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Journal Article•DOI•

Co-occurrence of Neusticosaurus edwardsii and N. peyeri (Reptilia) in the Lower Meride Limestone (Middle Triassic, Monte San Giorgio)

Rudolf Stockar1, Silvio Renesto2•
University of Lausanne1, University of Insubria2
12 Nov 2011-Swiss Journal of Geosciences (SP Birkhäuser Verlag Basel)-Vol. 104, Iss: 1, pp 167-178
TL;DR: A newly opened excavation in the Cassina beds of the Lower Meride Limestone (Monte San Giorgio UNESCO World Heritage List, Canton Ticino, Switzerland) has yielded a pachypleurosaurid (Reptilia: Sauropterygia) specimen which is identified as Neusticosaurus peyeri as discussed by the authors.
Abstract: A newly opened excavation in the Cassina beds of the Lower Meride Limestone (Monte San Giorgio UNESCO World Heritage List, Canton Ticino, Switzerland), has yielded a pachypleurosaurid (Reptilia: Sauropterygia) specimen which is identified as Neusticosaurus peyeri. The resulting co-occurrence of N. peyeri and N. edwardsii, the latter so far regarded as the sole species of the genus present in this horizon, challenges the hypothesis of a single anagenetic lineage in Neusticosaurus species from Monte San Giorgio. In addition, it leads to a reconsideration of the phylogenetic inferences about Neusticosaurus evolution in the Monte San Giorgio area. The stratigraphic distribution of the Neusticosaurus species in the Monte San Giorgio basin is updated on the basis of recent finds.

Summary (2 min read)

Jump to: [Introduction] – [Geological setting] – [Materials and methods] – [Systematic palaeontology] and [Conclusions]

Introduction

  • The Cassina (also known as ‘‘alla Cascina’’) beds belong to the world-renowned fossiliferous levels of the Middle Triassic Monte San Giorgio Lagerstätte (UNESCO World Heritage List, Canton Ticino, Southern Alps; Fig. 1), particularly famous for its rich and diverse fauna of Middle Triassic marine vertebrates (e.g. Kuhn-Schnyder 1974; Bürgin et al. 1989).
  • The aim of the ongoing excavation is to carefully re-document the level in order to provide a better characterization of the basin.
  • Besides over three hundred fish specimens, a new pachypleurosaurid (Reptilia, Sauropterygia) specimen of the genus Neusticosaurus was found, which is described and discussed below.

Geological setting

  • The Middle Triassic succession at Monte San Giorgio (Figs. 1, 2) starts with a fluvio-deltaic sequence dated to the late Anisian (Bellano Formation, Illyrian; Sommaruga Editorial handling: Jean-Paul Billon-Bruyat.
  • The overlying 400–600 m thick Meride Limestone (Furrer 1995) begins with the Lower Meride Limestone, 90 m (Wirz 1945) to 150 m thick (Furrer 1995), which bears three fossil tetrapod beds (Cava inferiore, Cava superiore and Cassina beds), each yielding different vertebrate assemblages (Sander 1989; Bürgin et al. 1989) and consisting of finely laminated limestones with intercalated volcanic ash layers.
  • The first diversification of pachypleurosaurids in the western Tethyan realm followed the marine transgression that began in the late Early Triassic and proceeded from east to west across central Europe.
  • If correct, the geographic and temporal distribution pattern of N. pusillus described above would support the view of Rieppel and Hagdorn (1997), according to which the Serpianosaurus–Neusticosaurus clade diversified in the southern Alpine intraplatform basin facies and later (N. pusillus) returned to the Germanic basin during the Ladinian via the Burgundy gate.

Materials and methods

  • The new excavation site lies to the south of the summit of Monte San Giorgio, a little way out of the outcrop where the Cassina beds were originally discovered in 1933 (Fig. 1).
  • So far, the upper third of the succession (Fig. 3) has been excavated bed by bed over a surface of around 40 m2, yielding a well-preserved vertebrate fauna mainly composed of fishes belonging to at least six species, dominated by the large predatory actinopterygian Saurichthys.
  • Reptiles turned out to be rare in the upper part of the Cassina beds and the specimen belonging to the genus Neusticosaurus described here is the only articulated find recovered so far.
  • The Cassina beds are traditionally regarded as early Ladinian in age (e.g. Hellmann and Lippolt 1981; O’Keefe et al. 1999) but reliable index fossils such as ammonoids and conodonts have never been reported from this horizon.
  • This preservation pattern is ascribed to the development of decay gas in the wide abdominal cavity which held the body with the ventral side upward (Furrer 2003).

Systematic palaeontology

  • Class Reptilia LAURENTI 1768 Superorder Sauropterygia OWEN 1860 Order Eosauropterygia RIEPPEL 1994 Infraorder Pachypleurosauroidea HUENE 1956 Family Pachypleurosauridae NOPCSA 1928 Genus Neusticosaurus SEELEY 1882 Neusticosaurus peyeri SANDER 1989.
  • The squamosal is visible on the right side of the skull, articulated with the small quadrate and quadratojugal by a lateral process.
  • Five pairs of caudal ribs can be observed, slightly displaced from their corresponding vertebrae; they show a tapering distal end and their size decreases abruptly after the fourth one.
  • The proximal head is thick and subtriangular in section, while the distal head is flattened; the distal articular surface is nearly flat with slightly raised margins.
  • In summary, the morphometrical and morphological features described above give, as a whole, reasonable support to the attribution of MCSN 8076 to Neusticosaurus peyeri.

