rhythm D6 of the Guinea Corn Formation, Macgil-
lavryia Bed 1, together with a rudist assemblage
including Praebarrettia sparcilirata (Whitfield),
Macgillavryia nicholasi (Whitfield), Chiapasella
trechmanni Mitchell & Gunter, Plagioptychus zansi
Chubb, Titanosarcolites sp.; Titanosarcolites cf. ala-
tus Chubb and Antillocaprina cf. occidentalis (Whit-
field). The pallial canals of the Jamaican specimens
are identical to the Cuban material, but the Jamaican
specimens are larger (about one and a half times the
size).
KEYWORDS.—Biostratigraphy, systematic palaeon-
tology, plagioptychid, Cretaceous.
Small plagioptychid rudists are common
in the Maastrichtian shallow-water lime-
stones of the Caribbean region with many
species recorded from Jamaica and Cuba
(Palmer 1933; Mac Gillavry 1937; Chubb
1971; Rojas et al. 1995). Large species are
rare and limited to Plagioptychus jamaicensis
(Whitfield) from Jamaica and Mitrocaprina
tschoppi (Palmer) from Cuba (Whitfield
1897; Mac Gillavry 1937; Chubb 1971). Pla-
gioptychus jamaicensis left valve attains 20
cm in diameter. The species is remarkably
rare, and Chubb (1971) only had two speci-
mens to study. Mitrocaprina tschoppi left
valve is up to 8 cm in diameter (Mac Gil-
lavry 1937). It contains four layers of pallial
canals −an inner double-layer of polygonal
canals and two outer layers of radially
elongated canals (Mac Gillavry 1937). In
this paper, M. tschoppi is reported and de-
scribed from Jamaica for the first time, and
is compared with similar Caribbean plagi-
optychid rudists.
The Guinea Corn Formation represents
the Titanosarcolites-bearing limestone of
central Jamaica and is of late Maastrichtian
age (Steuber et al. 2002). Based on varia-
tions in clastic:carbonate ratios, Mitchell
(1999) divided the Guinea Corn Formation
into units labeled A to G. A succession of
rudist and coral marker beds was corre-
lated across central Jamaica, and it is now
possible to match most sections of the for-
mation with the “standard succession”of
Mitchell (1999); e.g., see Mitchell and
Gunter (2002).
Mitrocaprina tschoppi was collected from
two localities (Fig. 1): a loose specimen in a
scree slope below the Guinea Corn Forma-
tion at Coffee Piece and two specimens in
situ from bed D6 in the type Guinea Corn
succession at Grantham (Fig. 2 Coffee Piece
NE of Mitchell 1999). Here they are associ-
ated with a rich fauna, including Praebar-
rettia sparcilirata (Whitfield), Macgillavryia
nicholasi (Whitfield), Chiapasella trechmanni
Mitchell & Gunter, Plagioptychus zansi
Chubb, Titanosarcolites sp.; Titanosarcolites
cf. alatus Chubb and Antillocaprina cf. occi-
dentalis (Whitfield), which represents the
Praebarrettia Bed of Mitchell (1999).
SYSTEMATIC DESCRIPTIONS
All material is preserved in the collec-
tions of the University of the West Indies
Geology Museum (UWIGM numbers).
NOTES392

Family Plagioptychidae Douville´, 1888
Genus Mitrocaprina Boehm, 1895
Type Species.—Coralliochama bayani Dou-
ville´, 1888, designated by Boehm, 1895.
Mitrocaprina tschoppi (Palmer, 1933)
Fig. 3; Pl. 1
1933 Plagioptychus tschoppi: Palmer, p. 103,
pl. 10, figs. 1-3.
1937 Mitrocaprina tschoppi (Palmer); Mac
Gillavry, p. 158, pl. 5, fig. 7; pl. 7, figs. 1,
4-5, 7-8; pl. 8, figs. 4, 7.
Diagnosis.—A large species of Mitrocap-
rina with a large convex left valve which is
larger than the right valve. Four layers of
pallial canals in the left valve −two polygo-
nal inner layers and two radially elongated
outer layers.
Material.—Three specimens from Ja-
maica. One loose specimen from the
Guinea Corn Formation, Coffee Piece
(UWIGM.RUD.2004.3) with the umbo re-
gion of the left valve extensively bored by
Entobia isp. Two specimens from upper
rhythm D6, Guinea Corn Formation,
Grantham (Coffee Piece NE) (UWIGM.
RUD.2004.1-2).
Description.—Right (attached) valve gen-
erally exogyrifom in shape. Attachment
area small, posterior side flat and separated
from the anterior side by a sharp ridge at an
angle of about 90°. Valve expands rapidly
in diameter towards the aperture. Surface
marked by rough growth lines. Inner layer
thin and poorly preserved; outer layer
thick, up to 7 mm, and composed of com-
pact, non-cellulose calcite.
Left (free) valve strongly inflated, umbo
rounded and strongly overhanging the
right valve. Outer shell layer thin. Inner
layer thick with four rows of pallial canals.
The inner two rows are composed of large
polygonal pallial canals up to 7 mm maxi-
mum size. The pallial canals in the outer
row are a little larger than those in the inner
row. The inner two rows of pallial canals
consist of narrow radially elongated canals,
the outermost row being narrower and
FIG. 1. Localities from which specimens of Mitrocaprina tschoppi were collected in the Central Inlier of Jamaica.
NOTES 393

