GEOLOGICA CARPATHICA
, DECEMBER 2016, 67, 6, 561 – 571
doi: 10.1515/geoca-2016-0035
www.geologicacarpathica.com
Palaeobiology, palaeoecology and stratigraphic significance
of the Late Miocene cockle Lymnocardium soproniense
from Lake Pannon
IMRE MAGYAR
1,2
, ISTVÁN CZICZER
3
, ORSOLYA SZTANÓ
4
, ÁRPÁD DÁVID
5
and MICHAEL JOHNSON
6
1
MTA-MTM-ELTE Research Group for Palaeontology, Hungarian Natural History Museum, H-1431 Budapest, POB 137
2
MOL Hungarian Oil and Gas Company, H-1117 Budapest, Október 23. u. 18; immagyar@mol.hu
3
Department of Geology and Palaeontology, University of Szeged, H-6722 Szeged, Egyetem u. 2-6; cziczer@yahoo.com
4
Department of Physical and Applied Geology, Eötvös Loránd University, H-1117 Budapest, Pázmány Péter sétány 1/c; sztano@caesar.elte.hu
5
Department of Mineralogy and Geology, University of Debrecen, H-4032 Debrecen, Egyetem tér 1; coralga@yahoo.com
6
Department of Geoscience, University of Wisconsin - Madison, 1215 W Dayton St, Madison, WI 53706 USA; mrjohnson23@wisc.edu
(Manuscript received January 25, 2016; accepted in revised form September 22, 2016)
Abstract: Stratigraphic subdivision of the Upper Miocene deposits in the Pannonian Basin has been traditionally based
on the endemic mollusc species of Lake Pannon. The cockle species Lymnocardium soproniense Vitális, apparently
evolving through a sympatric speciation event in the sublittoral zone of Lake Pannon about 10.2–10.3 Ma, attained wide
geographical distribution in the Pannonian basin and thus may serve as a good stratigraphic marker. Lymnocardium
soproniense was one of the few large-sized cockles in Lake Pannon, most closely related to its ancestor, L. schedelianum
(Fuchs), and to another descendant of the latter, L. variocostatum Vitális. According to the δ
18
O stable isotope record of
its shells, the large size of L. soproniense was coupled with an extended life time of more than 10 years, probably
reflecting a stable lake environment with increased resource availability and decreased predation. The species lived in
quiet offshore conditions, below the storm wave base, where clay was deposited from suspension and the influence of
currents was negligible. The base of the Lymnocardium soproniense Zone in the sublittoral deposits of Lake Pannon is
defined by the first occurrence of the species, whereas the top of the zone is marked
with the base of the overlying
Congeria praerhomboidea Zone, defined by the FAD of C. praerhomboidea.
Key words: Late Miocene, Pannonian Basin, Lake Pannon, molluscs, endemism, palaeoecology, stable isotopes.
Introduction
Lymnocardium soproniense Vitális, 1934 is one of the ca. 200
species of non-marine cockles that were described from the
deposits of Lake Pannon (Müller et al. 1999; Geary et al.
2000). This lake occupied the Pannonian basin in the Late
Miocene and Early Pliocene as a relict of the Paratethys Sea
(Harzhauser & Piller 2007). The stratigraphic subdivision of
its thick sedimentary pile has been traditionally based on the
prolific endemic mollusc fauna of the lake (for a summary, see
Magyar & Geary 2012). Of the many cockle species of Lake
Pannon, some possess a narrow stratigraphic span coupled
with a wide geographical distribution; these species are con-
sidered to be good stratigraphic markers.
Lymnocardium soproniense is one such species, and it is
used to designate the sublittoral L. soproniense Zone (Magyar
et al. 1999, 2007; Magyar & Geary 2012). This species, how-
ever, is usually known from poorly preserved and/or fragmen-
tary specimens, it was often confused with other large Lake
Pannon cockles, and remained poorly documented in the
palaeontological literature. In this paper we discuss its taxo-
nomic position, geographical distribution, palaeoecology,
phylogenetic relationships, and stratigraphic significance.
The palaeoecological and palaeobiological interpretations are
based on sedimentological facies analysis and δ
18
O stable
isotope profiles of shells.
Materials and methods
For this study we used the fossil mollusc collections of the
Geological and Geophysical Institute of Hungary (MFGI,
Budapest), the Hungarian Natural History Museum (TTM,
Budapest), the Bakony Natural History Museum (TTM-BTM,
Zirc), and the Naturhistorisches Museum Wien (NHMW,
Vienna). Field work was conducted in the brickyard claypit of
Mályi (northern Hungary, Fig. 1), the only outcrop known
to us where Lymncoardium soproniense can be studied and
collected from the embedding sediments today. We measured
the outcrop and interpreted the sedimentological features in
order to assess the palaeoenvironment in which L. soproniense
lived.
Stable isotope data from Lymnocardium soproniense and its
relatives were gathered as part of a larger study on cardiid
562
MAGYAR, CZICZER, SZTANÓ, DÁVID and JOHNSON
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
bivalves from Lake Pannon (Johnson 2016). Shells were sam-
pled by using a 0.5 mm bit to drill a series of grooves parallel
to growth lines and spaced ~1 mm apart along the entire height
of the shell. Samples were analysed at the University of Arizona’s
Environmental Isotope Laboratory using a KIEL-III device
coupled to a Finnegan MAT 252 gas-ratio mass spectrometer
at a precision of ± 0.1 ‰ for δ
18
O. The data pertaining to
L. soproniense and its closest relatives (L. schedelianum,
L. variocostatum) are summarized and discussed below.
Systematic palaeontology
Class BIVALVIA Linné, 1758
Family CARDIIDAE Lamarck, 1809
Subfamily LYMNOCARDIINAE Stoliczka, 1870–1871
Genus Lymnocardium Stoliczka, 1870–1871
Type species: Cardium haueri M. Hörnes, 1862 from the
Upper Miocene of Árpád (Pécs, Hungary)
Lymnocardium soproniense Vitális, 1934
1915. Limnocardium Penslii Fuchs — Papp S., p. 254, pl. 3, fig. 6.
[misidentification]
*1934a. Limnocardium soproniense n. sp. — Vitális, p. 705, pl. 7,
figs. 1–4.