Conclusions

  • The attribution of specimen MCSN 8076 to Neusticosaurus peyeri on the basis of both morphological and morphometrical data raises some questions regarding the strict correlation between pachypleurosaurid taxa and fossiliferous horizons in the Monte San Giorgio basin as originally proposed by Sander (1989) and afterwards supported by O’Keefe and Sander (1999).
  • Postulating a reversal from N. peyeri to N. edwardsii would no longer be necessary if the two species co-existed, possibly occupying different niches, as the finding of MCSN 8076 in the Cassina beds suggests.
  • The authors would also like to thank Heinz Furrer for information concerning the specimen from the Acqua del Ghiffo site and for permission to publish data on its identification.
  • The manuscript benefited greatly from the remarks and comments of the reviewers Michael Maisch (Tübingen) and Olivier Rieppel .

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Figures (8)

Content maybe subject to copyright    Report

Co-occurrence of Neusticosaurus edwardsii and N. peyeri
(Reptilia) in the Lower Meride Limestone (Middle Triassic,
Monte San Giorgio)
Rudolf Stockar
•
Silvio Renesto
Received: 4 March 2010 / Accepted: 7 February 2011 / Published online: 12 November 2011
Ó Swiss Geological Society 2011
Abstract A newly opened excavation in the Cassina beds
of the Lower Meride Limestone (Monte San Giorgio UNE-
SCO World Heritage List, Canton Ticino, Switzerland), has
yielded a pachypleurosaurid (Reptilia: Sauropterygia)
specimen which is identified as Neusticosaurus peyeri. The
resulting co-occurrence of N. peyeri and N. edwardsii, the
latter so far regarded as the sole species of the genus present
in this horizon, challenges the hypothesis of a single ana-
genetic lineage in Neusticosaurus species from Monte San
Giorgio. In addition, it leads to a reconsideration of the
phylogenetic inferences about Neusticosaurus evolution in
the Monte San Giorgio area. The stratigraphic distribution of
the Neusticosaurus species in the Monte San Giorgio basin is
updated on the basis of recent finds.
Keywords Neusticosaurus Lower Meride Limestone
Monte San Giorgio Middle Triassic Biostratigraphy
Phylogeny
Institutional abbreviations
MCSN Museo Cantonale di Storia Naturale, Lugano,
Switzerland
PIMUZ Pala
¨
ontologisches Institut und Museum der
Universita
¨
tZu
¨
rich, Switzerland
MUMSG Museo del Monte San Giorgio, Meride,
Switzerland
Introduction
The Cassina (also known as ‘‘alla Cascina’’) beds belong to
the world-renowned fossiliferous levels of the Middle
Triassic Monte San Giorgio Lagersta
¨
tte (UNESCO World
Heritage List, Canton Ticino, Southern Alps; Fig. 1), par-
ticularly famous for its rich and diverse fauna of Middle
Triassic marine vertebrates (e.g. Kuhn-Schnyder 1974;
Bu
¨
rgin et al. 1989).
In 2006 a new excavation (Fig. 1) was started by the
Museo Cantonale di Storia Naturale (MCSN), Lugano in
this fossiliferous horizon, first discovered in 1933 by the
University of Zurich which carried out several subsequent
excavations in 1937, between 1971 and 1973, and again in
1975 (see Stockar 2010 for a review). The aim of the
ongoing excavation is to carefully re-document the level in
order to provide a better characterization of the basin.
Besides over three hundred fish specimens, a new pac-
hypleurosaurid (Reptilia, Sauropterygia) specimen of the
genus Neusticosaurus was found, which is described and
discussed below.
Geological setting
The Middle Triassic succession at Monte San Giorgio
(Figs. 1, 2) starts with a fluvio-deltaic sequence dated to
the late Anisian (Bellano Formation, Illyrian; Sommaruga
Editorial handling: Jean-Paul Billon-Bruyat.
R. Stockar (&)
Museo Cantonale di Storia Naturale, Viale Cattaneo 4,
6900 Lugano, Switzerland
e-mail: rudolf.stockar@ti.ch
R. Stockar
Institut de Ge
´
ologie et Pale
´
ontologie, Universite
´
de Lausanne,
Anthropole, 1015 Lausanne, Switzerland
S. Renesto
Department of Structural and Functional Biology, Universita
`
degli Studi dell’Insubria, via Dunant 3, 21100 Varese, Italy
Swiss J Geosci (2011) 104 (Suppl 1):S167–S178
DOI 10.1007/s00015-011-0077-x
et al. 1997), overlying a Permian volcanic succession. The
upper Anisian sediments testify to the progressive trans-
gression of a shallow epicontinental sea and the related
growth of carbonate platforms (Salvatore Dolomite; Zorn
1971) north of a land area buried today under the Po Plain
(Brusca et al. 1981; Picotti et al. 2007). During the latest
Anisian and Ladinian, whereas in the north shallow-water
sedimentation continued, in the Monte San Giorgio area the
formation of a 30–100 m deep and 10–20 km wide intra-
platform basin with restricted circulation (Furrer 1995)
resulted in the deposition of the Besano Formation, the San
Giorgio Dolomite and the Meride Limestone.
The Besano Formation (‘‘Grenzbitumenzone’’; Frau-
enfelder 1916), is an alternation of black shales and
dolomites up to 16 m thick, including in its uppermost part
the Anisian–Ladinian boundary (Brack et al. 2005); a
volcanic ash layer lying a few metres below this boundary
resulted in an U–Pb minimum age of 242.1 ± 0.6 Ma
(Mundil et al. 2010). The Besano Formation, which yielded
most of the spectacular vertebrate fossils (fishes and rep-
tiles) together with important index fossils such as
ammonoids and daonellid bivalves, grades upwards into
the 60 m thick San Giorgio Dolomite. The overlying
400–600 m thick Meride Limestone (Furrer 1995) begins
with the Lower Meride Limestone, 90 m (Wirz 1945)to
150 m thick (Furrer 1995), which bears three fossil tetra-
pod beds (Cava inferiore, Cava superiore and Cassina
beds), each yielding different vertebrate assemblages
(Sander 1989;Bu
¨
rgin et al. 1989) and consisting of finely
laminated limestones with intercalated volcanic ash layers.
The top of the Lower Meride Limestone is defined by a
dolomite bed (‘‘Dolomitband’’; Frauenfelder 1916), reach-
