TAPHONOMY AND PALECOLOGY OF MOLLUSCAN ASSEMBLAGES AT GRUND
GEOLOGICA CARPATHICA, 55, 2, BRATISLAVA, APRIL 2004
TAPHONOMY AND PALEOECOLOGY OF THE LOWER BADENIAN
(MIDDLE MIOCENE) MOLLUSCAN ASSEMBLAGES AT GRUND
, MATHIAS HARZHAUSER
and OLEG MANDIC
Department of Paleontology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria; email@example.com;
Museum of Natural History Vienna, Burgring 7, A-1014 Vienna, Austria; firstname.lastname@example.org
(Manuscript received June 5, 2003; accepted in revised form December 16, 2003)
Abstract: The typical sandy, shell-rich deposits of artificial outcrops in the Grund Formation were identified as dis-
tinctly allochthonous event beds with channel-structures, sharp erosional bases, and graded bedding. They are inter-
preted as proximal tempestites and contain a densely packed, polytaxic molluscan assemblage. The faunal composition
and taphonomic features of shells indicate that transport occurred from wave- or current-agitated nearshore habitats into
a dysaerobic, pelitic, inner shelf environment. This pelitic environment was colonized by a single molluscan species, the
chemosymbiotic Thyasira michelottii, which occurs in life position, as confirmed by valve articulation and preservation
of the inhalant tube and postero-ventral tunnel networks. In contrast to the depauperate autochthonous fauna, the skeletal
concentrations contain a highly diverse molluscan fauna. We identified 130 species from more than 4200 individuals,
but two bivalve species, Timoclea marginata and Loripes dentatus, strongly dominate each of the five samples from
different shell beds. In contrast, the diversity (measured as species richness and heterogeneity diversity) and the fre-
quency distribution of shell sizes differ strongly between the five shell beds. A regression analysis identifies the diver-
sity of the shell beds as a function of shell sorting. Poorly sorted shell beds have higher species richness than well-sorted
shell beds. The diversity in Grund is therefore taphonomically controlled, because sorting of the allochthonous shell
beds is determined by their transport history.
Key words: Miocene, chemosymbiosis, diversity, paleoecology, taphonomy, shell beds, Mollusca.
Fig. 1. Study area and sample location.
The taxonomic composition of the famous molluscan assem-
blages at the Lower Badenian (Middle Miocene) locality Grund
(Fig. 1) is very well known from numerous taxonomic investi-
gations during the last 140 years (M. Hörnes 1856; M. Hörnes
& Reuss 18591870; R. Hoernes & Auinger 18791882; Sie-
ber 1947a,b, 1949). In contrast, due to very poor outcrop con-
118 ZUSCHIN, HARZHAUSER and MANDIC
ditions, virtually nothing was known about
the taphonomic character of the shelly as-
semblages, and so far no data on relative
abundances of the respective species are
Most paleontologists working in the re-
gion subliminally anticipated that the as-
semblage was parautochthonous (e.g. Sieber
1937 when discussing variations in sculp-
ture of gastropods from Grund) and recently
the locality Grund was included in a study
comparing Miocene alpha diversities be-
tween the Paratethys and the European Bo-
real bioprovince (Kowalewski et al. 2002).
Here, we examine the artificial outcrops
which were recently used to clarify the
stratigraphy, sedimentology and taphonomy
of the locality Grund (Æoriæ et al. 2004; Roet-
zel et al. 1999; Roetzel & Pervesler 2004;
Zuschin et al. 2001; Zuschin et al. submit-
ted). Based on the new data from this exten-
sive field work, we will show that most
shells at Grund were deposited in allochtho-
nous, most likely tempestitic, shell beds.
The shells were transported from shallow
water into a somewhat deeper environment
with autochthonous, monospecific Thyasira
in life position (Zuschin et al. 2001). We
present abundance data on the fauna pre-
served in the shell beds and reconstruct the
probable original habitats of the transported
shells. Finally, we estimate the diversity at
Grund, compare diversities between shell
beds and evaluate the influence of transport
on species richness.
