The Cenomanian amber of Fourtou (Aude, Southern France)

15 Pages·2013·2.19 MB·English

by  Vincent Girard

Disponibleenlignesurwww.sciencedirect.com

AnnalesdePaléontologie99(2013)301–315

Originalarticle

The Cenomanian amber of Fourtou (Aude, Southern

France): Taphonomy and palaeoecological implications

L’ambre cénomanien de Fourtou (Aude, Sud de la France):

taphonomie et implications paléoécologiques

Vincent Girarda,∗,b, Gérard Bretonc, Vincent Perrichotc, Michel Bilotted,
Jean Le Loeuffe, André N elf, Mar c Philipp eg, Frédéri c Theve nardg

aCentredebio-archéologieetd’écologie,UMR5059CNRS,universitéMontpellier2/EPHE/INRAP,institutde

Botanique,163,rueAuguste-Broussonet,34090Montpellier,France
bUniversitémon tpell ier2 ,placeEugène-Bata illon,3 4095Montpe llier,France
cUMRCNRS6118Géos ciences,OS UR ,263 ,avenueduGénéra l-Lecle rc,35042Re nnescedex,France
dUniversité Toulou se3, géosciencese nvironn emen tToulou se, UMRCNRS/UPS 5563, 14,ave nueEd ouard-Belin,

31400Toulouse,France
eMuséedesdinosa ures,1126 0Espéraza,France
fUMR7205,CP50,entomolo gie, Muséumna tionald ’histoiren aturelle,75005Paris,France
gUMR5276LGL- TPE(l abo rato iredegéolog iedeLyo n-TerreP lanèteEnv ironneme nt)duC NRS, universitéLyon1,

DarwinA,campusdelaDoua,DarwinA,7,rueR.-Dubois,69622Villeurbannecedex,France

Received8April2013;accepted14June2013

Availableonline30August2013

Abstract
ThediscoveryofnewamberoutcropsinFranceinthelastfifteenyearsandthereinvestigationofoutcrops

thathadbeenforgottenprovidenewsourcesofpalaeontologicaldata.Oneoftheseforgottenlocalitiesisthe

CenomanianoutcropofFourtouintheAudedepartment,SouthernFrance.Mentionedinoldmanuscripts

since1700,perhapsknownandusedsincethePalaeolithic,theCenomanianamberofAudeisstillpoorly

studied.Herewepresentasynthesisofthedataobtainedonthisamber,focusingontheoutcropofFourtouthat

providedthelargestquantityofamberinthearea.SystematicandtaphonomyofFourtouamberinclusions

aredescribedanddiscussedinordertoproposeahypothesisabouttheenvironmentinwhichCenomanian

Fourtouamberwasproduced.

©2013ElsevierMassonSAS.Allrightsreserved.

Keywords: Amberfossils;Cretaceous;Palaeoenvironment;Resiniferousforest;Taphonomy

∗ Correspondingauthor.

E-mailaddress:[email protected](V.Girard).

0753-3969/$–seefrontmatter©2013ElsevierMassonSAS.Allrightsreserved.

http://dx.doi.org/10.1016/j.annpal.2013.06.002
302 V.Girardetal./AnnalesdePaléontologie99(2013)301–315

Résumé
Depuis une quinzaine d’années, de nouveaux gisements à ambre ou de gisements «oubliés» depuis

longtempsontété(re)découverts.Mentionnédansdesécritsdès1700,peutêtreconnuetutilisédepuisle

Paléolithique,l’ambrecénomaniendel’Aude(suddelaFrance)enestunbelexemple,toutparticulièrement

legisementdeFourtou.Danscetarticle,nousfaisonsunesynthèsedesdonnéesexistantessurl’ambredece

gisementjusqu’alorspeuétudié.LasystématiqueetlataphonomiedesinclusionsambrifèresdeFourtousont

présentéesetdiscutéesafindeproposerunehypothèsesurlemilieudeproductiondecetambrecénomanien.

©2013ElsevierMassonSAS.Tousdroitsréservés.

Motsclés: Crétacé;Forêtrésinifère;Fossilesdel’ambre;Paléoenvironnement;Taphonomie

1. Introduction

AmberiswidelypresentinFrance,especiallywithintheCretaceousdeposits,andnumerous

localitieswereknownassoonasinthe18thand19thcenturies.Mostofthesehistoricaloutcrops

havebeencompletelyforgotten.Re-developmentofamberstudiesinFrance,sincetheendofthe

20thcentury,allowedtheirrediscovery.Inthepresentpaper,wepresentoneofthem:theoutcrop

ofFourtou(Aude,SouthernFrance).