ing a thickness of about 30 m (Wirz 1945). The overlying
Upper Meride Limestone is made up of alternating well-
bedded limestones and marlstones with an increasing clay
content towards the top, where strong seasonal variations of
salinity and water level together with the influence from a
neighbouring emerged area are documented. The uppermost
part comprises the so-called ‘‘Kalkschieferzone’’, which is
120 m thick and which represents the late evolution of the
intraplatform basin, followed by the Carnian regressive
phase (Pizzella Marls; Furrer 1995).
The pachypleurosaurids from Monte San Giorgio
Pachypleurosaurids (Sauropterygia) are generally small
Middle Triassic marine reptiles, restricted to shallow-water
habitats and widely reported from western Tethyan and
eastern Tethyan faunal provinces. According to Rieppel
(2000), the family Pachypleurosauridae N
OPCSA 1928 con-
stitutes a monophyletic taxon. Pachypleurosaurid genera
from China (Keichousaurus, Hanosaurus) are the sister-taxa
of European pachypleurosaurids (Rieppel 1998, 2000, but
Lower Salvatore Dolomite
San Giorgio Dolomite
Besano Formation
50m
Meride
Limestone
Switzerland
Italy
Arzo
Meride
Besano
Serpiano
Porto Ceresio
Poncione d'Arzo
Monte San Giorgio
Lake Lugano
Cassina beds / locality
Cassina
45°54' N
8°57' E
Fig. 1 Map of the Monte San
Giorgio area showing the
Middle Triassic carbonate
sequence and the location of the
excavation site of the Cassina
beds near Cassina (after Stockar
2010). Scale bar 1km
S168 R. Stockar, S. Renesto
Holmes et al. 2008 suggested that Keichousaurus is instead a
basal nothosauroid); amongst the latter, the central European
Muschelkalk (Germanic Triassic) pachypleurosaurids
(Anarosaurus, Dactylosaurus) are the sister-taxa of those
from the Alpine Triassic. Cladistic relationships thus indicate
a diversification from the eastern Tethyan faunal province into
the western Tethys (Rieppel 2000, 2010). The first diversi-
fication of pachypleurosaurids in the western Tethyan realm
followed the marine transgression that began in the late Early
Triassic and proceeded from east to west across central
Europe. This enabled the colonization of the central Euro-
pean Muschelkalk basin by pachypleurosaurids (and by
other sauropterygians and protorosaurs) from the eastern
Tethyan faunal province via the East Carpathian gate fol-
lowing the northern Paleotethys branch (Rieppel and
Hagdorn 1997; Rieppel 2010). The opening of southern
gateways (the Silesian–Moravian gate in the east and, above
all, subsequently by the late Anisian and early Ladinian the
Burgundy gate in the west) allowed pachypleurosaurids to
disperse into the southern Alpine intraplatform basins
(Rieppel and Hagdorn 1997; Rieppel 2010), where the
crown-group pachypleurosaurs (Serpianosaurus–Neustico-
saurus clade) further diversified. Admittedly, some isolated
remains from the middle Muschelkalk might be referred to
Serpianosaurus, but conclusive diagnostic remains are
missing (Rieppel and Hagdorn 1997). The increased taxic
diversity observed in Monte San Giorgio deposits might be
correlated with a greater habitat fragmentation in the intra-
platform southern Alpine basin facies, which from the late
Anisian is included in the ‘‘unstable shelf area’’ (Mostler
1993), compared to the habitat of the Muschelkalk basin
(Rieppel and Lin 1995).
The Alpine pachypleurosaurid genera Serpianosaurus
and Neusticosaurus occur in the Monte San Giorgio
sequence as abundant vertebrate fossils in the Besano
Formation and in all three tetrapod-bearing beds of the
Lower Meride Limestone (e.g. Cornalia 1854; Zangerl
1935; Sander 1989). According to Rieppel and Lin (1995),
Serpianosaurus R
IEPPEL 1989 is the sister-taxon of the
genus Neusticosaurus S
EELEY 1882. In his monographic
description, Sander (1989) stated that, at Monte San
Giorgio, four species occur in stratigraphic superimposition
(Fig. 2), namely, Serpianosaurus mirigiolensis R
IEPPEL
1989 (Besano Formation, Anisian–Ladinian boundary)
followed through the Ladinian by Neusticosaurus pusillus
S
EELEY 1882 (Cava inferiore beds), Neusticosaurus peyeri
S
ANDER 1989 (Cava superiore beds) and, finally, Neusti-
cosaurus edwardsii C
ORNALIA 1854 (Cassina beds), the
latter being the largest species, reaching 120 cm in length.
According to the same author, different species have never
been found together in the same horizon, suggesting that
their stratigraphic ranges never overlap; consequently, he
interpreted the genus Neusticosaurus not only as forming a
monophyletic taxon but also as possibly constituting a
single lineage undergoing anagenetic change within the
Monte San Giorgio sequence. Sander’s assumptions were
challenged by Kuhn-Schnyder (1994), but the treatment of
the three Neusticosaurus species as segments of an ana-
genetic lineage has subsequently been supported by
O’Keefe and Sander (1999). The implications of these
conclusions are discussed in Rieppel (2000, p. 52). Even
from a not strictly palaeontological point of view, the
assumption of a sequential temporal appearance such as
this, ruling out species co-occurrence, is particularly
intriguing, since it lends a biostratigraphic potential to
these commonly occurring tetrapods, even though limited
to the Monte San Giorgio where both N. peyeri and N.
edwardsii are found to be endemic. Elsewhere, N. pusillus
seems to have persisted virtually without morphological
change throughout the late Ladinian in both the Alpine and
Germanic Triassic (O’Keefe and Sander 1999; Rieppel 2000).
In the Germanic Triassic N. pusillus is the only diagnosable
Neusticosaurus species (Rieppel and Hagdorn 1997)and
*
*
Permian Triassic
Liassic
Anisian
Rhyolithe and
associated
volcaniclastics
Bellano Fm.
Cassina beds
Cava superiore beds
Cava inferiore beds
Kalkschieferzone
Pizzella Marls
Meride Limestone
Dolomia Principale
Tremona Series
"Dolomitband"
Lower Salvatore
Dolomite
Besano Fm.
Rhaet
Carnian
