Bollenino delh Societh Paleontologica ltaliana 43(3),2004 rssN0375-7633 36r-382 2 pls. Modena,Dicembre 2004

Eoderoceratidae(Mollusca, Ammonoidea) from tht Central Apennines, related to the Sinemurian-Plier the Mediterranean area

Federico VExruRI Carlo NnNNARoNE Massimiliano BIlor Dipartimento di Scienze dellaTerra Universitl di Perugia

KEY IVORD S - Mo lluscA, Ammono idea, Eoderoceratidae, S in emurian- P liens b ac h ian boui "Corniola" ABSTMCT - TheJurassic calcareous successions of the unit in the lJmbria- known bedsreferable to ti, lower Pliensbachianof the eitire MeditercaneanTbthys. These beds in this aret ofrht global faunal renewalarsociated"*;ttt the Sinemtrian-Pliensbatbia, transition. afrer the disippeirarcebf fch;oceratidae(as Paltechioceras/, and, in theApennines, it consistso. (mall, t*ooltl, Polymorihitidae, lacking a keel), Catriceras (primitiae anl morphologicallyqui, ukn keeledand ti;rttttl, Galaticeras(*att-otturrence), Radstockiceras. This bioeu/ntis-afcon i.t. b the moreo, lessclo,mplete loss of the ornumentation,u,ith the transition.fom b;spiyqyg,1 (( 'Quorry'DresentDaDer deak taith the Eoderoceiatidaefound in the rich fossiliferousbed-"Wnturi'78" (i4ount a iubstantial ,rrt*iftoipared to undoubtedlySinez Acuto), uthich represents 'Teffaspidoce-rai io"ti Oeconsidered the frst afiei-Sinemurianrecord (beginni"s ofrhe quadr All the taxa reDresentedin our collection(67 speii*"rrr, lnThidlns someforms lefr wiihout ious morphological'andstuctural (namelysutural)'features, and tbeffire wi think ihat theym, subfam ' ily, th it we called Parami ro derocerati n ae. Foi our specimenswe recognizedfourspecies, onb oneof -proposed u,hich.(Paramicroderoceras tf \itf The remainiiq threes\ecies arl ;nclidcd in two new, here {enera: Omode roceris (wh well as O. cfTarinodosum,which is aform comparableilth'a ta*in preuiouslyassigned toEpi new speciesP. picenum/. Tht orrttntt of an inner monos\inateDhase ofdeueloDment in the netil{enus Omoderocera the sooliation of thi Eodzroceratoidiawas i ,omn[expanirn, includins a paidomorphic transitio onri (this mon'ospinatecharacter is well establiihedin Caleites,Milt"oc.r"r and to*t yet unde: lnte Sinemurian',this uariation was mainly a peramorphosis,simply occurring with thi change1 smoothouter whorls (this is,for example,iht tatt ofBpiderocetis). The GSSPof the Sinemurian-Pliensbachianboundary proposed for the Wine Hauen sectit uidesa good refeiencefor Borealand Sub-borealregions (Nort[-Wesi Europe),but not for the etc.). Hoere,in"fact, thi stardard biosnatigraphicciteria that characterizeihe beginnini of tbe r ed'in the staioty7e with Bifericerasdon?vini, and/or presenceofTevaspidoceias qu-adtat-" the Sinemurianl?liensbachianboundary cannot be ideittified wiih precisionand, in- the bestca sectionsfor the earlyPliensbachian lacki reliabilitv and resolutionbeyond the Subzonescale. Sinc u.,ithaiceotabte cohfrdence the exDectedcorrekti'o, potrrtial outsirt the Boreal domain, d st/d.t, am basel on the tintrt knowledse,misht hauea ialaeogeographicualue limited merelyto that Tatifcition of thi aboui-*"triioned GSSPmight not {rttorytt. ,As a .matte,tft* 1 fornially Pliensbachianin the entire Tbthys. The difficulties in establishinqcareful correktions betweenBoreal and MeditennneAnZone by a numb"i of pakeobiogeograpE;toid/or pakeoecologicfactors. T'hismust induce the researc siudies,apeciilfy in the frthyai domain, wltere,exceptln-the Apenninel the recordfor thefirsr "Corniola" RIASSUNTO- [Gli Eoderoceratidae(Mollusca, Ammonoidea) nella dell'A Pliensbachianoin areamediterranea] - L,esuccessioni calcaree giurassiche aPPartenenti alk contenaonodei liuelli riferibiti at Plieisbachianoinferiore che tori probabilmiite i piil antichi ,o datTimportanti per?elinearein quest'areAil rinnouamentofaunisticoglobnle assiciato al pal ad ammoiit; qutti cambiamentoiuuiene dopok scompArsA.ZrSljEchif,ceratidae (come Paftec me di ,o*pirrc concomitanti: Furlites (piccoli Polymorphiti"daelisci e senzt care.nA,che (Tropidoceitinaeprimitiui, morfologicamenteassai airiabil;, ry(.pilt o menoeuoluti, lenticolat sa ii massa),Raditockiceras. ntt b"ioeuentob accompagnato dalli spoliazionedegli "ll Eoderocera dell'ornamentazione,con passagio da bispinateZ *onrspinite o spoliate. presentelau, 'Vnturi'78"forme uati nel riccoliuello fossilifero (bioeuentoa CatriCerascatriense) della Cat,adel [' sostanziileriipetto a indubitabilmentesinemuriane, ed anche questodot' nouamento faune 'Tetraspidoceras ") Per 'post-Sinemuriana (inizio'della Zoro o quadrarmatum dell'Appeinino. ':#",::,::;::::,:*:i'*;n'f';:;*::##'x!;,':t';i"l:;":;:;;:,'::,;:"i,:,:::,ii,,tti;i,'iti"l:,,ii),Tutti itaxa rappresentatinel nosto mateiiok (67 esinplari. cotnpresealc,tii lbrme ilon r't 362 F. VENTUN, C. NANNARONE, M. BILOTT,

Per i nosni esempkri abbiamo riconosciutoquatto specie,di cui solo una (Paramicroder generi p 'prrnd"'kaeneresih noto. Le ristanti ne sDeciesono state iicluse in'due nuoai, di cui uieneaui nuoaaspecie O. canti"n.rrr. ed ancheO. cf larinoJot.t-, cioi una forma confroit Epideroceras)' e Paraderoceras(istituito per k nuoat specieP. picenum/. LA presenz,adi uno stadio interno monospinatonel nuouo'gene.reOmoderoceras testimont ore, k sioliazione degli Eoderoceratoideai auuenuta con un passagtopedomorfico da giri intern si ? ooi'affermatoine"leiter, Miltoceras ed alcuni taxa mediterdnei-ancorA ineditil.-Nel Siner, di iioo' iira*orfico, com\ortundosokmente un transizioneda giri interni e medi bispinati a lisc If GSSPlet limite'Sinemuriano-PliensbachianoDroposto"per k sezionedi Vine Hauen (k un buon riferimento per le regioni borealie sub-bortafi Guropi Nord-occifuntale),tnd non per q ecc.),doui i principi biosnaiigrafici standard checaratterizzano l'inizio del Lias medio (pVagit Bifericeras donovani, e/o lreienza di Tetraspidocerasquadrarmatum,) -e, non sono appliu Pliensbachianonon pub tttirt indiuidunto con'precision€, nelk migliore delle ipotesi,'k , Pliensbachianoinferiore perdcaffi.dabitith e risofuzioneoltre il liuello di"Sonozona.PoichC k set accettabilesicureiza il [ouuto iitenziate di correlazioneal di fuori del dominio boreale,uno str basatosulle conuscenzeattualt potrebbeauere un ualorepaleogeografico esclusiaamente limitato co troppo ristetto. Di fono, s;e'siratificasse it GSSPin' quesTioir,"sipotebbe impedireforma, Ptienihachiano nell' iniera Tbtifu Le difficohh incontratenel correkreAccurAtamente le Zone borealie mediterraneeper il Plie ad un inslbmedi fanori paleobiogeograficie/o paleoecologici: questo deue spingere lz ricerchea n mentenel dominio teti/eo, doue,Zfoit l'Apfennino, li docimentaz;oni delk prima Zona del

FORE\TORD Mount Pietralata o The. present work fits into the researcheson that oyr car- ammonite biostratigraphy ?gp?ttment ries out since many years in the Umbria-Marche Apennines. Here , the calcareous-marly successioni beloneine to the lithostratisraphic units of Corniola, MarnE aJt Vt. Serrone and"RossoAmmonitico yield- ed an impressive documentation for the Lias, starting from th; early Sinemurian (Guide GeologichE Regionali no 7, 1994) as far as the entire Toarcian (Venturi, 1999). Nevertheless, there are many issues left to investigate, both for the biostratigraphy and for the underitanding of the evolutive relationships between the main s/stematic groups (superfamili-es and families), also in relation to-the vicissitudesof the palaeogeoqr.aphigdomains. r, . From this -ispoint of view, one of the most interest- i.g bioevents represented by the fossiliferous bed "%ntu ri'78" from the the Paliareto Qu arry (Mount Acuto, Umbria-Marche Apennines; Text-fig. l), char- BOSSO acterised by a very rich faunal content (Venturi, 1978; Venturi & Bilotta, 2001). Its chronostrati- graphic position h."r.been the object of contrasting lnterpretauons: ongrnally,-bioevent this b6d, also known as Catriceras catrieme (Faraoni et dl., 1996; Dommergues et Al., 1997a), was attributed to the late Lotharinfian -early Carixian (Venturi, 1978), but subsequ.it Authors erroneously placed it in the mid- dle Pliensbachian (Ibex Zonel Valdani Subzone: Dommergues et dl., 1984; Dommergues et dl., 1997a). It has been proved (Venturi & Bilotta, 2001) precedes that this bioevent the Miltoceras sellae beds, Mount Acuto and therefore thaf it cannot pertain to the middle Pliensbachian,but the issueof its precisedating was, A by now, never completely resolved. According to the results of recent studies (Faraoni et Al., 1996; Venturi & Bilotta, 2001) and current researches(includitg - Pallareto,Bosso and "Venturi '78" Text-fig. I Geographic location of the the present work), the bed contains a Furlo sections. LUSSrc EODEROCERATIDAEAMMONITES FROM THE APENNINES 363