Material and methods
Standardized quantitative bulk samples
were taken from five Middle Miocene shell
beds at the locality Grund in Lower Austria
(Fig. 1, Fig. 2). Each sample was divided
into 16 subsamples and four randomly cho-
sen splits were wet sieved through a 1 mm
screen. The material >1 mm of the four
splits was quantitatively picked for all bio-
genic components under a binocular micro-
We counted 4215 whole shells; wherever
possible, these were sorted into species. We
distinguished 130 species (61 bivalves, 68
gastropods, 1 scaphopod) from 4105 whole
shells (see Appendix for a complete list of
species). The data matrix was slightly sim-
plified into 125 species: Seven species were
summarized in the rissoid gastropod genera
Alvania (5) and Turboella (2) because they
could not be consistently distinguished. An
Fig. 2. The five studied logs are characterized by a rapid change of allochthonous psam-
mitic and autochthonous pelitic sedimentation. The sandy layers contain thick polytaxic
skeletal concentrations. Many double-valved shells of Thyasira michelottii occur in
sandy sediments in an anterior up position approximately 510 cm below a pelitic bed.
Arrows indicate the positions of the quantitative bulk samples.
TAPHONOMY AND PALECOLOGY OF MOLLUSCAN ASSEMBLAGES AT GRUND
additional 110 poorly preserved gastropods were summarized
into 11 taxa at the genus and family levels because the shelly
material was taphonomically strongly altered by abrasion
(Granulolabium? sp. (2 individuals), Potamididae indet. (11),
Turritella sp. (4), Calyptraea sp. (1), Naticidae indet. juv.
(15), Nassariidae indet. juv. (61), Perrona sp. (1), Turridae in-
det. (4), Scala sp. (1), Pyramidellidae indet. (1), Gastropoda
indet. (9)). These 11 taxa from poorly preserved material were
excluded from the diversity analysis.
Diversity was measured as species richness and as heteroge-
neity diversity (sensu Peet 1974), which is based on the pro-
portional abundance of species and considers species domi-
nance and evenness (for a review see Magurran 1988). The
Simpson index, which is affected by the 23 most abundant
species, was used to calculate species dominance. The Shan-
non-Wiener index, which is more strongly affected by species
in the middle of the rank sequence of species, was used to cal-
culate evenness (Gray 2000).
Diversity curves (species-split curves) were computed for
each sample using the program EstimateS, with 50 sample or-
der randomizations without replacement (Colwell 1997). Spe-
cies-split curves can be directly compared with each other be-
cause of standardized sampling intensity (the same number of
splits from standardized bulk samples was used).
To evaluate the influence of transport on the diversity of the
shell beds, the size frequency distributions of all molluscs
combined, for bivalves only, gastropods only, and for the five
quantitatively most important taxa were calculated for each
sample. For this, the maximum diameter of each shell was
measured by image analyses (Kontron Elektronik Imaging
System KS 400) and standard calipers. Standard descriptive
parameters (mean, median, mode, sorting, skewness, kurtosis)
were calculated and the size frequency distributions of mol-
luscs were compared by analysis of variance (ANOVA) be-
tween shell beds after loglog transformation to retain normally
distributed data. To identify which of the shell parameters
control the diversity of samples, a regression analysis (method
stepwise) was performed with species richness as the depen-
The statistical analyses were performed using the software
package SPSS 10.0 (SPSS Base 10 Applications Guide, Pren-
tice Hall, Chicago, 2000).
Five artificial outcrops of Lower Badenian deposits were
examined (Fig. 2), with special emphasis on sedimentological
features, taphonomic characteristics and paleontological com-
position. The studied section of the Grund Formation shows a
total thickness of approximately 9.5 m and is characterized by
a rapid change of allochthonous psammitic and autochthonous
pelitic sedimentation (Fig. 2). The sandy layers, especially in
the lower part of the section, show abundant channel-struc-
tures and consist predominantly of thick polytaxic skeletal
concentrations (sensu Kidwell et al. 1986), commonly with
sharp erosional bases, graded bedding and a densely packed
(bioclast-supported) biofabric (Fig. 3). Towards the top of the
section the polytaxic skeletal concentrations are distinctly
Fig. 3. Sharp erosional bases, graded bedding, and densely packed
(bioclast-supported) biofabric of skeletal concentrations are typical
features of the psammitic layers at Grund.
thinner and characterized by tabular beds and low-dip angle
cross-bedding instead of channel-structures (Roetzel et al.
1999). The intercalated pelitic layers increase in thickness to-
wards the top of the section and are characterized by intensive
bioturbation. Many articulated shells of Thyasira michelottii
occur in sandy sediments in a vertical position with the anteri-
or end pointing upwards approximately 510 cm below a pel-
itic bed (Fig. 4).
