VOL. 28, N° 2, 2009 - Ville de Genève

1661-5468VOL. 28, N° 2, 2009

Revue de Paléobiologie, Genève (décembre 2009) 28 (2) : 471-489ISSN 0253-6730Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910(Pachyceratidae, Ammonitina) with the exemple of the Vertebrale Subzonesample (Middle Oxfordian) of southeastern FranceDidier Bert *, 1AbstractThe Cheiron Mountain (Alpes-Maritimes, southeastern France) sample of Tornquistes Lemoine was collected in the Arkelli Biohorizon(Vertebrale Subzone, Plicatilis Biozone). Its study reveals its homogeneity whereas its morphology is between two nominal andclassical species of literature : Tornquistes tornquisti (de Loriol) and Tornquistes oxfordiense (Tornquist). It appears that the featuresusually taken into account to establish specific denominations in this genus (whorl section thickness, strength and density of theornamentation, widening of the umbilicus) are in fact manifestations of the laws of covariation of the characteristics, and the extrememorphologies are interrelated by all intermediaries. There is now no taxonomical reason not to consider all the nominal taxa describedin the Plicatilis Biozone as a single paleobiological species : Tornquistes helvetiae (Tornquist). On the other hand, the stratigraphicpolarity of the position of the primary ribs point of bifurcation (which decreases through time) is a major evolutionary feature inTornquistes. It now allows defining at least three, maybe four, successive chronospecies : (1) (?) Tornquistes greppini (de Loriol), (2)Tornquistes leckenbyi (Arkell), (3) Tornquistes helveticus (Jeannet) and (4) Tornquistes helvetiae (Tornquist). Finally, althoughProtophites Ebray has often been regarded as a microconch, it is clearly not the one of Tornquistes. The oldest species of Protophitesnow recognized is Protophites chapuisi (de Loriol) at the top of the Mariae Biozone (Praecordatum Subzone).Key wordsAmmonoidea, Tornquistes, Middle Oxfordian (Upper Jurassic), Arkelli Biohorizon, intraspecific variability, evolution, palaeobiology,Southeastern France.RésuméDiscussion, évolution et nouvelle interprétation des Tornquistes Lemoine, 1910 (Pachyceratidae, Ammonitina) avec l’exemplede l’échantillon de la sous-zone à Vertebrale (Oxfordien moyen) du sud-est de la France. – L’étude de l’échantillon de TornquistesLemoine récolté dans le biohorizon à Arkelli (sous-zone à Vertebrale, biozone à Plicatilis) de la Montagne du Cheiron (Alpes-Maritimes, sud-est de la France) révèle qu’il est homogène mais situé morphologiquement entre deux espèces nominales classiquesde la littérature : Tornquistes tornquisti (de Loriol) et Tornquistes oxfordiense (Tornquist). Il apparaît que les caractères longtempspris en compte pour établir des coupures spécifiques dans ce genre (épaisseur de tour, vigueur et densité de l’ornementation, ouverturede l’ombilic) sont en fait la manifestation des lois de covariation des caractères, et les morphologies extrêmes sont reliées entre ellespar tous les intermédiaires. Sur le plan taxinomique, il n’existe à présent aucune raison de ne pas considérer tous les taxons nominauxdécrits dans la biozone à Plicatilis comme une seule et même espèce paléobiologique à grande variabilité : Tornquistes helvetiae(Tornquist). D’autre part, la polarité stratigraphique de la position du point de bifurcation des côtes primaires, dont la hauteur décroîtau cours du temps, est un caractère évolutif majeur chez Tornquistes. Il permet à présent de définir au moins trois, peut-être quatre,chronoespèces valides successives : (1) (?) Tornquistes greppini (de Loriol), (2) Tornquistes leckenbyi (Arkell), (3) Tornquisteshelveticus (Jeannet) et (4) Tornquistes helvetiae (Tornquist). Enfin, si Protophites Ebray a souvent été considéré comme uneforme microconque, il n’est clairement pas le dimorphe de Tornquistes. La plus ancienne espèce de Protophites à présent reconnue estProtophites chapuisi (de Loriol), au sommet de la biozone à Mariae (Oxfordien inférieur).Mots-clésAmmonoidea, Tornquistes, Oxfordien moyen (Jurassique supérieur), Biohorizon à Arkelli, Variabilité intraspécifique, Evolution,Paléobiologie, sud-est de la France.I. IntroductionThis work is a further contribution to the study of theSubtethyan ammonite fauna of the Arkelli Biohorizonat the top of the Vertebrale Subzone (Plicatilis Biozone,Middle Oxfordian). This research is a continuation ofrecent works made in the Cheiron Mountain area (Alpes-Maritimes, southeastern France - Fig. 1) (Bert, 2003,2004, 2008 ; Bert et al., 2003 ; Bert & Bonnot, 2004).The genus Tornquistes Lemoine, 1910 is very scarce inthe Arkelli Biohorizon of this locality since it representsonly 0.69 % of the total faunal ammonite (see Bert et al.,*Corresponding address : Place de l’Eglise, F-04170 La Mure-Argens, France ; paleo-db@orange.fr1Université de Bourgogne, Laboratoire Biogéosciences, UMR CNRS 5561, 6 bd Gabriel, F-21000 Dijon, France.

472 D. BertFig.1 : Geographical location of the area listed. In blue are the Callovo-Oxfordian layers of the Cheiron Mountain (Alpes-Maritimes,southeastern France).2003, fig. 3), and less than ten specimens were collectedin a single layer (see op. cit. for the representation of theoutcrop-section). Under these conditions no real biometricstudy could be undertaken. But due to their morphologicalhomogeneity and their isochrony all the specimens weretreated as one sample. The biostratigraphic frameworkused for this work (Lower and Middle Oxfordian) isthat proposed by Cariou et al. (1997) and ammendedby Bert (2004, p. 11-12, fig. 1) especially when usingthe Arkelli Biohorizon (Głowniak, 2000) at the top ofthe Vertebrale Subzone, and the overlying AntecedensBiohorizon at the base of the Antecedens Subzone.The genus Tornquistes Lemoine, 1910 was previouslyrevised by Charpy (1976) then by Thierry & Charpy(1982). These autors have studied a total of over200 specimens divided into nine morphological nominalgroups for the single Plicatilis Biozone. Nevertheless,the significant statistical analysis did not permit them toestablish any clear division between most of these taxa.If this taxonomic multiplicity proves satisfactory of apurely descriptive point of view, it is much less in termsof paleobiology (Thierry & Charpy, 1982, p. 645-646).In fact by the Gause principle of competitive exclusionit appears improbable that so many similar species thatpotentially occupied the same ecological niche have beencoexisted such a long time without competition (Mayr,1974, p. 48-49). This fact has led these authors to groupsome of the literature’s “species” together as variants ofother taxa.The goals of the present work are to study the CheironMountain sample of Tornquistes, to clarify its taxonomicposition in relation to the literature nominal species,and to verify if these taxa have a real paleobiologicallegitimacy from the variability (studied in the literatureand unpublished datas). For this purpose a review of newor currently accepted criteria for the characterization ofthese taxa was performed. Finally, the taxonomic andevolutionary implications are discussed.

