VOL. 28, N° 2, 2009 Revue De Paléobiologie, Genève (Décembre 2009) 28 (2) : 471-489 ISSN 0253-6730

1661-5468

VOL. 28, N° 2, 2009 Revue de Paléobiologie, Genève (décembre 2009) 28 (2) : 471-489 ISSN 0253-6730

Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 (Pachyceratidae, Ammonitina) with the exemple of the Vertebrale Subzone sample (Middle Oxfordian) of southeastern France

Didier Bert*, 1

Abstract The 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 and classical species of literature : Tornquistes tornquisti (de Loriol) and Tornquistes oxfordiense (Tornquist). It appears that the features usually taken into account to establish specific denominations in this genus (whorl section thickness, strength and density ofthe ornamentation, widening of the umbilicus) are in fact manifestations of the laws of covariation of the characteristics, and the extreme morphologies are interrelated by all intermediaries. There is now no taxonomical reason not to consider all the nominal taxa described in the Plicatilis Biozone as a single paleobiological species : Tornquistes helvetiae (Tornquist). On the other hand, the stratigraphic polarity of the position of the primary ribs point of bifurcation (which decreases through time) is a major evolutionary feature in Tornquistes. 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, although Protophites Ebray has often been regarded as a microconch, it is clearly not the one of Tornquistes. The oldest species of Protophites now recognized is Protophites chapuisi (de Loriol) at the top of the Mariae Biozone (Praecordatum Subzone).

Key words Ammonoidea, Tornquistes, Middle Oxfordian (Upper Jurassic), Arkelli Biohorizon, intraspecific variability, evolution, palaeobiology, Southeastern France.

Résumé Discussion, évolution et nouvelle interprétation des Tornquistes Lemoine, 1910 (Pachyceratidae, Ammonitina) avec l’exemple de l’échantillon de la sous-zone à Vertebrale (Oxfordien moyen) du sud-est de la France. – L’étude de l’échantillon de Tornquistes Lemoine 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 classiques de la littérature : Tornquistes tornquisti (de Loriol) et Tornquistes oxfordiense (Tornquist). Il apparaît que les caractères longtemps pris en compte pour établir des coupures spécifiques dans ce genre (épaisseur de tour, vigueur et densité de l’ornementation, ouverture de l’ombilic) sont en fait la manifestation des lois de covariation des caractères, et les morphologies extrêmes sont reliées entre elles par tous les intermédiaires. Sur le plan taxinomique, il n’existe à présent aucune raison de ne pas considérer tous les taxons nominaux décrits 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 décroît au 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) Tornquistes helveticus (Jeannet) et (4) Tornquistes helvetiae (Tornquist). Enfin, si Protophites Ebray a souvent été considéré comme une forme microconque, il n’est clairement pas le dimorphe de Tornquistes. La plus ancienne espèce de Protophites à présent reconnue est Protophites chapuisi (de Loriol), au sommet de la biozone à Mariae (Oxfordien inférieur).

Mots-clés Ammonoidea, Tornquistes, Oxfordien moyen (Jurassique supérieur), Biohorizon à Arkelli, Variabilité intraspécifique, Evolution, Paléobiologie, sud-est de la France.

I. Introduction recent works made in the Cheiron Mountain area (Alpes- Maritimes, southeastern France - Fig. 1) (Bert, 2003, This work is a further contribution to the study of the 2004, 2008 ; Bert et al., 2003 ; Bert & Bonnot, 2004). Subtethyan ammonite fauna of the Arkelli Biohorizon The genus Tornquistes Lemoine, 1910 is very scarce in at the top of the Vertebrale Subzone (Plicatilis Biozone, the Arkelli Biohorizon of this locality since it represents Middle Oxfordian). This research is a continuation of only 0.69 % of the total faunal ammonite (see Bert et al.,

* Corresponding address : Place de l’Eglise, F-04170 La Mure-Argens, France ; [email protected] 1 Université de Bourgogne, Laboratoire Biogéosciences, UMR CNRS 5561, 6 bd Gabriel, F-21000 Dijon, France. 472 D. Bert