Ladinian
Norian
100 m
0 m
242.1 +/- 0.6 Ma
(U-Pb age; Mundil et al. 2010)
San Giorgio
Dolomite
S. mirigiolensis
N. pusillus
N. peyeri
N. edwardsii
Figure 8
Fig. 2 Stratigraphic distribution of the pachypleurosaurids from
Monte San Giorgio, according to Sander (1989) and O’Keefe and
Sander (1999). Stratigraphic log modified from Furrer (1995)
Neusticosaurus from Monte San Giorgio S169
occurs in the Hohenecker Limestone, a lateral equivalent of
the ‘‘Lingula Beds’’ of the upper part of Lower Keuper.
According to Brack et al. (1999), this time interval is
possibly somewhat younger than the Protrachyceras
gredleri ammonoid zone to which, in turn, occurrences of
N. pusillus from Monte San Giorgio (Cava inferiore beds)
are restricted (Stockar 2010, p. 105), being later substituted
by those of N. peyeri and N. edwardsii (at least in part still
within the P. gredleri zone; Stockar 2010, p. 105). If cor-
rect, the geographic and temporal distribution pattern of
N. pusillus described above would support the view of Rieppel
and Hagdorn (1997), according to which the Serpiano-
saurus–Neusticosaurus clade diversified in the southern
Alpine intraplatform basin facies and later (N. pusillus)
returned to the Germanic basin during the Ladinian via the
Burgundy gate. However, caution is necessary. As admit-
ted by Rieppel and Lin (1995), unequivocal identification
of Neusticosaurus species depends on the availability of
fairly complete specimens, which is not usually the case as
far as the upper Muschelkalk facies of the Germanic basin
is concerned, even though disarticulated pachypleurosaur
remains are abundant there. Consequently, the opposite
scenario of an initial migration of N. pusillus during the
early Ladinian from the Germanic to the Alpine basin,
where the genus subsequently further diversified, cannot be
ruled out a priori.
Materials and methods
The new excavation site lies to the south of the summit of
Monte San Giorgio, a little way out of the outcrop where
the Cassina beds were originally discovered in 1933
(Fig. 1). Here, the Cassina beds (Stockar 2010) form an
almost 3 m thick interval, mainly consisting of interbed-
ded, finely laminated, organic-rich shales and limestones
(laminite lithofacies) with intercalated thicker limestones
(turbidite lithofacies) and volcaniclastic layers derived
from volcanic ash suspension-fall (tephra lithofacies). The
sequence grades upwards into the thick-bedded dolomitic
limestones and dolomites belonging to the ‘‘Dolomitband’’.
So far, the upper third of the succession (Fig. 3) has been
excavated bed by bed over a surface of around 40 m
2
,
yielding a well-preserved vertebrate fauna mainly com-
posed of fishes belonging to at least six species, dominated
by the large predatory actinopterygian Saurichthys. Reptiles
turned out to be rare in the upper part of the Cassina beds
and the specimen belonging to the genus Neusticosaurus
described here is the only articulated find recovered so far.
The Cassina beds are traditionally regarded as early
Ladinian in age (e.g. Hellmann and Lippolt 1981; O’Keefe
et al. 1999) but reliable index fossils such as ammonoids
and conodonts have never been reported from this horizon.
Furrer et al. (2008) tentatively correlated the Cassina beds
with the lowermost Wengen Formation of the GSSP sec-
tion at Bagolino (Protrachyceras archelaus ammonoid
zone, late Ladinian; Brack et al. 2005). This correlation is
consistent with the occurrence of Echinitosporites iliaco-
ides (Scheuring 1978), a palynomorph which is regarded as
limited to the late Ladinian P. archelaus zone (see Stockar
2010 for a review of biostratigraphic data).
The Neusticosaurus specimen is mostly articulated and
exposed in ventral view, as reported for most pachypleu-
rosaurids from Cava inferiore and Cava superiore beds.
This preservation pattern is ascribed to the development of
decay gas in the wide abdominal cavity which held the
body with the ventral side upward (Furrer 2003). The
specimen was recovered from a 8 mm thick bed belonging
to the laminite lithofacies which, according to Stockar
(2010), testifies to anoxic to suboxic bottom-water condi-
tions with possible growth of benthic microbial mats and
consequent bio-armouring effect of carcasses.
According to our examination of the historical collection
stored at the Pala
¨
ontologisches Institut und Museum der
Universita
¨
tZu
¨
rich (PIMUZ) and to unpublished field data
(both courtesy Heinz Furrer, PIMUZ), the bulk of Neusti-
cosaurus material from the Cassina beds comes from just the
base of the sequence, which lies approximately 2 m below
the bed bearing the specimen described here. Consequently,
the latter is slightly younger than most (if not all) known
pachypleurosaurid specimens from the Cassina beds.
The specimen was mechanically prepared with the aid of
vibrotools and sharpened needles.
Systematic palaeontology
Class Reptilia L
AURENTI 1768
Superorder Sauropterygia O
WEN 1860
Order Eosauropterygia R
IEPPEL 1994
Infraorder Pachypleurosauroidea H
UENE 1956
Family Pachypleurosauridae N
OPCSA 1928
Genus Neusticosaurus S
EELEY 1882
Neusticosaurus peyeri S
ANDER 1989
Type species: PIMUZ T3615 (Sander 1989), a complete
specimen from Cava superiore beds.
See Sander (1989, p. 601–602) for synonymy.
Material: specimen MCSN 8076 of the collection of the
Museo Cantonale di Storia Naturale, Lugano, Switzerland,
collected from bed 34, Cassina beds, Lower Meride
Limestone (Figs. 4, 5, 6, 7).
Measurements (in mm):
Skull length (from the tip of the snout to the occipital
condyle): 22.3
S170 R. Stockar, S. Renesto
Fig. 3 Detailed
sedimentological log of the
upper part of the Cassina beds
being investigated, with an
indication of the distribution
and abundance of vertebrate
fossils (after Stockar 2010,
modified)
Neusticosaurus from Monte San Giorgio S171
Citations
More filters
Journal Article•DOI•
The Permian and Triassic in the Albanian Alps