1934b. Limnocardium soproniense n. sp. — Vitális, p. 77, pl. 1,
figs. 1–4. [redescription]
1971. Limnocardium soproniense Vit. — Bartha, pl. 29, figs. 1,4.
1971. Limnocardium (Pannonicardium) mihaili sp. n. — Mihaila and
Marinescu, p. 43, fig. 1, pl. 1, figs. 1–3.
2007. Lymnocardium soproniense — Magyar et al., p. 280, fig. 5.
Type specimen. Lectotype. MFGI, Pl. 97 (Fig. 2 a, b),
left valve.
Lymnocardium soproniense was first described by I. Vitális
(1934 a). Although this large bivalve species was very common
in the brickyard claypits of Sopron/Ödenburg (Fig. 1), full and
intact specimens were difficult to collect, thus Vitális chose to
photograph a museum specimen; the depicted individual had
been collected from the claypit of the Lenk brickyard (MFGI,
Pl. 97., Fig. 2 a, b). Boda (1964) indicated this specimen as a
“holotype”, but according to ICZN (1999, Art. 74.1 and 74.5),
it represents the lectotype of the species.
The pictures published by Vitális (1934 a, b), however, were
not the first representation of this species in the literature.
Papp (1915) published the photograph of a L. soproniense
specimen erroneously identified as “Limnocardium penslii
Fuchs” from Szilágynagyfalu (today Nuşfalau, Romania;
Fig. 1), from sandy marl exposed in a trench cut into the hill-
side SE of the village.
In 1971, Mihaila and Marinescu described a Pannonian
mollusc fauna from Sabolciu/Mezőszabolcs, valley of Crisul
Repede/Sebes-Körös (Fig. 1), containing a new cockle species
“Limnocardium (Pannonicardium) mihaili sp. n.”. The holo-
type and paratype specimens of the new species, however,
were collected from the village of Felcheriu/Felkér by
A. Mihai (after whom Mihaila and Marinescu named the new
species). The authors regarded the Sabolciu specimens as
syntypes. Based on the description, drawing and photographs
of L. mihaili, the Felcheriu specimens fully correspond to
L. soproniense.
Subsequent picture representations of L. soproniense
include a left valve (Bartha 1971) and a right valve of an arti-
culated specimen (Magyar et al. 2007, p. 281), both from
Sopron.
Fig. 1. Localities of Lymnocardium soproniense in the northern Pannonian Basin. 1 — confirmed occurrence; 2 — uncertain occurrence;
3 — no occurrence (mistaken identifications in the literature). Inset map shows a zoomed detail of the study area south of Miskolc.
563
LATE MIOCENE COCKLE STRATIGRAPHY OF LAKE PANNON DEPOSITS
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
Fig. 2. Specimens of Lymnocardium soproniense from Sopron (a–i) and Mályi (j–l). a–d — a left valve (a,b; MFGI Pl. 97, lectotype of
the species) and a right valve (c,d; MFGI Pl. 6361) from Sopron, Lenk brickyard, donated to the Hungarian Royal Geological Institute by
L. Károlyi in 1914; e, f — a left valve depicted (and probably collected) by Bartha (1971) from Sopron, Balfi út brickyard (MFGI Pl. 2016.1.1);
g — a right valve of a juvenile specimen from Sopron (TTM-BTM 2014-123-1); h, i — a right valve from Sopron (TTM M57/815);
j, k — a left valve from Mályi brickyard (collection of I. Cziczer); l — a partial shell and “steinkern” of an articulated specimen from Mályi
(collection of I. Cziczer). Scale bars 1 cm.
564
MAGYAR, CZICZER, SZTANÓ, DÁVID and JOHNSON
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
Type locality and type stratum. Sopron/Ödenburg,
Hungary, Szák Formation, Upper Miocene, Pannonian Stage.
The brickyard claypits of Sopron, mentioned by Vitális
(1934 a, b, 1951), have been closed and re-cultivated by today.
The only outcrop which was described in some detail in the
geological literature is the Balfi út claypit. Stratigraphic
columns of the outcrop were given by Bartha (1971), Korpás-
Hódi (1994), and most recently by Barna et al. (2010). Accor-
ding to the latter, the lower 4.5 m of the more than 10 m high
outcrop consisted of greyish-blue bioturbated clay with
variable silt content and dispersed molluscan shells. Silt con-
tent gradually increased from 4.5 to 9 m, and this interval con-
sisted of rhythmic depositions of clay, silt, and very fine sand.
Parallel lamination, cross-lamination, small-scale graded
bed ding and plant remains were common in the fine sand and
silt. The fine-grained sequence was capped by coarse-grained
silt, sand, and fine-grained gravel layers that displayed
cross-bedding, cross-lamination, and scour-and-fill structures
and erosional surfaces. The entire sequence was interpreted as
reflecting the transition from a sublittoral lacustrine environ-
ment to a distributary channel and mouth bar (Barna et al.
2010). According to Bartha (1971, p. 100), Lymnocardium
soproniense occurred in the lower, clayey part of the section
(Szák Formation).
Comparison. Lymnocardium soproniense is morphologi-
cally very close to L. schedelianum (Fuchs), and also to
L. variocostatum Vitális. When they are preserved as internal
moulds (steinkerns), it is very difficult or sometimes impossible
to tell the three species apart. The diagnostic difference is in
their rib architecture (Fig. 3). L. schedelianum has prominent
radial ribs (Fig. 3a). In L. soproniense, the ribs are not promi-
nent but quite flat, and the intercostal spaces are filled with
shell material so that they are even with the ribs, giving
the entire shell a smooth appearance (Fig. 3b). In L. vario
costatum, the ribs in the central and rear areas of the valve
are wide and flat, and the intercostal spaces are reduced to
a shallow groove (Fig. 3c).