fauna characterizedby numerous GalaticerasSpath Tbtraspi do c eras q uadrarmatum ( D umo rtier) ( Schlaff er, and many til(a referableto the Eoderoceratoidea, 1977, 1980; Dommergues 6c Meister, 1992; includitg- the first Thopidoceratinae(CatricerAs Dommergues et al., 1994b, 1997a; Hesselbo et Al., Venturi) and smooth Polymorphitidae (Furlites 2000; Meister et aL.,2003). This definition allows to Venturi & Ferri).This representsa substantialrenew- identify the Thylori Subzone throughout North- - 'Western al compared to the undoubtedly Sinemurian Europe, but in most cases its base can be Echioceratidaeassemblages. Since, historically, the only tentaiively determined with some Sinemurian-Pliensbachiatbound ary correspondsfor Eoderoceratoidearequiritg further studies (Hesselbo the ammonites to a qlobal-scalefaunal renewal, et al., 2000; Meister et aL.,2003). marked by the Echioceritidaedisappearance _and by The biostradgraphic relations with the Tethyan the subsequent Eoderoceratoideadiversification area are even -5r.'difficult to precise, because the (Dommergues& Meister,1992; Dommergues et Al., essentially Boreal tilra on which is founded the stan- 1996; Merister& Stampfli, 2000; Meister et dl., dard zonation are lacking, or very rare, or do not "Venturi'78" 2003),we assumethat the bed should allow sufficient accuracy.Tb obviat6 this matter, alter- be consideredthe first after-Sinemurianfossil record native zonations were elaborated (fot instance Braga in the Apennines. et al., 1984; Faraoni et Al., 1996), but their correla- Amohg the many forms pointing out the essential tions with the North-'Western Europe scheme are sdll "'Venturit78", novelryof,the bed thire arethe spined considered tentative (Dommergues et dl,, 1983; ammoniteswhich we believeto constitutea new sub- Meister, 1995; Dommergues et /tI., 1997a; Meister et family of Eoderoceratidae,endemic to Tethys.These dl., 2003), and sometinies subject to Subzone-scale forms can be ascribedto the genusParamicroderocerns uncertainties (Dommergues et al., 1997a). Dommergues,Ferretti 6{ Meister and to rwo new The zonation proposed for the Umbria-Marche genera,here created. Apennines by Faraoni et al. (1996) is the b5st suited According.to some palaeog,elsraphic to assessthe biostratigraphic position of the bed :econstruc- "Venturi'78". tions concerninga time intervalfrom the Sinemurlan Originally, it did not show great corre- (Dommergues, 2002), to the Sinemurian- lation problems with the standard Zones, becauseit Pliensbachian(Meister 6( Stampfli, 2000), to the partialfy recalled the hypotheses of G€czy (1976), middle Toarcian (Dercourt ei dl., 1993), the *ho atiribuited a Tenasjidottrat quadrarmatum hori- Apennine regionwas placed in the easternpart of the zon to the lower part of the Jameio ni Zone, thus sub- *trt.rn Teth"ys.Basing on the arealdistribution data stantially asreeine to the traditional definition of the for early Pfi6nsbachiinammonites, we hypothesize baseof iheTliens[achian. It is known, in fact, that T that, in this area,a sectorcomprising -Prealps,the Apennines quadrarmatum (index ta(on for the first Zone of and at least also middle-eaitern Sicily,/ Faraoni et dl., 1996) can be found together with ApoderocerAsnodogigas in some central Europe regiols Albania,'We Ionian Greeceand Tunisiacan be identified. believe that this region was separated,from a (Dommergues EeMeister, 1989, p. 467): Burgundy palaeobiogeographicpoittt of view, itt regardto the and Jura (France), Caussesand South-'Western France heighbouiingones. At the moment, in fact, the main (Dommergues 6( Meister, 1992, p. 213-214; "Venturi '78" ril€ present-inthe bed seemto repre- Dommergues , 1993), and, apparently, sometimes in sent a -provincial fauna, endemic to the Sub-domain Great Britain too (Dommergues-and & Meistet 1992, p. called by Meister 6( Stampfli (2000) Alpine 216). Elsewhere (French Swiss Prealps) T (DomTelguet. MediterraneanTethyr. quad,rarmatum replaces A. nodogigas + Meister, 1992; Dommergues et al., 1997a). For this CHRONO-AND BIOSTRATIGRAPHICFRAME\TORK reason,one could be indilced to believe that the base of the Thylori Subzone (Boreal Palaeoprovince) and ConnpLATroNS\rITH THESTANDARD ZoNr,s that of the T quadrarmAtum Zone (Mediterranean Tethys) were coirelatable without too much difficul- Basineon ammoniteassociations, the biostratigra- ties. However, detailed comparisons are not allowed phv of thi EuropeanPliensbachian refers to a detailed by the inadequacies (both sidimentary 1nd of fossil schemeof Zonis, Subzonesand horizons defined as content) whiih characterize most part of the succes- standard (Dean et dl., 196l; Dommergueset dl., sionsjust at the Sinemurian-Pliensbachiantransition. 1997a;Hesselbo et al., 2000; Meister et Al., 2003). The mafter is further complicated after an accurate The first layerof the early Pliensbachianis tradition- study of the Apennine Formt until now called "lly determinedby the beginnitg of the Jamesoni TenispidocerasquadrarmAtum, which must be actual- Zone (base of the Thylori Subzone).Originally ly asiribed to another genus. In fact, thev do not designedby the associationof Apoderocerasleckenbyi seem to have spheroconeor sub-spheroconeinner Nfrlght) "itd Phricodocerastaylori (Sowerby)(Spath, and middle whorls, e feature that, according to 1923), this beginnitg is now conventionallyrecog- Dommersues 6{ Meister ( I 9 99), characterizes nizedwith the presenceof ApoderocerasBuckman lA. Tetraspido\erass.s. (i.e. T gr. quadrarmatum\. The nodogigas(Q,t.tstedt) , A. leckenbyi,A. spp.l and/or absencefor the Apennine spEcimensof an ontogenet- 364 E VENTURI, C. NANNARONE,M, BILOTTA ic development diagnostic for TbnasyidocerAs,and found by Dommergues& Meister(l99lt Pl. l, figt. thus the need to inc-lude them in a different tanon, 5-6, p|.2, fig. 3, p|.4, Ftg.la-b) in the Meilleriesec- have already been noted by Dommergues et Al. tion lnorthe-rn Chablais,Sub-briangonnais domain) to our (2000). These Authors ProPosed an attribution to arethe only onesthat can be consideredsimilar Paramicroderoceras,as the presence of intercalated lat- forms, resemblingindeed a medium-sizedindividual eral secondary ribs gives evidence in favour of this fronr the Ful luriachella of the Furlo Pass.Actually, *e f,elieve that this character is not for their morphology with sub-platiconecoiling, designation, b.tt " suffi"cient. In fact, the inner whorls of our T rounded section and large spines, none of these quadrarmatum" , are poorly known, but ,!t.y seem ammonites can be striltly compared with the fikelv to correspond to some small unclassified speci- Tbtraspi doceras genero Wpe, *hi.h hai sub-spherocone -.trt from th6 unpublished Ful lumachella oF the inner'and midtrle whorls, high sub-traperoidalouter Furlo Pass(Pl. 2, figs. 5,9a-b, 12) and to two imma- whorl section,and smallspin-es (at least,judgitg from ture individuds from the Pallareto Quarry (Text-fig. the figure in fukell et dl., 1957). 7b; Pl. l, fig. 4). All of them are cadicone, involute In conclusion, although we can confirm the and broad, i"ith a depressed sub-trapezoidal whorl absenceof the rypical forir of T quadrarmAtumin for Apofurocerus, section and a monospinate inner stage,_in contrast the Apennines,thf sameis not tttt. with true Paramicroderocerusat the sarie diameter. In becauiein the Ful lumachella,a fragment refereable to this genus was recendy found (whereasin bed our opinion, considering these forms as a new genus "Venturi'78" is to be preferred, because their inclusion in this tu(on I missing).This specimen ParamicrodirocerAswould render the til(on nearly use- will be figured and widely describedin a forthcoming less, expanditg to9 much its already wide morplrg- ^""iDaDer foiusins on the spathiclumachellas Ful , Fu2 loeic rinse, and further muddling its stratigraphic Fu3 of thJ Furlo Pasi:for the moment we can say diitributiSn (which does not seettt-to be sufficiendy that its ornamentation and whorl section are very to Blau, 1998; Dommergues et dl., similar to those of the A. subtriangukre(toung 6( known,'S7'ilmsen according 2000; it al., 2002). Among the specimens Bird) presentedby Howarth (2002, pl. 6,.figl , !-5). attributed in the literature to T quadiarmatum, those This d"t.t-, however,does not eliminatethe-difficul-

\]Palaeoprovinces BOREAL MEDITERRANEAN TETHYS \ Stages \ (Meisteret al.,2003) (This paper)

Zones Subzones Horizons Bioevents Zones Tropidoceras Jamesoni U. bronni flandrini "Polymorphites" Pl. submuticumI Brevispina Pl. tenuilobus appenninicus Miltoceras Pl. brevispina I Farinaccites sellae EARLY Pl. brevispinoides clavatus PLIENSBACHIAN Uptonia Polymorphus ? P. polymorphus I Miltoceras jamesoni E.(C.)biru ---19-Y:-lP-:-- "Tetraspidoceras Phr. taylori 'Tetraspidoceras A. nodogigasI quadrarmatum" I Taylori T. quadrarmatum I Catriceras cf. quadrarmatum" A. aculeatum __- _qq!!ry !!!e!!te -- - - B. donovani Catriceras cotriense ,l ? ,l ,l ,l LATE Echioceras Pal. tardecrescensI SINEMURIAN Aplanatum Paltechioceras raricostatum Pal. romanicum romanicum

Text-fig. 2 - Correlation hypothesisamong th9_late. Sinemurian-early Pliensbachian biostr zons/bio.n.ttir) for rhe BoreJand MediterraneanPalaeoprovinces. Note that, by now, the C not be safelvcorrelated to rhe Bifericerasdonouani horizon. This fact has impoitant implic: rion of the Sitt.-,trian-Pliensbaihian boundary and for its actualapplicabilt.'' at a global s LASvC EODEROCEMTIDAE AMMONITES FROM THE APENNINES 365