[...]

Maurizio Gaetani1, Selam Meço, Roberto Rettori2, Charles M. Henderson3, Accursio Tulone2 •
University of Milan1, University of Perugia2, University of Calgary3
26 Sep 2015-Acta Geologica Polonica
TL;DR: In this article, the sedimentary succession of the Permian to Middle Triassic of the Albanian Alps is described, as part of the eastern Adria passive margin towards the Tethys.
Abstract: The sedimentary succession of the Permian to Middle Triassic of the Albanian Alps is described, as part of the eastern Adria passive margin towards the Tethys. A carbonate ramp deepening towards NE in present day coordinates developed during the Middle Permian and was affected by block faulting with the deposition of carbonate breccia. The Early Triassic was characterized by intense terrigenous deposition with several cobble conglomerate units up to 80 m-thick, and by oolitic carbonate shoals. The fine clastic deposition ended gradually during the earliest Anisian and a wide calcarenitic ramp occupied the area, with small local carbonate mounds. Basinward, the red nodular limestone of the Han Bulog Formation was interbedded with calcarenitic material exported from the ramp. Drowning to more open conditions occurred towards the end of the Pelsonian. Subsequently, cherty limestone and tuffitic layers spread over the entire area. Towards the end of the Ladinian, with the end of the volcanic activity, red pelagic limestone was deposited locally for a short period. By the latest Ladinian most of the area returned to shallow-water conditions, with a peritidal carbonate platform. In the Theth area, in contrast, a basin with black organic-rich dolostone and limestone developed which seems to be unique in that part of the Adria passive margin. The occurrence of cobble conglomerate units in the Lower Triassic testifies to very active block faulting and high accommodation, not yet described for the area.

62 citations

Journal Article•DOI•
Integrated Ladinian bio-chronostratigraphy and geochrononology of Monte San Giorgio (Southern Alps, Switzerland)

[...]

Rudolf Stockar1, Peter Baumgartner1, Daniel J. Condon2•
University of Lausanne1, British Geological Survey2
15 May 2012-Swiss Journal of Geosciences
TL;DR: In this article, a single-zircon U-Pb dating was performed using ID-TIMS and chemical abrasion (CA) pre-treatment technique on volcanic ash layers intercalated in the biostratigraphically defined intervals of the Meride Limestone.
Abstract: New biostratigraphic data significantly improve the age assignment of the Ladinian succession of Monte San Giorgio (UNESCO World Heritage List site, Southern Alps, Switzerland), whose world-famous fossil marine vertebrate faunas are now dated to the substage and zone levels. High-resolution single-zircon U–Pb dating was performed using ID-TIMS and chemical abrasion (CA) pre-treatment technique on volcanic ash layers intercalated in the biostratigraphically-defined intervals of the Meride Limestone. It yielded ages of 241.07 ± 0.13 Ma (Cava superiore beds, P. gredleri Zone), 240.63 ± 0.13 Ma (Cassina beds, P gredleri/P. archelaus transition Zone) and 239.51 ± 0.15 Ma (Lower Kalkschieferzone, P. archelaus Zone). Our results suggest that the time interval including the vertebrate-bearing Middle Triassic section spans around 4 Myr and is thus significantly shorter than so far assumed. The San Giorgio Dolomite and the Meride Limestone correlate with intervals of the Buchenstein Formation and the Wengen Formation in the reference section at Bagolino, where the Global boundary Stratotype Section and Point (GSSP) for the base of the Ladinian was defined. The new radio-isotopic ages of the Meride Limestone are up to 2 Myr older than those published for the biostratigraphically-equivalent intervals at Bagolino but they are consistent with the recent re-dating of the underlying Besano Formation, also performed using the CA technique. Average sedimentation rates at Monte San Giorgio are by more than an order of magnitude higher compared to those assumed for the Buchenstein Formation, which formed under sediment-starved pelagic conditions, and reflect prevailing high subsidence and high carbonate mud supply from the adjoining Salvatore/Esino platforms. Finally, the high-resolution U–Pb ages allow a correlation of the vertebrate faunas of the Cava superiore/Cava inferiore beds with the marine vertebrate record of the Prosanto Formation (Upper Austroalpine), so far precluded by the poor biostratigraphic control of the latter.

52 citations

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  • ...…S. curionii, ‘‘Archaeoseomionotus’’ sp., Eoeugnathus sp., Eosemionotus sp., Peltopleurus sp.) as well as land plant remains and quasi-anaerobic foraminiferal faunas (Peyer 1931; Rieppel 1985; Bürgin 1999; Hänni 2004; Stockar 2010; Stockar and Kustatscher 2010; Stockar and Renesto 2011)....

    [...]

  • ...Recovered vertebrate fossils include marine reptiles (Ceresiosaurus calcagnii, Neusticosaurus edwardsii, N. peyeri) and fishes (Saurichthys sp., Eosemionotus sp., Besania micrognathus) (Peyer 1931; Sander 1989; Furrer 1999a, 2001, 2003; Stockar and Renesto 2011)....