Fig.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 collected purely descriptive point of view, it is much less in terms in a single layer (see op. cit. for the representation of the of paleobiology (Thierry & Charpy, 1982, p. 645-646). outcrop-section). Under these conditions no real biometric In fact by the Gause principle of competitive exclusion study could be undertaken. But due to their morphological it appears improbable that so many similar species that homogeneity and their isochrony all the specimens were potentially occupied the same ecological niche have been treated as one sample. The biostratigraphic framework coexisted such a long time without competition (Mayr, used for this work (Lower and Middle Oxfordian) is 1974, p. 48-49). This fact has led these authors to group that proposed by Cariou et al. (1997) and ammended some of the literature’s “species” together as variants of by Bert (2004, p. 11-12, fig. 1) especially when using other taxa. the Arkelli Biohorizon (Głowniak, 2000) at the top of The goals of the present work are to study the Cheiron the Vertebrale Subzone, and the overlying Antecedens Mountain sample of Tornquistes, to clarify its taxonomic Biohorizon at the base of the Antecedens Subzone. position in relation to the literature nominal species, The genus Tornquistes Lemoine, 1910 was previously and to verify if these taxa have a real paleobiological revised by Charpy (1976) then by Thierry & Charpy legitimacy from the variability (studied in the literature (1982). These autors have studied a total of over and unpublished datas). For this purpose a review of new 200 specimens divided into nine morphological nominal or currently accepted criteria for the characterization of groups for the single Plicatilis Biozone. Nevertheless, these taxa was performed. Finally, the taxonomic and the significant statistical analysis did not permit them to evolutionary implications are discussed. establish any clear division between most of these taxa. If this taxonomic multiplicity proves satisfactory of a Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 473

II. The Tornquistes at the top of the Lemoine, 1910 (Marchand et al., 2002 ; this work). Vertebrale Subzone of southeastern The presence of such parabolic nodes is clearly not a France Stephanocerataceae feature but rather Perisphinctaceae.

Order Ammonoidea Zittel, 1884 Suborder Ammonitina Hyatt, 1889 Family Pachyceratidae Buckman, 1918 Superfamily Perisphinctaceae Steinmann, 1890 Genus Tornquistes Lemoine, 1910