between the ment ascribed to Apod.erocerAs,xs well as smooth ties in establishing accurate correlations "ahticipate" Apennine zonation and the standard one, and as to ammonites that some characters of th^is subject, we can only present hypothetical rela- Gemmellaroceras Hyatt (Furlites and other forms tionships (Text-frg. 2). belongitg to an unpublished microconch gengs). All these El.ir.nts seem to show that the age 6f the Ful THE C,arucrn qs IATRIENSEBIoEVENT lumachella is closer to that of the bedsZ 5-46 of the Bosso section (tentatively correlated to the The use of zonal schemes based upon different Apoderocerasnodogigas horizon of the standard zona- it may be later than the tal€ implies^tn. many correlation problems even if we tion), and there6ft that restrict study'to the Mediterranean Tethys and Pallareto fossiliferousbed (Text-fig. 3). neighbouring areas:an example is given by the cases For all these reasons,we curre-ntly think that the of Flungary (Geczy, 1976; Do*ti.rgues'& G€czy, age of the Catriceras catriense bioevent can be com- 1989) ind Turkey (Otkun, 1942; Bremer, 1965; p"aredto that of the bed 39 of the Bosso section, thus Alkaya 6( Meister, 1995), where the successions are we can confirm the biostratieraphic attribution for- often incomplete, and the ammonites adopted in the merly prgqosed UyY.^"r.,rti(li7d). U1Qrtunately, we its position comPared Apennines- "i ,otal markers are seemingly-lacking. are not able to specifr precise Local-scale correlations are far more accurate, to the Bifericeras doiot ani horizon (the first of the therefore we will limit iust to the Apennine area. If we Thylori Subzone), so we do not know if it actually want detailed indications on the position of the fauna documents the base of the Pliensbachian in the studied in the present paper, it is necessaryto analYze Apennines. In our area (but it seems to be a nearly the relationships ben"e6n the s..iion of ihe wbrldwide condition) it is sdll lacking a truly com- " rype Tbtraspidocerasquad.rarmntum" Z6ne (Bosso section) ^toplete and continuous succession,that-would -earlierpermit and tlie Pallareto Quarry section, xs they show non- verifr the presence or the absence of neelieible differet.it, both in thickness'and in fossil Pliensbachian bioevents. This fact is clearly exempli- .oiltJttt (quantitative and qualitative). In the fied by the two Bosso river valley sections (Stirpeto Pallareto seltion in fact, where the succession is an and Bbsso), where, between the list Sinemurian^fos- intermediate between a basin and a structural high siliferous beds and the first Pliensbachian ones there one, the fossil record is abundant only in bed is a barren interval of more than 5 metres, to which is "Venturi'78" (Venturi & Bilotta,200l), while in the added a hiarus due to a fault (with a probable slip of Bosso section it is scarce, but distributed over more 6 metres), that implies the,lack of at least 20-40 beds. it representsa definitely thicker basin suc- layers, and " cession. Furthe-rmore, in the Bosso section, the T THE EODEROCERATID'AEOF THE PALI.ARETO quadrarmatum" Zone lower boundary was located by in assemblage with merely GalaticerAs sp. and MnrH oDoloc ICAL oBSERVATIoNS Radstockiceraigemmellaroi (Pirmpeckj)'(from (bed 59), .tb. systematic study of the Eoderoceratidae index speciesbccurring iust abbve bed 46), For the subject of the present work, we based on a quite after the fauna of Hd' 45, which also contains "reitrictive" Catricerns. On the other hand, in the Pallareto sec- approach. For practi.."l purposes we pre- " tion, T quadrarmntum" is nearly absent (beitg reP- fer, in fact, (eicept in very well-documented cases, that is with abundant material and precise strati- resented tiy only'GakticerAs, two nuclei), bur there are numerous specimens of various Eoderoceratidae graphic references) to keep not excessiveranges of variabiliry especially for tilra whose assigned rank is (inainly bispinate, but also mongspinate) - ?n4 'With Polymorphitid". either smooth (Furlitis)_ or ribbed senus and/of speciis. this method the differ- (Caniceias). It was therefore suggested (Venturi & E r..r (in -orphology and in geographic and strati- Bilotta, 2001) that the fossiliIerous bed of the graphic distribution) are markidli uhderlined, thus Pallareto misht have an age either comparable to that harring a precise characterization for the formally " of the base o"fth. T qu.o7.rar*Atum" Zon defined at named groups. In our experience,the long time inter- (last- the Bosso section (beil 39) or earlier. val rep6r.tt.d even by " single ammonitJ Zone These considerations are supported by recent dis- itg some 500.000-1.000.000years) is generallyregis- ter d in rock bodies where the sedimentation and fos- coveries made at the Furlo Pass(Grilli Q,t"try), in a successionof structurd high, formed by many spath- sil record are often disturbed, episodic or very dis- ic lumachella beds. The fa.-unaof the stiatigr"phic"lly continuous (sometimesdespite their aPParentphvsi- lowest bed ever recognized (the already-mentioned cal continuiry). This generatesso much uncertainties Ful, matter of a forthcoming publication) aPPearsto that we believefar more useful for the biostratigraph- be chronologically close to the Pallareto assemblagg ic resolutiononly the taxawith clearlvrestricted mor- for the contemporaneous presence of pholory and stratigraphic-geographicdistribution. Eoderoceratidae, CatricerAs and Galaticerts. Such fioups are easifvrecognizable, independentlv oi Nevertheless, it contains also til€ absent in bed their possiblebiological value. "Venturi '78", including the above-mentioned frag- To obtain greatercompleteness in the svstematic 366 F. WNTURI, C. NANNARONE,M. BILOTA

Fu3e 46 @-l 45 ,@f t",O@ -J 4l

€ncrinitic bcd I 39 ,@

37 - Bd Vernri ?t H'*

Grilli Quarry (Furlo Pass)

PallaretoQuarry (Mount Acuto) PROBLELTANC INTERVAL (sINEIWrt NAN-PLIENS BACHIAN Tn/'NS Ino t9

l9 LEGEND l6 t5 l9lsl rT.l calcnroousbed l=Fl bed with chert LEGEND bed with cnsinitic layer biocvent of thc EO Echiocerus raricostatum Zcl.nre (Late Sincmurian) with Kil rn bGd stylolite ; biocvent of the slump ' " frm ['- T e traspi doc e tra.squadrarmalum @ Znne (Early Pliensbach ian)

biocvent ol the Miltoceras selloc I I A 7rrlrc (Early Pliensbach ian) BossoRiver section (situationat APril 3, 1999)

Text-fig.3 - Short-distancebiocorrelation.among three lower Pliensbachiansections of the ;il;"; Tri.z.The BossoRiver seltion-(in the middle) is the most extendedone, and it ;;;il; ff;;.rriot s thir it rhe only ol the thre. pr.i.ttted sectionsthat contains late I pri;;i;;t;;tbeJ 16: vici"iA;ir^"tia Pbsechiotrr^\. The PallaretoQuarry section (on the riiio"J'; t.rrn berween.o*pl.re successionsand incomplete ones,and contains three encri tion (on the right) is an incbmplete and reducedsuccession of sffuctural high. "Ve"-il;f . The bed if"-;f;hei5rti"t.ro qtt,"rry (Catricerascatiensebioevgni) should€orres bioi"."t frJrr tht Furlo Passis supposedto be more or lesscc Bossosection, *ttit. itt.-p"f "Polymoryhltes" The Fu3 bed'(tut;[toitr^"o". qp. ""d nov. rp. b^ib.vgnt),probably represen' lne Zoie, and ih.t.fore it is inferred to pt'eced6the bioevettt lo.ated on the top of the bed LUS%C EODEROCEMTIDAE AAIMONITES FROM THE APENNINES 367 distinctionswe iointly examinedall the availableele- lesslong trunk, possessingbifid aspector, as a form ments:morphofogy (toiling, shellshape, ornamenta- derived?om thii, trifid, .iith e*terhalbranch havitg tion), ,tructure fConformationof the suture line), the more or lessaccentuated tendence to invade the stratigraphicand geographiclocalization. ventralarea; inclined umbilical lobes, sometimes with U3 nearlyperpendicular to L; broadES and LS1 sad- Sysrnv,arlc DESCRIPTIoNS dles,with ES bUliquetoward the externalside. All the til€ of this sroup are exclusivelyknown in "Venturi '78" In the fossiliferousbed of the the late Sinemurian-ea"rly Pliensbachian of the Tethys. Pallareto that, as alreadystated, is placeable Quarry " ar the base of the T quadrarlmatum"Zone (early Genus9t"toDERocERASnov. gen. Pliensbachian),67 Eodeioceratidaespecimens repre- sented by silicified internal moulds were found. TtPt species- Omoderocerascantianense nov. sP. Gener"lly,they show most part of tlle phragmocone and at leastthe beginni.g oTthe body ihamber. The Name d.eriaation- From the Greek omds(= simi- descriptionof the identifi"'edforms is presentedbelow, lar) and DerocerAs,origin ary denomination of with di"gttot.t that partially retain some ideas of Eo'deroceruts(again from t[e Greek: diros = sheath, Venturi 5. Ferri (2001). T6e terminology used in shell,test; kirh = horn, due to the resemblancewith ram horns of the ancientgod ZeusAmmon), tra-_ describi"sthe generalshape of the shelland its orna- the "termination" mentation is tliat of Ark efi et al. (1957), alsoPresent ditionally adoptedas in the namesof in Venturi (1985),Venturi 6( Ferri (2001). For the many spinousammonites. sutureline we adoptedthe samecomplete nomencla- ture (both for lobesand saddles)ofVenturi (1978, Ttpt locality Mount Catria (Umbria-Marche 1985, 1997),that can be found alsoin Viedmann 6c Apennines). Kullmann(1981). biometric Tvpicbeds - Calcareous-micriticsuccession of the For eachspecies the followitg Parame- "Coiiiola", ters are eiven, statedin millimeires (fot linear mea- with decimetriccalcareous beds and mil- suremenis)or as adimensionalnumbers (fot ratios): limetric clayeyjoints; early Pliensbachian. diameter (d), umbilicd diameter (u), whorl height (h), whorl width (*), umbilical ratio or involution Material Twenry-eight different-sized- speci- index (u/d), whorl shapeor flattenittgindex (w/h), mens, assignedto two tp.ii.t, preservedas silic'ified height ratio (h/4), widih ratio.(w/d). Esdmated val- internal nioulds, without trace of the shell (pro'te- -. nance:Pallareto ues'Weare precededby the symbol Quarry). would finally trot. that, accordi.g to the ICZN (1985) recomendations,the desinenceadopt- Diagnosis Inner whorls moderately involute, ed in the presentpaper to designatesuperfamilies is - with quite broad ribs, almostrectiradiate, ending in a oidea (rather than th. sdll witrespt.td, but formally single-row of spines; middle whorls (sometimes lesscorrect, -aceae). bisiinate) and o,tt.t ones becominehisher, ellipdc "rd compressed,and tending to lSose"at first the Superfamily^Family EooEnocEMToIDEA Spath, 1929 spines,^ thln to undergoa *ea[ening of the ribs. iiooERocEMTIDAESpath, 1929 Characteristicis the presenceof a ribbed mono- Subfamily PnnnvICRoDERocERATINAE nov. subfam. spinatephase, that can be rather short and limited only to ihe inner whorls (bemeenthe initial smooth Typt genas ParamicroderocernsDommergues, staseand the ribbedbispinate middle one),or longer Ferre[ti & Meister, 1994. "rJ involvitg outer "td middle whorls (in this casl a bispinate ornamentation is never dgvel,op.d).The - Evolute to involute shell, with whorl transluon from middle to outer whorls, when it Pioy"osis secdonvariable in shape(sub-rectangular, sub-trape- occursthe spoliation(i.e. the weakeningand lossof zoidal,sub-quadrate) . the ornamentation),takes place alwaysquite preco- The ornimentation is rypical of the superfamily, ciously. with primary ribs normallvioining rwo rowsof spines The ventral area,especially in the inner and middle (tubeicleson internal -o,t[d) and thinner and iloset whorls, is crossedby stcondaryribs; at dmes, on the secondary ribs, which pasgth9 ventral areawithout flank there may be alsosmall intercalatedlateral ribs. interruption; small intercalatedlateral ribs (or striae) The suture'isindented, and possessesthe charac- are otten presenttoo. tersof the subfamily:E lobe shorterthan L (in small Discriminant for this subfamily is the suture, specimensthis feature is not much evident), with indentedand with arborescentlobes: E asa rule quite sub-parallelmain branches;large and arborescentL, narrow as long as L or shorter (but never longer), essendallybifid, with outer braich tending-Ua to invade with deep -.di"n saddleand sub-parallelor slightly the ,r.ttftd area; suspensiveIJz and lobes, divergi"s main branches;L with a narrow more or inclinedin comparisonto L; U2 more or lessclosed 368 F. VENTURI, C. NANNARONE,M. BILOTTA on the bottom by U3 ("s a rule more inclined than Omoderocernshtinodosum (Bremer, 1965) U2) and by the dorsal branch of L; ES saddle slight- OmoderocerAscf. htinodosum ?nov. sp ly broader than LS l. OIvIOOEROCERASCANTIANENSE nov. sP. Remarks To a quite superficid examination, Text-fi g. 4a-b; Pl. l, figs l-3 Omoderocerasmay recall some forms assigned in the 1985 sp.ind. Vrxruru p. 47 fig. 48. literature to EpiderocerasSpath, either for its ontoge- Jamesonites" , , 1996 EpiderocerAs"ktinodosum Bremer FRRRoNI,MARINI, netic changes in morphglogy and ornamentation, or Pnt-uNt6c VrNruRI, pl. 12, fig.4. " for the general aspect of its sheil. However, the two 2001 EpiderocerAs"htinodosum Bremer - VnNruru & BtrcTTA, genera are well distinguishable, mainly for the fol- P.328,:'ab.2. lowing characteristics: 2001Epideroceruts sp.ind. VrNruru 6cFnnnr, p. 127,pl. 11,c. - Epiderocernshas a different-shaped whorl section (for ihstance it is higher) compared to that of Name deriuation- From Cantiaro, small town not Omoderocer*s,xt any stage of development; far from Mount Catria. - for Epiderocernsan inner monospinate stage was Holotype - Pa78-E19, specimen with the begin- never explicitely described {Donovan, 1958, p. 37, (Text-fig. 4a;Pl. l, fig.-la- fig. 6, do show a drawitg of E. aff. steinmanni (Hufl ning-housed of ilie body chamber in the Earth Sciences Department, with inner whorls bearing only one spine, but he does c), Studi di Perugia. not mention this fact in the text], whereas in Universiti degli Omoderocerasthis stage is dways present; ParatyDes- Pa78-E21, specimen with the begin- - Epiderocerusofteil mantairis a ribbed stage on the ning of ihe body chamb.r (Pl. l, fig. 3), and p{Zg- body ihamber while in OmoderocerAsribs aie always E24, specimen with only phragmoco-ne(Pl. l, fig.2); lost in the outer whorls of the phragmocone; both are housed in the Earth Sciences Department, EpiderocerAslooses the ventral second ribs ?ry Universitl degli Studi di Perugia. duringontogenesis, whereas in Omoderocerasthis ten- dence"is absent or poorly-developed; Typt hcality - As for the genus. Epiderocerns normally does not seem to have small lateral ribs, but in Omoderocerasthese are some- "Venturi'78" Typit section- Pallareto bed . times evident; Quarry Epiderocernshas a suture in which the external Material - Eleven specimens, includirg the holo- brancli of L lobe does not have the tendence to ryPe. invade the ventral area, whereas in Omoderocernsthis normally is enhanced during tendence is clear, and Measurements(in mm) - the growth; -" Epiderocerushas a suture with a relatively broad Numberduhwu/ddhh/ddd E lobe, which possessesdivergitg -nairow, branches, but in OmoderocerAsthis lobe is quite with sub-par- allel main branches; Pa78-E18 -52.0 17.5 I1.5 0.66 0.34 0.22 - Epiderocernshas a suture with ES and LS I sad- Pfl8-EL9 39.7 15.0 r4.0 10.8 0.38 0.77 0.35 0.27 dles normally of the same size, whereas in Pa.78-E20 36.8 r5.2 r2.0 9.00 0.4r 0.75 0.33 0.24 Pa,78-E2l 37.2 l4.l r4.0 9.90 0.38 0.7r 0.38 0.27 OmoderocernsES is always a little broader than LS l; Pa,78-E22 28.1 10.0 l l .5 9.90 0.36 0.86 0.4r 0.35 Epiderocerns reaches large size (according - to Pa78-E23 28.0 9.90 10.6 8.60 0.35 0.81 0.38 0.31 Donovan, 1958, the diameter for complete individu- P^78-824 23.2 7.90 8.00 6.50 0.34 0.81 0.34 0.28 als is between2T and 35 cm), but Omoderocerasseem Pa,78-E25 18.7 6.30 6.50 5.60 0.34 0.86 0.35 0.30 10.0 4.00 0.33 1.08 0.37 0.40 (the Pe78-E26 3.30 3.70 to have only middle size estimable maximum Pa78-E27 -9.60 3.70 3.70 1.00 0.39 0.39 diameter is about 6-7 cm); Pa,78-E28 8.80 3.00 3.20 3.50 0.34 1.09 0.36 0.40 - Epiderocernsis safely known almost exclusively in Boreaf or Sub-boreal regions, while Omoderottr^ is by now recorded only in the Tethys; - Epiderocerasis safely known almost exclusively in Desription of the holotype- Moderarcly involute late Slnemurian [even if Alkaya 6( Meister, 1995 shell, with pooi coil .orr.iitg; inner whori probably report a species,E nodafissum(Q.t.tstedt), classicily rounded sub-quadrate,tending to rise and bbcomitg whereas attributed to the early Pliensbachian], hieh"The elliptical. Omoderocerasis by now recorded only in the early ornamentation in the inner and middle Pliensbachian. whorls (the embryonalones are not visible) is repre- sented by ribs with a ventro-lateralrow of spines; Included species OmoderocerAscantianense nov. from the diameterof about 20 mm the ornamenta- sp. (ryp. speciesby original designation) tion is completelylost. LUSSrc EODEROCERATIDAEAAIMONITES FROM THE APENNINES 369

