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Terrain 2012
Lien Terrain 2011
Lien Terrain 2010
Lien Terrain 2009


2015


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)

Vue Terrain 2015
 

2012 


This year, our team of twenty people, including ourselves (Jérémy Martin, Guillaume Suan, Peggy Vincent, Baptiste Suchéras-Marx, Louis Rulleau and Kévin Janneau), assisted by volunteering students and researchers from four different countries (Estonia,
Terrain Figure 1
Figure 1 : Example of a carbonate nodule matching the shape of the nucleus, in that case an ammonite. Serpentinum zone (lower Toarcian).
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 2012.

  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! 
... especially when excavating nodules.  


Terrain Figure 2
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 2012. Under 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 connection.               Terrain Figure 3
Terrain Figure 4Figure 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).

Terrain Figure 5
Figure 5 :
Block associated with the large nodule from the serpentinum and presenting a series of vertebral apophysesin anatomical connection.

  The 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 6C). 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.
   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.
Terrain Figure 6

  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.
Terrain Groupe 2012
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2011



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.

Terrain Groupe 2011  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 toutes

Terrain 2011
  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.
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2010


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.

Terrain Groupe 2010  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.
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2009


    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 palaeontological content.

Terrain 2009 bandeau

   
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.
Terrain 2009
  The 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 Toarcian.



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