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 473II. The Tornquistes at the top of theVertebrale Subzone of southeasternFranceOrder Ammonoidea Zittel, 1884Suborder Ammonitina Hyatt, 1889Superfamily Perisphinctaceae Steinmann, 1890The classification of the family PachyceratidaeBuckman, 1918 has been problematic for a long time.For some authors it should be classified within theStephanocerataceae Neumayr, 1875 (Douvillé, 1912 ;Arkell, 1950, 1952 ; Arkell et al., 1957 ; Charpy,1976 ; Bourseau, 1977 ; Charpy & Thierry, 1977 ;Thierry & Charpy, 1982 ; Besnosov & Michailova,1983, 1991 ; Gil et al., 1985 ; Krishna & Thierry,1987). So for Arkell (1950, and in Arkell et al.,1957) the Pachyceratinae are Cardioceratidae Hyatt,1892 intermediate between the Cadoceratinae Hyatt,1900 and the Cardioceratinae Hyatt. On the other handArkell proposes the Tulitidae Buckman, 1921 asancestors of the Pachyceratidae and he classified themdirectly between the Sphaeroceratidae Neumayr, 1875and the Macrocephalitidae Buckman, 1922.In contrast, for other authors the Pachyceratidae schouldbe classified within the Perisphinctaceae Steinmann,1890 (Westermann, 1956 ; Schindewolf, 1963 ;Sturani, 1967 ; Callomon, 1981 ; Donovan et al.,1981 ; Lominadzé, 1982 ; Mangold, 1988 ; Page,1993, 1996 ; Courville et al., 1998). Sturani (1967)also suggested an origin of the Pachyceratidae amongthe Tulitidae probably derived from the ZigzagiceratinaeBuckman, 1920. For Callomon (1981), followedin this by Mangold (1988), the Pachyceratidaesuddently appear from the subboreal PerisphinctidaeSteinmann, 1890 (Grossouvrinae Spath, 1931) inthe Middle Callovian. Finally Lominadzé (1982)proposes an origin of the Pachyceratidae within theProplanulitinae Buckman, 1921. On the other hand,Schindewolf (1923) studied the ontogeny of the sutureline in ammonites, and he founds that the introductionof umbilical lobes in the Stephanocerataceae shows thecharacteristic appearance of an additional accessory lobe :the internal lateral lobe U n. But this lobe is absent in bothPachyceratidae and Tulitidae as in the Perisphinctaceae.This led Schindewolf in 1963 (following Westermann,1956, p. 9) to classify these families together withinthe Perisphinctaceae. Courville et al. (1998) suggestBullatimorphites Buckman, 1921 as the oldest Tulitidaebecause (p. 61-62) « d’après la morphologie de la lignede suture et des tours internes, Hahn (1971) enracine legenre dans un ancêtre « périsphinctoïde » (Zigzagicerasou Procerozigzag) du Bathonien inférieur ». One canalso note the presence of parabolic structures in theTulitidae at least from the lower Bathonian (Courvilleet al., 1998 ; P. Branger, personal communication) like(but very rarely) in the Lower Oxfordian TornquistesLemoine, 1910 (Marchand et al., 2002 ; this work).The presence of such parabolic nodes is clearly not aStephanocerataceae feature but rather Perisphinctaceae.Family Pachyceratidae Buckman, 1918Genus Tornquistes Lemoine, 1910Type species : Macrocephalites helvetiae Tornquist,1894 in Tornquist, 1894, p. 8-10, pl.1, fig. 1a-d.The specimen n° J19574 (coll. Basel Natural HistoryMuseum) from Anvill (Swiss) was featured by Charpy(1976) as a neotype of Tornquistes helvetiae (Tornquist,1894). But this designation is not valid because this thesisremains unpublished. Moreover, this specimen has beenobjected as a neotype by Bourseau et al., 1979 becauseof too large ornamental differences from the originaltype-specimen. The same specimen was included in themorph kobyi de Loriol, 1896 by Thierry & Charpy(1982, p. 633, pl. 2, fig. 1), therefore it was not proposedagain as a neotype of Tornquistes helvetiae (Tornquist).But in agreement with ornamental parameters (height ofthe bifurcation point of the ribs over half of the flanks- see discussion) this specimen is probably not of theTornquist’s species neither of the de Loriol’s one :it could be in fact older than the Plicatilis Biozone. Inaddition the Bukowkii and Costicardia subzones (LowerOxfordian) are also both represented in the originlocality of the Anvill specimen (Thierry & Charpy,1982, p. 634, 645). In that case this specimen is rather aTornquistes leckenbyi (Arkell, 1946) (see below).Remark on subgenera of Tornquistes Lemoine, 1910From their morphological and biometric study Thierry& Charpy (1982) proposed to divide the genusTornquistes into two subgenera : Tornquistes Lemoine,1910 and Pachytornquistes Thierry & Charpy, 1982.In practice these two subgenera are mainly distinguishedby the thickness of their section and the strength oftheir ornamentation. These features are also commonlyused to differentiate the taxa of this group. HoweverWestermann (1966) used Buckman’s work (1892 in hiswork of 1887-1907) on the Sonninnidae (early Bajocian),and he clarified in ammonites the “laws” of covariation,basing mainly on the relationship between the width of thesection and the strength of the ornamentation. Since then,numerous studies have demonstrated that Buckman’s“First Law” can be extended to ammonites ranging in agefrom Paleozoic to Cretaceous (see Morard & Guex,2003, tab. 1 for a summary). It appears that these lawsof covariation are also applicable for the Tornquistes. Inthat case the distinction into different subgenera basedsolely on these variable features (thickness of section /strength of ornamentation) becomes purely typological.This is what finally emerges of the revision of Thierry& Charpy (1982) whose recognize the existence ofmany intermediate forms between the extremes. So thesesubgenera are not used here.

474 D. BertComments on the laws of covariation of the characteristicsapplied to the differents species of Tornquistes and theirconsequences are developed in the discussion.Tornquistes helvetiae (Tornquist, 1894)Pl. I and IISynonymy1885. Aspidoceras nicolisi sp. nov.– Parona in Nicolis& Parona, p. 39, pl. 1, fig. 5.1894. Macrocephalites helvetiae sp. nov.– Tornquist,p. 8, pl. 1, fig. 1a-d.1894. Macrocephalites oxfordiense sp. nov.–Tornquist, pl. 2, fig. 1a-c.1896. Macrocephalites kobyi sp. nov.– de Loriol, p.20-22, pl. 4, fig. 1 ; pl. 5, fig. 1.1896. Macrocephalites liesbergensis sp. nov.– deLoriol, p. 22-23, pl. 5, fig. 2 ; pl. 6, fig. 1.1896. Macrocephalites tornquisti sp. nov.– de Loriol,p. 22, pl. 2, fig. 2 ; pl. 3, fig. 1-2.1912. Pachyceras (Tornquistes) helvetiae (Tornquist,1894).– Douvillé, p. 51, pl. 3, fig. 13.1912. Pachyceras (Tornquistes) helvetiae kobyi (deLoriol, 1896).– Douvillé, p. 52, pl. 3, fig. 2.v1912. Pachyceras lalandei mutation romani nov.–Douvillé, p. 50-51, pl. 3, fig. 14.1938. Tornquistes helvetiae (Tornquist, 1894).–Roman, p. 220, pl. 20, fig. 205.1940. Pachyceras kobyi (de Loriol, 1896).– Arkell(in 1934-1948), p. 215-216, text-fig. 75.1974. Pachyceras (Tornquistes) gr. kobyi (de Loriol,1896).– Sequeiros, p. 48, pl. 3, fig. 4 ; pl. 4, fig.2-4.1974. Pachyceras (Tornquistes) romani (Douvillé,1912).– Sequeiros, p. 54, pl. 4, fig. 1, 5.1974. Pachyceras (Tornquistes) gr. romani (Douvillé,1912).– Sequeiros, p. 54, pl. 4, fig. 5 ; pl. 5, fig. 2(specimen with teratology), 4.1974. Pachyceras (Tornquistes) liesbergensis (deLoriol, 1896).– Sequeiros, p. 58, pl. 5, fig. 3.v 1977. Pachyceras (Tornquistes) aff. oxfordiense(Tornquist, 1894).– Bourseau, p. 82, pl. 10,fig. 1a-b.vvv1977. Pachyceras (Tornquistes) kobyi (de Loriol,1896).– Bourseau, p. 84, pl. 11, fig. 1a-c.1977. Pachyceras (Tornquistes) aff. romani (Douvillé,1912).– Bourseau, p. 83, pl. 11, fig. 2-3.1979. Pachyceras (Tornquistes) nicolisi (Parona inNicolis & Parona, 1885).– Bourseau et al., p.127, pl. 1, fig. 5.1982. Tornquistes (Pachytornquistes) oxfordiense(Tornquist, 1894).– Thierry & Charpy, p.638-639, pl. 1, fig. 2a-b ; pl. 4, fig. 2a-b ; pl. 10,fig. 1, 4 ; pl. 11, fig. 1a-b ; pl. 12, fig. 2-3.1982. Tornquistes (Pachytornquistes) cf. oxfordiense(Tornquist, 1894).– Thierry & Charpy, p.639-640, pl. 4, fig. 2a-b.1982. Tornquistes (Pachytornquistes) liesbergense (deLoriol, 1896).– Thierry & Charpy, p. 640-641,pl. 6, fig. 1.1982. Tornquistes (Pachytornquistes) tornquisti tornquisti(de Loriol, 1896).– Thierry & Charpy,p. 641-643, pl. 1, fig. 3 ; pl. 5, fig. 1-2a-b ; pl. 8,fig. 1 ; pl. 9, fig. 3 ; pl. 13, fig. 2.1982. Tornquistes (Pachytornquistes) tornquisti tuberculatumnov.– Thierry & Charpy, p. 643-644,pl. 5, fig. 3 ; pl. 7, fig. 3 ; pl. 9, fig. 2.1982. Tornquistes (Tornquistes) romani (Douvillé,1912).– Thierry & Charpy, p. 630-632, pl. 1,fig. 1 ; pl. 2, fig. 3 ; pl. 3, fig. 2 ; pl. 4, fig. 1a-b ; pl.7, fig. 2 ; pl. 9, fig. 1 ; pl. 10, fig. 2.pars 1982. Tornquistes (Tornquistes) helvetiae helvetiae(Tornquist, 1894).– Thierry & Charpy, p.632-634, pl. 3, fig. 3a-b ; pl. 11, fig. 4 ; non pl. 11,fig. 2, nec pl. 12, fig. 1.pars 1982. Tornquistes (Tornquistes) helvetiae kobyi (deLoriol, 1896).– Thierry & Charpy, p. 634-636,pl. 2, fig. 2a-b ; pl. 7, fig. 1a-b ; pl. 8, fig. 2a-b ; nonpl. 2, fig. 1a-b.pars 1982. Tornquistes (Tornquistes) multicostatum multicostatumnov. sp.– Thierry & Charpy, p. 636-637, pl. 10, fig. 3 ; pl. 11, fig. 3 ; non pl. 3, fig.1a-b ; nec pl. 13, fig. 1a-b.1982. Tornquistes (Tornquistes) multicostatum nodosumnov.– Thierry & Charpy, p. 637-638, pl. 6, fig.2a-b.1995. Tornquistes (Tornquistes) helvetiae kobyi (deLoriol, 1896).– Branger et al., p. 26, pl. 5, fig.5.1995. Tornquistes (Tornquistes) multicostatum nodosumThierry & Charpy, 1982.– Branger et al., p.26, pl. 5, fig. 6.2000. Tornquistes (Tornquistes) helvetiae kobyi (deLoriol, 1896).– Quereilhac, p. 45, pl. 42, fig.1-2.2000. Tornquistes (Tornquistes) romani (de Loriol,1896).– Quereilhac, p. 45, pl. 42, fig. 3.v 2006. Tornquistes tornquisti (de Loriol, 1896) morphetuberculatum Thierry & Charpy, 1982.– Bert,p. 36-37, fig. 8.Remarks about the synonymy : In the strict applicationof the ICNZ principle of priority, the taxon nicolisiParona, 1885 should have priority on the taxonhelvetiae Tornquist, 1894 because of the identity ofthe two species (see the discussion below). However thistaxonomic option is not satisfactory and several pointsare to be considered : (1) the use of precedence wouldcreate instability in the nomenclature which woulddefeat the goals of the principle of priority because thegenus Tornquistes Lemoine, 1910 is based on the typespecies Tornquistes helvetiae (Tornquist, 1894). (2)The Article 67.1.2 of the ICZN precise that “the nameof a type species remains unchanged even when it is ajunior synonym or homonym, or a suppressed name”(see also the recommendation 67B). (3) Contrariwise toT. helvetiae Tornquist, the taxon nicolisi Parona wasreally poorly studied by authors (only at one time in the20th century – cf. synonymy) even if the conditions of theArticle 23.9 of the reversal of precedence are not reaching(it is really difficult in palaeontology of these rare groupsto gather 25 works of 10 different authors on the same