The classification of the family Pachyceratidae Type species : Macrocephalites helvetiae Tornquist, Buckman, 1918 has been problematic for a long time. 1894 in Tornquist, 1894, p. 8-10, pl.1, fig. 1a-d. For some authors it should be classified within the The specimen n° J19574 (coll. Basel Natural History Stephanocerataceae Neumayr, 1875 (Douvillé, 1912 ; Museum) from Anvill (Swiss) was featured by Charpy Arkell, 1950, 1952 ; Arkell et al., 1957 ; Charpy, (1976) as a neotype of Tornquistes helvetiae (Tornquist, 1976 ; Bourseau, 1977 ; Charpy & Thierry, 1977 ; 1894). But this designation is not valid because this thesis Thierry & Charpy, 1982 ; Besnosov & Michailova, remains unpublished. Moreover, this specimen has been 1983, 1991 ; Gil et al., 1985 ; Krishna & Thierry, objected as a neotype by Bourseau et al., 1979 because 1987). So for Arkell (1950, and in Arkell et al., of too large ornamental differences from the original 1957) the Pachyceratinae are Cardioceratidae Hyatt, type-specimen. The same specimen was included in the 1892 intermediate between the Cadoceratinae Hyatt, morph kobyi de Loriol, 1896 by Thierry & Charpy 1900 and the Cardioceratinae Hyatt. On the other hand (1982, p. 633, pl. 2, fig. 1), therefore it was not proposed Arkell proposes the Tulitidae Buckman, 1921 as again as a neotype of Tornquistes helvetiae (Tornquist). ancestors of the Pachyceratidae and he classified them But in agreement with ornamental parameters (height of directly between the Sphaeroceratidae Neumayr, 1875 the bifurcation point of the ribs over half of the flanks - see discussion) this specimen is probably not of the and the Macrocephalitidae Buckman, 1922. In contrast, for other authors the Pachyceratidae schould Tornquist’s species neither of the de Loriol’s one : it could be in fact older than the Plicatilis Biozone. In be classified within the Perisphinctaceae Steinmann, addition the Bukowkii and Costicardia subzones (Lower 1890 (Westermann, 1956 ; Schindewolf, 1963 ; Oxfordian) are also both represented in the origin Sturani, 1967 ; Callomon, 1981 ; Donovan et al., locality of the Anvill specimen (Thierry & Charpy, 1981 ; Lominadzé, 1982 ; Mangold, 1988 ; Page, 1982, p. 634, 645). In that case this specimen is rather a 1993, 1996 ; Courville et al., 1998). Sturani (1967) Tornquistes leckenbyi (Arkell, 1946) (see below). also suggested an origin of the Pachyceratidae among the Tulitidae probably derived from the Zigzagiceratinae Remark on subgenera of Tornquistes Lemoine, 1910 Buckman, 1920. For Callomon (1981), followed From their morphological and biometric study Thierry in this by Mangold (1988), the Pachyceratidae & Charpy (1982) proposed to divide the genus suddently appear from the subboreal Perisphinctidae Tornquistes into two subgenera : Tornquistes Lemoine, Steinmann, 1890 (Grossouvrinae Spath, 1931) in 1910 and Pachytornquistes Thierry & Charpy, 1982. the Middle Callovian. Finally Lominadzé (1982) In practice these two subgenera are mainly distinguished proposes an origin of the Pachyceratidae within the by the thickness of their section and the strength of Proplanulitinae Buckman, 1921. On the other hand, their ornamentation. These features are also commonly Schindewolf (1923) studied the ontogeny of the suture used to differentiate the taxa of this group. However line in ammonites, and he founds that the introduction Westermann (1966) used Buckman’s work (1892 in his of umbilical lobes in the Stephanocerataceae shows the work of 1887-1907) on the Sonninnidae (early Bajocian), characteristic appearance of an additional accessory lobe : and he clarified in ammonites the “laws” of covariation, the internal lateral lobe Un. But this lobe is absent in both basing mainly on the relationship between the width of the Pachyceratidae and Tulitidae as in the Perisphinctaceae. section and the strength of the ornamentation. Since then, This led Schindewolf in 1963 (following Westermann, numerous studies have demonstrated that Buckman’s 1956, p. 9) to classify these families together within “First Law” can be extended to ammonites ranging in age the Perisphinctaceae. Courville et al. (1998) suggest from Paleozoic to Cretaceous (see Morard & Guex, Bullatimorphites Buckman, 1921 as the oldest Tulitidae 2003, tab. 1 for a summary). It appears that these laws because (p. 61-62) « d’après la morphologie de la ligne of covariation are also applicable for the Tornquistes. In de suture et des tours internes, Hahn (1971) enracine le that case the distinction into different subgenera based genre dans un ancêtre « périsphinctoïde » (Zigzagiceras solely on these variable features (thickness of section / ou Procerozigzag) du Bathonien inférieur ». One can strength of ornamentation) becomes purely typological. also note the presence of parabolic structures in the This is what finally emerges of the revision of Thierry Tulitidae at least from the lower Bathonian (Courville & Charpy (1982) whose recognize the existence of et al., 1998 ; P. Branger, personal communication) like many intermediate forms between the extremes. So these (but very rarely) in the Lower Oxfordian Tornquistes subgenera are not used here. 474 D. Bert