Two species, Timoclea marginata and Loripes dentatus,
strongly dominate the molluscan fauna of the shell beds at
Grund. In the total assemblage, they make up 56 % of the
shells, contributing 52.265.6 % to the shells in each of the 5
samples (Fig. 5, Fig. 6). The next three important species,
Sandbergeria perpusilla, Clausinella vindobonensis and Er-
vilia pusilla, each contribute between 3.6 and 6.3 % to the to-
tal assemblage. Most species, however, contribute less than
1 % to the total fauna and to the fauna in each of the five sam-
ples (Fig. 5).
Diversity was evaluated for the total fauna and for the sam-
ples of the individual shell beds. Although the number of
counted individuals is relatively high, species richness does
not level off for the site (alpha diversity) or individual sam-
ples (point diversities) (Table 1, Fig. 7). In contrast to spe-
cies richness, heterogeneity diversity is very stable within
samples and for the site: the Shannon-Wiener index and the
Simpson index do not increase with sample size (Fig. 7).
Huge differences are evident between the total number of
species present (125) and the number of species in individual
Table 1: Number of individuals, number of species, values of the
Shannon-Wiener index, and values of the Simpson index for each
Sample Number of Number of Shannon-Wiener Simpson
120 ZUSCHIN, HARZHAUSER and MANDIC
Fig. 4. Photograph of Thyasira michelottii (Hoernes 1875) in situ,
showing the life position of the specimen, the perfectly preserved in-
halant tube, and the single long tunnel extending from the animal
downwards deep into the underlying sediment.
Table 2: Analysis of variance (ANOVA) of the size-frequency dis-
tributions of molluscan taxa in shell beds after loglog transforma-
tion. df degrees of freedom used to obtain the observed signifi-
cance level, F the ratio of mean squares between groups to mean
squares within groups, p significance level.
Table 3: Descriptive parameters of the size-frequency distribution
of all molluscs combined.
Table 4: Results of regression analysis with diversity (species rich-
ness, heterogeneity diversity) as the dependent variable. Among the
descriptive parameters of the shell size frequency distribution, only
sorting is a significant predictor for diversity. Bold numbers indicate
the statistically significant differences. t the results of the t-statis-
tics, p significance level.
samples, which range from 43 to 83 (Table 1). Also, the slopes
of the diversity curves (species-split curves) differ strongly be-
tween samples (Fig. 7, see also Zuschin et al. submitted). For
heterogeneity diversity, the comparatively low values of the
Shannon-Wiener index and the Simpson index of sample E5,
and the relatively high Simpson index of sample B7 are most
evident (Table 1).
The size-frequency distributions of all molluscan shells
combined, for gastropods only, for bivalves only and for each
of the five quantitatively most important species differ signifi-
cantly between samples from individual shell beds (Fig. 8,
Fig. 9, Table 2).
Of the descriptive parameters (Table 3), only sorting is
clearly related to diversity (Table 4). Between samples of indi-
vidual shell beds, sorting explains nearly 85 % of the variance
in species richness, nearly 98 % of the variance of the Shan-
non-Wiener index, and more than 77 % of the variance of the
Simpson index (Fig. 10).
Most shells are taphonomically altered and show distinct
evidence of abrasion (Fig. 6).
The tempestitic shell beds
Channel-structures, sharp erosional bases, and graded bed-
ding identify the shell-rich psammitic layers as the product of
high energy, short-term events; most likely they represent
proximal tempestites (Kidwell 1991; Fürsich & Oschmann
TAPHONOMY AND PALECOLOGY OF MOLLUSCAN ASSEMBLAGES AT GRUND
Fig. 5. Taxonomic composition and percentage abundance of the
quantitatively important taxa with 95% confidence intervals in shell
1993; Fürsich 1995). Decreasing hydrodynamic energy to-
wards the top of the section is indicated by the geometries of
the skeletal concentrations, which are distinctly thinner and
characterized by tabular beds and low-dip angle cross-bed-
ding instead of channel-structures (Roetzel et al. 1999). Cor-
respondingly, the intercalated and intensely bioturbated pelit-
ic layers, which indicate quiet-water conditions, increase in
thickness towards the top of the section.