Audeamberisknownatleastsincethebeginningofthe18thcentury.Itismentioned,indeed,

ina“Mémoiresurl’ambrejaune”writtenbytheAcadémieRoyaledesSciencesin1705(Cassini,

1723;Anonymous,1730)that,inJanuary1701,thefamousastronomersJean-DominiqueCassini

(1625–1712)andhissonJacquesCassini(1677–1756),togetherwithMrMaraldi,discovereda

kindofyellowamberinajetmineclosetoamountaincalledBugarach.Thisreferenceconstitutes

the first report of the Aude amber and probably the first from Fourtou. Indeed the mine debris

of Fourtou, that contain the amber presented here, are located on the north side of the Mount

Bugarach. According to Cassini and Maraldi, the amber was at that time burnt with coal and

lignitic wood to serve as fuel by the local people and that the main activity of the mines was

theextractionofjet,locallyusedinmanufacturingjewellery(Anonymous,1730).InNovember

1739, the botanist Le Monnier joined the Jacques Cassini’s son, César-Franc¸ois Cassini, and

visitedagainwhathecalledthejetminenearBugarach(CassinideThury,1744).LeMonnier’s

descriptionofthemine(apileofcoalagainstahighrock)evokestheoutcropinFourtou,although

LeMonniersuspectedthatseveralotherminesexistedinthevicinity.Gensanne(1778)mentioned

thatjetextractionhadceased,andnomoreevokedtheuseofamber.Laterinthe1820s,somecoal

wasextractednearFourtoufromdifferentLateCretaceouslevelsbuttheseworkswereabandoned

in1830(Vène,1834).

Inthepresentarticle,wefocusonthelocalityofFourtouthatprovidedthegreatestquantityof

amber.InrealitythenameofFourtoucomesfromthenearesttownFourtoubuiltonaTuronian

basement,buttheso-calledamberoutcropofFourtouislocatedontheCenomanianpartofthe

Fourtou area, i.e. close to the Mont Burgarach. Historically, amber from this outcrop is called

Fourtouamber,butitmightbebettertocallitBugarachamber.Howevertoavoidanyconfusion

withpreviousstudies,wemaintainedthetermofFourtouamber.Herewepresentthedifferentdata

availableonthesedimentologyofthislocalityandontheamberinordertoproposeamodelof

reconstitutionoftheCenomanianamberforestofAude.Comparisonswithcoevalamberforests
V.Girardetal./AnnalesdePaléontologie99(2013)301–315 303

knowninSouthernFranceandNorthernSpainaremadetoreplaceAudeamberforestintothe

geographicalcontextoftheEuropeduringtheCenomanian.

2. Geologicalsetting

More recent studies on the Middle to Upper Cretaceous strata of the Corbières are those

of Bilotte (1985) (Fig. 1). Southward, deposits representing an “open basin” with planktonic

foraminifersarepreservedinthetectonicunitcalled“lamedeCamps-Peyrepertuse”.Thisunitis

overlappingnorthwardthedepositsofamiddletoinnerplatformmostlycomposedofterrigenous

and/orcarbonaceoussedimentsdatedfromtheCenomanianandtheTuronian.

During the Cenomanian, layers of lignitic clay with occasional amber progressively trans-

gressedontheemergedlandscape.AtFourtou,transgressiveontheAptian,ligniticclaywithamber

alternates with sandy limestones containing large foraminifers (Orbitolina concava Lamarck

1816,O.conicad’Archiac1837,Praealveolinacretacead’Archiac1835).TheendoftheCeno-

manianismarkedbymorecarbonaceousdepositsandbytheestablishmentofbioconstructions

withrudists(CaprinidaeandRadiolitidae)(Bilotte,1973).

Sénesse(1937)preciselymentionedFourtouamberintheMiddleCenomanianligniticclayof

Roque-Rouge(darkmarlswithamberonFig.1B).Bilotte(1973),studyingthesedimentological

andmicropalaeontologicalcontentsoftheCenomanianlayersoftheCorbières,alsomentioned

the presence of molluscs in the amber layers, indicating that the sedimentation took place in a

brackishenvironment.