Remarks. Prior to the description of Lymnocardium
soproniense as a new species by Vitális (1934a), its specimens
were identified as, or were considered to have been related to,
various other large Lake Pannon cockles. For instance, the
specimens collected by L. Roth in Balf were first labelled
as “Cardium schmidti (Hörnes)”. Later the curator of
the museum of the Hungarian Royal Geological Institute,
Gy. Halaváts, corrected the labels of these specimens to
“L. dumicici Gorjanovic-Kramberger” (see in Vitális 1934 a,
p. 707). Papp (1915) described his L. soproniense specimen
from Szilágynagyfalu as L. penslii (Fuchs). Even after Vitális
described L. soproniense as a new species, and discussed all
the morphological traits that distinguish L. soproniense from
L. schmidti, L. croaticum (Brusina), and L. dumicici, Strausz
(1942) expressed his opinion that L. soproniense is identical to
L. variocostatum Vitális, which is, according to him, a sub-
species of L. penslii. Mihaila and Marinescu (1971) assigned
L. mihailii (= L. soproniense) into Pannonicardium, a sub genus
erected by Stevanović (1951) for L. dumicici, L. schmidti, and
L. penslii. On the other hand, A. Papp (1953) thought that
L. soproniense is very closely related to L. schedelianum,
therefore he regarded Sopron/Ödenburg as a L. schede lianum-
bearing locality (Papp 1953, p.198).
Distribution. The localities where Lymnocardium
soproniense has been found so far are clustered in several
areas in the northern part of the Pannonian Basin (Fig. 1).
The most abundant material is from Sopron and its vicinity.
The second-richest material was collected from the SE margin
of the Bükk Mts., northern Hungary (in the vicinity of
Miskolc). A few specimens have been documented from three
localities in the northwestern foreland of the Apuseni Mts. in
Romania (vicinity of Oradea/Nagyvárad). Finally, museum
materials indicate occurrences of the species in Budapest and
in the Balaton region, but these are considered uncertain and
require future confirmation (see Appendix).
Lymnocardium soproniense in the Mályi outcrop
The claypit of Mályi brickyard
The only outcrop known to us where Lymnocardium
soproniense-bearing sediments are exposed today is the
brickyard claypit of Mályi in the vicinity of Miskolc, northern
Hungary. The outcrop, located in the northern outskirts of the
village, exposes a 20–25 m thick homogeneous, bluish-grey,
fossiliferous clay/argillaceous marl, overlain rather sharply by
a coarsening upward series of white, fine sand, gravelly sand,
and conglomerate (Fig. 4). The clay is fully bioturbated; the
only indication of bedding is represented by accumulations of
randomly oriented mollusk shells, first of all dis articulated
valves of small (juvenile) individuals of Congeria czjzeki
Hörnes. Many of these beds are poorly cemented with iron
oxide-hydroxides, and limonitic concretions also occur with
shells in their cores. These beds do not contain sand, gravel or
any other coarse material that would indicate vigorous currents,
therefore the varying abundance of shells is probably related to
the original living conditions rather than post- mortem transport
and accumu lation. Scattered shells also occur in the clay; most
of the large L. soproniense and
Congeria ungulacaprae
Münster specimens were found in such position. The abun-
dance of molluscs apparently decreases upwards. The upper-
most 2 m of the clayey interval is grey- yellow variegated clay,
overlain by 2 m yellow siltstone. This change in colour is
related to ground waters percolating in the overlying sand.
Fig. 3. Rib structure of Lymnocardium schedelianum (A; Wien-
Hennersdorf, TTM), Lymnocardium soproniense (B; Sopron, MFGI),
and L. variocostatum (C; Bicske, TTM-BTM). Scale bars represent
5 mm.
565
LATE MIOCENE COCKLE STRATIGRAPHY OF LAKE PANNON DEPOSITS
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
The transition of silt to sand was covered by debris in the
outcrop, but morphology of the terraces suggests a sharp tran-
sition. The white, fine-grained sand is moderately to well-
sorted, attaining a total thickness of 20 m. Much of the sand
lacks structure, mostly due to bioturbation. Plane lamination,
cross-lamination, decimetre-scale cross-bedding, shallow and
wide erosional scours rarely occur. The scours and cross-
bedding are paved by granule to small-grained pebbles. The
abundance and thickness of these cm-scale pebbly layers
increase upwards. Some small, v-shaped burrows, large
pebble-filled vertical burrows, carbonaceous material (wood
fragments) and granule-size rip-up mud clasts also can be
found. The uppermost metres of the outcrop consists of pebbly
sand and sandy gravel, made up of well-rounded “pearl” gravel.
The clay was deposited from suspension settling in quiet
offshore conditions (i.e. below storm wave-base). The over-
lying sands and gravels are products of shallow, nearshore
waters above wave-base. Most of the structures indicate
shallow currents, but the swash-zone of breaking waves is also
clearly demonstrated. We cannot distinguish deposits of a pro-
grading wave-dominated coast from those of a small, coarse-
grained deltaic lobe. No large-scale architecture (i.e. foresets)
support the latter. The sharp transition reveals a pronounced
shift of facies from offshore to nearshore (i.e. a regression).
It points to a drastically increased rate of sediment input,
which can be the result of either development of a delta entry
nearby or a lake-level fall (or their combined effect). The clay
is assigned to the Szák Formation (see Cziczer et al. 2009 and
references therein), whereas the gravelly white sand belongs
to the Kálla Formation (see Csillag et al. 2010 and references
therein).
Palaeoecological interpretation
Environment. In the Mályi outcrop, the shells of Lymno
cardium soproniense are most common in the lower layers
that were deposited in a distal offshore environment. The
unstratified, bioturbated clay was deposited from suspension
in the sublittoral zone of Lake Pannon, which means below the
storm wave-base. Shells are usually found with articulated
valves, either in closed or open position (Fig. 4c). There are no
indications of storm- or gravity-induced currents, a fact that
may point to a flat depositional surface far away from sedi-
ment input. Water depth is difficult to reconstruct, but studies
of the Szák Formation elsewhere and comparisons with the
present-day Caspian Sea as an analogue of Lake Pannon sug-
gest that the sublittoral argillaceous marl was deposited at
20–30 to ?80 m water depth (Korpás-Hódi 1983; Cziczer et al.
2009). L. soproniense becomes less common and finally dis-
appears from the record as sediment input increased and water
depth decreased up to and even above the wave-base.