The molluscan fauna of Grund
From a historical perspective, the molluscan fauna from var-
ious localities in the area of Hollabrunn such as Immendorf,
Guntersdorf, Braunsdorf, and Windpassing have been labelled
in collections and were referred to in the literature simply as
Grund. Hence, the fauna of the Grund Formation contains
taxa not only from its type locality at Grund, but also from the
above localities. All in all the so-called Grunder fauna con-
sists of 138 bivalve species and about 170 gastropod species
(database in preparation). The taxonomic inventory seems to
be quite complete because during the recent intense investiga-
tions only four new species were added to this faunal list
From a taphonomic perspective, however, the molluscan
fauna of the type locality Grund can be divided into the mono-
specific occurrence of autochthonous, chemosymbiotic Thya-
sira michelottii and the polytaxic fauna of the bioclast-sup-
ported allochthonous, tempestitic shell beds.
The bivalve T. michelottii is the only molluscan species of
the diverse fauna at Grund occurring in life position. This is
confirmed by articulated valves and preservation of the inhal-
ant and posterio-ventral tunnel networks (Fig. 4, see also Per-
vesler & Zuschin 2004). This bivalve burrowed in sandy sedi-
ments in an anterior up position approximately 510 cm
below a pelitic bed, to which it was connected by the inhalant
tube. Based on the comparative ecology of modern thyasirid
bivalves we suppose that active ventilation of the inhalant
tube was the mode of oxygen acquisition and that the promi-
nent postero-ventral tunnel reflects the search of the vermi-
form foot for short-lived pockets of sulphidic material in an
otherwise low-sulphide environment (see Zuschin et al. 2001
for a detailed discussion of the life habit of this bivalve).
In contrast to the depauperate autochthonous fauna, the
skeletal concentrations contain a highly diverse molluscan
fauna, which is strongly dominated by two bivalve species,
Timoclea marginata and Loripes dentatus. These quantitative-
ly most important species differ strongly from those species
that were considered to be important elements of the fauna by
shell collectors and taxonomists. For example, the first report
of molluscs from Grund (Foetterle 1850) mentioned a crate of
molluscs of 59 Pfund, which was stored at the Geological Sur-
vey in Vienna, and emphasized the large numbers of Turritel-
la vindobonensis, Pyrula rusticula and Crepidula among oth-
er gastropods and of Cytherea chione and Venus brocchii
among the bivalves. This weighting of certain conspicuous,
large-sized taxa is the typical collectors approch and is
strongly contrasted by the quantitative data presented in the
current study. Similarly, Hörnes (1851) enumerated Ancillaria
glandiformis, Murex trunculus, Pyrula rusticula and Fasci-
olaria burdigalensis along with 10 other species as the most
frequent taxa in the Grund fauna. In fact, these species com-
prise less than 1 % of the quantitative samples. Even those
species noted by Sieber (1947a,b, 1949) as frequent or very
frequent in the Grund fauna are hardly important in respect to
a rigorous quantitative treatment.
122 ZUSCHIN, HARZHAUSER and MANDIC
Fig. 6. The quantitatively most important species with typical taphonomic features. The external views of the species demonstrate the strong
abrasive reduction of sculptural features (best seen in Timoclea and Clausinella). Additionally, the numerous point-like holes in the shells
(here best seen on Ervilia) result from compactional pressure of quartz-sand grains into the shells. 1 Timoclea marginata [L = 5.2 mm].
a internal view of right valve; b external view of right valve. 2 Clausinella vindobonensis [L = 7.6 mm]. a internal view of right
valve; b external view of right valve. 3 Loripes dentatus [L = 3.7 mm]. a internal view of right valve; b external view of right
valve. 4 Ervilia pusilla [L = 3.7 mm]. a internal view of right valve; b external view of right valve. 5 Sandbergeria perpusilla
[L = 4.0 mm]. a apertural view; b adapertural view.
TAPHONOMY AND PALECOLOGY OF MOLLUSCAN ASSEMBLAGES AT GRUND
Fig. 7. Species richness (number of species) and heterogeneity di-
versity (measured with the Shannon-Wiener index and the Simpson
index) for the total tempestitic fauna and for the samples of the indi-
vidual shell beds. Within samples and for the site, species richness
does not level off, but heterogeneity diversity is very stable. The
slopes of the species-split curves differ strongly between samples.