Duringseveralfieldtripsin2000s,wefailedinlocatingtheinsitulayer;onlypickingintomine

debrisordumpswaspossible.Thesefieldtripsallowedthediscoveryofmillimetrictocentimetric

translucentamberpiecesofyellowtoredcolour,andtotallingabout2kg.

MinedumpsatFourtouarecomposedofclayswithplantdebris(wood,cuticles).Noshellor

vertebrate debris was found. Lithology and fossils from this mine debris, as well as data from

Sénesse(1937)andBilotte(1973,1985),argueforcoastalperhapslagoonaldeposits.

3. Materialandmethods

DataaboutthesedimentologicalcontextweremainlyobtainedduringfieldtripsmadebyM.B.

duringhisthesisandduringarecentfieldtripofG.B.,M.B.andDanielVizcaïno(Carcassonne)

(July2011).

SedimentwascollectedforbulkmacerationinH O andplantcuticlesisolated.Thesewere
2 2

treatedwiththeclassicalSchultze’smaceration.Abouttwentywoodsampleswerecollectedin

2003 by JLL and 2004 by MP, on two outcrops: Fourtou and Cubières-sur-Cinoble (Fig. 1A).

SortingunderthemicroscopeallowedustoselectfivespecimensfromFourtou(M.P.1468–1472

inPhilippe’scollection,Lyon1University)andonefromCubières(M.P.1473).Thesespecimens

werestudiedusingtwodifferent methods: razorbladethinsections andcasts.Specimens were

searchedforafreshfractureinradialplanor,intheabsenceofsuchasurface,gentlysplitwith
adisposa ble ra zorb lade.On th efract urep lan th ick Collodio n® (cel lu loseacet ate)wa sap plied

andallowedtodryforaday.Thecastwasthenstrippedoffandstudiedwithanormaltransmitted

lightmicroscope.

The greatest part of the amber samples was collected from mine debris in Fourtou during

one field trip by V.P., A.N. and a team of the MNHN in April 2004, and during two field trips

by V.G. in August 2005 and July 2006 (Fig. 2). The amber pieces were washed and a first

screening for arthropods made using a stereomicroscope. The pieces were then polished on a
3
0
4

V
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ira
rd
e
ta
l./A
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n
a
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e
P
a
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o
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to
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ie
9
9
(2
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5
Fig.1. SimplifiedgeologicalmapofAudeDepartment(A)andstratigraphiclogobservedatRoque-Rouge(B).1-LocalityofFourtou.2-LocalityofCubières-sur-Cinoble.

ModifiedfromBilotte(1989).

Cartegéologiquesimplifiéedudépartementdel’Aude(A)etcoupestratigraphiqueobservéeàRoque-Rouge(B).1-LocalisationdeFourtou.2-LocalisationdeCubières-sur-

Cinoble(d’aprèsBilotte,1989,modifié).
V.Girardetal./AnnalesdePaléontologie99(2013)301–315 305

Fig.2. MinedebrisofFourtouinwhichRomainLiard(Espérazadiggerteam2005)isseekingforamber(A).Thisamber

ismainlyofredcolourandcanbetranslucentortotallyopaque(B).

DéblaisdeminesdeFourtoudanslesquelsRomainMiard(équipedefouillesd’Espéraza2005)estentraindechercher

del’ambre(A).Cetambreestgénéralementdecouleurrouge,etpeutêtretranslucideoutotalementopaque(B).

grinder using different abrasive discs, and pieces containing arthropod inclusions were cut and

eitherincludedinCanadabalsamorfurtherpolishedforanoptimalexaminationofthespecimens

under a stereomicroscope. The microfossils were studied following the method described by

Girard et al. (2009b). Samples were first decontaminated using a three-step protocol (Girard

etal.,2009b):

• anultrasoniccleaning;
• an oxidation with9–10%H O and;
2 2
• an acidattac kwit h5%HF .