Accompanying species. The most common accompanying
mollusc species in Mályi include Congeria czjzeki, C. ungula
caprae, Lymnocardium brunnense Andrusov, Caladacna
steindachneri (Brusina), and Pisidium krambergeri (Brusina)
Fig. 4. Stratigraphic column of the Mályi outcrop. a — cross- and
plane lamination with small vertical burrows in fine-grained sand;
b — trough cross-bedding in sand, pebbly sand points to south-
ward transport; c — articulated valves of Lymnocardium soproniense,
embedded into clay in life position; d — shell-bed with Congeria
czjzeki in the blue clay. Spade is 10 × 22 cm for scale (a, b).
566
MAGYAR, CZICZER, SZTANÓ, DÁVID and JOHNSON
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
(Fig. 5). The first three of these are also common at other
localities in the vicinity of Miskolc and Sopron. In particular,
C. czjzeki is known to be a characteristic form of sublittoral
deposits. In the Sopron area, Balfi út outcrop, dominance of
candoniid ostracods over cypridiids in the lower layers of the
section also indicates a deeper water, offshore environment
(Barna et al. 2010). All these patterns confirm that
L. soproniense was a sublittoral dweller.
Stable isotope records of Lymnocardium soproniense
and closely related species
Ontogenetic ages and growth rates
Recent stable isotope work on various Lymnocardium
species including L. soproniense offers additional palaeoenvi-
ronmental data as well as information about the longevity and
growth rate of L. soproniense and its relatives (Johnson 2016).
Stable oxygen isotope profiles in mollusc shells typically
consist of quasi-sinusoidal patterns that have been interpreted
as annual cycles (e.g., Dettman & Lohmann 1993; Dettman et
al. 1999; Andreasson & Schmitz 2000; Goodwin et al. 2001;
Schmitz & Andreasson 2001; Ivany et al. 2004; Ivany &
Runnegar 2010). Winters are recognized from high δ
18
O ratios,
whereas summers produce low δ
18
O ratios.
The profile of a large (~ 90 mm in height) Lymnocardium
soproniense from Sopron (Fig. 6) contains ~ 10 winter- summer
cycles, indicating at least 10 years of growth (Johnson 2016).
Shell growth may slow or stop seasonally if temperatures
exceed the tolerances of the species, or during a reproductive
event when the animal reallocates resources (Dettman et al.
1999). The seasonal signal may also be obscured by low
seasonality of the ambient temperature — potentially buffered
by depth — and/or seasonality in the δ
18
O values of lake water,
which may destructively interfere with temperature effects.
Later in ontogeny, the growth rate slows, which makes it more
difficult to detect annual cycles using isotopes due to
Fig. 5. Mollusc species accompanying Lymnocardium soproniense in the Mályi outcrop. a,b — Congeria ungulacaprae Münster; c–f — Congeria
czjzeki Hörnes; g–j — Lymnocardium brunnense Andrusov; k — Caladacna steindachneri (Brusina); l — Pisidium krambergeri (Brusina).
All specimens are from the collection of I. Cziczer. Scale bars 1 cm.
567
LATE MIOCENE COCKLE STRATIGRAPHY OF LAKE PANNON DEPOSITS
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
time- averaging of samples (Goodwin et al. 2001, 2003).
High-resolution microsampling can mitigate this time-
averaging by greatly increasing the sampling density (Dettman
et al. 1999; Patterson & Cheatham 1999; Surge et al. 2001;
Wurster & Patterson 2001; Schöne et al. 2004, 2005; Ivany &
Runnegar 2010), but these methods require time and resources
not available in the collection of these data (Johnson 2016).
Given these considerations, 10 years is a mini mum onto-
genetic age of the Sopron shell. Maximum rate of growth for
the Sopron shell was 16 mm/yr based on the best-preserved
year within the shell.
The growth rates and ontogenetic ages of the two most
closely related cockle species, Lymnocardium schedelianum
and L. variocostatum, have been estimated and compared to
L. soproniense using the same method (Fig. 7; Johnson 2016).
The studied shells of L. schedelianum are smaller (~ 40 mm in
height) and have a maximum growth rate of 17 mm/yr based
on the best-resolved year from 5 individuals. The studied
L. variocostatum is of similar size to L. soproniense, although
the shell presented here was broken near the umbo. Because
of this breakage, the initial ~ 30 mm of shell is missing. The
complete individual should be ~ 80 mm in height. The best-
preserved year from this specimen indicates a growth rate of
13 mm/yr. Among these three species, body size and growth
rate appear unrelated.
Ontogenetic age and body size do seem to be related among
Lymnocardium soproniense, L. schedelianum, and L. vario
costatum (Johnson 2016). The smaller L. schedelianum have
the shortest lifespan, with only 2 to 4 years detected by isotope
analysis. Although the L. variocostatum shell was broken,
6 years were detected in 53 mm of shell growth; a complete
specimen would likely contain ~ 8 years. L. soproniense, the
largest specimen, appears to have the longest lifespan (at least
10 years).
Geary et al. (2012) observed that the Pannonian snail
Melanopsis also seemed to achieve increased body size
through increased longevity. They proposed that the repro-
ductive advantage of larger body size coupled with an increase
in resource availability and/or a decrease in predation drove
this evolutionary trend in Melanopsis. Perhaps lymnocardiids
were also able to take advantage of a stable lake environment
by undergoing more reproductive events and at larger body
size via longer lifespans (Johnson 2016).
Palaeoenvironmental interpretation
Environmental conditions are reflected in the stable oxygen
isotope composition of shell carbonate. The amplitude or
intrashell range in δ
18
O values is related to seasonal variations
in temperature and δ
18
O
water
, although these factors can be
difficult to distinguish (Dettman & Lohmann 1993; Ivany et
al. 2004) especially from a single shell. Mean shell values,
however, are useful for habitat comparisons. For example, in
closed lakes there is a gradient in δ
18
O values from lower
values near-shore (under the influence of freshwater) to higher
values off-shore (where water is better mixed and more
evaporated) (Talbot 1990; Goodwin et al. 2003). This contrast
is observed between high mean δ
18
O values of sublittoral
L
ymnocardium schedelianum (– 1.6 to – 1.0 ‰) and lower
mean values of littoral L. variocostatum (– 5.4 to – 2.8 ‰).
L. soproniense has a mean δ
18
O value of – 1.2 ‰, which is very
similar to that of L. schedelianum, and supports a similar sub-
littoral habitat (Fig. 8).