Comments on the laws of covariation of the characteristics p. 641-643, pl. 1, fig. 3 ; pl. 5, fig. 1-2a-b ; pl. 8, applied to the differents species of Tornquistes and their fig. 1 ; pl. 9, fig. 3 ; pl. 13, fig. 2. consequences are developed in the discussion. 1982. Tornquistes (Pachytornquistes) tornquisti tuberculatum nov.– Thierry & Charpy, p. 643-644, pl. 5, fig. 3 ; pl. 7, fig. 3 ; pl. 9, fig. 2. Tornquistes helvetiae (Tornquist, 1894) 1982. Tornquistes (Tornquistes) romani (Douvillé, Pl. I and II 1912).– Thierry & Charpy, p. 630-632, pl. 1, fig. 1 ; pl. 2, fig. 3 ; pl. 3, fig. 2 ; pl. 4, fig. 1a-b ; pl. Synonymy 7, fig. 2 ; pl. 9, fig. 1 ; pl. 10, fig. 2. 1885. Aspidoceras nicolisi sp. nov.– Parona in Nicolis pars 1982. Tornquistes (Tornquistes) helvetiae helvetiae & Parona, p. 39, pl. 1, fig. 5. (Tornquist, 1894).– Thierry & Charpy, p. 1894. Macrocephalites helvetiae sp. nov.– Tornquist, 632-634, pl. 3, fig. 3a-b ; pl. 11, fig. 4 ; non pl. 11, p. 8, pl. 1, fig. 1a-d. fig. 2, nec pl. 12, fig. 1. 1894. Macrocephalites oxfordiense sp. nov.– pars 1982. Tornquistes (Tornquistes) helvetiae kobyi (de Tornquist, pl. 2, fig. 1a-c. Loriol, 1896).– Thierry & Charpy, p. 634-636, 1896. Macrocephalites kobyi sp. nov.– de Loriol, p. pl. 2, fig. 2a-b ; pl. 7, fig. 1a-b ; pl. 8, fig. 2a-b ; non 20-22, pl. 4, fig. 1 ; pl. 5, fig. 1. pl. 2, fig. 1a-b. 1896. Macrocephalites liesbergensis sp. nov.– de pars 1982. Tornquistes (Tornquistes) multicostatum multi- Loriol, p. 22-23, pl. 5, fig. 2 ; pl. 6, fig. 1. costatum nov. sp.– Thierry & Charpy, p. 636- 1896. Macrocephalites tornquisti sp. nov.– de Loriol, 637, pl. 10, fig. 3 ; pl. 11, fig. 3 ; non pl. 3, fig. p. 22, pl. 2, fig. 2 ; pl. 3, fig. 1-2. 1a-b ; nec pl. 13, fig. 1a-b. 1912. Pachyceras (Tornquistes) helvetiae (Tornquist, 1982. Tornquistes (Tornquistes) multicostatum nodosum 1894).– Douvillé, p. 51, pl. 3, fig. 13. nov.– Thierry & Charpy, p. 637-638, pl. 6, fig. 1912. Pachyceras (Tornquistes) helvetiae kobyi (de 2a-b. Loriol, 1896).– Douvillé, p. 52, pl. 3, fig. 2. 1995. Tornquistes (Tornquistes) helvetiae kobyi (de v 1912. Pachyceras lalandei mutation romani nov.– Loriol, 1896).– Branger et al., p. 26, pl. 5, fig. Douvillé, p. 50-51, pl. 3, fig. 14. 5. 1938. Tornquistes helvetiae (Tornquist, 1894).– 1995. Tornquistes (Tornquistes) multicostatum nodosum Roman, p. 220, pl. 20, fig. 205. Thierry & Charpy, 1982.– Branger et al., p. 1940. Pachyceras kobyi (de Loriol, 1896).– Arkell 26, pl. 5, fig. 6. (in 1934-1948), p. 215-216, text-fig. 75. 2000. Tornquistes (Tornquistes) helvetiae kobyi (de 1974. Pachyceras (Tornquistes) gr. kobyi (de Loriol, Loriol, 1896).– Quereilhac, p. 45, pl. 42, fig. 1896).– Sequeiros, p. 48, pl. 3, fig. 4 ; pl. 4, fig. 1-2. 2-4. 2000. Tornquistes (Tornquistes) romani (de Loriol, Pachyceras (Tornquistes) romani ouvillé 1974. (D , 1896).– Quereilhac, p. 45, pl. 42, fig. 3. equeiros 1912).– S , p. 54, pl. 4, fig. 1, 5. v 2006. Tornquistes tornquisti (de Loriol, 1896) morphe 1974. Pachyceras (Tornquistes) gr. romani (Douvillé, tuberculatum Thierry & Charpy, 1982.– Bert, 1912).– Sequeiros, p. 54, pl. 4, fig. 5 ; pl. 5, fig. 2 p. 36-37, fig. 8. (specimen with teratology), 4. 1974. Pachyceras (Tornquistes) liesbergensis (de Loriol, 1896).– Sequeiros, p. 58, pl. 5, fig. 3. Remarks about the synonymy : In the strict application v 1977. Pachyceras (Tornquistes) aff. oxfordiense of the ICNZ principle of priority, the taxon nicolisi (Tornquist, 1894).– Bourseau, p. 82, pl. 10, Parona, 1885 should have priority on the taxon fig. 1a-b. helvetiae Tornquist, 1894 because of the identity of v 1977. Pachyceras (Tornquistes) kobyi (de Loriol, the two species (see the discussion below). However this 1896).– Bourseau, p. 84, pl. 11, fig. 1a-c. taxonomic option is not satisfactory and several points v 1977. Pachyceras (Tornquistes) aff. romani (Douvillé, are to be considered : (1) the use of precedence would 1912).– Bourseau, p. 83, pl. 11, fig. 2-3. create instability in the nomenclature which would v 1979. Pachyceras (Tornquistes) nicolisi (Parona in defeat the goals of the principle of priority because the Nicolis & Parona, 1885).– Bourseau et al., p. 127, pl. 1, fig. 5. genus Tornquistes Lemoine, 1910 is based on the type 1982. Tornquistes (Pachytornquistes) oxfordiense species Tornquistes helvetiae (Tornquist, 1894). (2) (Tornquist, 1894).– Thierry & Charpy, p. The Article 67.1.2 of the ICZN precise that “the name 638-639, pl. 1, fig. 2a-b ; pl. 4, fig. 2a-b ; pl. 10, of a type species remains unchanged even when it is a fig. 1, 4 ; pl. 11, fig. 1a-b ; pl. 12, fig. 2-3. junior synonym or homonym, or a suppressed name” 1982. Tornquistes (Pachytornquistes) cf. oxfordiense (see also the recommendation 67B). (3) Contrariwise to (Tornquist, 1894).– Thierry & Charpy, p. T. helvetiae Tornquist, the taxon nicolisi Parona was 639-640, pl. 4, fig. 2a-b. really poorly studied by authors (only at one time in the 1982. Tornquistes (Pachytornquistes) liesbergense (de Loriol, 1896).– Thierry & Charpy, p. 640-641, 20th century – cf. synonymy) even if the conditions of the pl. 6, fig. 1. Article 23.9 of the reversal of precedence are not reaching 1982. Tornquistes (Pachytornquistes) tornquisti torn- (it is really difficult in palaeontology of these rare groups quisti (de Loriol, 1896).– Thierry & Charpy, to gather 25 works of 10 different authors on the same Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 475