From an ecological point of view most of the fauna in the
shell beds at Grund indicates a shallow to moderately deep
sublittoral, soft bottom environment (e.g. infaunal suspen-
sion-feeding venerids and cardiids, chemosymbiotic lucinids,
deposit-feeding tellinids, suspension-feeding turritellids,
scavenging nassariid). But species with other habitat charac-
teristics also occur. The herbivorous Potamididae probably
lived in a nearshore brackish-water environment, and some
terrestrial gastropods of the genus Cepaea (as well as disartic-
ulated bones of terrestrial mammals) are also found in the
skeletal concentrations. The abrasive features of most shells in
the skeletal concentrations can be interpreted to stem from
continuous reworking by waves or currents in the source area
of the tempestites, because the tempestitic transport itself is
very unlikely to affect the preservation quality of single shells
(Davies et al. 1989; for review see Fürsich & Oschmann
Species richness versus heterogeneity diversity
In contrast to species richness, heterogeneity diversity
(measured with the Shannon-Wiener index and with the Sim-
pson index) does not increase with increasing sample size for
both, individual samples and the site (Fig. 6). This indicates
that incorporating more samples or more individuals per sam-
ple would simply add more rare species, but would not change
the rank order of the most abundant and the middle ranked
The influence of transport on diversity measurements
The diversity (species richness and heterogeneity diversity)
of the shell beds at the locality Grund decreases with increas-
ing sorting of the shells indicated by the size-frequency distri-
bution. This feature clearly points to transport of the assem-
blages (e.g. Cummins et al. 1986; Miller & Cummins 1990).
The alternative scenario, that is that differences in sorting are
only apparent because the shell beds consist of different taxa,
can be ruled out because 1) the quantitatively most important
species are the same in the five shell beds, 2) the ecological
composition of the fauna in the different shell beds is very
similar and 3) the size frequency distribution of all molluscs
combined, gastropods only, bivalves only, and the five quan-
titatively most important species follows the same pattern of
differences between samples. It is therefore safe to conclude
that the studied shell beds consist of shells from the same
source area and that their differences in species richness re-
flect different transport histories, most probably due to differ-
ent storm intensities. Therefore, all the samples are inappro-
priate for measuring the diversity of the original habitat,
although poorly sorted samples (indicating relatively minor
transport) will approximate the diversity of single samples of
the habitat better than well-sorted samples (which indicate
The short distance of estimated 1520 km to the paleo-
coastline, along with the faunal composition of the skeletal
124 ZUSCHIN, HARZHAUSER and MANDIC
Fig. 8. Size-frequency distribution with normal curve of all molluscs combined, gastropods only, and bivalves only for each sample of
shell beds as well as for the total tempestitic fauna.
TAPHONOMY AND PALECOLOGY OF MOLLUSCAN ASSEMBLAGES AT GRUND
126 ZUSCHIN, HARZHAUSER and MANDIC
Fig. 10. Diversity (species richness and heterogeneity diversity) as a
function of sorting of the shell size frequency distribution of mol-
concentrations (mainly representative of a sublittoral soft bot-
tom environment), whose geometries suggest proximal tem-
pestites, indicate a shelf environment of less than one hundred
meters water depth (Spezzaferri 2004). The deepening-up-
ward trend in the section is interpreted as coinciding with the
major transgressive cycle of the Lower Badenian; a proximal
facies at the base passes into a slightly more distal facies to-
wards the top of the Grund section. Alternatively, the change
in sedimentation may be due to a local influence, such as the
fluctuating input and changing course of a fluvial system in
The autochthonous occurrence of monospecific Thyasira
indicates that the chemical and physical conditions of the sed-
iment were preferred by this thyasirid species, but were un-
suitable for other molluscs. The bivalves prominent posterio-
ventral tunnel network (Fig. 4, see also Pervesler & Zuschin
2004) probably reflects the search of the vermiform foot for
short-lived pockets of sulphidic material in an otherwise low-
sulphide environment (cf. Cary et al. 1989; see Zuschin et al.
2001 for a detailed discussion). The combination of bioturbat-
ed pelitic sediments and a monospecific macro-fauna suggests
a dysaerobic biofacies (Tyson & Pearson 1991). Global
warming, coinciding with a far-reaching transgression at the
base of the Middle Miocene, indicates warm water conditions
1. The original, restricted outcrops at the locality Grund
were sufficient to identify the taxonomic composition of the
shelly assemblage. A reliable paleoecological and taphonomic
treatment of the fauna, however, was only possible with artifi-
cial outcrops, which allowed the taphonomic framework of
the deposit to be evaluated.