Phylogeny and stratigraphy
Stratigraphic record of Lymnocardium soproniense and
its relatives
Of the closely related species of Lymnocardium schedelia
num, L. soproniense, and L. variocostatum, L. schedelianum
Fig. 6. Stable oxygen isotope profile of Lymnocardium soproniense
from Sopron (MTM, M.571815) arranged with ontogenetically
youngest values at left, and oldest values at right (Johnson 2016).
Arrows indicate local maxima, interpreted as winter signals.
Fig. 7. Stable oxygen isotope profiles of Lymnocardium schedelianum
from Wien-Vösendorf (NHMW coll.), L. soproniense from Sopron
(MTM, M. 571815), and L. variocostatum from Dáka (private
collection). Profiles are arranged with ontogenetically youngest
values at left, and oldest at right. The profile of L. variocostatum is
incomplete due to missing shell. Modified from Johnson (2016).
568
MAGYAR, CZICZER, SZTANÓ, DÁVID and JOHNSON
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
appears first in the stratigraphic record. Its oldest occurrences
are known from the well-studied outcrops of southern Vienna
(Vösendorf, Hennersdorf, Laaerberg; Papp 1953), where it
occurs both in sublittoral clays and in sandy shoreface deposits
(Papp 1951; Schultz 2003). Based on the evaluation of their
vertebrate fossils, these layers are correlated with the middle
part of Zone MN9, and dated about 10.4 Ma (Harzhauser et al.
2004; Fig. 9).
Lymnocardium soproniense enters the fossil record some-
what later, and it is restricted to sublittoral clays.
Molluscs
from the overlying littoral deposits in Sopron and its vicinity
contain a series of species that are common in younger deposits
but missing in the Vienna basin, and vertebrates from the same
deposits indicate uppermost MN9 to lowermost MN10 Zones
(Harzhauser et al. 2004). Based on the normal magnetic polarity
measured in the Balfi út claypit, the Sopron occurrence of
L. soproniense is thus correlated with the upper part of C5n,
and dated about 10 Ma (Magyar et al. 2007; Fig. 9).
Appa-
rently, L. soproniense replaced L. schedelianum in the sub-
littoral zone of Lake Pannon about 10.2 – 10.3 Ma, and from
that time the latter became confined to the littoral zone. In
eastern Austria (Burgenland), L. schedelianum occurs in the
littoral deposits (e.g., Oggau, Grösshöflein; Magyar et al.
2000), whereas L. soproniense characterizes the coeval sub-
littoral sediments (Sopron; Fig. 9).
Finally, Lymnocardium variocostatum is known from litto-
ral sands, correlated with Zone MN10, and dated roughly
9.5 – 9.0 Ma (Lymnocardium ponticum zone; Szilaj et al. 1999;
Magyar et al. 2000, 2007). This species seems to have replaced
L. schedelianum in the littoral zone of Lake Pannon at some
time between 9.7 and 9.5 Ma (Fig. 9).
Evolutionary history of the Lymnocardium soproniense lineage
Based on the stratigraphic and palaeoecological patterns
discussed above, the following scenario is considered most
probable for the phylogenetic relationship of the three species.
A sympatric speciation event in Lymnocardium schedelianum
led to the appearance of L. soproniense in the sublittoral zone
of Lake Pannon, and subsequent habitat partitioning between
L. soproniense and L. schedelianum; the first was confined to
the sublittoral, whereas the latter was limited to the littoral
zone of the lake. Later, the now littoral L. schedelianum
evolved into L. variocostatum, possibly anagenetically, as no
common occurrence of the two species has been found so far
(Fig. 9).
Definition of the Lymnocardium soproniense Interval Zone
Although Lymnocardium soproniense is not a very common
species, it appears in widespread localities of the Pannonian
Basin, apparently with very similar accompanying fauna. This
feature makes it a valuable biostratigraphic marker, therefore
its first occurrence is used to define the base of the
L. soproniense mollusc zone in the sublittoral sediments of Lake
Pannon (Magyar et al. 1999, 2007; Magyar & Geary 2012).
The last occurrence of Lymnocardium soproniense in the
stratigraphic record is more difficult to establish. The age of
the uncertain Budapest occurrences is estimated at 8 – 9 Ma
(Magyar et al. 2006). For practical reasons we suggest marking
the top of the L. soproniense Zone with the base of the over-
lying Congeria praer
homboidea Zone, defined by the first
appearance datum of C. praerhomboidea at ca. 8.9 Ma
Fig. 8. Mean and range of within-shell δ
18
O values of Lymnocardium
schedelianum (NHMW coll.), L. soproniense (MTM, M. 571815),
and L. variocostatum (private coll.). Data are arranged by species (at
bottom) and locality (at top), and do not necessarily indicate relative
stratigraphic positions. Both L. variocostatum shells were incomplete,
potentially affecting within-shell range. Data from Johnson (2016).
Fig. 9. Stratigraphic correlation of the Lymnocardium soproniense
Interval Zone to the Geomagnetic Polarity Time Scale and the
European mammal zonation (Hilgen et al. 2012). L sch — L. schede
lianum, L sop — L. soproniense, L var — L. variocostatum.
569
LATE MIOCENE COCKLE STRATIGRAPHY OF LAKE PANNON DEPOSITS
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
(Magyar et al. 1999; Magyar & Geary 2012), regardless of
whether L. soproniense itself occurs in younger deposits or not
(Fig. 9).
Conclusions
Lymnocardium soproniense was a Late Miocene brackish-
water cockle living in the quiet offshore environment of Lake
Pannon. It evolved from L. schedelianum some 10.2 – 10.3
million years ago by attaining larger size and increased
longevity (>10 years). The species was widely distributed in
the northern part of the Pannonian basin, and it is well repre-
sented in museum collections. Although full and intact speci-
mens of this fossil are rare, it can be distinguished from other
species even when found in small fragments. Consequently, it
is a good biostratigraphic marker in the sublittoral deposits of
Lake Pannon.
Acknowledgements: Lajos Katona (TTM-BTM) is thanked
for photographs of specimens from the collections of MFGI
and TTM. Tímea Szlepák (MFGI Library) helped the authors
to identifiy the first original description of L. soproniense.