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  • ...The first author is indebted to Evelyn Kustatscher (Bozen) and David Bodman (Sheffield) for the stimulating discussions about palynological aspects, to Paulian Dumitrica (IGP, UNI Lausanne) for the revision of the determination of the radiolarian specimens illustrated herein and especially to Daniel Bernoulli (UNI Basel) for comments on an earlier version of the manuscript....

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  • ...Bentonite layer, weathered to an orange colour, 5 cm thick, intercalated between the laminated limestones of this fossiliferous interval yielding marine reptiles (Ceresiosaurus lanzi, Neusticosaurus edwardsii, N. peyeri, Macrocnemus bassanii, Tanystropheus meridensis) and fishes (Saurichthys macrocephalus, S. curionii, ‘‘Archaeoseomionotus’’ sp., Eoeugnathus sp., Eosemionotus sp., Peltopleurus sp.) as well as land plant remains and quasi-anaerobic foraminiferal faunas (Peyer 1931; Rieppel 1985; Bürgin 1999; Hänni 2004; Stockar 2010; Stockar and Kustatscher 2010; Stockar and Renesto 2011)....

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  • ...…a high-resolution correlation tool outside the Monte San Giorgio basin is hampered by the possibility of some degree of endemism (e.g. Rieppel 2000; Stockar and Renesto 2011) and, above all, by the patchy occurrences of vertebrate fossils in the Ladinian of the Southern Alps and in the Buchenstein…...

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Journal Article•DOI•
New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland)

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Adriana López-Arbarello1, Toni Bürgin2, Heinz Furrer3, Rudolf Stockar•
Ludwig Maximilian University of Munich1, University of St. Gallen2, University of Zurich3
19 Jul 2016-PeerJ
TL;DR: The new neopterygian genus Ticinolepis, including two new species T. longaeva and T. crassidens, is described from Middle Triassic carbonate platform deposits of the Monte San Giorgio and shows interesting patterns of intraspecific variation including ontogenetic changes and morphological variation over time.
Abstract: The new neopterygian genus Ticinolepis, including two new species T. longaeva and T. crassidens is described from Middle Triassic carbonate platform deposits of the Monte San Giorgio. The anatomy of this fish shows a mosaic of halecomorph and ginglymodian characters and, thus, the new taxon probably represents a basal holostean. During the latest Anisian to earliest Ladinian the two new species coexisted in the intraplatform basin represented by the uppermost Besano Formation, but only T. longaeva sp. nov. inhabited the more restricted basin represented by the Ladinian Meride Limestone (except for the Kalkschieferzone). The more widely distributed type species shows interesting patterns of intraspecific variation including ontogenetic changes and morphological variation over time. The second species presents anatomical features that strongly indicate a strictly durophagous diet. The different distribution of the species is interpreted as a result of habitat partitioning and different adaptability to palaeoenvironmental changes.

21 citations

Cites background from "Co-occurrence of Neusticosaurus edw..."

  • ...Along with sauropterygian remains (Stockar & Renesto, 2011), land plant remains (Stockar & Kustatscher, 2010) and quasi-anaerobic foraminiferal faunas (Stockar, 2010) the new excavations brought to light many complete and well-preserved specimens of several actinopterygian fishes, including the…...

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  • ...…three fossil vertebrate levels: Cava inferiore, Cava superiore and Cassina beds, each yielding different vertebrate assemblages (e.g., Sander, 1989; Furrer, 1995; Bürgin, 1999b; Stockar & Renesto, 2011) and consisting of finely laminated limestones and marls with intercalated volcanic ash layers....

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Journal Article•DOI•
Palaeoenvironmental significance of organic facies and stable isotope signatures: the Ladinian San Giorgio Dolomite and Meride Limestone of Monte San Giorgio (Switzerland, WHL UNESCO)

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Rudolf Stockar1, Thierry Adatte1, Peter Baumgartner1, Karl B. Föllmi1•
University of Lausanne1
01 Jan 2013-Sedimentology
TL;DR: In this article, the over 600m thick Ladinian carbonate section of Monte San Giorgio (World Heritage List, United Nations Educational, Scientific and Cultural Organization, Switzerland), including the San-Giorgio Dolomite and the Meride Limestone, was analysed with respect to its sedimentology, organic-matter content (Rock-Eval and palynofacies) and stable carbon and oxygen-isotope composition.
Abstract: The over 600 m thick Ladinian carbonate section of Monte San Giorgio (World Heritage List, United Nations Educational, Scientific and Cultural Organization, Switzerland), including the San Giorgio Dolomite and the Meride Limestone, was analysed with respect to its sedimentology, organic-matter content (Rock-Eval and palynofacies) and stable carbon and oxygen-isotope composition. Application of geochemical proxies and optical data (transmitted light microscopy, epifluorescence, cathodoluminescence and scanning electron microscopy) allowed the assessment of the relative sea-level trend and the characterization of the organic-matter content. Three main organic-matter assemblages were defined according to their composition and stratigraphic position. Overall, results suggest immature organic matter, predominantly of marine bacterial origin with an upsection-increasing land plant-derived contribution. Forcing factors controlling organic-matter accumulation include changes in sea-level, productivity and runoff which, in turn, were probably promoted by periods of rainfall following explosive volcanic activity. Enhanced productivity during sea-level highstands is considered to have played a key role in black-shale formation under anoxic–sulphidic conditions (mainly in the Besano Formation). In contrast, sea-level lowstands, coupled with intensified runoff, resulted in increased basin restriction and in deposition of laminated limestone, mainly under lower dysoxic to anoxic conditions (chiefly in the Lower Meride Limestone). Under the latter conditions, benthic microbial activity produced most of the hydrogen-rich organic matter, contributed to carbonate precipitation and also played a major role in taphonomic control on vertebrate fossil preservation. In more general terms, the Monte San Giorgio section proved to be an excellent testing ground, making it possible to compare diverse approaches with each other and, more specifically, to relate optical evidence to geochemical signatures.