The suture is typical of the genus,with E much one half the length of L, and L itself tends to invade shorterthan L (that^invadesthe ientrd area),and U3 markedlythe veitral area,closing E on the boffom. nearlyperpendicular to them. Remarksand comparisons This speciesmight Diagnosis- Moderately involute shell, with fmt- remind some forms attributed to Epiderocer*s, growin[ whorl height; roundedsub-qua-dra1e or cadi- becauseof its loosingof the spinesbetween inner and Eon. seItion in the-innerwhorls, ogival-highellipticd outer whorls, accompainedby e contemporaneous in the outer ones;rounded umbilical wall. increasein the whoil heieht' (from rounded sub- The ribs, presentfrom the diameter of about 4 quadrate to ogival-ellipticJ), and for its indented mm (when th-esmooth embryonalwhorls end), are r,rt,tt. line. HJwever, the presenceof a single row of rectiradiate,not much reliefing,enditg with moder- spinesis indeed an intereslitg innovation: this char- ately long ventro-lateralspines; as far is can be seen,_ acter, combined with those"concerning the shell ,r-bili."I spinesare never present.At a diameter of shapeand to the detailsof the suture linl, make O. about 20 millimetres the sliell completelylooses the caitianense substantiallv different from all other ornamentation,or mantains it as iteak, broad and known forms, and justifies its inclusion in a new depressed^ umbilical bulqes. genusv and species. - The suture is indenied, possessingthe characters Amone the remarkablefeatures, the length differ- of the subfamily,with the peculiarity that E is about encebewien E and L lobes,os well asthe imount of invasion of the ventral areaby L, are both enhanced during the ontogenesis. ES Stratipraohic distribution Early Pliensbachian rsl " t-l L :$,tl-.. (basalp"?t 6f ,h. T quadrarmntum'(Zone).

OvooERocERAScf,, uqrlNoDosuM (Bremer,1965) Text-fig.7cl-c3;Pl. 1, figs 5-9,1I

1965Epiderocerus ktinodosumBxnMER, p. 160, pl. 15, fig.2a-b; tbxt-fig.3 l. 1985 Hyperfurocerashungaricum G(uy - VENTURI,p. 46, fig.47 . " 1996 EpiderocerAs"ancyrense Bremer FRnRoNt,MAruNI, Pnu-lNl& VENIuRI.,pl. 12, fig. l. " tsr ES 1996 Epiderocerns"ktinodosum Bremer FRRRoNI,MRruNI, - PnruNI& VrNruRI.,pl. 13,figs 1, 5-8. " T 2001 Epiderocerns"ktinodosum Bremer - VENIUT & BttOTTn, p. rab.2. oEpiderocerAs"328, 200I sp.ind. VENruru& FERRI,p. 116. " 2001 EpidnocerAs"sp. ind. VEvruru & FEnru,p. i 27, pl.l l, i, m.

Materia/ - Seventeenspecimens.

Measurements(in mm) -

Numberduhwu/ddhh/dw/d Ltt f-l Pa78-E0l 52.2 22.0 18.0 13.0 0.42 0.72 0.34 0.25 Px78-802 47.8 r9.2 r5.7 10.5 0.40 0.67 0.33 0.22 Pa78-E03 -51.0 14.0 12.0 0.86-0.27 -0.24 Pfl8-804 -4t.5 r4.0 12.3 -0.47 0.88 0.34 0.30 Pa78-E05 4r.0 16.6 r4.0 rr.4 0.40 0.8r 0.34 0.28 Pe78-806 39.6 15.8 r2.9 10.5 0.40 0.81 0.33 0.27 Pa78-807 32.0 l 1.9 r2.4 I 1.6 0.37 0.94 0.39 0.36 L Pa78-E08 25.5 8.50 9.50 10.6 0.33 r.r2 0.37 0.42 Pe78-E09 -13.5 6.00 3.80 4.90 -0.44 r.26 -0.28 -0.36 - Text-fig. 4 Omofurocents-sutures;a) -O. cantianenseholyyPe Pa78-El0 12.6 4.r0 4.60 6.10 0.33 r.33 0.37 0.48 (Pa78-E19),drawn er e diameterof about 40 mm Pa78-El| 12.6 4.30 4.70 5.60 0.34 l.l9 0.37 0.44 (magnified abour x 4); b) fragment of the same P^78-Er2 -12.5 4.30 6.00 -0.35 t.40-0.34 -0.48 specles(Pa78-El8), showing alio the inner part of Pa78-El3 I 1.5 3.l0 4.80 5.00 0.27 | .04 0.42 0.43 the suture line; drawn at ariesdmated diam-eterof Pa78-Er4 ll.4 4.20 4.60 4.I 0 0.37 0.89 0.40 0.36 50 mm (magnifiedabour x 4); c) formdly unclas- Pa78-El5 I 0.5 3.l0 4.20 4.l0 0.30 0.98 0.40 0.19 sified smdl specimen,belonging to a speciesof Pa78-El6 - 10.0 3.00 4.00 5.10 -0.30 1.28-0.40 -0.ir Ornoderoceraspe rhaps close to O. cantianense; Pa78-El7 9.40 3.00 3.50 5.l 0 0.32 t.46 0.17 0.54 drawn et a diametef of about 13 mm (magnified about * 6) (drawing by F. Venruri). 370 E VENTURI, C. NANNARONE, M. BILOTTA