Reviews by Oleg Mandic (NHMW) and an anonymous
reviewer have substantially improved the original version of
the manuscript. Mathias Harzhauser (NHMW) and Alfred
Dulai (TTM) are thanked for permitting destructive sampling
on fossil bivalve shells. This research was supported by the
Hungarian Research Fund 81530 and National Research,
Development and Innovation Office — NKFIH 116618. This
is MTA-MTM-ELTE Paleo contribution No 227.
References
Andreasson F.P. & Schmitz B. 2000: Temperature seasonality in the
early middle Eocene North Atlantic region: Evidence from
stable isotope profiles of marine gastropod shells. Geol. Soc.
Amer. Bull. 112, 628–640.
Barna P., Starek D. & Pipík R. 2010: Middle Pannonian sublittoral
ostracod fauna from the locality Sopron (Hungary). Geologické
výzkumy na Moravě a ve Slezsku, Kenozoikum 17, 8–9.
Bartha F. 1971: Biostratigraphy of the Pannonian Stage in Hungary.
In: Góczán F. & Benkő J. (Eds.): Research of Pannonian forma-
tions in Hungary.. Akadémiai Kiadó, Budapest, 9–172 (in
Hungarian).
Boda J. 1964: Catalogus originalium fossilium Hungariae. Pars Zoo-
logica. Magyar Állami Földtani Intézet, Budapest, 1–229.
Csillag G., Sztanó O., Magyar I. & Hámori Z. 2010: Stratigraphy of
the Kálla Gravel in Tapolca Basin based on multi-electrode
probing and well data. Földtani Közlöny 140, 183–196 (in Hun-
garian with English abstract).
Cziczer I., Magyar I., Pipík R., Böhme M., Ćorić S., Bakrač K.,
Sütő-Szentai M., Lantos M., Babinszki E. & Müller P. 2009: Life
in the sublittoral zone of long-lived Lake Pannon: paleonto-
logical analysis of the Upper Miocene Szák Formation, Hungary.
Int. J. Earth Sci. 98, 1741–1766.
Dettman D.L. & Lohmann K.C. 1993: Seasonal Change in Paleogene
Surface Water δ
18
O: Fresh
‐Water Bivalves of Western North
America. Geophysical Monograph 78, 153–163.
Dettman D.L., Reische A.K. & Lohmann K.C. 1999: Controls on the
stable isotope composition of seasonal growth bands in arago-
nitic fresh-water bivalves (Unionidae). Geochim. Cosmochim.
Acta 63, 1049–1057.
Goodwin D.H, Flessa K.W., Schöne B.R. & Dettman D.L. 2001:
Cross-calibration of daily growth increments, stable isotope
variation, and temperature in the Gulf of California bivalve
mollusk Chione cortezi: implications for paleoenvironmental
analysis. Palaios 16, 387–398.
Goodwin D.H., Schöne B.R. & Dettman D.L. 2003: Resolution and
fidelity of oxygen isotopes as paleotemperature proxies in
bivalve mollusk shells: models and observations. Palaios 18,
110–125.
Geary D.H., Magyar I. & Müller P. 2000: Ancient Lake Pannon and
its Endemic Molluscan Fauna (Central Europe; Mio-Pliocene).
In: Rossiter A. & Kawanabe H. (Eds.): Ancient Lakes: Bio-
diversity, Ecology, and Evolution. Academic Press, Advances in
Ecological Research 31, 463–482.
Geary D.H., Hoffmann E., Magyar I., Freiheit J. & Padilla D. 2012:
Body size, longevity, and growth rate in Lake Pannon mela-
nopsid gastropods and their predecessors. Paleobiology 38,
554–568.
Harzhauser M. & Piller W.E. 2007: Benchmark data of a changing sea
— palaeogeography, palaeobiogeography and events in the
Central Paratethys during the Miocene. Palaeogeogr. Palaeo
climatol. Palaeoecol. 253, 8–31.
Harzhauser M., Daxner-Höck G. & Piller W.E. 2004: An integrated
stratigraphy of the Pannonian (Late Miocene) in the Vienna
Basin. Austrian J. Earth Scie. 95–96, 6–19.
Hilgen F.J., Lourens L.J. & Van Dam J.A. 2012: The Neogene Period.
In: Gradstein F.M, Ogg J.G., Schmitz M. & Ogg G.: The Geo-
logic Time Scale 2012. Elsevier B.V., 923–978.
Ivany L.C. & Runnegar B. 2010: Early Permian seasonality from
bivalve
18
O and implications for the oxygen isotopic composi-
tion of seawater. Geology 38, 1027–1030.
Ivany L.C., Wilkinson B.H., Lohmann K.C., Johnson E.R., McElroy
B.J. & Cohen G.J. 2004: Intra-annual isotopic variation in
Venericardia bivalves: Implications for early Eocene tempe-
rature, seasonality, and salinity on the US Gulf Coast. J. Sed.
Res. 74, 7–19.
Johnson M.R. 2016: An integrated stable isotope record from the Late
Miocene Pannonian Basin System: the ecology of horses, the life
histories of bivalves, and mass-balance modeling. PhD Thesis,
University of WisconsinMadison, 1–171.
Korpás-Hódi M. 1983: Palaeoecology and biostratigraphy of the Pan-
nonian Mollusca fauna in the northern foreland of the Trans-
danubian Central Range. Annals of the Hungarian Geological
Institute 66, 1–163.
Korpás-Hódi M. 1994: The Neogene of the Sopron Mts. Claypit,
Sopron, Balfi street, Pannonian. In: Nagymarosy A. (Ed.): IGCP
329 Project “The Neogene of the Paratethys”. Workshop Meeting
1994, Sümeg, Excursion Guide, 34–36.
Magyar I. 1988: Mollusc fauna and flora of the Pannonian quartz
sandstone at Mindszentkálla, Hungary. Annales Universitatis
Scientiarum Budapestinensis de Rolando Eötvös Nominatae,
Sectio Geologica 28, 209–222.
Magyar I. & Geary D.H. 2012: Biostratigraphy in a Late Neogene
Caspian-type lacustrine basin: Lake Pannon, Hungary. In:
Baganz O.W., Bartov Y., Bohacs K. & Nummedal D. (Eds.):
Lacustrine sandstone reservoirs and hydrocarbon systems.
AAPG Memoir 95 255–264.