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 475subject). However (4), this problem was also been roseby Thierry & Charpy (1982) who have proposedthe nomen oblitum for the taxon nicolisi Parona.Unfortunately this principle was neither recognized bythe version applicable in 1982 of the ICZN nor by theactual one (the 4th - Article 23.12). For cons the actualArticle 23.2 is very explicit : ”Purpose. In accordancewith the objects of the Code (see Preamble), the Principleof Priority is to be used to promote stability and it is notintended to be used to upset a long-accepted name in itsaccustomed meaning by the introduction of a name thatis its senior synonym or homonym […]”. ConsequentlyTornquistes nicolisi (Parona) should not be used to thedetriment of Tornquistes helvetiae (Tornquist) and thislatter should be taken as an available species.Material studied (n=7) : All the specimens are fromthe Cheiron Mountain (Alpes-Maritimes, southeasternFrance). They were collected in the Arkelli Biohorizon(Vertebrale Subzone, Plicatilis Biozone of the MiddleOxfordian). Specimens n°ox.32 (A. Magnin’scollection), n°AA98, AB55, AL09, AL97 and AP41are from bed 100d, and specimen n°AA06 is from bed101 (D. Bert’s collection). See Bert et al., 2003 fora figuration of the outcrop-section. In waiting of theirdeposition in a public institution all the specimens arevisible from the author.Measurements : See Table.DescriptionTwo main morphological types of Tornquistes are bothrepresented in the sample of the Cheiron Mountain.Following Charpy (1976) and Thierry & Charpy(1982) these morphologies are interpreted here as theresult of a sexual dimorphism : the potentially largeadult specimens are macrochonchs [M] and the smalleradult specimens are microconchs [m]. On the graphs, themacrochonchs’ average curves of H and O=f(D) (Fig.2) are of Y=bD a type (R² still highly significant), but ais very close to 1 indicating a growth almost isometricand harmonic. The microconch differs by its stronglydisharmonic growth due to the uncoiling of the adultbody chamber. The break of slope is clearly visible onthe graphs H and O=f(D) (Fig. 2), and on the graphO/H=f(D) (Fig. 3) which is generally used to displaydimorphic couples in ammonites (Marchand, 1986).The two morphological types are described separatelybut the wholy septate specimens smaller than 70-80 mmare impossible to relate to one or other dimorph. Thesuture lines are not sufficiently preserved to be described.Inner whorls (D < 70-80 mm) : The incomplete andwholly septate specimens n°AL09 (Pl. II, fig. 2) and AP41(Pl. II, fig. 4a-c) are representative of both dimorphs. Atthis stage of growth the shell is very involute (O/D=1.89Table of measurementsN° sp. DDiameterAA06[M]AA98[M]AB55AL09AL97[M]AP41125.9109.197.192.270.037.531.171.461.393.384.174.768.050.0HHeigth57.553.948.343.133.318.815.534.830.146.741.337.633.023.8EThickness-----26.221.5-43.4-49.045.7--OUmbilic27.321.719.918.612.46.75.712.911.218.114.813.012.910.1H/D E/D O/D E/H O/H αdegrees0.460.490.500.470.480.500.500.490.490.500.490.500.490.48-----0.700.69-0.71-0.580.61--0.220.200.210.200.180.180.180.180.180.190.180.170.190.20-----1.391.39-1.44-1.191.21--Average 0.49 0.66 0.19 1.32 0.39Standard deviation 0.01 0.06 0.01 0.12 0.04Coefiscient ofvariation (%)2.86 8.68 6.92 8.72 9.08ox.32[m]128.4114.797.678.048.851.546.840.4----35.523.116.113.6Average 0.46 0.20 0.460.380.450.480.52----0.280.200.170.17----0.470.400.4160°60°0.430.37 135°0.360.37 100°0.370.37 75°0.390.360.3560°70°0.390.43 140°0.730.450.350.3480°75°100°

476 D. BertFig. 2 : Representation of H (height) and O (umbilicus) in function of D (diameter) for the sample of Tornquistes of the CheironMountain. Circles are for macroconchs.Fig. 3 : Representation of O/H=f(D) for the sample of Tornquistes of the Cheiron Mountain. Circles are for macroconchs.