ThensmallfragmentsofamberweredetachedwithascalpelandmountedinCanadabalsam

on a slide. Preparations were then observed under a Leica DMLP microscope. Helicon Focus

software was used to combine photos of an inclusion at different foci, which facilitates better

illustration.
4. AmberandassociatedplantremainsfromFourtou

4.1. Plantremains

The fossil woods preserved in the middle Cenomanian mine debris of Fourtou correspond

to lignite. This is quite diagenetically evolved, with several pieces being jet-like. Some other

fragments are oxidised and looked like fusain, suggesting fossil charcoal. From a xylological

point of view the xyloflora of Fourtou is homogenous, the wood assemblage being entirely

composed of the conifer morphogenus Agathoxylon Hartig. Specimen M.P. 1471 (Fourtou)

andM.P.1473(Cubrières)canbeassignedmoreaccuratelytoAgathoxylongardoniense(Crié)

Philippe,afossilspeciescommonlyencounteredintheCenomanianofFrance(Néraudeauetal.,

2002).
Plant cuticles are abundant and well preserved, although only conifers were recog-

nised. Two fossil taxa are documented, Frenelopsis alata (K.Feistmantel) E.Knobloch

with its characteristic three-leaved whorls and Glenrosa sp., readily recognised by its
306 V.Girardetal./AnnalesdePaléontologie99(2013)301–315

deep stomatal crypts. The excellent preservation of cuticle evidences deposition in anoxic

environment.
4.2. Amber

Fourtou amber corresponds to irregular nodules that range from few millimetres to 4–5cm

in diameter. They are mostly red in colour (being more or less translucent in that case), more

rarelybrownandcompletelyopaque.Theseirregularnodulesoriginatedfromthefragmentation

ofbiggersamplesandonlyfewsampleshavekeptanoriginalsurface.Thelattercorrespondsto

adarkperipheralcortex.ComparativethermalanalysesondifferentCretaceousFrenchambers

byRagazzietal.(2009)showedthatFourtouamberhascharacteristicsofothermidCretaceous
◦
ambers,andthemaindifferentialthermogravimetricpeakat415 Cisconsistentwithamiddle

Cenomanian age. Ragazzi et al. (2009) also showed that Fourtou amber is characterised by a

high concentration of sulphur as compared to most of Cretaceous amber, a concentration they

interpretedastheresultofadiffusionoftheelementfromtheembeddingsedimentintotheresin.

It may indicate reductive conditions in the depositional environment. We cannot confirm this

hypothesissincenopyriteorsulphurmineralshavebeenfoundinFourtou.Anotherexplanation

canbethediffusionofsulphuricionintheamberforestsoil.Theresinaccumulatedonthesoil

beforeitstransportationbywateruntilthedepositionalenvironment.Sulphursareanimportant

componentinsoilandthustheirdiffusioncannotbetotallyexcluded.

The botanical origin of Fourtou amber is unclear yet, as only few data are available. FTIR

analyseshaveyetnotbeenperformedonFourtouamber.Thepresenceofthearaucaria-likewood

AgathoxylonandCheirolepidiaceousleave(mesorestsofFrenelopsisalatafoliageandputatively

Glenrosasp.)amongtheplantremainsassociatedwiththeambersuggeststheresinwasproduced

by conifers such as the Araucariaceae and/or the Cheirolepidiaceae. Palaeobotanical evidences

led to similar conclusion about the trees which were the probable sources of the Albian and

CenomanianamberfromthesurroundingareaslikeCharentesinFrance(Perrichotetal.,2010)

andBasque-CantabriainnorthernSpain(Pen˜alverandDelclòs,2010).

4.2.1. Microinclusions

4.2.1.1. Bacteria.

4.2.1.1.1. Rod-shaped bacteria. Colonies of rod-shape bacteria were observed in many
preparations (Fig.3A).Th ecolonies haveadiam et erof30–50 (cid:2)mand areco mposedo fco ccito
bacillieleme ntsof 0.5– 1.2(cid:2) m.

4.2.1.1.2. Actinobacteria. Dichotomously-branched actinobacteria. Colonies of

dichotomously-branched actinobacteria are present in Fourtou amber (Girard, 2010; Breton,
2012) (Fig. 3B). These colonies are 1 0–2 0(cid:2)m in di ameter a nd are compose d of r egularly
dichot omou slybr anched filaments (1(cid:2) mind iame ter ).Thesec oloni esa resimilarto th osefound

in Charentes amber (Girard et al., 2009c; Girard, 2010) even if their diameter is smaller than

thoseofCharentesamber.