2. Instead of the anticipated simple parautochthonous paleo-
community, the fauna has to be divided into a monospecific
autochthonous assemblage of Thyasira michelottii in life po-
sition, and a distinctly transported and highly diverse assem-
blage present in shell beds.
3. For the five samples from individual shell beds the taxo-
nomic composition of the most abundant species and the
taphonomic features of the shells are very similar, but species
richness and the size frequency distribution of the shells differ
strongly. Therefore, the ecological characteristics and tapho-
nomical features of the molluscan fauna in the shell beds al-
low the original habitats and the source area of the tempestites
to be reconstructed. The diversity, however, depends on sort-
ing and is therefore very sensitive to transport.
4. The present study shows that extensive field work is nec-
essary to evaluate the paleoecological and taphonomic fea-
tures of shelly assemblages and that especially diversity mea-
surements should not be made from samples taken from
Acknowledgments: We thank Gudrun Höck, Peter Pervesler
and Reinhard Roetzel for help with field work, Fred Rögl and
Michael Stachowitsch for stimulating discussions, Johann
Hohenegger for comments on our statistical results, and Franz
T. Fürsich and Barbara Studencka for their careful review of
the manuscript. The study was supported by project P-13745-
Bio of the Austrian Science Fund (FWF).
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128 ZUSCHIN, HARZHAUSER and MANDIC
Appendix: The species list contains the 130 distinct morphospecies used in this study plus 11 taxa of poorly preserved gastropods, which
were mostly summarized at the genus and family level because the shelly material was taphonomically strongly altered (Granulolabium? sp.,
Potamididae indet., Turritella sp., Calyptraea sp., Naticidae indet. juv., Nassariidae indet. juv., Perrona sp., Turridae indet. Scala sp., Pyra-
midellidae indet., Gastropoda indet.).
Fissurellidae Scutum bellardii
Phasianellidae Tricolia sp.
Vitrinellidae Tornus pseudotinostoma
Alvania (Taramellia) alexandrae
Alvania montagui ssp.
Alvania venus transiens
Turboella sp. (cf. johannae/dilemma)
Bittium cf. reticulatum
Potamididae Granulolabium bicinctum
Turritellidae Turritella eryna
Crepidulidae Calyptraea chinensis
Crepidula (Janacus) crepidula
Trivia (Sulcotrivia) dimidiatoaffinis
Cancellariidae Narona (Aneurystoma) austropolonica
Columbellidae Mitrella sp. juv.
Hinia sp. 1 (cf. toulai)
Hinia sp. 2 (cf. styriaca)
Hinia sp. 3
Hinia sp. 4
Hinia sp. 5
Hinia sp. 6
Hinia sp. 7
Sphaeronassa dujardini s.l.
Conus cf. dujardini
Perrona cf. jouanetti
Turridae sp. 1
Turridae sp. 2
Turridae sp. 3
Turridae sp. 4
Acrilla cf. orientalis
Pyramidelloidea Pyramidellidae Odostomia plicata
Ringicula auriculata ssp.
Scaphandridae Acteocina lajonkaireana heraclitica
Cepaea cf. etelkae
Saturnia cf. pusio
Nuculana (Lembulus) emarginata
Nuculana (Saccella) fragilis
Nucula (Nucula) nucleus
Anadara (Anadara) adametzi
Anadara (Anadara) diluvii
Aequipacten aff. zenonis
Limea (Limea) strigilata
Anomia (Anomia) ephippium
Loripes (Microloripes) dentatus
Thyasira (Thyasira) michelottii
Chama (Psolopus) gryphoides
Galeommatoidea Galeommatidae Spaniorinus bobiesi
Lutraria (Lutraria) lutraria
Mactra (Eomactra) basteroti
Spisula (Spisula) subtruncata
Mesodesmatidae Donacilla cornea
Donax (Paradonax) intermedia
Donax (Paradonax) sallomacensis
Donax (Paradonax) variegatus
Psammobiidae Gari (Psammobia) uniradiata
Mesodesmatidae Ervilia pusilla
Angulus (Peronidia) bipartitus
Angulus (Moerella) donacinus
Quadrans (Serratina) schoenni
Petricola (Rupellaria) lithophaga
Dosinia (Asa) lupinus
Pitar (Pitar) cf. rudis
Tapes (Ruditapes) decussatus
Corbula (Caryocorbula) basteroti
Corbula (Varicorbula) gibba
Hiatella (Hiatella) arctica