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 477in average) with a sub-circular depressed section (E/D=0.71 in average), very convex flanks, and with a verypoorly individualised rounded venter which gives theshell a very globular general appearance. The umbilicalwall is high and vertical, and the peri-umbilical area isnarrow and slightly angular. The primary ribs are slightlyinclined forward ; they are broad but not very prominenton the peri-umbilical area. Ribs bifurcate from the baseof flanks where they remain inconspicuous and withoutthickening. The wedge-shaped secondary ribs are betterexpressed beyond the lower third of flanks. These aresometimes separated by interribs of same robustness.On the venter all the ribs are wide and slightly curvedforward.The macrochonchs : The specimens n°AA98 (Pl. II, fig.3) and AL97 (Pl. I, fig. 2) are wholy septate (D=92.2 and98.3 mm respectively). They certainly represent nuclei ofmacrochonchs, because at this diameter the microconchsare already differentiated. The specimen n°AA06 (Pl. II,fig. 1) is also a macroconch : it reaches a diameter of 126mm and the last septa is visible at 120 mm. With a bodychamber extrapolated to 2/3 of whorl, this specimen wouldexeed D=200 mm without being adult (no approximationof the last septa). Beyond 70-80 mm in diameter the shellhas exactly the same characteristics as those observedin the inner whorls. The ornamentation retains the samegeneral appearance but with a broadening and a gradualspacing of the ribs. The ribs are also less pronounced thanon previous whorls especially in the first third of flanks.The microconch : The specimen n°ox.32 (Pl. I, fig. 1) is theonly complete adult (D=128 mm) collected in the CheironMountain which enter this category. The phragmoconeends at D=77 mm and the body chamber is about 3/4 ofwhorl. The body chamber shows a significant uncoilingof scaphitoïde type following a break of slope in the shellgrowing at D=110 mm (Fig. 2-3). While remaining broadthe section tends to compress slightly from the youngerwhorls with less convex sides than on the phragmocone.At the last third of whorl the peri-umbilical area becomevery angular with an almost overhanging umbilical wall.On the other hand, the thickness of the section remainsalmost constant regarding to the height of the whorl. Theornamentation blurs at the base of the flanks from thefirst third of the body chamber and the ribs are thereforemore widely spaced than on the phragmocone. From theend of the second third of the adult body chamber thearea where the ribs are weakened gradually up from thehalf of the flanks ; that make the shell almost completelysmooth when approaching the peristome.Differential diagnoseStrictly morphologically, the specimens of the CheironMountain are different from Tornquistes romani(Douville, 1912) for their sub-circular section andblunter ornamentation. The sample studied herediffers from Tornquistes helvetiae (Tornquist, 1894),Tornquistes kobyi (de Loriol, 1896) and Tornquistesliesbergense (de Loriol, 1896) for its ornamentationconstantly blunt and its more depressed section. TheCheiron Mountain’s specimens have fewer ribs perwhorl and a narrower umbilicus than in Tornquistesmulticostatum (Thierry & Charpy, 1982) and itsvariety nodosum (Thierry & Charpy, 1982).On the same morphological point of view, the specimensfrom the Cheiron Mountain largely and perfectlyreflect Tornquistes oxfordiense (Tornquist, 1894)and Tornquistes tornquisti (de Loriol, 1896) by theirsize, ornamentation, and the shape of their section.The sample of the Cheiron Mountain however seemssomewhat closer to Tornquistes tornquisti (de Loriol,1896) according to the graphic of the morphodiversity inthe Plicatilis Tornquistes (Fig. 4). Some specimens witha more compressed section are intermediate to the bothtaxa and it is not possible to assign them preferentially toone or other.It would be tempting to attribute the Tornquistes of theCheiron Mountain in part to Tornquistes tornquisti (deLoriol, 1896) and in part to Tornquistes oxfordiense(Tornquist, 1894). However, the study shows thatthe Cheiron Tornquistes sample is homogeneous andwithout real break. All this implies that the currentlyaccepted criteria for differentiating the taxa of this genus(section thickness, strength of ornamentation) are basedon correlated features which we know now that theyare an important part in intraspecific variability. Thesefeatures do mostly not define real species in a view asfar paleobiological as possible, but only morphologicalgroups. As a result of the discussion below (see also theremarks about synonymy) the sample of the CheironMountain is finally assigned to Tornquistes helvetiae(Tornquist, 1894).Stratigraphic range : Middle Oxfordian, Plicatilis Zone,Vertebrale Subzone. Tornquistes helvetiae (Tornquist)is also present in the Antecedens Subzone.III. Discussion and new interpretationof the Tornquistes lineageThe problem of the species and the variability inTornquistes Lemoine, 1910As already been remarked, the main criteria usuallyadvocated in the literature to differentiate taxa of thegenus Tornquistes Lemoine, 1910 concern the thicknessof the section and the strength of the ornamentation. Thisobservation is accentuated as a result of the revision ofthe Tornquistes by Charpy (1976) then by Thierry &Charpy (1982). However the two parameters are bothoften linked and the role played by the shape of thesection in the specific differentiation among ammonitesis to put into perspective with application of covariationBuckman’s laws (see above). The strength and density

478 D. BertFig. 4 : Representive table of the morphodiversity (relative section and rib-index) occupied by different nominal species of TornquistesLemoine, 1910. Data taken from the literature and unpublished collects. The named “species” are all morphological variants ofone paleospecies : Tornquistes helvetiae (Tornquist, 1894).of the ornamentation and the width of the umbilicusare more or less directly associated to the thickness ofthe section by the expression of different mechanicaland biochemical constraints (Hammer & Bucher,2005 ; Guex et al., 2003). In addition to the BajocianSonninniidae studied by Westermann (1966), severalvery demonstrative examples have been given by Guexet al. (2003), Morard & Guex (2003), and Morard(2006) for the Domerian Amaltheus de Montfort,1808, and the Toarcian Osperleioceras Krimholtz,1957 and Dactylioceras Hyatt, 1867. Examples are alsoknown in the Oxfordian Cardioceratidae Hyatt, 1892(Marchand, 1977, 1986) and Gregoryceras Spath,1924 (Bert et al., 2003 ; Bert, 2004 ; Bert & Enay,2004 ; Bert et al., 2009). The laws of covariation of thecharacteristics are perfectly applicable to the case ofTornquistes Lemoine, 1910.The harvest of several very well dated Tornquistes in

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 479the Cheiron Mountain and other nearby localities of theAlpes-Maritimes (southeastern France, Fig. 1) is spreadfrom the Cordatum Subzone to the Antecedens Subzone.These collections were placed in parallel with specimensof literature as well as those from different localities andprivate collections (Poitou, Calvados, Burgundy, Alpesde-Haute-Provence,Drôme, Hautes-Alpes) : first for theLower Oxfordian (Arkell, 1946 [in 1934-1938] ; Gygiet al., 1994 ; Marchand et al., 2002 ; Quereilhacet al., 2009) and secondly for the Middle Oxfordien(Bourseau, 1977 ; Branger et al., 1995 ; Quereilhac,2000 ; Sequeiros, 1974 ; Thierry & Charpy, 1982pars). There are three main extreme morphologiesconnected by all intermediaries in the case of theTornquistes of the Plicatilis Biozone (the only enough -Fig. 4) : (1) the morphology with very thick section andwith a high average number of ribs (usually blunt) (=“tornquisti” type) ; (2) the morphology with compressedsection and numerous thin ribs (= “romani” type) ; and(3) the morphology with compressed section but withfewer robust ribs (= “helvetiae” type). The first typeis connected with the two others by the “liesbergense”and “oxfordiense” morphotypes. The second and thirdtypes are connected by the “multicostatum nodosum”morphotype which is figured here for comparison (Fig.5). Thus, although extreme morphologies seem verydifferent at first sight (for exemple Fig. 5 vs Pl. I, fig. 1a-b)in fact a large number of nominal species of Tornquistesactually correspond to different morphological variantsof the same paleobiological species. This possibilityhas been raised long ago by authors (de Loriol, 1896,p. 21-22 ; Douvillé, 1912, p. 53 ; Charpy, 1976, p.86, 143 ; Thierry & Charpy, 1982, p. 646-647 ; Gygiet al., 1994, p. 465). In this context, several taxa wereincorporated by Charpy (1976) and Thierry & Charpy(1982) as morphotypes of other “species” (helvetiae/kobyi and tornquisti/tuberculata).On the other hand, comparisons between the TornquistesFig. 5 : Tornquistes helvetiae (Tornquist, 1894), “multicostatum nodosum” type, specimen n°tal01 from Talant (Burgundy, France),C. Beaudoin’s collection.

480 D. Bertof different age permit to consider the relative height ofthe primary ribs point of bifurcation as the best criterionfor differentiation between samples. In that case, atevery time there was only one variable species and thiscriterion could potentially serves for a chronospecificdifferentiation (Fig. 6). The ribs point of bifurcation maybe located (1) relatively high between half and the upperthird of flanks (Praecordatum and Bukowskii subzones),(2) between the first quarter and half part of the height offlanks (Cordatum Subzone), or (3) around the base of theflanks (Vertebrale and Antecedens subzones). However,depending on the thickness of the ribs themselves andsometimes on their high attenuation in the lower part ofthe flanks it is not always possible to be very precise inthis positioning.Discussion about species of Tornquistes Lemoine,1910Ammonites hermione d’Orbigny, 1850 has been put intosynonymy of Tornquistes romani (Douvillé, 1912) byThierry & Charpy (1982) with reference to Article 23bof the International Code of Zoological Nomenclature(ICZN) that made the species of the d’Orbigny’sProdrome (1850) a nomen oblitum. This article has beenchanged in the 4th version of the ICZN (art. 23.2 and23.9) but the Ammonites hermione d’Orbigny remainsunusable : this species (of no type specimen have everbeen designed) is also species dubia. Most of the differentspecimens of the d’Orbigny’s collection classified underAmmonites hermione d’Orbigny have now disappearedand they are too small (10-25 mm) to ensure a reliabledetermination (Cottreau, 1927, p. 107-108, pl. 44, fig.6-7 et 8-9). They also belong from different levels andfrom different geographical origin localities.The bifurcation point of the main ribs on the typespecimenof Tornquistes helvetiae (Tornquist, 1894)is clearly located at the edge of the umbilical wall. Thestrong ornamentation and the compressed section areall features that plead for a synonymy with Tornquistesnicolisi (Parona in Nicolis & Parona, 1885). Theonly difference between the two type specimens of thesetaxa is the presence of trifurcated ribs in the latter but itis a highly variable feature among the Tornquistes and itcan not be considered here to differentiate species. Onthe other hand, if considering the morphological changesassociated with variation in thickness of the section as theexpression of intraspecific variability (see above) and theFig. 6 : Evolution of the umbilicus width and of the position of the primary ribs bifurcation point through time for the genus TornquistesLemoine, 1910.

