New adventures for the Association Paleorhodania. Prospection in new outcrops
in the "réserve géologique de Haute Provence" is promising.
Stay tuned for updates! (see also our Press section)
our team of twenty people, including ourselves (Jérémy Martin,
Guillaume Suan, Peggy Vincent, Baptiste
Rulleau and Kévin Janneau),
assisted by volunteering students and researchers from four different
Slovakia, Great Britain and France) and with
financial and logistical support
from Le Musée des Confluences and Lafarge, achieved a new
palaeontological excavation from the 2nd of July to the 14th July
Example of a carbonate nodule matching the shape of the nucleus, in
that case an ammonite. Serpentinum
zone (lower Toarcian).
This campaign was successful with the discovery of many plant
fossils, invertebrates and vertebrates. The fossils are sometime found
in soft rocks such as clay and are easy to extract from the matrix.
This is the case for sea urchins and plants found this year. For some
other volunteers, the work becomes extremely laborious!
when excavating nodules.
Figure 2 : Kristjan (left) and
Martin posing in front of their discovery.
Indeed, these highly indurated concretions are very massive and
can weigh up to several hundred pounds. Theses nodules are nevertheless
known to harbor fossils preserved in three dimensions (Figure 1). Among the discovered nodules, a nodule
of large size (>1m in diameter; Figure
2) has delivered the most significant discovery of the year
mechanical fracturation, it has indeed revealed a series of connected
vertebrae with an excellent preservation, which shape is typical of
the compact axial skeleton of ichthyosaurs (Figure 3).
These vertebrae are associated with a series of ventral and dorsal ribs
visible in cross section and arranged in a subcircular fashion,
surrounding a 'Beaujolais-coloured' staining (Figure 4). Blocks associated with the same nodule
also consist of a series of fully articulated vertebral elements (Figure 5).
|Figure 3 : Fragment of the large
nodule from the serpentinum
zone exposing a series of vertebrae (arrows) and ribs in anatomical
|Figure 4 :
Fragment of a large nodule from the serpentinum
zone exposing a portion
of the rib cage in section. Observe the subcircular arrangement of
ventral and dorsal ribs (arrows).
in-situ thorough cleaning of one of the surface of the large block then
revealed the anterior end of the skull (rostrum), aligned in the axis
of the vertebrae (Figure 6A) as
well as part of the swimming paddle (Figure
The natural cut at the end of the rostrum shows that it is preserved in
dental occlusion, the teeth of the upper jaw fitting in the lower jaw (Figure 6B).
The state of preservation of cranial and post-cranials elements (ribs,
phalanges) and their configuration and alignment indicate very limited
postmortem displacement. In addition, the subcircular arrangment of the
ribs indicates that the specimen has not been flattened and retains its
original proportions in three dimensions, in contrast to the vast
majority of ichthyosaur specimens known throughout the world.
Figure 5 : Block associated with the large nodule from the serpentinum and presenting a series
of vertebral apophysesin anatomical connection.
Finally, the peculiar 'Beaujolais' staining visible in the
rib cage might correspond to traces of soft parts (organs?) or stomach
contents (Figure 4). The
limestone nodule discovered therefore contains a truly exceptional and
complete ichthyosaur specimen in anatomical connection and preserved in
three dimensions !
Figure 6 : A: Overview of the large
nodule from the serpentinum
area; B: tip of the rostrum showing teeth in section
(arrows) and preserving their pattern of occlusion; C: Paddle; D:
Series of vertebrae in anatomical connection at the edge of the nodule.
The proud owner of this
ichthyosaur is the Musée des Confluences in Lyon, which finances our
field work since 2009. This remarkable discovery has not yet revealed
all of its secrets. Indeed, several months of work will now be required
to prepare the ichthyosaur specimen. This work should be done by a
professional in order to avoid damage to the bones and to the possibly
exceptionally preserved soft parts! The scientific study, would
therefore begin after this work and will better characterise the
palaeobiology and palaeoecology of these animals in response to climate
change that affected this key Jurassic interval.
The 2011 excavations took place from July the 10th to the 22nd. This
year, the Paleorhodania team welcomed twenty volunteers as well as some
of the faithful memebers of the section Geo-Paleo. A preliminary
surface stripping was carried out by heavy machinery from Lafarge and
made more than 200m² available for excavation.