Magyar I., Geary D.H., Sütő-Szentai M., Lantos M. & Müller P. 1999:
Integrated biostratigraphic, magnetostratigraphic and chrono-
stratigraphic correlations of the Late Miocene Lake Pannon
deposits. Acta Geol. Hung. 42, 5–31.
570
MAGYAR, CZICZER, SZTANÓ, DÁVID and JOHNSON
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
Magyar I., Müller P., Geary D.H., Sanders H.C. & Tari G.C. 2000:
Diachronous deposits of Lake Pannon in the Kisalföld basin
reflect basin and mollusc evolution. Abhandlungen der
Geo logischen Bundesanstalt 56, 669–678.
Magyar I., Müller P.M., Sztanó O., Babinszki E. & Lantos M. 2006:
Oxygen-related facies in Lake Pannon deposits (Upper Miocene)
at Budapest-Kőbánya. Facies 52, 209–220.
Magyar I., Lantos M., Ujszászi K. & Kordos L. 2007: Magnetostrati-
graphic, seismic and biostratigraphic correlations of the Upper
Miocene sediments in the northwestern Pannonian Basin
System. Geol. Carpath. 58, 277–290.
Mihaila N. & Marinescu F. 1971: Limnocardium (Pannonicardium)
Mihaili sp. n. de la faune á Congeria subglobosa du Bassin de
Crisul Repede. Dari de seama ale sedintelor 57, 41–48 (in
Romanian with French abstract).
Müller P., Geary D.H. & Magyar I. 1999: The endemic molluscs of
the Late Miocene Lake Pannon: their origin, evolution, and
family-level taxonomy. Lethaia 32, 47–60.
Papp A. 1951: Das Pannon des Wiener Beckens. Mitteilungen der
Geologischen Gesellschaft in Wien 39–41, 99–193.
Papp A. 1953: Die Molluskenfauna des Pannon im Wiener Becken.
Mitteilungen der Geologischen Gesellschaft in Wien 44, 85–222.
Papp S. 1915: Das neue Vorkommen der pannonischen Petrefakten
Congeria Spathulata Partsch und Limnocardium Penslii Fuchs
in Ungarn und die auf dieselben bezügliche Literatur. Földtani
Közlöny 45, 251–254.
Schmitz B. & Andreasson F.P. 2001: Air humidity and lake δ
18
O
during the latest Paleocene–earliest Eocene in France from
recent and fossil fresh-water and marine gastropod δ
18
O, δ
13
C,
and
87
Sr/
86
Sr. Geol. Soc. Amer. Bull. 113, 774–789.
Schöne B.R., Freyre Castro A.D., Fiebig J., Houk S.D., Oschmann W.
& Kröncke I. 2004: Sea surface water temperatures over the
period 1884-1983 reconstructed from oxygen isotope ratios of
a bivalve mollusk shell (Arctica islandica, southern North Sea).
Palaeogeogr. Palaeoclimatol. Palaeoecol. 212, 215-232.
Schöne B.R., Houk S.D., Freyre Castro A.D., Fiebig J., Oschmann
W., Kröncke I., Dreyer W. & Gosselck F. 2005: Daily growth
rates in shells of Arctica islandica: assessing sub-seasonal
environmental controls on a long-lived bivalve mollusk.
Palaios 20,78-92.
Schréter Z. 1939: Geologische Verhältnisse der so-lichen Seite des
Bükk-gebirges. Annual Report of the Hungarian Royal Geolo
gical Institute of 193335, Volume II, 511–532 (in Hungarian
with German summary).
Schultz O. 2003: Catalogus Fossilium Austriae. Bivalvia neogenica,
Band 1/Teil 2. Verlag der Österreichischen Akademie der
Wissenschaften, Wien, 381–690, plates 57–95.
Stevanović P.M. 1951: Pontische Stufe im engeren Sinne — obere
Congerienschichten Serbiens und der angrenzenden Gebiete.
Serbische Akademie der Wissenschaften, Sonderausgabe 187,
Mathematisch-Naturwissenschaftliche Klasse 2, Beograd,
1–361.
Strausz L. 1942: Das Pannon des mittleren Westungarns. Annales
HistoricoNaturales Musei Nationalis Hungarici, pars Mine
ralogica, Geologica et Palaeontologica 5, 1–102.
Surge D.M., Lohmann K.C. & Dettman D.L. 2001: Controls on
isotopic chemistry of the American oyster, Crassostrea virginica:
implications for growth patterns. Palaeogeogr. Palaeoclimatol.
Palaeoecol. 172, 283–296.
Szilaj R., Szónoky M., Müller P., Geary D.H. & Magyar I. 1999:
Stratigraphy, paleoecology, and paleogeography of the “Congeria
ungulacaprae beds” (=Lymnocardium ponticum Zone) in NW
Hungary: study of the Dáka outcrop. Acta Geol. Hung.
42,33–55.
Talbot M.R. 1990: A review of the palaeohydrological interpretation
of carbon and oxygen isotopic ratios in primary lacustrine
carbonates. Chem. Geol.: Isotope Geosci. Section 80, 261–279.
Vitális I. 1934a: A Limnocardium soproniense n. sp. A Magyar
Tudományos Akadémia Matematikai és Természettudományi
Értesítője (Mathematischer und Naturwissenschaftlicher Anzei
ger der Ungarischen Akademie der Wissenschaften) 51,
705–716.
Vitális I. 1934b: Zwei neue Muschelarten aus den pontischen Sedi-
menten von Sopron. Publications of the Department of Mining
and Metallurgy, Royal Hungarian Palatin – Joseph University of
Technical and Economical Sciences, Faculty of Mining, Metal
lurgy and Forestry of Sopron, Sopron, Hungary, 6, 77–92.
Vitális I. 1951: Les sédiments et fossiles sarmatiens et pannono-
pontiens des environs de Sopron. Annals of the Hungarian Geo
logical Institute 40, 1–75 (in Hungarian with French abstract).
Wurster C.M., Patterson W.P. & Cheatham M.M. 1999: Advances in
micromilling techniques: a new apparatus for acquiring high-
resolution oxygen and carbon stable isotope values and major/
minor elemental ratios from accretionary carbonate. Computers
& Geosciences 25, 1159–1166.