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 481existence of many intermediaries between the extremes(Fig. 4), there is no reason to consider the nominaltaxa of the Plicatilis Biozone as belonging to severalspecies. Thus Tornquistes helvetiae (Tornquist, 1894),Tornquistes nicolisi (Parona in Nicolis & Parona,1885), Tornquistes multicostatum nodosum Thierry &Charpy, 1982, Tornquistes kobyi (de Loriol, 1896),Tornquistes liesbergensis (de Loriol, 1896), Tornquistestornquisti tuberculatum Thierry & Charpy, 1982,Tornquistes tornquisti (de Loriol, 1896), Tornquistesoxfordiensis (Tornquist, 1894) and Tornquistes romani(Douvillé, 1912) are morphological representativesof a single paleospecies and are to be considered assynonymous of Tornquistes helvetiae (Tornquist) (seeabove the remarks about synonymy for the taxonomicchoice).Tornquistes leckenbyi (Arkell, 1946) was doubtfullydated by Arkell (1946) of the Praecordatum Subzone.Thierry & Charpy (1982) have replaced this species inthe Bukowskii Subzone. This new datation is consistentwith the recent discovery of a specimen of the H.Châtelier’s collection (unpublished but visible to theURL : http ://www.ammonites.fr/Fiches/0492.htm) in thelevel of ferruginous ooids (H15) at Villers-sur-Mer in theVaches Noires cliff outcrop-section (Calvados, North-West of France). The bed H15 is very characteristicof the Bukowskii Biohorizon (see Bonnot, 1995, p.53-54). Two other specimens of the same species werediscovered by Ch. Cornago in the Blieux area (Alpesde-Haute-Provence,southeastern France). The mostcomplete is an adult microconch of about 130 mm indiameter (Fig. 7). Tornquistes leckenbyi (Arkell) ischaracterized by the primary ribs point of bifurcationFig. 7 : Tornquistes leckenbyi (Arkell, 1946), specimen unnumbered of the Ch. Cornago’s collection from Blieux (Alpes-de-Haute-Provence, southeastern France). The specimen was harvested with scree fauna of the Bukowkii Subzone (Cordatum Biozone,Lower Oxfordian).

482 D. Berthighly positioned between half and the upper third ofthe flanks. This criterion does not occur in the MiddleOxfordian Tornquistes (Fig. 6). The shell is usually moreevolute in Tornquistes leckenbyi (Arkell) regardless tothe scaphitoïde coiling of adult microconchs or variationsdue to the covariation laws of characteristics. Thespecimen of the H. Châtelier’s collection has the furtherinterest to present parabolic structures on the ribs like inTornquistes greppini (de Loriol, 1900) (PreacordatumSubzone, see Marchand et al., 2002).Four specimens of the Tornquistes represented byThierry & Charpy (1982, pl. 2, fig. 1b ; pl. 3, fig. 1 ; pl.12, fig. 1 ; pl. 13, fig. 1) have the same type of morphologyand ornamentation than Tornquistes leckenbyi (Arkell)with the bifurcation points located fairly high on theflanks. They have almost all been attributed to differentspecies and placed with doubts in the Plicatilis Biozone.But in accordance with this ornamental parameterthese specimens may actually come from the CordatumBiozone (Costicardia or Bukowskii subzone) especiallybecause their localities of origin include concentrated/condensed levels (Thierry, 1966, p. 649 ; Marchand& Pascal, 1979, p. 110 ; Thierry & Charpy, 1982,p. 634 ; Courville & Colin, 1997 ; Collin et al.,1999). This is particularly true with the type specimenof Tornquistes multicostatum multicostatum (Thierry &Charpy, 1982) (pl. 10, fig. 3 ; pl. 11, fig. 3) and someothers specimens of this taxon cited by Thierry &Charpy (1982). This identity would results in placingTornquistes multicostatum multicostatum (Thierry& Charpy) in synonymy with Tornquistes leckenbyi(Arkell) which both have already been close togetherby Thierry & Charpy (1982, p. 637). The remainingspecimens of the Plicatilis Biozone are more akin toTornquistes helvetiae (Tornquist, 1894) as designed inthis work : they represent the slender morphotype withcompressed section (“multicostatum nodosum” type inFig. 4).Tornquistes helveticus (Jeannet, 1951) of the CordatumSubzone of Aargau (Switzerland) was revised by Gygiet al. (1994) ; it is also known in the Cordatum Subzoneof the Cheiron Mountain (Alpes-Maritimes, southeasternFrance - unpublished data). From its general appearanceand the shape of the section, Gygi et al. (1994, p. 465)have considered the possibility of an eventual synonymyof this species with the Tornquistes helvetiae-kobyioxfordiensegroup [= Tornquistes helvetiae (Tornquist,1894), this work]. However, according to the stratigraphiclevel and the position of the primary ribs bifurcation pointbetween the first quarter to the mid-flanks the Jeannet’sspecies (1951) is located between Tornquistes leckenbyi(Arkell, 1946) and Tornquiste helvetiae (Tornquist,1894) as designed in this work (Fig. 6). This positionconfirms its status as independent species.In view of R. Enay (personal communication),Perisphinctes pancerii Gemmellaro, 1878 couldpossibly be a Tornquistes. This species was interpretedas a Rasenia Salfeld, 1913 (Eurasenia Geyer, 1961),a Lower Kimmeridgian Aulacostephanidae Spath,1924, by Oloriz in the Revision of the Gemmellaro’scollection (in Pavia & Cresta, 2002, p. 377-378). Infact, this species is only known with its type specimenwhich is from an unknown level of Sicily (Trapani), out ofthe habitual biogeographical of Rasenia (Hantzpergue,1989). The shape of the ornamentation, the whorl sectionand the uncoiling of the body-chamber are all featuresof Tornquistes. In this hypothesis, the type specimen ofPersiphinctes pancerii Gemmellaro should probably ofan Oxfordian age, but further data are still necessary tostatute.Origin and evolution of the Tornquistes lineageSince a long time ago it is universally recognized thatthe origin of the Oxfordian Tornquistes Lemoine, 1910is from the Callovian genus Pachyceras Bayle, 1875.Although some differences in the sutural line, bothgenus have a very strong morphological and ornamentalconvergence as the common uncoiling of the last whorlin the microconchs (Douvillé, 1912, p. 51 ; Charpy,1976, p. 84). The presence of parabolic structures andthe high position of the main ribs bifurcation point of theoldest Tornquistes are clearly of Perisphinctacea type.But additional researches at the top of the Callovian andin the Mariae Biozone are still required to consider allevolutionary trends related to the origin of the genusTornquistes Lemoine.Depending to the age of the samples of the genusTornquistes Lemoine it is possible to recognize astratigraphical polarity for the primary ribs bifurcationpoint position. From Lower Oxfordian to MiddleOxfordian the evolution of the Tornquistes graduallyproceeds in the relative decline of this point on the flanksand a discrete narrowing of the umbilicus (Fig. 6). Thusit is possible to define three, maybe four, successivechronospecies :1(?) - Tornquistes greppini (de Loriol, 1900) in thePraecordatum and Costicardia subzones (Mariae andCordatum biozones) ;2 - Tornquistes leckenbyi (Arkell, 1946) at least inthe Bukowskii Subzone (Cordatum Biozone of theLower Oxfordian). These species have the primary ribsbifurcation point located between half and the upper thirdof the flanks ;3 - Tornquistes helveticus (Jeannet, 1951) whichthe bifurcation point is located between half and thelower quarter of the flanks. This species is ranged inthe Cordatum Subzone (Cordatum Biozone, LowerOxfordien) ;4 - Tornquistes helvetiae (Tornquist, 1894) of thePlicatilis Biozone which the bifurcation point is locatedaround the base of the flanks.