The discovery and the study of invertebrates
from several key intervals (eg. tenuicostatum
zone, falciferum subzone,
variabilis zone) complete the
significantly complete the biochronostratigraphic setting. These
findings show that all the ammonite zones of the Toarcian are
represented in the quarry, making the site one of the most complete
Toarcian deposits known in France and Europe. Vertebrate remains,
particularly interesting from the point of view of their stratigraphic
position, have been found this year in the levels of the Toarcian (tenuicostratum
zone) and those of the Aalenian. These new remains, although mainly
consisting of isolated fragments do complement our understanding of the
evolution of faunas during the transition at the Lower and Middle
Jurassic. The discovery of many well-preserved remains in Aalenian
levels, which usually yield very little vertebrates invite for a
systematic prospection in future campaigns. the investigations of large
excavated areas of in the upper half of the serpentinum
zone has not yielded any discovery of macrovertebrate remains this
year, but nevertheless provides many belemnites and ammonites valuable
for geochemical and biostratigraphic studies. A particularly
interesting result of this campaign is the precise dating of the
interval with many large nodules at the base of the studied series (serpentinum
zone). These ages indicate that indeed these correspond to the lateral
equivalents of nodules producing an extremely abundant and well
preserved vertebrate fauna in contemporary deposits. In addition,
surface surveys have confirmed the extreme wealth for level BB1,
probably related to the fact that this level represent the highest
stratigraphic surface exposed in the quarry. In this context, it
appears highly desirable to continue and expand our strategy of
investigation for very large surfaces in the lowermost levels of the
quarry. le cadre biochronostratigraphique de la
succession de manière significative. Ces découvertes montrent que
The new sedimentological samples and descriptions will permit to study
the relationship between high resolution sea temperatures, storm events
and sea level at a time of climate change at the base of the Toarcian.
Changes in physical parameters of the environment will also be studied
in detail for the Middle Toarcian interval thanks to the the sampling
of many belemnites. The new observations confirm that this year, the
site offers an original succession in several respects: the black
shales and limestones of the serpentinum
zone present a dramatic differential weathering, which had not
previously been documented else- where; all Toarcian ammonite zones are
represented, suggesting that sedimentation was continuous in spite of a
relatively slow accumulation rate of sedimentation characterizing the
series; the lower Toarcian records heavy storm deposits, particularly
suitable for studying response of shallow marine environments to
environmental perturbations of the lower-middle Jurassic transition. In
addition, the depositional conditions are particularly favorable to
concentration and rapid burial of remains of articulated organisms and
encourage continued palaeontological research efforts.
This mission confirmed the potential
of the site and the presence of vertebrates at several levels. This
year, the levels of the Toarcian yielded cranial remains of an
ichthyosaur apparently belonging to a single specimen. These remains
must be prepared with extreme care before a detailed study can be
achieved. The good preservation of the specimen and the mode of
deposition of the sediment (a tempestite) suggest a strong
fossiliferous potential in these levels for future campaigns. The
discovery of cranial and postcranial remains of marine crocodilians in
marls of the base of the bifrons zone confirms the presence of this
group in the Middle Toarcian levels.
The discovery and study of invertebrate specimens from several key
intervals (eg. Aalenian) significantly helped in refining the
biochronostratigraphic framework of the succession. This framework will
be essential for future paleo- environmental reconstructions. The
relatively low number of discoveries in comparison with the excavations
of 2009 is partly due to the different methodological approaches used
in the two campaigns, as well as the nature of the levels explored: the
prospective campaign of 2009 was conducted on a larger number of levels
including levles of 'bonebeds'. These levels correspond to deposit
formed by concentration and producing accordingly a large number of
isolated remains (mainly teeth). However, specimens discovered this
year are particularly interesting from the point of view of
paleodiversity. Indeed, taxa whose presence was not documented on the
site or in certain levels in 2009 have been unearthed this year. These
findings will help to better understand the evolution of marine reptile
diversity at the end of the Jurassic.
The purpose of this mission was
prospective: identify the scientifically interesting levels in the
Toarcian deposits of the Lafarge quarry in Belmont. This mission of
reconnaissance focused on two types of approaches, first on the
stratigraphic framework then on the investigation of the
The purpose of the
palaeontological mission, coordinated by J.E. Martin, A. Lena and P.
Vincent, was to harvest new data, mainly on vertebrate faunas of the
Toarcian. One underlying question: whether a prospective short-term
excavation carried out by a small team would be fruitful or not. It
also appeared necessary to target levels rich in vertebrate remains and
establish a preliminary compilation of vertebrates collected in these
levels. These data can be compared with faunal lists already
established in Germany and in England for the Toarcian.
stratigraphic study, coordinated by G. Suan and B. Suchéras-Marx, was
centered on Lower and Middle Toarcian strata in order to detail the
stratigraphy of the site. The sedimentary contexts for the Toarcian and
the Pliensbachian are still largely enigmatic. The mission also aimed
to uncover the Pliensbachian-Toarcian boundary who does not naturally
crop out in the quarry so as to identify changes in depositionnal
environments throughout the Toarcian. This approach fits with a wealth
of sedimentological studies during oceanic anoxic events of the
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