18 citations

Cites background from "Co-occurrence of Neusticosaurus edw..."

  • ...It is, in particular, world-famous for the exceptionally well-preserved fossil fishes and marine reptiles (Rieber, 1973a; Kuhn-Schnyder, 1974; B€urgin et al., 1989; Sander, 1989; Furrer, 1995; Etter, 2002; Stockar, 2010; Stockar & Renesto, 2011)....

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  • ...Three intervals, mainly consisting of finely laminated limestone, yielded different vertebrate fossil assemblages (Peyer, 1931; Sander, 1989; Furrer, 1995; Stockar, 2010; Stockar & Renesto, 2011)....

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Journal Article•DOI•
A new basal actinopterygian fish from the Late Ladinian of Monte San Giorgio (Canton Ticino, Switzerland)

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Cristina Lombardo1•
University of Milan1
20 Nov 2013-Swiss Journal of Geosciences
TL;DR: The species is characterized by a single plate-like branchiostegal, a suboperculum larger than the operculum, a maxillary fixed and posteriorly expanded, a large and rectangular dermopterotic and a large triangular dermosphenotic.
Abstract: A new taxon of Late Ladinian basal actinopterygian is described on the basis of a single specimen from the Meride Limestone (Kalkschieferzone) of Meride (Canton Ticino, Switzerland). The species is characterized by a single plate-like branchiostegal, a suboperculum larger than the operculum, a maxillary fixed and posteriorly expanded, a large and rectangular dermopterotic and a large triangular dermosphenotic; the scales are rectangular to rhomboidal, the lepidotrichia of median fins are segmented from their base and the caudal fin shows epaxial rays. These features resemble the condition of the Redfieldiiformes, a freshwater fish group, whose presence in Europe is still controversial, owing to poor preservation of specimens found so far.

9 citations

Cites background from "Co-occurrence of Neusticosaurus edw..."

  • ...…the uppermost levels of Meride Limestone, the Kalkschieferzone (=KSZ), dating from the Late Ladinian, turned out to be very interesting for their faunal composition, and also for paleoenvironmental studies (Lombardo and Tintori 2002; Stockar 2010; Stockar and Renesto 2011; Stockar et al. 2012)....

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  • ...In particular, the uppermost levels of Meride Limestone, the Kalkschieferzone (=KSZ), dating from the Late Ladinian, turned out to be very interesting for their faunal composition, and also for paleoenvironmental studies (Lombardo and Tintori 2002; Stockar 2010; Stockar and Renesto 2011; Stockar et al. 2012)....

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References
More filters
Book•
Der Monte San Giorgio im Südtessin - vom Berg der Saurier zur Fossil-Lagerstätte internationaler Bedeutung

[...]

Heinz Furrer
01 Jan 2003

26 citations

"Co-occurrence of Neusticosaurus edw..." refers background in this paper

  • ...This preservation pattern is ascribed to the development of decay gas in the wide abdominal cavity which held the body with the ventral side upward (Furrer 2003)....

    [...]

Journal Article•DOI•
Paleontological paradigms and inferences of phylogenetic pattern; a case study

[...]

F. Robin O'Keefe1, P. Martin Sander2•
University of Chicago1, University of Bonn2
01 Oct 1999-Paleobiology
TL;DR: The phylogeny of a clade of pachypleurosaurs occurring in Triassic-age deposits in the Monte San Giorgio region, Switzerland is reconstructed, and the test case results for phylogeny reconstruction in general are discussed, with a call for pluralism in approach.
Abstract: In this paper we reconstruct the phylogeny of a clade of pachypleurosaurs (Reptilia: Sauropterygia) occurring in Triassic-age deposits in the Monte San Giorgio region, Switzerland. We also present the phylogeny of this clade as a case study for two paradigms of phylogeny re- construction: cladistics and phenetic/ stratigraphic methods. While this dichotomy is not held rig- idly by all workers, its advancement by cladists leads us to retain it initially for rhetorical purposes. We review the philosophical bases of species, species concepts, and speciation, as well as clado- grams and phylogenies, before introducing the experimental system. Data are presented from cladistic analyses, phenetic analyses, and stratigraphic information. Phylogeny of the clade is interpreted from both paradigms, and the interpretations are found to be inconsistent. Resolution of the phylogeny rests on the emphasis of one type of data over another. An interpretation of cladogenesis within the genus Neusticosaurus entails rejection of suggestive phenetic and stratigraphic data, whereas an anagenetic interpretation entails reversal of autapo- morphies in ancestral taxa. Anagenesis is deemed to be the more probable interpretation, based on the strength of the stratigraphic and phenetic data relative to the character data. Implications of the test case results for phylogeny reconstruction in general are discussed, ending with a call for pluralism in approach.

26 citations

"Co-occurrence of Neusticosaurus edw..." refers background or methods or result in this paper

  • ...…of N. edwardsii and N. peyeri in spatial and temporal distribution would refute the view of a single anagenetic lineage without a branching event separating the different Neusticosaurus species (O’Keefe and Sander 1999), since such a scenario would require a complete lack of species cooccurrence....

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  • ...Elsewhere, N. pusillus seems to have persisted virtually without morphological change throughout the late Ladinian in both the Alpine and Germanic Triassic (O’Keefe and Sander 1999; Rieppel 2000)....

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  • ...Pachypleurosaurid genera from China (Keichousaurus, Hanosaurus) are the sister-taxa of European pachypleurosaurids (Rieppel 1998, 2000, but Holmes et al. 2008 suggested that Keichousaurus is instead a basal nothosauroid); amongst the latter, the central European Muschelkalk (Germanic Triassic) pachypleurosaurids (Anarosaurus, Dactylosaurus) are the sister-taxa of those from the Alpine Triassic....