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 483IV. Is Protophites Ebray, 1860 aPachyceratidae ?The strictly Oxfordian genus Protophites Ebray, 1860is not related to the Callovian genus OechoptychiusNeumayr, 1878 with which it presents a morphological(peristome) and stratigraphical relatively large hiatus.Moreover, according to Schweigert & Dietze(1998) Oechoptychius Neumayr would be a possiblemicroconch of Phlycticeras Hyatt, 1900 so ProtophitesEbray can not be included in the family OechoptychiidaeArkell, 1957 (= Strigoceratidae Buckman, 1924).Because of some morphological convergences, Enay(1977) then Bourseau (1977) have considered thepossibility of a dimorphism between TornquistesLemoine, 1910 and Protophites Ebray thereforeproposing it as a Pachyceratidae Buckman, 1918as Arkell (1957, p. L.298) then Callomon (inDonovan et al., 1981, p. 181) did. But Charpy (1976)then Thierry & Charpy (1982) were the first toconvincingly demonstrate the existence of a dimorphismin the genus Tornquistes Lemoine. They were also thefirst to have described and figured the macroconch of thisgenus which can grow quite large (D=300 mm) ; all theprevious depictions of literature are regarded as thoseof microconchs (120>D>160 mm). This dimorphism isalso well documented in the Cheiron Mountain sampleof the Arkelli Biohorizon (this work). Moreover, therelative height of the ribs bifurcation point is differentbetween the two genera : in Protophites Ebray it evolvesduring growth (but remains substantially around half ofthe flanks – Bert, 2003) unlike in Tornquistes Lemoinewhere it shows a stratigraphic polarity (this work).“Macrocephalites” greppini de Loriol 1900 (non1898) and “Sphaeroceras” chapuisi de Loriol, 1900were recently revised by Marchand et al. (2002) andwere both considered as dimorphs of the same species ofTornquistes Lemoine. Tornquistes greppini (de Loriol,1900) is from the Mariae Biozone (PraecordatumSubzone), making it the oldest Tornquistes known todate. As in Tornquistes leckenbyi (Arkell, 1946) theribs bifurcation point is fairly high on the flanks and thereare parabolic nodes on some ribs (cf. Marchand et al.,2002). It would have been tempting to consider the bothspecies as synonym on these criteria alone ; inasmuchthe de Loriol’s species has also been reported in theCosticardia Subzone (Enay, 1966, p. 142, 244 ; Charpy,1976, p. 137, pl. 3, fig. 5). But it still seems a bit prematurebecause Tornquistes greppini (de Loriol) is only knownas nuclei of small size. This fact is accentuated by thespecial preservation in the Renggeri marls where largefossils are usually absent. In contrast, complete adultsof “Sphaeroceras” chapuisi de Loriol do not seemsexceed 20 mm in diameter. In fact a number of featuresseparates the latter from the genus Tornquistes Lemoine :(1) a very much less size while the barely more recentTornquistes leckenbyi (Arkell) [m] are already of thesame order of diameter known in the Middle Oxfordiansamples (Fig. 7) ; (2) the length of the body-chamber isonly a half whorl in “Sphaeroceras” chapuisi de Loriolwhereas for the microconchs of Tornquistes (of any age)it is about three-quarters of a whorl ; (3) the existence of apreapertural constriction (Marchand et al., 2002, p. 472)is totally unknown in Tornquistes ; and (4) there are cleardifferences in the sutural line at the same diameter (deLoriol, 1900, fig. 10 vs Thierry & Charpy, 1982, fig.2a). In particular the external saddle of “Sphaeroceras”chapuisi de Loriol is clearly incised in the middle by asmall accessory lobe and it is much broader and shallowerthan in Tornquistes Lemoine. Similarly the internalsaddle of “Sphaeroceras” chapuisi de Loriol is wideand incised in the middle by a small accessory lobe whilein Tornquistes Lemoine the lobe U 2is directly broad anddeep. All this suggests that “Sphaeroceras” chapuisi deLoriol is neither the microconch of Tornquistes greppini(de Loriol) nor a Tornquistes. However, in agreementwith G. Schweigert (in Marchand et al., 2002) allthese peculiar characteristics compare “Sphaeroceras”chapuisi de Loriol with the genus Protophites Ebray,1860 of which this species would be the currentlyoldest known representative. In this regard some of theProtophites represented by Jeannet (1951, pl. 31, fig. 10and 11) show a very similar morphology of the uncoiledbody chamber that is not completely folded-down ontothe inner whorls. Note that this gradual “fold-down” ofthe body chamber is one of the main evolutionary featuresof the genus Protophites Ebray over time (Bert, 2003).Even if Protophites Ebray is not the microconch ofTornquistes Lemoine there are certain morphologicalconvergences between the both genera, so in waiting ofmore data Protophites Ebray should be placed in thePachyceratidae Buckman, 1918 in which it could haveits origin (?). But this position remains to be confirmed.In particular, the presence of parabolic nodes on the ribsis a feature of Perisphictaceae Steinmann, 1890.V. ConclusionsEven if the genus Tornquistes Lemoine, 1910 is stillvery rare the study of the sample collected in the CheironMountain (Alpes-Maritimes, southeastern France) is anew contribution to knowledge of the Arkelli BiohorizonSubtethyan ammonite-fauna at the top of the VertebraleSubzone (Plicatilis Biozone, Middle Oxfordian). Thedeposits of this age are indeed uncommon in WesternEurope and the top of the Vertebrale Subzone (ArkelliBiohorizon) is still paleontologicaly relatively unknown.On the other hand, this sample of Tornquistes Lemoinewas collected in a single level and it has revealed itshomogeneity whereas its morphology is located betweentwo nominal and classical species of literature : Tornquistestornquisti (de Loriol, 1896) and Tornquistes oxfordiense(Tornquist, 1894). The study of the bibliography

484 D. Bertand of new specimens now allows completing ourunderstanding of the variability of this group for thePlicatilis Biozone (Middle Oxfordian). It appears that thefeatures usually taken into account to establish specificdenominations (section thickness, strength and densityof the ornamentation, widening of the umbilicus) are infact interrelated and are manifestations of the “normal”variability in a single species of Tornquistes (laws ofcovariation of characteristics) taken throughout itspaleogeographical range. However, this variability seemsnot necessarily uniform from one area to another andpaleoecological factors could be envisaged to explain theabsence of certain morphological type in certain places atcertain times. Thus the absence of the morphology withcompressed section at the top of the Vertebrale Subzonein the Cheiron Mountain could possibly be the result of amore distal environment than in the Burgundy platformat the same age, or at the base of the Antecedens Subzonein other localities of the Alpes-Maritimes where thistype of morphology is more frequent. Specific collectsare still needed to study the evolution of this variability,particularly in the Lower Oxfordian. Taxonomically,there is now no reason not to consider all the nominaltaxa described in the literature in the Plicatilis Biozoneas a single paleobiological species : Tornquistes helvetiae(Tornquist, 1894).On the other hand, the stratigraphic polarity of a hithertocharacter seldom considered by the authors (the positionof the primary ribs bifurcation point) now allows definingat least three, maybe four, successive chronospecies fromLower to Middle Oxfordian : (?) Tornquistes greppini (deLoriol, 1900), Tornquistes leckenbyi (Arkell, 1946),Tornquistes helveticus (Jeannet, 1951) and Tornquisteshelvetiae (Tornquist, 1894).Finally, the study of the sample of Tornquistes from theCheiron Mountain confirms the findings of Charpy(1976) and Thierry & Charpy (1982) concerningthe dimorphism in this genus. Although ProtophitesEbray has often been regarded as a microconch, itis clearly not the one of Tornquistes Lemoine. Notethat this micromorphic genus has perhaps simply notenough visible differences between its dimorphs to bedifferentiable only on the basis of the fossilized shell justas observed in other forms suddenly emerged by processesof progenesis type. The oldest species of Protophites nowrecognized is Protophites chapuisi (de Loriol, 1900) atthe top of the Mariae Biozone (Praecordatum Subzone).The apparent hiatus at the base of the Cordatum Biozoneis probably due to a lack of observation of these formswhich are still very rare.AcknowledgmentsI would especially like to thank Mrs. Chantal Cornago,Mr. Jean Arbault, Cyril Beaudoin, Pierre-YvesBoursicot, Patrick Branger, Gérard Delanoy, Jean-Louis Latil and Albert Magnin for the help they haveprovided and/or for the loan of their specimens. Mr. AbelPrieur gave me broad access to the collections of theFaculty of Science of Lyon which he is responsible, heis warmly thanked. I also express my thanks to RaymondEnay for his constructive remarks on the manuscript.ReferencesArkell, W.J. (1934-1948) - A monograph of the EnglishCorallian Beds. Paleontological Society, London : 420 pp.Arkell, W.J. (1950) - A classification of the Jurassicammonites. Journal of Palaeontology, London, 24(3) :354-364.Arkell, W.J. (1952) - Jurassic ammonites from Jebel Tuwaiq,Central Arabia. Philosophical Transaction of the RoyalSociety of London, Series B, Biological Sciences, 236, B.633 : 231-313.Arkell, W.J., B. Kummel & C.W. Wright (1957) -Mesozoic Ammonoidea. In : Moore, R.C. (Ed.), Treatiseon Invertebrate Paleontology. Part L, Mollusca 4,Cephalopoda, Ammonoidea. The Geological Society ofAmerica and the University of Kansas Press, New Yorkand Lawrence : 80-437.Bert, D. (2003) - Etude de Protophites vannii sp. nov.(Ammonoidea), sous-zone à Cardioceras vertebrale,Oxfordien moyen, et évolution du genre ProtophitesEbray, 1860. Riviéra Scientifique, Nice, 87 : 69-84.Bert, D. (2004) - Révision, étude systématique et évolutiondu genre Gregoryceras Spath, 1924 (Ammonoidea,Plate IAll specimens are X1. When possible an arrow points out the beginning of the body-chamber.Tornquistes helvetiae (Tornquist, 1894).Fig. 1a-b : Specimen n°bez.mg.ox32 [m] from the Arkelli Biohorizon (top of the Vertebrale Subzone) of the CheironMountain (Alpes-Maritimes, southeastern France), bed 100d. A. Magnin’s collection.Fig. 2a-b : Specimen n°AL97 [M] from the Arkelli Biohorizon (top of the Vertebrale Subzone) of the Cheiron Mountain(Alpes-Maritimes, southeastern France), bed 100d. D. Bert’s collection.