subject). However (4), this problem was also been rose Measurements : See Table. by Thierry & Charpy (1982) who have proposed the nomen oblitum for the taxon nicolisi Parona. Description Unfortunately this principle was neither recognized by Two main morphological types of Tornquistes are both the version applicable in 1982 of the ICZN nor by the represented in the sample of the Cheiron Mountain. actual one (the 4th - Article 23.12). For cons the actual Following Charpy (1976) and Thierry & Charpy Article 23.2 is very explicit : ”Purpose. In accordance (1982) these morphologies are interpreted here as the with the objects of the Code (see Preamble), the Principle result of a sexual dimorphism : the potentially large of Priority is to be used to promote stability and it is not adult specimens are macrochonchs [M] and the smaller intended to be used to upset a long-accepted name in its adult specimens are microconchs [m]. On the graphs, the accustomed meaning by the introduction of a name that macrochonchs’ average curves of H and O=f(D) (Fig. is its senior synonym or homonym […]”. Consequently 2) are of Y=bDa type (R² still highly significant), but a Tornquistes nicolisi (Parona) should not be used to the is very close to 1 indicating a growth almost isometric detriment of Tornquistes helvetiae (Tornquist) and this and harmonic. The microconch differs by its strongly latter should be taken as an available species. disharmonic growth due to the uncoiling of the adult body chamber. The break of slope is clearly visible on Material studied (n=7) : All the specimens are from the graphs H and O=f(D) (Fig. 2), and on the graph the Cheiron Mountain (Alpes-Maritimes, southeastern O/H=f(D) (Fig. 3) which is generally used to display France). They were collected in the Arkelli Biohorizon dimorphic couples in ammonites (Marchand, 1986). (Vertebrale Subzone, Plicatilis Biozone of the Middle The two morphological types are described separately Oxfordian). Specimens n°ox.32 (A. Magnin’s but the wholy septate specimens smaller than 70-80 mm collection), n°AA98, AB55, AL09, AL97 and AP41 are impossible to relate to one or other dimorph. The are from bed 100d, and specimen n°AA06 is from bed suture lines are not sufficiently preserved to be described. 101 (D. Bert’s collection). See Bert et al., 2003 for Inner whorls (D < 70-80 mm) : The incomplete and a figuration of the outcrop-section. In waiting of their wholly septate specimens n°AL09 (Pl. II, fig. 2) and AP41 deposition in a public institution all the specimens are (Pl. II, fig. 4a-c) are representative of both dimorphs. At visible from the author. this stage of growth the shell is very involute (O/D=1.89