Remarks and comparisons- For the general shape (more involute and with an early change in orna- of the shell, with biqpinate middle wholls and spine- mentation and coiling) may be stratigraphically less sub-rounded section in outer whorls, our speci- youngerthan Bremer's( 1965)one. mens resemble the speciesthat Bremer ( I 965) called Epiderocerns latinodostlm. However, in Bremer's Stratigraphicdistribution - Bremer ( I 965, text-fig. (i965, pl. 15, fig.2a-b) holorype, the change of orna- 5) suppo-sedfor his speciesa location in the basalpart mentation berween middle and outer whorls occurs of th-ejamesoni Zoie, but without more precise-ref- relatively late, becausethe bispinate stageis kept until erences,because his material is erratic. The prove- the diameter of about 33 millimetres. In our speci- nanceof the exemplarsof Cope (1991) it generically mens the transition between middle and outer whorls statedas late Sinemurian(Raricostatum Zone)-early takes place much earliet at around 20 mm (Text-fig. Pliensbachian(Jamesoni Zone). 7cl-r3). Furthermore, the inner whorls of the holo- type are considerably more evolute, and it is GenusPnneUICRoDERocERAS Dommergues, unknown wether they have a monospinate phase or Ferretti 6c Meister, 1994 not. The evolute stage of our forms is much shorter, and its inner part bEars a single row of spines. The Diagnosis- Mid- to large-sizedforms, with evo- holorype's suture has lot beerifigured,.being perhaps lute suF-platiconewhorls; olnamentationrepresented not preserved; in our forms it repeats the characteris- by primary bituberculateribs and by clearsecond"ry tics of OmoderocernscantiAnense.- fin; ribs (striae),which crossthe ,r.tttd areafrom th'e The specimensfigured by Cope (1991, pl. 3, fig. flank. Coiling and ornamentationare kept essentially 4; pl. 4, fig. l0) are sliehtly more involute and less constantfor most part of the growth, with both outer co"isely rib'bed than Brelmei's (196, holorype. Thus whorls and body^chamberiharacterized by higher they are more close to our forms, to which they than wide whorl section(elliptical or sub-rectangular) resemble also for the broad-ribbed ornamentation and flattenedventral area. (mantaining this aspect even at large diameter), fot The suture is not much different from that of the presenceof a short inner monospinate stage,and Omoderoceras. for ihe indented suture, with very ilor. U lobes (of This genushas been reportedchiefly in the upper which U3 is very oblique, nearly perpen&cular to L). part of the late Sinemurian(Raricostatum Zone) of the A careful eximination of th'e lharacters possessed Mediterraneanregions (Dommergueset al., 1994a), by this form lead us to think that they do not corre- but it was also- found in thE Austrian Upper spond with those of Epiderocerns(that, by the way, Austroalpine (Blau, 1998) and in the Southern rb.-r to have been subject to various misuttd.trt"td- CalcareousAlpr (Dommergueset al., 1997b)in ando- ings and erroneousinterpretations), being rather clos- gous biostratigraphic situations. According to er to those of Omoderoceras cantianeise, we thus Ftittebrandt (ZiOzj, earlier Paramicroderocerasirieht believe more suitable to ascribe it to the same genus. date back to the Obtusum Zone (baseof the [-ate As the tendence from evolute forms to in-volute Sinemurian).If the attribution of our specimensis cor- ones is a common phyletic pattern among rect, later forms are present(even though rare) in the ammonites, we can hypothesize that our specimens first bedsof the earlyPliensbachian (Jamesoni Zone).

EXPTANATION OF PLATE I

Various specimensof the new subfamily Paramicroderoceratinae(Eoderoceratidae), Quarry). All specimens^ are at natural size.A white circle marks the beginning of the body Fig. li, b, . - Ventral view, lateral view and whorl section of Omotr rottril cantianenti ( Fig. 2 - Laterd and ventral views of Omoderocerascantianense (pararype, Pa78-E2, Fie. n - Lateral view and whorl section of Omoderocerascantiaiense (paratype, Pai FiE. 4 - Lateral view and whorl section of an indeterminate Paramicroderoieratin: " of the so-calledApennine TbnaspidocerasquadrarmAtum"). Fig. 5 Lateral view and *horl section (partially restored)of Omoderoceru$cf. lati FiE. 6 Laterd view and whorl section of Omoderocerascf. ktinodosum (Bremer) Fig.7 - Vhorl section and lateral view of Omoderocerascf. ktinodosum (Bremer) ' Fig. 8 - Lateral view and whorl section of Omoderocerascf. ktinodosum (Bremer) Fig. 9 - Lateral view and whorl section of Omoderocerascf. ktinodosum (Bremer) ' Fig. 10 - Vrhorl sectionand lateralview of an indeterminateParamicroderoceratin: Fig. I 1 - Vhorl section and lateral view of Omoderocerascf. ktinodosum (Bremer) r Fig. 12 - Lateral view and whorl section of an indeterminate Paramicroderoceratin: Fii. 13 - Lateralview and whorl sectionof an indeterminateParamicroderoceratin: Fig. 14 - \7horl sectionand lateralview of an indeterminateParamicroderoceratini E VENTURI, C. NANNARONE,M. BILOTTA, LTASSICEODEROCERATIDAE AMIV nw 2 1c U O -3s"[i7 -H$tf

4* -1f ti,# i:] n 4 +tG qF" t3 6 Q O /''--\ (\w fi .-,nr- Il}L f\.za' LJ )( / r,H. \*l &" tf # )\---*,-/ ii w,,o zn- ./',,^\,\- lr )( rr 4 JL f..n/ _.-tE& A I ( \^/r +I ^ --- '-

*A-+r \**F*-# 4 )r , ( -A4. r*-s' - \J'l ,- 12 13 Irr--.._z 372 F. WNTURI, C. NANNARONE,M. BILOTTA

PenervucRoDERocERASaff SIsPINATUM figr 27-29; pl. 4, fig. la-b). The sutureis visibleonly (Geyer,1886) oi the largefragmJnrPaTS-829 and, from what can Text-fig.7al-a3;Pl. 2, figt 6, 8a-c be made but, it looks like that figured by Gey'er (1886,pl. 4, fig. t3): E is shorterthan L; L itselfis 1886 Aegocerasbispinatum GsvzR,p. 27, pl. 4, figs 4-13. bifid and hasvery divergi.g main branches,the outer - 1978 Minoderoceiasaff. birchiafusRosenberg Vnvruru, p. 109. tend to invade tht ventral area;the umbili- " (Bremer) - VPNruru 6( of which 2001 ParamicroderocerAs"ancyrense of Bu-orrn, p. 328, :ab. 2. cd lobes are rather inclined. The ornamentation " 2O0I Epifurocetras"sp. ind. VnNruru & FEnnr,P. I 27 , pl. 1l, g. this specimen(Text-fig. 7a3;PL.2, fig. 8a;c),remains coarseeven on the Sody chamber, and has closer Material- Eight specimens(mainly fragments). spines compared to what can be seen on Geyer's (i 836) figuies.-our On the other hand, all other speci- Measurements(in mm) - mens of collection have more distant spines (Text-fig. 7 al-a2). Numberduhwu/ddhh/ddd Stratigraphicdistribution According to Bremer (1965, 1fi), Geyer's (1886) material probably Pa78-E29-162.4 -59.0 38.0 17.3 -0.36 0.46 -0.23 -0.1I p. Pe78-830 23.0 8.70 7.00 8.00 0.38 r.r4 0.30 0.35 belongtio the RaricostatumZone (late Sinemurian). Pa78-E3l -20.3 -6.20 6.60 6.10 -0.47 0.92 -0.33 -0.30 Pa78-E32 -20.2 6.20 6.00 -0.27 0.97 -0.31 -0.30 Pe78-E33 -14.0 5.10 4.90 4.90 0.36 1.00 -0.35 -0.35 Genus PnneoERocERASnov. gen. Pe78-E34 r3.5 4.80 5.20 5.40 0.36 r.04 0.39 0.40 Pa,78-835 -13.3 5.30 5.20 -0.35 0.98 -0.40 -0.39 Typt species- Parad.eroceraspicenum nov. sP. Pe78-E36 rr.2 4.30 3.80 4.20 0.38 l.l l 0.'( 0.38 Name deriuation- From the Greekpard (= near-_ by) and Derocerns,origin ary denomination of Remarks and comParisons- For their evolute form, Eoderocerns. narrow section (as wide as high), their ventral eree, (Umbria-Marche the coarse ribs with two evident rows of sharp spines, Typt locality Mount Catria the intercdation of lateral striae and the fine ribs on Apennines). the ventral aree, our specimens seem quits close to Typit beds- Calcareous-micriticsuccession of the Aegocerasbispinatum Geyer, 1886 (pl. 4, figt 4-13), "Coiniola", wliich in tuin can be considered the same species(or with decimetriccalcareous beds and mil- joints; early Pliensbachian. nearly so) as AegocerasPraecursor Geyer, 1886 (pl. 3, limetric clayey

EXPIANATION OF PIATE 2

Various specimensof the new subfamily Paramicroderoceratinae(Eoderoceratidae), Quarry) and Ful lumachella (Furlo Pass).Unless contrary indications, all specimensare at ning of the body chamber. Fig."l $7horl section and lateral view of Parafurocerutspicenum (holorype, Pa78-83 fii. Z \7horl section and lateral view of Paraderoceruts'picenum(pararj'p e, Pa78-81' Ffi. 3 Lateral view and whorl section of Paraderocents'picenum(-pararyp e, Pe78-E4t FiE 4 Lateral view and whorl section of an indeterminate Paramicroderoceratinae. Laterd view and whorl section of an indeterminate Paramicroderoceratinae fi[. I " the so-cdled Apennine Tbtaspid.ocerasquadrarmAtum"). Phragmocone and body chamb Provenance:Furlo. Fig. 6 Lateral view and whorl section of Paramiroderoceruucf . bispinatum (Geyer) ( chamber.Provenance: Pdlareto. Fig.7 V/horl section and lateral view of an indeterminate Paramicroderoceratinae(a new species to O. cantianense).Provenance: Pallareto. Fig. 8a, b, c - Bodv chamber*horl section (partially restored),lateral view (fragmentsof body chamber : -ocbn. whorl secrion (oardally restoied) of Paramicroderocerascf. bispinatum(Geyer) (Pe7i ,ri.* magnified lateral view (* 2) of an indeterminate Paramicro Fig. 9a, b V/horl secdon,laterd rtrd " spond to the inner whorls of the rJ-."ll.d Apennine Tbtraspid.ocerasquadrarmatum"). Phrz clnnot be disdnsuished. Provenance:Furlo. Fig. 10 Vhorl section "ild laterd view of an indeterminate Paramicroderoceratinae.Provenance: P: Fig. 11 - Lateral view and whorl section of an indeterminate Paramicroderoceratinae(perhaps a sPec Phraemocone and bodv chamber cannot be distinguished. Provenance:Furlo. Later?l view and whorl section of an indeterminate"Paramicroderoceratinae(it should corr Fig. 12 " the so-calledApennine Tetraspidocerasquadrarmatum"). Phragmoconeand body chambe Provenance:Furlo. E VENTURI, C. NANNARONE,M. BILOTTA, LTASSICEODEROCERATIDAE AI4IV Pl.2

-***.. n 1t \--,,/ It w It \,^rr J4" ){ -taa--..-f

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U.^r )-^-( ivh J^ .-"',yjt12 1r*lI ,J - 374 E VENTURI, C. NANNARONE,M. BILOTTA

Material Four different-sized specimens, Paratypes- Pa78-E37, specimenwith more than a assigned to the same species, preserved as silicified whorl ofbody chamber(Text-fig. 5c-d; Pl. 2, fig. 2) inte"rnal moulds, without trace of the shell (prove- and Pa78-E40,specimen with t"hebeginnitg oI the nance: Pallareto Quarry), and two spathic immature body chamber(Tbxt-fig. 5b; Pl. 2, fi;. 3);5oth are specimens (provenance: Fu2 lumachella of the Furlo housedin the Earth SciencesDepartment, Universit). Pass). degli Studi di Perugia.

