Santander, February 19th-22nd 2008 - Aranzadi

202
ESTEBAN ÁLVAREZ-FERNÁNDEZ & JUAN CARLOS CASTRO
Biometric data were determined in whole specimens
in order to establish possible climate indicators
or selective gathering. All the data obtained,
both qualitative and quantitative, has been processed
using selected statistical tests.
Figure 1. Left: location of the archaeological site. Right: archaeological
excavations at the medieval city walls in Pontevedra (Spain).
characteristics such as size and shape, ornamentation
and hinge, and by comparison with our reference
collection of modern specimens. The nomenclature
used for both gastropods and bivalves has been
taken from CLEMAM (Check List of European Marine
Mollusca, Muséum National d´Histoire Naturelle,
Paris: http://www.somali.asso.fr/clemam).
The methodology used in the present work was
adapted from R. Moreno’s methods (Moreno 1994,
Álvarez-Fernández 2007). The total number of
remains (NR) was defined as the total number of
specimens from each archaeological level.
For gastropods, in order to avoid the overrepresentation
of species with a tendency to fragment,
the minimum number of individuals (MNI)
was defined using R. Moreno’s formula:
MNI =ICOM + IFRA + [FAPI or (FEST + FUMB),
whichever is the greater], where
ICOM = number of whole specimens
FAPI = number of apex fragments (without neither
buccal zone nor umbo)
FEST = number of stoma fragments
FUMB = number of umbo fragments
IFRA = number of fragmented specimens with
intact columella end and a broken lip. This parameter
differs from R. Moreno, who included specimens
with the apex but without the buccal zone.
For bivalves, NMI = VCOM + VFRA + FCHC +
(FCHA or FCHP, whichever is the greater), where:
VCOM = number of whole valves
VFRA = number of fragmented valves
FCHC = number of whole hinge fragments
FCHA = number of anterior hinge fragments
FCHP = number of posterior hinge fragments
This index was calculated, separately, for right
and left valves. The greater value was taken as the
final MNI.
3. MALACOLOGICAL REMAINS FROM THE CITY
WALLS AT PONTEVEDRA (SPAIN): CLASSIFICA-
TION, QUANTIFICATION, TAPHONOMY
A total of 1545 malacological remains were
recovered from the rubbish dump, and the MNI
has been calculated as 810. The sample of
molluscs was varied, and a total of 14 different
species of gastropods and bivalves were identified.
The latter were the most common (90.6% of
the total MNI). Among the bivalves the most abundant
species was the flat oyster Ostrea edulis
(Linné 1758) which represented nearly 50% of
these molluscs. It was followed by the clam
Ruditapes decussatus (Linné 1758) and the cockle
Cerastoderma glaucum (Poiret 1789), with quite
similar percentages (24.25% and 22.60%, respectively).
Only 21 specimens of mussel Mytilus galloprovincialis
(Lamarck 1819) were found (2.9%).
Regarding gastropods, the most common species
was the periwinkle Littorina littorea (Linné 1758),
with 68 specimens. With percentages below 2%,
the other species were represented by specimens
of the bivalves: Glycymeris glycymeris (Linné 1758),
Pecten maximus (Linné 1758) and Venus verrucosa
(Linné 1758), and the gastropods: Patella vulgata
(Linné 1758), Patella intermedia (Murrai in Knapp,
1857), Patella sp., Neptunea contraria (Linné 1771),
Charonia lampas (Linné 1758), Gibbula sp. and
Nassarius reticulatus (Linné 1758) (Fig. 2, 3; Table 1).
Figure 2. MNI percentages for the different mollusc species recovered by
the city walls at Pontevedra (Spain).
3.1. The great majority of molluscs found were
edible (99.5% of the MNI).
Ostrea edulis is usually found in estuaries, in all
substrates, mainly sandy or muddy. Littorina liitorea,
Patella sp. and Mytilus galloprovincialis live attached
to the rocks in the intertidal fringe. Ruditapes decussatus
and Cerastoderma glaucum live in sandy
MUNIBE Suplemento - Gehigarria 31, 2010
S.C. Aranzadi. Z.E. Donostia/San Sebastián