longer than the inner row (Fig. 3). Dentition
and ligament poorly visible.
Measurements.—UWIGM.RUD.2004.3
(Coffee Piece Specimen), right (attached)
valve 13.5 cm dorsal-ventral diameter, 8 cm
in posterior-anterior diameter, and 4.5 cm
high; left (free) valve up to 5.5 cm high.
UWIGM.RUD.2004.1 (Grantham, Coffee
Piece NE), right valve measures 12 cm dor-
sal-ventrally, 8 cm posteriorly-anteriorly,
and is 7.5 cm high; left valve 7 cm high.
UWIGM.RUD.2004.2 (Grantham, Coffee
Piece NE), right valve measures 12 cm dor-
sal-ventrally, 9.5 cm posteriorly-anteriorly,
and is 7.5 cm high, left valve incomplete.
Age.—The Jamaican material collected
from Grantham comes from bed D6 (Mac-
gillavryia bed 1). Strontium (
87
SR/
86
SR) iso-
topic values indicates that this is late Late
Maastrichtian in age (Steuber et al. 2002).
M. tschoppi in Cuba is also of probable
Maastrichtian age (Rojas et al. 1995).
Discussion.—The Coffee Piece and Gran-
tham specimens show differences in the
shape of the shells. The Coffee Piece speci-
men is more strongly elongated in a dorsal-
ventral diameter than the Grantham speci-
mens. The pallial canals of the specimens
are identical and the three specimens are
regarded as conspecific.
FIG. 2. Logged section through the Guinea Corn Formation at Coffee Piece NE showing distribution of rudists.
Scale bar in meter intervals.
FIG. 3. Camera Lucida drawing of pallial canals in
ventral shell wall of Mitrocaprina tschoppi from Coffee
Piece (RUD.2004.3). Section is cut 25 mm from the
commissure ×1.
NOTES394

The Jamaican material shows similarities
to that described by Mac Gillavry (1937)
from Cuba. Both sets of samples have four
rows of pallial canals, with the innermost
two rows polygonal, and the outer two, ra-
dially elongated. The maximum diameters
of the polygonal canals in the innermost
row are also closely similar (7 mm in the
Jamaican material; 6 mm in the largest Cu-
ban specimen). The Jamaican material only
differs from the Cuban material in size. The
largest Cuban specimen has a maximum
PLATE 1. Specimens of Mitrocaprina tschoppi. 1, RUD.2004.1, showing attached valve (AV) and crushed free
valve (FV), ×0.5; 2, RUD.2004.2, Detail showing pallial canals in ventral shell wall, ×1. Both specimens from
Grantham (Coffee Piece NE).
NOTES 395

diameter of 8 cm (Mac Gillavry 1937),
whereas the largest Jamaican specimen has
13.5 cm. The Cuban specimens also have a
large attachment area −they are attached to
specimens of Antillocaprina. In contrast the
attachment areas of the Jamaica specimens
appear to be small. The differences in the
size of the attachment areas are not consid-
ered of taxonomic importance, and are re-
garded as substrate specific. Since all other
taxonomically important characters are
similar between the Jamaican and Cuban
specimens (i.e., the pallial canal systems),
the Jamaican material is placed in M.
tschoppi herein.
The only other species of Mitrocaprina re-
corded from Jamaica is M. multicanalicula-
tus Chubb. This is a small species with 6
to 8 rows of polygonal pallial canals in
the left valve which distinguishes it from
M. tschoppi.
The only other large plagioptychid from
Jamaica, Plagioptychus jamaicensis, contains
radial plates that are not divided to form
pallial canals and is also considerably
larger than M. tschoppi.
The new material described from Ja-
maica demonstrates that M. tschoppi had an
extended geographical range in the Maas-
trichtian of the Caribbean region. These
large plagioptychids seem rare, and we
hope that further collecting may extend the
ranges of these taxa to other areas of the
Caribbean.
Acknowledgements.—We thank J. M. Pons
for reviewing this paper.
LITERATURE CITED
Boehm, G. 1895. Beitra¨ge zur Kenntnis der Kreide in
den Su¨dalpen. I. Die Schiosi- und Calloneghe-
Fauna. Palaeontograph 41:81-148.
Chubb, L. J. 1971. Rudists of Jamaica. Palaeontograph.
Am. 7:161-257.
Douville´, H. 1888. Etudes sur les Caprines. Bull. Soc.
Geol. Fr.,Se´rie 3 16:699-730.
Mac Gillavry, H. J. 1937. Geology of the Province of
Camaguey, Cuba with revisional studies in rudist
paleontology (mainly based upon collections from
Cuba). Geograph. Geol. Mededeel, Utrecht 14:1-168.
Mitchell, S. F. 1999. Stratigraphy of the Guinea Corn
Formation (Upper Cretaceous) at its type locality
between Guinea Corn and Grantham (northern
Clarendon, Jamaica). J. Geol. Soc. Jamaica 33:1-12.
Mitchell, S. F., and G. C. Gunter. 2002. Biostratigraphy
and taxonomy of the rudist Chiapasella in the Tita-
nosarcolites Limestones (Maastrichtian) of Jamaica.
Cret. Res. 23:473-487.
Palmer, R. H. 1933. Nuevos rudistes de Cuba. Rev.
Agr. 14:95-125.
Rojas, R., M. Iturralde-Vinent, and P. W. Skelton. 1995.
Stratigraphy, composition and age of Cuban rud-
ist-bearing deposits. Rev. Mex. Cienc. Geol. 12:272-
291.
Steuber, T., S. F. Mitchell, D. Buhl, G. Gunter, and
H. U. Kasper. 2002. Catastrophic extinction of Car-
ibbean rudist bivalves at the Cretaceous-Tertiary
boundary. Geology 30:999-1002.
Whitfield, R. P. 1897. Descriptions of species of Rud-
istae from the Cretaceous rocks of Jamaica, W. I.,
collected and presented by Mr. F. C. Nichols. Bull.
Am. Mus. Nat. Hist. 9:185-196.
NOTES396