Diagnosis Evolute shell, with sub-trapezoidal Typt locality- As for the genus. wider than high whorl section. "Venturi area not much rised, ranging from slight- Typit section Pallareto bed Ventral '78" Quarry lv roof-like (in the inner and middle whorls) to . iounded (at larger diameter, includitg the body chamber). Material - Four different-sized specimens, includ- The ornamentation, which mantains its aspect irg the holorype. even on the body chamber, is made of quite broad primary ribs ioining two rows of spines (umbilical Measurements(in mm) - and 'n.tttro-laferal) "]ita by finer and lloser secondary ribs which, from the ventro-lateral edges, cross the Numberduhwu/dw/hh/ddd ventral area without interruption. The spines seem Pe78-E37 68.2 35.9 r4.0 13.0 0.53 0.93 0.2r 0.19 directed obliquely to the coilins plane of the shell: the Pa78-E38 45.5 23.6 l r.9 r2.0 0.52 I .01 0.26 0.26 ventro-lateral ott.r upwards,- ihe umbilical ones Pe78-839 37.2 14.6 r2.0 l 1.0 0.39 0.92 0.32 0.30 (apparendy shorter arid smaller) downwards. The Pa78-840 29.0 13.7 8.00 7.20 0.47 0.90 0.28 0.25 smill specimens from the Fu2 lumachella show that the inner whorls are smooth until a variable diameter berween 4 and 7 millimetres, and then the broad riha- ES aPPear.- -The t-l suture is moderately indented, with arbores- cent lobes rypical of the subfamilv 6ut a little short- er than thoie of Omoderoceras):E ne arly as long as L (which do not seem to have an accentuated tendence to invade the ventral area); inclined umbilical lobes, with U3 nearly perpendicular to L and approaching very close to ths outer branch of L itselfi, closing U2 on the boftom.

Remarks - \fith the few available specimens, we ES t-t LSl are not able to give an exhaustive appraisal of the vari- 1-l abiliry of Pariderocerns. However, its verJr peculiar b aspect allows a quite^Only easy differentiation from other bispinate forms. *h.tt other ammonites safely "rrisn"ble to this g.trr will be discovered, it will b; porlible a comple6 definition of its variabiliry range. LS1 Included species Paraderocerls picenum nov. sp. - LSl (rype speciesby original designation). |-]

PnneoERocERASPICENUM nov. sp. Text-figs. 5a-d; 6a-c; Pl. 2, figt l-3 " 2001 Epideroceras"sp. ind. VeNruru& Fenm,p. I 27, pl. I 1, l.

Name deriuation - From Piceni, ancient popula- tion inhabiting the present-day Marche region. Text-fig. 5 - Paraderocerutspicenum sutures,showing the charac- Holotype - Pa78-838, specimen with part of the tersof this n6w genus(all magnifiedabout x 4); e) holorype (Pa78lE38), drawi ar e diameter of body chimber (Text-fig. 5a; 6a-c; Pl. 2, fig. l), aboui 34 ^ ; b) pararype(Pa78-E 40), drawn at a housed in the Earth SciencesDepartment, Universitl diameter of aboui 22 mm, c, d) pararype(Pa78- degli Studi di Perugia. E37; respectivelydrawn at a diameterofabout 40 mm and 20 mm) (drawing by F. Venturi). LASSrc EODEROCERATIDAEAALMONITES FROM THE APENNINES 375

Polymorphus/Brevispina Zone, seem to have some (rather elementi in common with Parad,eroceras 'We than Eoderoceras)for suture, coiling and rib sryte. can- not say anithing more, becausethe whorl section is not figured, thetnly drawn suture is incomplete, and almosi all the specimens are deformed. Conce_rning the biostratigraphic position that Alkaya 6C Meister (1995) "ssigied to th.t. clearly bispinate' so-called " Eod.eroceri tardecrescens", it must be noted that, in the Apennines, similar forms never occur in the beds " above the T quadrarmntum" Zone (corresponding more or lessto the Thylori Subzone).

Stratigraphic distribution Early Pliensbachian " Text-fig. 6 - Holorype of ParaderoceruLtpicenum (Pa78-E38); a) (basal part of the T quadrarmAtrtm" Zone). lateralrrie*; b) sectionof the last whorl; c) section of the lastwhorl with restoredspines, to show their length and inclination; natural^size(drawing by F. THN UNCLASSIFIEDFORMS Venturi). The strons morpholoeical variabiliry noticed in the Eodero..t?tidae^from"the Pallareto made impos- Diagnosis - As for the genus. sible the identification (at least, at a specieslevel) of 27 specimens(Pl. l, figs4, 10, 12-14; Pl. 2, \gs 4r7 , Remarks and comparisons- The peculiar character l0).^'We cannot excludl that, among this unclissified be reco in the future. combination explained in the diagnosis_"asgive_s to material, new til€ might gnlzgd Paraderocerasa very well distinct "rp.".t and, far as As an example, two sriall individuals have very btogd we can ascertain, tliere are only few Lomparable forms whorl and ironospinate inner stage (Text-fig..7b; Pl. in the literature. The speciescalled bV Bremer ( 1965) I , fig. 4), closely resembling nvo other untlassified nuclEi from the irul lumachella of the Furlo Pass(Pl. CrucilobicerasPhry7iti* (a generic'attribution that seemsto us nol much accurate, as this form does not 2, figt 5, 9a-b, l2): all of them probably must be share many characters with the generotyP€ of ascribed to a new speciesof Omoderocerns.As previ- ously said, these foims should indeed.fPresent also Crucihbiceras Buckman), shows some resemblance 'inner " with Paraderocerasfor its flattened shell with evolute the whorls of the Apennine Tetraspid'oceras coiling. However, contrary to the caseof our materi- quad,rarmatum" (not visible bn the specimen figured al, th; ornamentation hai more projecting and less in Faraoni et al., 1996) that, moreover, show evident broad ribs, on which the spines connection are not Paramicroderoceratinaecharacters (e.g. the ornamen- much visible, and in which-the second row of spines tation sryle). is more close to the umbilical edge. On the ventral The suture of the unclassified specimens has area the secondary ribs are apparently missing (nor always the same basic characteristics, diagnostic for *Jrereas the they are mentioned; but it may be a lack in the Preser- the subfamilv Paramicroderoceratinae, whorl width and the details of the orna- vation), the whorl section is more narro% never roof- coiling,. the "mal- like, and the whorl development is different; the mentation show a considerable morphologic suture and the stratigraphic reference are unkno'wn. leabiliry". Besidessome rather evolute-and persistent- The specimen dJsignated by Cope ( l99l; pl. 4, ly bispinate forms, or that in any caseloose later their (features fig. I I ) ai Uptonia sp. ii nearly identital to the abone- #itt.i that can be considered plesiomor- in which three innovative char- m"enrioned Bremer'; ( 196, CrucilobicerasPhrygictlm, phic), there are others and thus is somehow comparable wirh Paraderoceras icters simultaneously appear (features that are com- too. This early Pliensbachian form is said to be a pletely established it i6. Eoderoceratoidea of the worn out and perhaps deformed specimen, but to us subsequent parts of the early and middle (judging ftg- th. photograph) i,tsprgservation seems Pliensbachian): its stroftg resem- I tendence to whorl widening; qgite fine. 4"n"ay, one cannot dgly ) increasein involution; blance to the holorype of CrucilobicerasP4rygitxtm. 2) tendenceto early loss of a toy of spines (presenceof the Considerations of the same kind also aPply to the . 3) ammonite (probably of early Pliensbachian age) lnner monospinate stage). called by Cope (199 l; pl. 4, Frg. 12) Coeloderocerns Among th.t. formsl four quite involute sPecimens likely belSng to a species oF Omoderoceraiperhaps 'phrygicumponticum (Pi;), but its- similariry to Crucilobiceras close to O. iantianeise (Text-fig. 4c; Pl. 2, figs 4,, 7). ' and Paraderocernsis less marked. or evolure, The specimens figured by Alkaya & Meister Some specimens,either involute Tigh: (1995, pl. 8, figt l, T6) as EoderocerAstardtcrescens somenmeshave lateral secondary ribs (or intercalated (Pia), localised as lower Brevispina Zone or striae)(Pl. I , figt 10, 12-14), bui this does not neces- 376 E VENTURI, C. NANNARONE, M. BILOTTA sarily imply that they must be ascribed to the genus ment for the first group of this superfamily and its Parimit-itrocerus. A dready stated above (also in main genera, basing on our data: the diagnosis),we believe that is advisableto limit the use of tlis name to a more restricted range, compared Superfamily^Family EooEnocERAToIDEASpath, 1929 to that normally admitted in the_ Past. Such a iiooERocERArtDAE Spath, 1929 methodolopy, which prefers the use of riell-character- lribbed forms with one or two rows of spines, ized and deTimited taxa, induced us to caution in the sometimes with the tendence to spoliation during systematic designations. This is the main reason we the growth, or, as hiehlv derived condition, par- choose not to give a specific ("t times nor generic) tialli spoliated (only-ribbed); secondary ribs that assignment to ammonltes unprovided of all the diag- ,m,rilli cross without interruption the ventral trorii. features of safely t.iogttizable forms. As; area;lntercalated small lateral iibt are often pre- "intermediate" whole, they are specimenswidi char- sent; suture more or less indented, with more or acters between those of the individuals that we have lessarborescent L, essentiallybifid]. 1929 identified as rypical-and for the genera Paramicrod,eroceras, Subfamily EoDERocERATINAESpath, Omoderoceras Parad,erocerasibecause in our fBoreal Sinemurian-early Pliensbachianforms; palaeogeographic area a sufficient record of faunas with one or two rows of spines, more or less ^prec.dltrg" "Venturi '78" permanent; relatively simple suture, with E as "ttd subsequent to bed "trunk"]. (which aitually seems to be a yet isolated event) is lotg as L, that lacks'" t "r^to'w lacking, it is impossible to understand the phyloge- Genera: Eod.erocerasSpath, Xipherocerts netic ind taxonomic meaning of the variabiliry here Buckman, Microderoceris Hyatt, Bifericeras observed. Buckman, etc. Subfamily PnnevtcRoDERocERATINAEnov. DrscussloN oN THE AFFINITIES [Tethyan- late Sinemurian- early Pliensbachian ontoge- forms; bispinate without lppreciable All the Paramicrod,eroceras, Paraderoceras, netic variations, or monospinate with tendence OmoderocerAsas well as the unclassified forms coming to spoliation during the growth (monospinate "Venturi '78" from bed of the Pallareto share the lnner stage;subseq,Lttt lo-ssof spinesand ribs); stratigraphic position, the,ftthyan, geographic sutures #ith E always shorter than L, which Prove- "trunk" nance and severalmorphologic and structural charac- has a narrow and the outer branch teristics (see the above-t.poited diagnoses). This led often tending to invade the ventral area; us to ascribe them to the same subfamily inclined umbTlical lobes; broad ES and LS I Paramicroderoceratinae.Mainly on the basis of the saddles]. inner whorl development of these genera and on the Genera: Paramicrod.erocer*sDommergues, charactersof their ornamentation during ontogenesis, Ferretti 6( Meister, ParaderocerAs rlov., "ancestral" we think that the form of ihe t,tbf"-ily Omoderocerns llov.; + other forms erro- might be ParamiroderocerAs:it has actually many ple- neously ascribed in the past to siomorphic features,such as the greaterevolution and Tbtraspidoceras. the perrnanenceof spines;moreover it has the earliest Subfamily EIIDERocERATINaEDommergues & record, being alr^eady present from the late Meister, 1999 (nom. transl. nov, ex Epide- Sinemurian. 6n the oih.f hand, Parad,erocerasand roceratidae Dommergues 6c Meister, 1999) "derived" OmoderocerAsare to be considered as forms [Sub-boreal and/Jr Sub-Tethyan late (especially the latter, having marked innovative ten- Sinemurian-early Pliensbachian forms; dences). bispinate with tendence to spoliation during In our opinion, no further already-known taxa the'growth, or partially spoliated (only ribbefli can be ascribed to this new group. For instance, subiriangular bgival ieciion in the adult body Microderoceras Hyatt is often coitidired a close rela- chamb.tih. suture seemsknown only for the tive of Paramicroderoceras(Dommergues 6( Meister, first three genera (the remainitg two are there- 1999; Hillebrandt, 2002), but it shows some charac- fore included in this group with reservation, ters (concerning chiefly the suture and the geograph- indicated by the qn.tiiorr^rn"rk), and has E that lead us to exclude it generally quite as fong as L or a little less, L ic-stratigraphic distribution) "trunkt from thE Piramicroderoceratinae. At the moment, we iuittt a narrow and the outer branch believe that it must be placed it in a different sub- that never seem to invade the ventral area]. family (seebelow). Genera: Epiderocerns Spath, Coeloderoceras A-systematicrevision of all the Eoderoceratoideais Spath , Pseuduptonia Bremer, ?? beyond the aim of this work, and we cannot exhaus- Pseudoohricodoceias Dommergues, tively appraise many classification hypotheses' Moute?de 6( Rocha; ? CapreolicerasAlkay" .*prLs.d' by various Authors (fot inrt"nce & Meister. Dommergues 6( Meister, 1999). Nevertheless, we Subfamily CoELocERATINAEHaug, 1910 would like to propose a rough hierarchical arrange- [Boreal and lor Tethyan late Sinemurian- LUSSrc EODEROCERATIDAEAMMONITES FROM THE APENNINES 377