Perpendicular-branchedactinobacteria.Extensivenetsofactinobacteriawereobservedinmany

preparations(Breton,2012)(Fig.3C).Theyhaveapproximatelythesamediameterthanthefirst

kindofactinobacteria,buttheyarecharacterisedbyanisotomousperpendicularbranching.Similar

actinobacteriawerereportedintheCharentesamber(Girardetal.,2009c;Girard,2010).Inthe

Fourtouamber,suchfilamentsaremostlylocatedatthesurfaceoftheambernoduleswherethey

formthincortex.
V.Girardetal./AnnalesdePaléontologie99(2013)301–315 307

Fig.3. RepresentativeBacteriainFourtouamber.A.Rodshapedbacteria.B.Dichotomously-branchedactinobacteria.

C.Perpendicularly-branchedactinobacteria.D.Twistedactinobacteria.E.cf.Leptotrichitesfilaments.F.cf.Sphaerotilus

filaments.
Inclusions de bactéries dans l’ambre de Fourtou. A.Bactéries en bâtonnets. B.Actinobactéries à subdivisions

dichotomiques. C.Actinobactéries à subdivisions perpendiculaires. D.Actinobactéries torsadées. E.cf. Leptotrichites

filamenteuses.F.cf.Sphaerotilusfilamenteuses.

Twistedactinobacteria.Thesefilamentshaveadiameterof1.0–1.3(cid:2)mandsomeofthemare

characterised by a twisted aspect (Breton, 2012) (Fig. 3D). They develop extensive net in the

ambersamples.Partofthesefilamentsisparalleltotheresinflow.Similarfilamentswerefound

intheCenomanianamberofSalignac(Alpes-de-Haute-Provence,SEFrance)(Girard,2010).

Sheathed Bacteria. Two kinds of sheathed filaments were identified in Fourtou amber. They

canoccurassyninclusionsinthesameamberpieces.
T hefir stk indofsheathe d bact eriais comp osedbyatrichomawithadiameterof0.9–1.4(cid:2)m
protect ed by a sh ea th 6–7(cid:2)m in diam e ter (Fig. 3 E). T he sheath gen er ally has a d usty asp ect.
Trichoma cel ls havea leng thc om prisedbe tween 1.5 and2 .0(cid:2)m. Thefilam ents d ichoto mously

branchatregularintervals.Itcanbefoundindarkareasattheperipheryofsomeredtranslucent
308 V.Girardetal./AnnalesdePaléontologie99(2013)301–315

amberpieces.Insuchpreservations,thefilamentshaveacentripetalgrowth(itmeansfromthe

outerpartoftheamberpiecetotheinnerpart).Thisorganismisalsopresentinopaquebrown

pieces in which the filaments entirely occupy the samples. It seems that these first sheathed

filamentsgrewintotheresinbeforeitssolidificationandwereprobablyresincolonisers.Morpho-

logically,thesefilamentsareverysimilartothoseoftwootherstaxadescribedfromCretaceous

ambers: the cyanobacterium Palaeocolteronema cenomanensis Breton and Tostain, 2005 was

described from Sarthe amber (France, Lower Cenomanian) (Breton and Tostain, 2005) and the

sheathedbacteriumLeptotrichitesresinatusSchmidt,2005inSchmidtandSchäfer,2005fromthe

CenomanianamberofSchliersee(Germany)(SchmidtandSchäfer,2005).Girardetal.(2009a)

performedmeasurementsofphycocyaninconcentrationspreservedintosheathedfilamentsfrom

diverseCretaceousambers.ConcerningFourtouamber,theyshowedthatthefirstkindofsheathed

filamentslackssuchbluepigments,indicatingthatitprobablybelongstothespeciesL.resinatus.

The second kind of sheathed filaments from Fourtou amber is less frequent (Girard, 2010;

Breton,2012)(Fig.3F).Itisalwaysfoundattheperipheryoftheredtranslucentamberpiecesof

Fourtouinwhichtheyformathincortex.Sometimesthesesheathedfilamentsofthesecondtype
aremixe d withth oseo fL.r es inat us.The yarecompo sedo fatracho ma,0.9–1 .1 (cid:2)m indiam eter
(sli ghtlys malle rthan th ose ofL.resi natus) ,pr otectedby ab ro wnandsm oothsh eath ,6 –7(cid:2)min
diameter . Tricho ma c ells ar e 1 .5 to 1.7(cid:2)m in length. Th e filame nts, centripe tally or iente d, a re

rarely branched and their diameter is more or less constant all along the filaments, excepted at
theirt ipswhere thefi lame ntsbecom e inflate da ndr ounded( the diame teri ncreaseto 10–12(cid:2)m ).