Plate I1b1a2 cm2a2b

486 D. BertOxfordien). Annales du Muséum d’Histoire naturelle deNice 19 : 1-183.Bert, D. (2006) - Sur quelques Céphalopodes de la collectionSipp. Minéraux et Fossiles, Cedim, Paris, 350 : 24-39.Bert, D. (2008) - Etude de Paraspidoceras colloti Zeiss, 1962(Aspidoceratidae Zittel, 1895, Ammonitina) au sommetde la sous-zone à Vertebrale (Oxfordien moyen, zone àPlicatilis) du Sud-Est de la France. Revue de Paléobiologie,Genève, 27(2) : 335-356.Bert, D. & A. Bonnot (2004) - Etude paléobiologiqued’une population d’Euaspidoceras davouxi sp. nov.(Apidoceratidae Zittel, 1895, Ammonitina) du sommetde la sous-zone à Vertebrale (Oxfordien moyen, zoneà Plicatilis) dans le sud-est de la France. Revue dePaléobiologie, Genève, 23(1) : 81-98.Bert, D. & R. Enay, (2004) - Les Gregoryceras (Ammonitina,Oxfordien moyen) de la Cluse de Chabrières (sudestde la France) : étude paléobiologique et nouvellesinterprétations. Revue de Paléobiologie, Genève, 23 : 441-461.Bert D., R. Enay & F. Atrops (2009) - Les Gregoryceras(Ammonitina) de l’Oxfordien moyen terminal et supérieurtéthysien : révision systématique, biostratigraphie etévolution. Géobios, Villeurbanne, 42 (4) : 451-493.Bert, D., D. Marchand, R.A. Gygi & G. Delanoy(2003) - Gregoryceras defayi sp. nov. et Gregorycerastenuisculptum Gygi, 1977 : deux espèces successivesde la sous-famille des Peltoceratinae Spath, 1924(Ammonitinae, Aspidoceratidae Zittel, 1895) del’Oxfordien moyen. Eclogae geologicae Helvetiae, Basel,96 : 475-493.Besnosov, N.V. & I.A. Michailova (1983) - The evolutionof the Jurassic-Cretaceous ammonoids. Doklady AkademiiNauk SSSR, 269 : 733-737 [in russian].Besnosov, N.V. & I.A. Michailova (1991) - The higher taxaof Jurassic and Cretaceous Ammonitida. PaleontologicalJournal, 25 : 1-19.Bonnot, A. (1995) - Les Aspidoceratidae d’Europe occidentaleau Callovien supérieur et à l’Oxfordien inférieur. Thèse 3 ecycle, Dijon (unpublished) : 537 p.Bourseau, J.-P. (1977) - L’Oxfordien moyen à nodules des“Terres Noires” de Beauvoisin (Drôme) (Ammonitinade la zone à Plicatilis, paléontologie et biostratigraphie ;milieu de sédimentation et genèse des nodules carbonatés).Nouvelles Archives du Muséum d’Histoire Naturelle deLyon, 15 : 116 p.Bourseau, J.-P., J. Charvet & R. Enay (1979) - Fauneoxfordienne dans les Dinarides internes au nord deSarajevo (Bosnie orientale, Yougoslavie). Géobios,Villeurbanne, 12(1) : 123-131.Branger, P., P. Nicolleau & A. Vadet (1995) - Lesammonites et les oursins de l’Oxfordien du Poitou. Muséede Niort et APGP Poitou-Charentes-Vendée : 1-149.Buckman, S.S. (1887-1907) - A monograph of the ammonitesof the Inferior Oolite Series. Palaeontological Society,London : 1-456.Callomon, J.H. (1981) - Dimorphism in ammonoids. In :House M. R. & Senior J. R. (Eds.). The Ammonoidea.The Systematics Association, Academic Press, Spec. Publ.,18 : 257-273.Cariou, E., R. Enay, F. Atrops, P. Hantzpergue, D.Marchand & M. Rioult (1997) - Oxfordien. In :Cariou, E. & P. Hantzpergue (Coords). Biostratigraphiedu Jurassique Ouest-Européen et Méditerranéen : zonationsparallèles et distribution des invertébrés et microfossiles.Bulletin du Centre de Recherche Elf Exploration-Production, 17 : 79-86.Charpy, N. (1976) - Le genre Pachyceras (Ammonitina,Pachyceratidae, Callovien supérieur à Oxfordien moyen)– Systématique, phylogénie, paléobiologie, stratigraphie.Thèse de Doctorat, Université de Bourgogne (unpublished),Dijon : 160 p.Charpy, N. & J. Thierry (1977) - Dimorphisme etpolymorphisme chez Pachyceras Bayle (Ammonitina,Stephanocerataceae) du Callovien supérieur (Jurassiquemoyen). Haliotis, 6 : 185-218.Colin, P.-Y., Ph. Courville, J.-P. Loreau, D. Marchand& J. Thierry (1999) - Séries condensées et indice depréservation d’unité biostratigraphique : exemple del’ennoiement de la plate-forme nord-bourguignonne(France) au Callovo-Oxfordien. Comptes Rendus àl’Académie des Sciences, Paris, Sciences de la Terre et desplanètes, 328 : 105-111.Cottreau, J. (1927) - Types du prodrome de paléontologiestratigraphique universelle de d’Orbigny - II. Annales dePaléontologie, Paris, 16(2-3) : 101-132.Courville, Ph. & P.-Y. Colin (1997) - La série du Callovienet de l’Oxfordien de Veuxhaulles (Châtillonais, CôtePlate IIAll specimens are X1. When possible an arrow points out the beginning of the body-chamber.Tornquistes helvetiae (Tornquist, 1894).Fig. 1 : Specimen n°AA06 [M] from the Arkelli Biohorizon (top of the Vertebrale Subzone) of the Cheiron Mountain(Alpes-Maritimes, southeastern France), bed 101. D. Bert’s collection.Fig. 2 : Specimen n°AL09 from the Arkelli Biohorizon (top of the Vertebrale Subzone) of the Cheiron Mountain(Alpes-Maritimes, southeastern France), bed 100d. D. Bert’s collection.Fig. 3 : Specimen n°AA98 [M] from the Arkelli Biohorizon (top of the Vertebrale Subzone) of the Cheiron Mountain(Alpes-Maritimes, southeastern France), bed 100d. D. Bert’s collection.Fig. 4a-c : Specimen n°AP41 from the Arkelli Biohorizon (top of the Vertebrale Subzone) of the Cheiron Mountain(Alpes-Maritimes, southeastern France), bed 100d. D. Bert’s collection.