Pliensbachian forms; with a single row of weakening and subsequentmore or lessgomplete loss spines (medial or ventrolateral); suture with E of ornamentation wasa peramorphic variation. It was longer than L, U2 lobe more develoPed than normally realized with the transition from the ribbed U3: oblique ES saddlel. bispinate stageof the inner and middle whorls to the Geneia: Coeloceras Hyatt, Apod.eroceras ribbed o, ,--ooth stage of the outer whorls (this h"P- Buckman, HyperderocerusSpath, Miltoceras pens, for instance, ii Epideroceras).On the contrary Spath, itt the Eoderoceratidie assignable to the early Viedenmayei, Metad.eroceras "Ventu Dubaricerts Dommergues, Mouterde 6( Pliensbachian (bed ri'78" and Ful lumachel- Rivas, etc. l"), a ribbed bispinate phase (if present) involves only the middle whbrls, frbm which the transition to a In our opinion, the family Eoderoceratidae is a non-ornate phase (ribbed or smooth) is rather Preco- rather homogeneous group, being well separated cious. Moreover, as can be seen in some small from the othe"r ta>(aofihe o-. ."tik ascribed to the Paramicroderoceratinae nuclei from the Pallareto, a Eoderoceratoidea (Polymorphitidae, Liparoceratidae, stage without ribs is present also in the innermost Dacrylioceratidae).As'it can be observed,the division pait of the whorl (Text-fig. 7 cl-c3). In few speci- in subfamilies is operated on the basis of all the avail- hens, between this phase and the ribbed bispinate able elements: morphologic (shell shape and orna- one of the middle whorls, it occurs a stage at first mentation), structural (Iutural features), biogeo- monospinate without ribs, then ribbed monospinate graphic and stratigraphic distribution. (Text-fig. 7b). This leads to think that the spoliation of theselndividuals is actually a paedomorPhosis, pre- THr, SPoLIATIoN luding a complete establishment of the monospinate charaiter in- other early Pliensbachian Eodero- One of the most interesting featurespossessed by ceratoidea (Caleites Venturi 6( Ferri, MiltocerAs most of the Eoderoceratidae itudied in the Present Viedenmayer and some still unpublished Mediter- paper is their innovative manner of spoliation. This is ranean to"). Therefore, the losi of spines, besides I ttitt not completely known paffern, which started at being an ontogenetic variation of the individual orna- least from the^late Sitt.-uriin, and is accomplished mentatlon, iriplies also an evolutive modification, ways (Venturi, 1999). progressivelydeveloped within the superfamily dur- through different times and " In"late Sinemurian forms of the same family, the irg"the Teiraspidocirasquadrarmatumr' Zone.

- rext-ng 7 3i1ft"il*l'r:t$'i,:::*'T,'l'fr:::t on specimensfrom the PallaretoQ.*"tt1t Neai each individual in lateral view is placedits whorl section.al0-a3) onto- (;r:rn:';^3::!i{;i':#,^S:{;i};":qenetic development of Paramicro- still present it large diameter (al: @iffi-\rirrr Pa78-E34,viith originary dia- nucleus al I s2 rnerer = 13.5 mm; a2: young sPecimen Pa78-830,with originary diameter= 23 mm; a3: adult with[ody chamber Pa78' 829, originary diameter = about 160 mm); b)"unclissifiedimmature (proba- blv belonging to a new speciesof Omoderoceiaiithat should correspond to the inner whorls of the so-called "TbtrAspidocerasquadrarmt- Apennine " tim" (and perhapi also to thot. of T quadrarmntum" sensuDommergues E{ Meister,l99l); note the initial mono- spinatestage without ribs, on smooth whorls; ma[nified x 2 (originarydiame- {4fr rer = 9 mm); cl-c2-c3) onrogeneric- developmentof Omoderocerascf. latino- @a*(ffi dosum(Bremer), showing its varioussta- cl W/ ges,until the spoliatedEnal phase(cl: iucleus magnifiedx 6. rvith'orieinary c2 diameter= I mm; c2: \'oungspecimen magnifiedx 2, with originan'-dii-.rer_= 8 mm; c3: adult x l) (draw'ingbv F. Venturi). 378 F. VENTURI, C. NANNARONE,M. BILOTA

the Comparing late Sinemurian forms with.. early Yorkshire, England), completely agrees with Pliensb".hi"tt"on.r, it can be observedthat spoliation already-mentio.'nedstandatd d.finitioi of the _begin- (Thylori In fact, is accompained by an increase in whorl width and ning of the Jamesoni Zone Subzone). ma,nI char- thetr"r. of ihe Bifericerasd,onouani horizon (bed 73b) coiling: be.ing" phyletic *"tge,invol"iTq acters-at the same tlme, it can be considered a mor- is considered th. beginnitg of the Pliensbachian jtt phologic covariation (term here used in a broader because it contains ^i epod4rocernssP. ; further- -."trihs than in Guex,200l). This phenomenon, as more, it overlies the last Upper Sinemurian "already Lower in part noted by Bremer (196r' concerned Echioceratidae, and precedes the first classic *aitrly the -ot. involute Eoderoceratidae (for Pliensbachian ApodeVocerasand Phricod,cerastaylo1i et 41., instan'ce Omod.eroceras,Epiderocerns and Pseuduptonia (Dommergues & Meister, 1992; Hesselbo Bremer), which have ribbed (and normally spined), 2000; Meister et a1.,2003). (presence of relatively lesscoiled inne r andlor middle whorls, and The conventional criterion quad'rarmatum) it compleiely (or nearly) loose their ornamentation in Aooderocerusand/or Tbtraspid'oceras as the o,rt.i whorls. The evolute taxa, instead' mantain uiually accepted, also for traditionil reasons' begin- throughout their growth or semi-perma- only bio.rr.ttt ptoviding an indication for the Permanent to rec- nent sprnoslty an4 degree of coiling (e.g. nins of the Pli6nsbachiin. At present, it allows in Paramicro derocerAs and ParaderocerAs). oguirrcthe actual base of the Thylori Subzone only The causesleading to spoliation are unknown, but tli.'Wine Haven section: this biostratigraphic datum out- we can observe that-this pattern is only one of the cannot be used apPropriately'belonging in other known numerous modifications that the ammonite fauna crops (neither Boreal, nor 19 different underwent during the Sinemurian-Pliensbachian "reas) (Meist er et al., 2003). Anyw iy, trfthis -provides regions transition. Its final"phase is contemPoraneous to the a good reference for Boreal and Sub-boreal is not adaptive radiation of the Polymoiphitidae, which G.[orth-\7est Europe), we think that the same (Itafy, ,t"rt.d from the base of the Pliensbichian and con- true for the Tethyan ones Morocco, Tunisia, tinued for most part of the early Pliensbachian. Even Albania, etc.). Here, in fact, the standard biostrati- Lias though the complete understanding of. the spines' eraphic principles that characterize the middle in funct-ionsis a field oPen to sPeculations(Donovan et (.rp..ially its beginning) are inapplicable..Thus, bound ery dl., 198 I ), these str^ucturescan be interpreted as a ih.r. "r."r, the 5i..-u-rian-Pliensbachian the passivedefence system, but they can be important in cannor be precisely determinated. The fauna of ref- helping the sheil stabiliry too.'Therefore the loss of bed 73b ofVine Haven, recommended as world of the spinesTrr"v also depend from variations in the ethol- erence for the biostratigraphic recognition Bifericeras iW and/or in the hydrodynamic requirements of the basal Pliensbachian, is m-adeof nume-rous "fri-"l. Considering that forms such as Omoderoceras d.onouani Dommergues & Meister, a few Gleuiceras (Tutcher Trueman), xr were not particuhlly adapted to active swimmiTg, 'Apod,erocerusiuv. aff. iridesceis 6( then this morpho-functional changg may be an index sp. jtt and, accordilg to Howarth of palaeoenvironmental alterations (Venturi, 1999). QOOZ), also ah A. subtriangulare. In our opinion, tnit suggeststhe hypothesis that the loss of orna- none of these til(a (neither sEparatelynor as associa- "i"'n for mentation the Eodiroceratoidea and the faunal tion) seem to offer a good correlation potential is chanse of the Sinemurian-Pliensbachian transition extra-Boreal areas. In" fact, Bifericeras d.onouani (il migh"t have at least some causes in common. The strictly endemic to \7ine Haven hT never been in the ren"ewalobserved in ammonite assemblages,in fact, found elsewhere) and Gleaicerasis also known corresponds to stable isotope variations (positive for late Sinemurian. So, Apoderocerasis the only signifi- absent in a''O, hegative for a"C)- "tt{ also to evolutive and/or cant enough form, buf it seemscomPletely same extinctio"n epsiodes of calcareous nannoplankton most part of the Tethyan localities, and the (Brag? et recorded in tn. same time interval (Mattioli et Al., happehs for Tbtraspid.oiqrasquqdrarmAtum 2003). In particular, the negative D''C shift, accord- at.',igg(; El Harifi et dl., 1996; Lachkar et dl., 1998; accepted interpretations of simi- Dommergues et dl., 2000). In the Apeqnines, as i"g to the ggqera.lly lar cases,mtght tmply a decreaseln water temPera- already ,{id, true T quadra.rmatum are lacking, and tures: perhap-sthis iould be related to seaway open- the ottly known representative of Apodgroc.erascomes ings,(it more.in general, change in the palaeogeo- from the Ful lumichella, which seemingly is subse- "Venturi'78" (that griphic seffing). quent to the bed is, to an unques- tionably renewed fauna, compared to rypical late THE SINEMURTAN-PLIENSBACHTANBOUNDARY Sinemurian assemblages) \We believe that a GSSB to have a world true use- THE GSSP CORRELATIONPOTENTTAL fulness, must at first (not to neglect other crtiteria) allow sufficiently reliable correlltions for as many The stratotype (GSSP) for the Sinemurian- areasas possible,'and not onh for a single P"l.agogeq- Pliensbachian bound tA, recently recommended for graphic domain. The'Wine Haven secdon' dthg.tph the \fine Haven section (Robin Hood's B"y, possessingmany of the necessary requirements to be LUSYC EODEROCERATIDAEAMMONITES FROM THE APENNINES 379