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  • ...…with an humerus/femur ratio of 1.13; but this specimen has been regarded as incorrectly classified by O’Keefe and Sander (1999, p. 510) and by O’Keefe et al. (1999, p. 528), since it does not possess the features characterizing the N. edwardsii population as a whole (O’Keefe and Sander 1999, fig....

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  • ...In the Germanic Triassic N. pusillus is the only diagnosable Neusticosaurus species (Rieppel and Hagdorn 1997) and occurs in the Hohenecker Limestone, a lateral equivalent of the ‘‘Lingula Beds’’ of the upper part of Lower Keuper....

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Journal Article•DOI•
On a Nothosaurian Reptile from the Trias of Lombardy, apparently referable to Lariosaurus.

[...]

G. A. Boulenger
01 Apr 1896-The Transactions of The Zoological Society of London

6 citations

Un pachipleurosauride sai livelli centrali del Calcare di Meride in Canton Ticino (Svizzera)

[...]

Silvio Claudio Renesto, M. Felber
01 Jan 2007

1 citations

"Co-occurrence of Neusticosaurus edw..." refers background in this paper

  • ...…evidence against this assumed sequential temporal appearance is provided by a specimen from the Upper Meride Limestone (likely late Ladinian in age), thus stratigraphically even younger than that described here, and ascribed to Neusticosaurus cf. N. peyeri (MUMSG 134; Renesto and Felber 2007)....

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Related Papers (5)
A new genus of shark from the Middle Triassic of Monte San Giorgio, Switzerland

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01 Jan 1982-Palaeontology
Olivier Rieppel
Clarazia and Hescheleria: A re-investigation of two problematical reptiles from the Middle Triassic of Monte San Giorgio (Switzerland)

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01 Jan 1987-Palaeontographica Abteilung A-palaozoologie-stratigraphie
O Rieppel
Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina beds (Meride Limestone, Monte San Giorgio, Switzerland)

[...]

28 May 2010-Swiss Journal of Geosciences
Rudolf Stockar
An exceptionally well-preserved scorpion from the Besano Formation (Monte San Giorgio, Middle Triassic, Southern Alps): preliminary study

[...]

01 Jan 2020
Marco Viaretti, Gabriele Bindellini, Cristiano Dal Sasso
A trigonotarbid arachnid from the upper carboniferous of the san giorgio basin, sardinia

[...]

31 Jul 2009-Rivista Italiana Di Paleontologia E Stratigrafia
Paul A. Selden, Gian Luigi Pillola
Frequently Asked Questions (15)
Q1. What are the contributions in "Co-occurrence of neusticosaurus edwardsii and n. peyeri (reptilia) in the lower meride limestone (middle triassic, monte san giorgio)" ?

In 2006, a new excavation in the Cassina beds of the Lower Meride Limestone ( Monte San Giorgio UNESCO World Heritage List, Canton Ticino, Switzerland ), has yielded a pachypleurosaurid ( Reptilia: Sauropterygia ) specimen which is identified as Neusticosaurus peyeri this paper. 

Five pairs of caudal ribs can be observed, slightly displaced from their corresponding vertebrae; they show a tapering distal end and their size decreases abruptly after the fourth one. 

The overlying Upper Meride Limestone is made up of alternating wellbedded limestones and marlstones with an increasing clay content towards the top, where strong seasonal variations of salinity and water level together with the influence from a neighbouring emerged area are documented. 

The chevrons of the third to the seventh/eighth caudal vertebrae are preserved; they are small elements, showing the distally expanded shape and rounded ventral margin which is typical of neusticosaurs. 

The first diversification of pachypleurosaurids in the western Tethyan realm followed the marine transgression that began in the late Early Triassic and proceeded from east to west across central Europe. 

The wedge-shaped skull with a waisted postorbitalregion which is shorter and wider than the antorbital region rules out N. pusillus, which has a narrow skull table with parallel margins (Carroll and Gaskill 1985; Sander 1989; Rieppel and Lin 1995; Rieppel 2000). 

The first 10 caudal vertebrae are also preserved in lateral view (Fig. 7); they show the rib articulations shifting gradually from the neural arch to the centrum, so that, from the fifth caudal vertebra on, the transverse process lies on the centrum only. 

They are short, stout and straight, converging on one point to meet the ilium, where they form a well-developed articular surface. 

The co-occurence of N. peyeri and N. edwardsii in the same levels implies that the two species indicate possible adaptations toward different size- and/or trophic-related niches rather than representing an anagenetic lineage. 

the third carpal in N. edwardsii is a tiny element so that its absence in MCSN 8076 could be due to either a preservation bias or a lack of ossification in case of its being a juvenile specimen. 

The Cassina beds are traditionally regarded as early Ladinian in age (e.g. Hellmann and Lippolt 1981; O’Keefe et al. 1999) but reliable index fossils such as ammonoids and conodonts have never been reported from this horizon. 

The palatines are thin and wide, and close the palate completely; they cover the bones of the skull roof, precluding the description of the latter. 

The femur/standard length ratio of MCSN 8076 is 1.01, well within the range of N. peyeri (0.78–1.06), while the range for N. edwardsii extends from 0.65 to 0.96, averaging 0.73 in juvenile specimens (specimen 3447 in Carroll and Gaskill 1985), therefore indicating a distinctly shorter femur than in MCSN 8076. 

According to their examination of the historical collection stored at the Paläontologisches Institut und Museum der Universität Zürich (PIMUZ) and to unpublished field data (both courtesy Heinz Furrer, PIMUZ), the bulk of Neusticosaurus material from the Cassina beds comes from just the base of the sequence, which lies approximately 2 m below the bed bearing the specimen described here. 

This preservation pattern is ascribed to the development of decay gas in the wide abdominal cavity which held the body with the ventral side upward (Furrer 2003).