Plate II2134a2 cm4b4c

488 D. Bertd’Or) : problèmes de datation, de géométrie et depaléoenvironnements dans une série condensée. BulletinScientifique de Bourgogne, Dijon, 49 : 29-43.Courville, Ph., J. Thierry & E. Cariou (1998) - Modalitésévolutives du genre Bullatimorphites (Ammonitina)au Bathonien-Callovien (Jurassique moyen) en Europeoccidentale. Comptes Rendus à l’Académie des Sciences,Paris, Sciences de la Terre et des planètes, 328 : 59-65.Donovan, D.T., J.H. Callomon & M.K. Howarth (1981) -Classification of the Jurassic Ammonitina. In : House,M. R. & J. R. Senior (Eds.). The Ammonoidea. TheSystematics Association, Academic Press, Spec. Publ. 18 :101-155.Douvillé, R. (1912) - Etudes sur les Cardiocératidés de Dive,Villers-sur-Mer et quelques autres gisements. Mémoires dela Société Géologique de France, Paris, 45 : 89 pp.Enay, R. (1966) - L’Oxfordien dans la moitié sud du Jurafrançais. Etude stratigraphique. Nouvelles Archives duMuséum d’Histoire Naturelle, Lyon, 8(2) : 323 p.Enay, R. (1977) - A propos du dimorphisme chez lesammonites jurassiques. Quelques réflexions. Colloquesur le Polymorphisme chez les Invertébrés, Dijon, 1975.Haliotis 6 (1976), 96-118.Gil, G.A., J. Thierry & H. Tintant (1985) - Ammonitescalloviennes du Sud d’Israël : systématique, biostratigraphieet paléobiogéographie. Géobios, Villeurbanne, 18(6) : 705-751.Głowniak, E. (2000) - The Platysphinctes immigration eventin the Middle Oxfordian of the Polish Jura Chain (CentralPoland). Acta Geologica Polonica, 50(1) : 143-160.Guex, J., A. Koch, L. O’Dogherty & H. Bucher (2003) -A morphogenetic explanation of Buckman’s law ofcovariation. Bulletin de la Société Géologique de France,Paris, 174(6) : 603-606.Gygi, R.A., D. Marchand & J. Thierry (1994) - Tornquisteshelveticus (Jeannet, 1951) (Ammonitina, Pachyceratidae)de l’Oxfordien inférieur du Jura Suisse ; Nom. nov. pro« Herznachites » helveticus Jeannet, 1951. Géobios,Villeurbanne, 27(4) : 459-466.Hahn, W. (1971) - Die Tulitidae S. Buckman, SphaeroceratideS. Buckman und Clydoniceratidae S. Buckman(Ammonoidea) des Bathoniums (Brauner-Jura epsilon)im südwestdeutschen Jura. Jahreshefte des GeologischenLandesamt Baden-Würtemberg, 14 : 55-122.Hammer, Ø. & H. Bucher (2005) - Buckman’s first law ofcovariation – a case of proportionality. Lethaia, Oslo, 38 :67-72.I.C.Z.N. (International Commission on ZoologicalNomenclature) (1999) - International Code of ZoologicalNomenclature, 4th ed. International Trust for ZoologicalNomenclature, London, 29 : 306 p.Hantzpergue, P. (1989) - Les ammonites kimmeridgiennesdu haut-fond d’Europe occidentale. Biochronologie,systématique, paléobiogéographie. Cahiers dePaléontologie, CNRS, Paris : 428 p.Jeannet, A. (1951) - Stratigraphie und palaeontologiedes oolithischen Eisenerzlagers von Herznach undseiner Umgebung. Beiträge zur Geologie der SchweizGeotechnische, Berne, 13(5) : 354 p.Krishna, J. & J. Thierry (1987) - Discovery of the genusErymnoceras from the Middle Callovian of Kachchh,Western India : paleontological, stratigraphical andpaleobiogeographical implications. Newsletter onStratigraphy, Berlin, Stuttgart, 17(2) : 71-78.Lominadzé, T.A. (1982) - Les Ammonitidae calloviennesdu Caucase. Académie des Sciences de Géorgie, SSR,Tbilissi : 272 p. [in russian].Loriol, Ch. de (1896) - Etude sur les mollusques etbrachiopodes de l’Oxfordien supérieur et moyen du JuraBernois. Mémoires de la Société Paléontologique Suisse,Genève, 23 : 97 p.Mangold, Ch. (1988) - Les Pachyerymnoceras (Pachyceratidae,Perisphictaceae, Ammonites) du Callovien moyen etsupérieur de la région de Saida (Algérie occidentale).Origine phylétique et biogéographique des Pachyceratidae.Géobios, Villeurbanne, 21(5) : 567-609.Marchand, D. (1977) - Quelques précisions sur lepolymorphisme dans la famille des CardioceratidaeDouvillé (Ammonoidea). Haliotis, Dijon, 6 : 119-140.Marchand, D. (1986) - L’évolution des Cardioceratinaed’Europe occidentale dans leur contexte paléobiologique(Callovien supérieur-Oxfordien moyen). Thèse deDoctorat, Université de Bourgogne (unpublished), Dijon :603 p.Marchand, D. & A. Pascal (1979) - Précisionsstratigraphiques et sédimentologiques sur la limite Dogger-Malm en Haute-Marne (région de Latrecey). Bulletin dela Société des Sciences Naturelle et d’Archéologie de laHaute-Marne, 21(5) : 101-112.Marchand, D., Ph. Courville, A. Bonnot, J. Rossi &Qu. Scoufflaire (2002) - Very small Ammonites(Micromorphs) from Lower Oxfordien Marls (MariaeZone). In : Summesberger, H., K. Histon & A. Daurer(Eds). Cephalopods - Present and Past. Abhandlungen derGeologischen Bundesandstalt, Wien, 57 : 467-478.Mayr, E. (1974) - Populations, espèces et évolution. Hermann,Paris : 496 p.Morard, A. (2006) - Covariation patterns in ammonoids :observations, models, and open questions. 4th SwissGeoscience Meeting, Bern 2006.Morard, A. & J. Guex (2003) - Ontogeny and covariationin the Toarcian genus Osperleioceras (Ammonoidea).Bulletin de la Société géologique de France, 174, 607-615.Nicolis, E. & C.F. Parona (1885) - Note stratigrafiche epaleontologiche sul Giura superiore della Provincia diVerona. Bolletino della Società Geologica Italiana, 4 : 105p.Orbigny, A. d’ (1850) - Prodrome de paléontologiestratigraphique universelle des animaux mollusques etrayonnés. Masson, Paris : 432 p.Page, K.N. (1993) - Mollusca : Cephalopoda (Ammonoidea,Ancyloceratina). In : Benton, J.M. (Ed.). Fossil Record 2.Chapman & Hall : 213-228.Page, K.N. (1996) - Mesozoic ammonoids in space and time.In : Landman, N. H., K. Tanabe & R. A. Davis (Eds).Ammonoid Paleobiology. Plenum Press : 755-794.Pavia, G. & S. Cresta (2002) - Revision of JurassicAmmonites of the Gemmellaro Collections. Quadernidel Museo Geologico “G. G. Gemmellaro”. Dipartimentodi Geologia e Geodesia, Università di Palermo : 401 p.Quereilhac, Ph. (2000) - … A propos de quelques ammonitesrécoltées dans l’Oxfordien du Poitou. Ph. Quereilhac Ed.,Poitier : 207 p.Quereilhac, Ph., D. Marchand, R. Jardat, A. Bonnot,D. Fortwengler & Ph. Courville (2009) - La fauneammonitique des marnes à fossiles ferrugineux de la régionde Niort, France (Oxfordien inférieur, Zone à Cordatum,

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 489Sous-Zone à Cordatum). Carnets de Géologie / Notebookson Geology, Brest, Article 2009/05 (CG2009_A05).Roman, F. (1938) - Les ammonites jurassiques et crétacées.Essai de Généra. Masson et Cie., Paris : 607 p.Schindewolf, O. (1923) - Über die Ausgestaltung derLobenlinie bei den Neoammonoidea. Centralbl. fürMineralogie, Geologie und Paläontologie : 337-370.Schindewolf, O. (1963) - Studien zur Stammesgeschichteder Ammoniten. III. Abhandlungen der Matematish-Naturwissenschaftlichen Klasse Jahrgang, Wiesbaden, 6 :147 pp.Schweigert, G. & V. Dietze (1998) - Revision der dimorphenAmmonitengattung Phlycticeras Hyatt - OechoptychiusNeumayr (Strigoceratidae, MittelJura). StuttgarterBeiträge zur Naturkunde, Serie B, 269 : 60 p.Sequeiros, L. (1974) - Paleobiogeografía del Calloviense yOxfordiense en el sector central de la Zona Subetica II.Tesis Doctorales, Universidad de Granada : 361 p.Sturani, C. (1967) - Ammonites and stratigraphy of theBathonian in the Digne-Barrême area (South-easternFrance, dept. Basses-Alpes). Bolletino della SocietàPaleontologica Italiana. 5(1) : 3-57.Thierry, J. (1966) - Analyse stratigraphique de la sérieBathonien-Oxfordien du Châtillonnais. Bulletin de laSociété Géologique de France, Paris, (7), 8 : 642-651.Thierry, J. & N. Charpy (1982) - Le genre Tornquistes(Ammonitina, Pachyceratidae) à l’Oxfordien inférieuret moyen en Europe occidentale. Géobios, Villeurbanne,15(5) : 619-677.Tornquist, A. (1894) - Ueber Macrocephaliten im Terrainà-Chailles.Abhandlungen der Schweizerischenpaläontologischen Gesellshaft, Zürich, 21 : 31 p.Westermann, G.E.G. (1956) - Philogenie derStephanocerataceae und Perisphinctaceae des Dogger.Neues Jahrbuch für Geologie und PaläontologieAbhandlungen, Stuttgart, 103 : 233-279.Westermann, G.E.G. (1966) - Covariation and taxonomy ofthe Jurassic ammonite Soninia adicra (Waagen). NeuesJahrbuch für Geologie und Paläontologie Abhandlungen,Stuttgart : 124 : 289-312.Accepté décembre 2009