a GSSP.(good exposure and accessibiliry sedimenta- ceratinae,more or lesslenticular, keeled and without ry conunuiry, fosiil abundance, etc.), dbes not seem spines). Contemporaneous to these appearances,the to assure with acceptable confidence the expected final phase of the spoliation of the Eoderoceratidae correlation potential (at least, with a resolution takes place. "Venturi '78" beyond the Subzone scale) outside the Boreal The bed contains exacdy all the domain. Due also to the great sedimentary differ- just-mentioned elements, with taxa characterizedby ences (both qualitative and of thickness) that con- marked polymorphism and high diversiry which tribute to mike so hard any comparison between have p"rrbd ih.o,tgh many (and 5ft.tr rapid) changes Boreal and Tethyan successions,we think that a stra- over ihe time: Catricerascatriense (Thopidoceratinae), torype for the Sinemurian-Pliensbachian bound a\y Furlites (smooth Polymorphitidae), numerous speci- based on Apod,erocerasand Bifericeras d.onouanimight mens of Galaticeras,Eoderoceratidae with tendence have, at the present state of knowledge, x palaeogEo- to spoliation (Omod.eroceras),Orynoceratidae (four graphic value limited merely to the Boreal domain, Raditockiceras and a GleuicerasBuckman). The rare I"d thus a too restricted significance. Paramicrod.erocerlsand two interesting unpublished All these reasons were Explained in detail to the ammonites similar rc Asterocer*sHyatt or Riparioceras Pliensbachian'Working Group during the voting ses- Schindewolf are probably to be interpreted as late "leftovers", sion on the GSSP proposal for the'Wine Haven sec- Sinemurian ".td perhaps they may testi$/ tion (with complete results in Meister et al., 2003, p. a not yet complete faunal change. However, the absolutl predominance of formf which are not 276),'W'e and motivated our abstain. believe that there is a strong need for more recorded in the Raricostatum Zone (being further- "new"), biostratigraphic studies, especially in extra-Boreal more significandy suggeststo consider the "Venturi'78" as the first assem- areas,to t.r? the real applic"biliry of the Sinemurian-'$fine bed post-Sinemurian Pliensbachian bound ary concept used at blaee of the Apennines, also becauseit seemsto pre- Haven, thus confirming"-"tt.r or denying its practical effec- cedi the more openly Pliensbachianfauna of the Fu I tiveness as GSSP.As a of fIct, the ratification lumachella. of this bound ary stratotype before such studies, It is interesting to observe that in Morocco, mieht formallv not allow a safe recognition of the Tunisia, Albania, ind partially also in Turkey, the befinnirg of the Pfiensbachian in the Intire Tethys. biostratigraphic data for the early Pliensbachianseem to be qni"'t."tit . to the Apennine ones, but they come THp Eenrv PIInNSBACHIANIN THE ApENNINES from generally more incomplete sections, and some- times ih.y were apparently underestimated.This hap- The impossibiliry to apply in the Tethyan regions pened, for instance, in the Jebel-Bou-Hamid section the biostratigraphic criteria used in the North-'West (Morocco), where the presence of Galaticerasin the Europe to dEteimine the base of the Pliensbachian, final part of a very thick Sinemurian succession does hot eliminate the need to reco gnize with appro- (Lachkar et dl., 1998), was not considered a safe becausethe Authors did not ^"Ut.priate accuracy the possible presence'Weof fossils refer- Pliensbachian bioevent, to this time inte^rvalin ottt areas. can sdll fol- exclude (quite inexplicably) the occurrence of this low the historical definition of the Sinemurian- genus in th. late Sinemurian (a fact, by now never Pliensbachian bound "tft which implies for the do..t-ented). Considerations of the same kind apply ammonites a elobal faunal change, with disappear- to the Turkey (Asaei Gokdere section), where a ance of the Ejhioceratidae and rilbr.quent diversifi- Radstockicerai sp. bioenent, found between a cation of the Eoderoceratoidea,but we must baseon Pabechiocerasromanicum horizon and a Pseuduptonia different genera and species. micromphala one, was not deemed to represent the In th6 Apenninei, the first assemblage corre- baseof'the Pliensbachian(Alkaya & Meist-er,1995, p. spondirg to these features is r€presented by the 165). In this case,however, the caution is justified, "Venturi'78" Catricerascatriensebioevent (bed of the because the first occurrence of Radstockiceras, Pallareto Quarry), and partially also by the bed 39 of although often considereda marker for the beginnitg the Bosso section, which is more or lessequivalent to of the Pliensbachian(..g. Meister 6( Sciau, 1988; it. Venturi & Ferri, 2001), is also reported in the latest As already reported by Venturi & Ferri (2001), the Sinemurian (Donovan et al., 1981; Donovan, 1994: Apennine associations which overlie the last Dommergues et al., 1994a, 2000). Eihioceratidae of the late Sinemurian (Paltechioceras In th? Djebel Oust-Est condensed secrion Buckman, PlesechiocerasTi"ueman 6( \Tilliams), do (Tunisia) a Pliensbachianlayer containing GalaticerAs show a substantial renewal.They are characterizedby and Tbtraspidocerasis registered (Rak(s 6{ Guex,, the concomitant first occurrence of Galaticeras(mass 2002): it might be referableto the faunascharacteriz- "T appearance), RadstockicerasBuckmxr, Polymor- ing of our qradrarmatum" Zone, but is assigned, phitidae (small, smooth forms without a keel, evolute pr6UrUly in.ori.ctlv, to a later biostratigraphici-nter- or passing from involute to evolute) and above all val (Aenigmaticum/DemonenseZones). CatricerAs (morphologicallv variable Tropido- Converselv.in more distant areas,there seemsto 380 E VENTURI, C. NANNARONE,M, BILOTTA exist the premises for a good biocorrelation with the systems and competition might provided htgh. lt"y. Apennines: in Argentina, (Arroyo Las Chilcas sec- many favourable incentives for the evolutive process- "biologic tion) is reported a Catriceras bioevent, correcdy es, making it a true forge" (or a somehow placed after the Paltechioceras and before the privileged areafor this aspect). It is certainly risky to "cen- Mihoceras ones (Hillebrandt, 1990, 2002, and per- state unconditionally that the Apennines were a sonal communication). tre of origin" for.,.b. ammonites, also because this In all the above-mentioned sections the Boreal concept is too difficult to appraise, and surely is taxa which provide an indication for the early rather disputed. However, we believe that the prob- Pliensbachian are absent, and vice versa, the first lem of the origin of the til(a is a sdll important itudy Apennine forms which can be considered as post- field, and it ca-nnotbe ignored. For instance, the great Sinemurian (chiefly Catriceras and Furlites, but also diversification of the Alennine forrns, includi"f the true Gakticeran, have never been found in the Boreal earliest Tiopidoceratinie (Catriceras) and smioth domain. Obviously, it is not our intention to propose Polymorphitidae (Furlites) ever recorded, might be "Ventu the fauna of the Md ri'78" as a global^marker interpreted as a sign of their native origin (or-nearly for the base of the early Pliensbachian,.'b..",rr. (as a so). However, the objective support for this conjec- whole) it is unknown elsewhere, not even in other ture is scarce: between Catriceias and its supposed parts of Italy: this is reasonably due also to the con- Eoderoceratidae ancestorsthere is a tremendous mor- siderable faunal and/or sedimentary differences exist- phologic gap, neither are known transitional forms, irg among the various Tethyan areas. Nevertheless, nor reasonabledirect forerunners. There are indeed the renewal represented by this bioevent must warn many motivations that one can adduce: lack in us on the ratification of a GSSP for the Sinemurian- foundirg the forms, outcrop absence,immigration of Pliensbachian bound tA, becauseit demonstrates the extra-Apennine til(a (helped also by the changed scarcity of knowledges concerning this time interval, palaeogeographicsefting), etc. Clearly, these are ohly and the impossibili-ty to establisF for it careful and hypotheses suggestedby ^ few data, that serve as an reliable global correlations. incentive for further and more accurate studies. "Venturi '78" The fauna of the bed is important CONCLUSIONS to characterize in the Apennines the renewal associat- ed with the Sinemurian-Pliensbachian boundaryi The high morphologic variabiliry of the Eodero- unfortunately, its taxa are different from those -Havenpresent ceratidae studied in the present work is a good exam- in the Boreal domain (including the \Vine ple of the polymorphism showed by am--monitesin GSSP), and perhaps reflec-t,palaeogeographic *r":y the Umbria-Marche Apennines at the beginnirg of isolation as well as different palaeoenvironmental the early Pliensbachian.This is perhaps "'-ore gen- conditions. Many points are still left open in the eral condition, which can occur also^in other ir."t Apennines: the presenceof beds lacking fossils (for at with similar situations. The abundance of ecolosical least l0- I 5 m) in the Bosso river iection makes niches, and the consequent great diversificatioil of impossible to define a precisebound ary at the transi- ammonite assemblages(.rp..iilly in Teth yan areas,as tion between late Sinemurian and early Pliensbachian noted Uy 1986), is f-i,tt, settled within a generalized faunas. Only with further researchesin the Tethyan transgresslvephase, and seemsto be facilitlted by the successionsit will be possible to solve the problem, t iassic displacement of the great carbonatic plat- clarifyirg its various implications. For this reason,w€ forms. AIso linked to this, is ln increased develop- intend to publish as soon as possible the results of a ment of the provincialism, which in Pliensbachian-is study on the Pliensbachian faunas from the Furlo strongly marked than during Sinemurian or Toarcian Pass (Fu I , Fu2 and Fu3 lumachellas), repeatedly times (Meister 6c Stampfli, 2000). The already-noted mentioned in the present paper. biocorrelation difficulty berween Boreil and Mediterranean successionsperhaps ^and may depend also AcTNovlEDGMENTS on this set of palaeogeogriphic palaebecologic 'We factors. would like to thank:G. Lucarini,who took the pho- Our data suggestthat the Apennine faunas are rel- tographsof the specimenspresented in rhe platesof this paper;P. Faiaoni A. Marini (i.e. and for some unpublished biostratjgiaphic atively isolate endemic) not only compared to the data on the Bossosection; G.C. Pozzi for her hints conlerning farthermost part of western Tethys (Mbrocco and the plates;G. Rea, who gave us mosr part of the marerial herE Southern Spain), but probably even more in regards widily used; F. Cecca and C. Meirter *ho reviewed the manu- to the South-eastern (Arabia, Madagascar and India) script and helped us to greatlyimprove it with their suggestions an(l correcuons. and North-eastern ones (Himalaya ind Karakorum). 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