Table of measurements

N° sp. D H E O H/D E/D O/D E/H O/H α Diameter Heigth Thickness Umbilic degrees 125.9 57.5 - 27.3 0.46 - 0.22 - 0.47 AA06 109.1 53.9 - 21.7 0.49 - 0.20 - 0.40 60° [M] 97.1 48.3 - 19.9 0.50 - 0.21 - 0.41 60° AA98 92.2 43.1 - 18.6 0.47 - 0.20 - 0.43 [M] 70.0 33.3 - 12.4 0.48 - 0.18 - 0.37 135° 37.5 18.8 26.2 6.7 0.50 0.70 0.18 1.39 0.36 AB55 31.1 15.5 21.5 5.7 0.50 0.69 0.18 1.39 0.37 100° 71.4 34.8 - 12.9 0.49 - 0.18 - 0.37 AL09 61.3 30.1 43.4 11.2 0.49 0.71 0.18 1.44 0.37 75° 93.3 46.7 - 18.1 0.50 - 0.19 - 0.39 AL97 84.1 41.3 49.0 14.8 0.49 0.58 0.18 1.19 0.36 60° [M] 74.7 37.6 45.7 13.0 0.50 0.61 0.17 1.21 0.35 70° 68.0 33.0 - 12.9 0.49 - 0.19 - 0.39 AP41 50.0 23.8 - 10.1 0.48 - 0.20 - 0.43 140° Average 0.49 0.66 0.19 1.32 0.39 Standard deviation 0.01 0.06 0.01 0.12 0.04 Coefiscient of 2.86 8.68 6.92 8.72 9.08 variation ( %) 128.4 48.8 - 35.5 0.38 - 0.28 - 0.73 ox.32 114.7 51.5 - 23.1 0.45 - 0.20 - 0.45 80° [m] 97.6 46.8 - 16.1 0.48 - 0.17 - 0.35 75° 78.0 40.4 - 13.6 0.52 - 0.17 - 0.34 100° Average 0.46 0.20 0.46 476 D. Bert

Fig. 2 : Representation of H (height) and O (umbilicus) in function of D (diameter) for the sample of Tornquistes of the Cheiron Mountain. 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 477