Wurster C.M. & Patterson W.P. 2001: Seasonal variation in stable
oxygen and carbon isotope values recovered from modern
lacustrine freshwater molluscs: paleoclimatological implications
for sub-weekly temperature records. J. Paleolimnology 26,
205-218.
571
LATE MIOCENE COCKLE STRATIGRAPHY OF LAKE PANNON DEPOSITS
GEOLOGICA CARPATHICA
, 2016, 67, 6, 561 – 571
Review of collection and literature data on the
distribution of Lymnocardium soproniense
Sopron / Ödenburg and Vicinity
There are many specimens of Lymnocardium soproniense from
various claypits of Sopron and from a well in Balf (17 m depth
from the surface) in the collection of the MFGI, obtained between
1872 and 1971. This material includes a beautiful pair of valves
from Sopron, Lenk brickyard, donated to the institute by
L. Károlyi in 1914 (the original label of these specimens was
written and signed by L. Roth). The left valve is the type of the
species (Pl. 97; Fig. 2 a, b), photographed by Vitális (1934 a, b),
whereas the right valve is slightly damaged and partly filled with
sediment (or glue?) in the inner part (Pl. 6361; Fig. 2 c,d).
The relatively large collection of F. Bartha from the Balfi út
claypit contains an outstandingly well-preserved left valve
(Bartha 1971; Pl. 2016.1.1; Fig. 2 e, f), along with some large and
quite complete but sediment-filled specimens (Pl. 6336, 6337,
6354, 6355, 6359) and many shell fragments (Pl. 6332, 6341,
6344, 6345, 6347).
The Hungarian Natural History Museum (TTM) also has
a relatively large collection of L. soproniense from Sopron,
including specimens that were purchased from the legacy of
I. Vitális (M57/807-817, M64/1200). In this material, however,
there is only one right valve which is a complete and fully cleaned
specimen (M57/815; Fig. 2 h,i). The Bakony Natural History
Museum (TTM-BTM) in Zirc also houses a few nice though not
fully intact specimens (Fig. 2 g).
Vicinity of Miskolc
While mapping the southwestern hilly region of the Bükk Mts.
between 1932 and 1934, Z. Schréter, geologist of the Hungarian
Royal Geological Institute, collected fossils from shallow test
holes (Schréter 1939) and deposited them in the MFGI collection.
The best-preserved specimens are from Bükkaranyos (MFGI
Pl. 4535, Pl. 4613, Pl. 4614); although the shells are broken and
dissolved, the diagnostic rib pattern of Lymnocardium soproniense
can be recognized in some of them. However, specimens from
Borsodgeszt (Pl. 4627), Harsány (without inventory number),
Sály (Pl. 4569), and Mályi (Pl. 4602) are poorly preserved; the
shells are usually partly or entirely dissolved. They are identified
as L. cf. soproniense (Schréter 1939, p. 520; Fig. 1).
Better-preserved specimens in the area were collected after the
brickyard claypit in Mályi was opened. Apart from a stein kern
(L. cf. soproniense, Pl. 4603), the museums have shelly speci-
mens from this outcrop (Pl. 6438 and a specimen without inven-
tory number in the collection of the MFGI; M. 68.32 in the
collection of the TTM; and several specimens in the private
collection of I. Cziczer, including an intact left valve
(Fig. 2 j, k).
Bartha (1971) mentioned the occurrence of L. soproniense from
Alsódobsza, but these specimens, deposited in the collection of
the MFGI, belong to L. schedelianum (Fig. 1).
Vicinity of Oradea/Nagyvárad
We have no information on the whereabouts of Papp’s (1915)
specimen from Nuşfalau. Mihaila and Marinescu (1971) claim
that the holotype of Lymnocardium mihaili from Felcheriu is
reposited in the Geological Institute in Bucharest, but no mention
is made of the whereabouts of fossils collected by Mihaila and
determined by Marinescu from Sabolciu (Mihaila and Marinescu
1971). As the latter material has not been depicted, we cannot
confirm the presence of L. soproniense in Sabolciu (Fig. 1).
Budapest
In the TTM collection, there is a beautiful specimen of
Lymnocardium soproniense (M57/38) preserved in clay with
double and open valves. According to the label and the original
sticker on the specimen, it was collected by Ferenc Kubinyi in
1849 from Budapest-Rákos. This locality and the immediately
neighbouring Kőbánya outcrops are well-known from the
palaeontological literature (see Magyar et al. 2006 and refe rences
therein), but no mention is made of fossils that could be identified
with L. soproniense.
In the collection of the MFGI, however, there are two speci-
mens from Budapest-Kőbánya (Pl. 2864), determined as
“Limnocardium cfr. schmidti” by Bartha, that might be related to
L. soproniense. Both specimens are articulated valves; one is a
steinkern, the other with shells but compressed and broken.
The latter has 18 ribs, the structure of which resembles that of
L. soproniense.
This scarce material indicates that L. soproniense might have
lived in the area, but further data are needed to strengthen that
claim (Fig. 1).
Balaton
Bartha (1971, p. 101) reported Lymnocardium soproniense
from the Kisapáti-2 borehole at 18 – 35 m depth (Fig. 1).
The core sample (18.50 – 18.70 m) is deposited in the collection of
the MFGI (Pl. 6327). It contains Congeria czjzeki specimens and
a poorly preserved fragment of a large Lymnocardium species in
fine-grained sediments. The sediment and the accompanying
species make it probable that the large species is indeed
L. soproniense, but its rib architecture is not visible, thus the
determination remains highly uncertain.
Magyar (1988) depicted large Lymnocardium moulds (stein-
kerns) from Mindszentkálla as “Lymnocardium cf. soproniense”
(Fig. 1). Although the preservation of these fossils, deposited in
the TTM, does not allow distinction between L. soproniense and
the closely related species L. variocostatum and L. schedelianum,
the accompanying species — such as Congeria pancici Pavlović,
Unio atavus Partsch, and Mela nopsis fossilis (Martini-Gmelin) —
as well as the shoreface depositional environment of the embed-
ding pebbly sandstone – suggest that these large cockles probably
belong to L. schedelianum. The entire association is typical of
a littoral “Burgenland fauna” (Magyar et al. 2000; Csillag et
al. 2010).
Appendix