Measurementsofphycocyaninconcentrationsofthecortexcomposedbythesesheathedfilaments

showthattheyalsocorrespondtosheathedbacteriaandnottocyanobacteria.Theroundedends

ofthefilamentsindicatethattheyprobablybelongtothegenusSphaerotilusKützing,1833.

4.2.1.2. Fungi. Inagroupofellipticalfungalsporeswerefound(Fig.4A).Theyhavealength
of 5.7 t o 7.2(cid:2)m a nd a wid th of 4.4 to 5.7(cid:2)m . No o rnam entatio n or a pertu re wa s obs er ved at

their surface. They are associated with decomposed organic matter, probable plant remains on

whichthefungusgrew.Absenceofmyceliummakesthepreciseidentificationofthefungalspores

difficult.ThustheyareherereportedasFungiindet.

4.2.2. Macroinclusions

4.2.2.1. Arthropods. Arthropodinclusionsarefairlyinfrequent,withonly35specimensfound

amongca.2kgofambercollectedtodate(Fig.4B–D).Yettheycomposearatherdiverseassem-

blage of insects, arachnids, myriapods, and crustaceans. Six of them were too partial or too

degradedtobeofsystematicallyassigned.Surprisingly,themostabundantorderisnottheDiptera

as in many amber deposits, but, it is the Hymenoptera, which account for 17% of all observed

arthropods.Allareparasiticwasps,andScelionidaearecommon(Fig.4B)asinallotherCreta-

ceousambers.Asinglechalcidoidwasfound,whichisheretentativelyassignedintheEupelmidae

beforeamorethoroughstudy.Twospecimensbelongtoextinctsubfamiliesofwasps:oneinthe
Falsifo rm icida e(Fig.4C )1and the otheronein anund et ermined ceraphrono id family with cl ose

affinitiestotheStigmaphronidae.Diptera,andHemipteraareeachrepresentedbythreespecimens

each,mostofwhicharetoofragmentaryortoopoorlypreservedforapreciseassignmenttoany

family. The only identifiable dipteran is a Chironomidae, the two other ones are undetermined

1 Perrichot,V.,Engel,M.S.,Nel,A.,Ortega-Blanco,J.,Delclòs,X.,Soriano,C.,Tafforeau,P.,(InPrep).Insearchof

antancestors:rulingouttheFalsiformicidae(Hymenoptera:Chrysidoidea).SystematicEntomology.
V.Girardetal./AnnalesdePaléontologie99(2013)301–315 309

Fig.4. Representativeeukaryotesandprotist-likeinclusionsinFourtouamber.A.Fungalspores.B.Onespecimenofthe

extinct,CretaceouswaspfamilyFalsiformicidae(coll.MNHNno.F.A33607).C.Onespecimenofthecommonlivingwasp

familyScelionidae(coll.Univ.Rennes1no.IGR.FOU-10.2).D.LarvaofanundeterminedColeopteraorNeuropteroidea

(Morelcoll.no.IGR.FOU-106).E.Firstkindofprotist-likeinclusions.F.Secondkindofprotist-likeinclusions.

Inclusionsd’eucaryotesetdeprotistessupposésdansl’ambredeFourtou.A.Sporesdechampignons.B.Spécimende
lafamille crétacée(étei nte )d esguêpe sFalsiform icida e(coll. MN HNnoF. A3 3607). C. Spécimendela fa mille,viva nt
en coreau jourd’hui ,desguê pesS celioni dae(coll.Univ.R enne s1noIG R.FOU-10.2). D. Larved’u nc olé optèreo uneu-
roptéro ïdeindéterm iné( Morelc oll.noIGR.F OU-1 06).E .Premi er typed’inclusionra ppo rtéeà des protistes.F .Se cond

typed’inclusionrapportéeàdesprotistes.

brachyceranremains.Otheridentifiedinsectordersareeachrepresentedbyasingleoracoupleof

specimens. These include one thorny lacewing (Neuroptera: Rhachiberothidae), a neuropteroid

orcoleopteranlarva(Fig.4D),twobarklice(Psocoptera),andremainsoftwocockroaches(Blat-

taria).Otherarthropodsfoundinthisamberaretwomites(Acari)andonespider(Araneae)ofthe

arachnids, and one synxenid millipede (Diplopoda: Polyxenida). Finally five crustaceans were

discovered,whichbelongtotheaquaticTanaidacea,anorderwhosemostlivingrepresentatives

aremarine,whilesomeothersarefoundinfreshwatercoastalhabitatorestuaries.Thefossilrecord
310 V.Girardetal./AnnalesdePaléontologie99(2013)301–315

oftanaidsisexcessivelymeagre,withnomorethan15speciesknownbetweentheCarboniferous

andtheCretaceous.Withinamber,theywerementionedpreviouslyonlyfromtheCretaceousof

Spain(VonkandSchram,2007)andsouthwesternFrance(Perrichotetal.,2010).Theirpresence

inamberisindicativeofacoastalhabitatfortheresin-producingforest.

Finally arthropods are also recorded in Fourtou amber through their traces, in the form of

coprolites(Breton,2012).Unfortunatelynoplantorfungalremainscomposethesecoprolitesand

theydonotexhibitanycharacteristicshape,thusitisnotpossibletoassignthemtoanygroupof

arthropodsasforsomeothercoprolitesinCretaceousamber(Schmidtetal.,2010;Colinetal.,

2011).
4.2.2.2. Plantsremains. Plantsremainsareratherabundantinclusionsinamber,presentinmany

pieces.Mostofthemcorrespondtowoodfibresortostellatehairs.Otherremainsarescantand

toopoorlypreservedforaprecisedetermination.

4.3. Protist-likeinclusions

Fourtouambercontainsmanyprotist-likeinclusions(sensuGirardetal.,2011)thataremostly

oftwokinds.Oneformrepresentsdarkredsphericalinclusionssometimeswithadistinctorien-

tationintheresinflow(Fig.4E).Theirshaperecallsthoseofsomeunicellularorganismssuch

as the Arcellinida. However, no surface ornamentation was observed and the variation of size
(fr om a few (cid:2)m to more tha n 1 00(cid:2)m i n diameter) is too i mportant to re liab ly attribut e t hese

inclusionstomicroorganisms.Thesecondkindofprotist-likeinclusionsareelongatedinclusions

ofreddishtobrowncolour(Fig.4F).Theyarealwaysorientedintheresinflowandmanyofthem

arecharacterisedbytwomoreorlesslongandpointedendings.Asforthefirstkindofprotist-like

inclusions,theirsizevariesalot,beingcomprisedofbetweenadozensofmicrometersinlength

toseveralhundredsmicrometers.

Itispossiblethattheprotist-likeinclusionsareartefactsthatresembleprotists.Itcouldbea

substanceproducedatthesametimethantheresinoraproductofitspolymerisation.

5. TheCenomanianamberforestofAude

5.1. Botanicaloriginoftheamber

The botanical origin of Fourtou amber is unclear yet, as only few data are available. FTIR

analyseshaveyetnotbeenperformedonFourtouamber.Plantremainsassociatedtotheamber

allowhypothesisingthatFourtouamberwasproducedbyconifers.CenomanianamberinFrance

(such as this of Archingeay-les Nouillers, Fouras, etc.) is always found associated to the fossil

wood Agathoxylon (Néraudeau et al., 2002, 2003, 2005, 2008, 2009), an araucaria-like wood,

and often exclusively to this wood genus. It is often assumed that, at least by the Late Creta-

ceous, in Europe, Agathoxylon can be safely assigned to the Araucariaceae, an extant conifer

family. This family is reported from the Cretaceous, e.g. in northern Spain (Barale, 1992) and

south-eastern France (Onoratini et al., 2009). Leafy plant remains reported here from Fourtou

Cenomanianlevels,belongtotheCheirolepidiaceae(FrenelopsisandGlenrosaalso).Although

thewoodofCheirolepidiaceaeisoftensupposedtofitwithinthemorphogenusProtocupressinoxy-

lon Eckhold, a taxonomically poorly circumscribed genus, or Brachyoxylon Hollick et Jeffrey,

thewoodofGlenrosaisnotyetknown,whereasthatofFrenelopsiswasreportedinoneunique

case(Doludenkoetal.,1992).InthisLateAlbianUkrainianspecimenofFrenelopsiskaneviensis