in average) with a sub-circular depressed section (E/ liesbergense (de Loriol, 1896) for its ornamentation D=0.71 in average), very convex flanks, and with a very constantly blunt and its more depressed section. The poorly individualised rounded venter which gives the Cheiron Mountain’s specimens have fewer ribs per shell a very globular general appearance. The umbilical whorl and a narrower umbilicus than in Tornquistes wall is high and vertical, and the peri-umbilical area is multicostatum (Thierry & Charpy, 1982) and its narrow and slightly angular. The primary ribs are slightly variety nodosum (Thierry & Charpy, 1982). inclined forward ; they are broad but not very prominent On the same morphological point of view, the specimens on the peri-umbilical area. Ribs bifurcate from the base from the Cheiron Mountain largely and perfectly of flanks where they remain inconspicuous and without reflect Tornquistes oxfordiense (Tornquist, 1894) thickening. The wedge-shaped secondary ribs are better and Tornquistes tornquisti (de Loriol, 1896) by their expressed beyond the lower third of flanks. These are size, ornamentation, and the shape of their section. sometimes separated by interribs of same robustness. The sample of the Cheiron Mountain however seems On the venter all the ribs are wide and slightly curved somewhat closer to Tornquistes tornquisti (de Loriol, forward. 1896) according to the graphic of the morphodiversity in The macrochonchs : The specimens n°AA98 (Pl. II, fig. the Plicatilis Tornquistes (Fig. 4). Some specimens with 3) and AL97 (Pl. I, fig. 2) are wholy septate (D=92.2 and a more compressed section are intermediate to the both 98.3 mm respectively). They certainly represent nuclei of taxa and it is not possible to assign them preferentially to macrochonchs, because at this diameter the microconchs one or other. are already differentiated. The specimen n°AA06 (Pl. II, It would be tempting to attribute the Tornquistes of the fig. 1) is also a macroconch : it reaches a diameter of 126 Cheiron Mountain in part to Tornquistes tornquisti (de mm and the last septa is visible at 120 mm. With a body Loriol, 1896) and in part to Tornquistes oxfordiense chamber extrapolated to 2/3 of whorl, this specimen would (Tornquist, 1894). However, the study shows that exeed D=200 mm without being adult (no approximation the Cheiron Tornquistes sample is homogeneous and of the last septa). Beyond 70-80 mm in diameter the shell without real break. All this implies that the currently has exactly the same characteristics as those observed accepted criteria for differentiating the taxa of this genus in the inner whorls. The ornamentation retains the same (section thickness, strength of ornamentation) are based general appearance but with a broadening and a gradual on correlated features which we know now that they spacing of the ribs. The ribs are also less pronounced than are an important part in intraspecific variability. These on previous whorls especially in the first third of flanks. features do mostly not define real species in a view as The microconch : The specimen n°ox.32 (Pl. I, fig. 1) is the far paleobiological as possible, but only morphological only complete adult (D=128 mm) collected in the Cheiron groups. As a result of the discussion below (see also the Mountain which enter this category. The phragmocone remarks about synonymy) the sample of the Cheiron ends at D=77 mm and the body chamber is about 3/4 of Mountain is finally assigned to Tornquistes helvetiae whorl. The body chamber shows a significant uncoiling (Tornquist, 1894). of scaphitoïde type following a break of slope in the shell growing at D=110 mm (Fig. 2-3). While remaining broad Stratigraphic range : Middle Oxfordian, Plicatilis Zone, the section tends to compress slightly from the younger Vertebrale Subzone. Tornquistes helvetiae (Tornquist) whorls with less convex sides than on the phragmocone. is also present in the Antecedens Subzone. At the last third of whorl the peri-umbilical area become very angular with an almost overhanging umbilical wall. On the other hand, the thickness of the section remains III. Discussion and new interpretation almost constant regarding to the height of the whorl. The of the Tornquistes lineage ornamentation blurs at the base of the flanks from the first third of the body chamber and the ribs are therefore The problem of the species and the variability in more widely spaced than on the phragmocone. From the Tornquistes Lemoine, 1910 end of the second third of the adult body chamber the area where the ribs are weakened gradually up from the As already been remarked, the main criteria usually half of the flanks ; that make the shell almost completely advocated in the literature to differentiate taxa of the smooth when approaching the peristome. genus Tornquistes Lemoine, 1910 concern the thickness of the section and the strength of the ornamentation. This Differential diagnose observation is accentuated as a result of the revision of Strictly morphologically, the specimens of the Cheiron the Tornquistes by Charpy (1976) then by Thierry & Mountain are different from Tornquistes romani Charpy (1982). However the two parameters are both (Douville, 1912) for their sub-circular section and often linked and the role played by the shape of the blunter ornamentation. The sample studied here section in the specific differentiation among ammonites differs from Tornquistes helvetiae (Tornquist, 1894), is to put into perspective with application of covariation Tornquistes kobyi (de Loriol, 1896) and Tornquistes Buckman’s laws (see above). The strength and density 478 D. Bert

Fig. 4 : Representive table of the morphodiversity (relative section and rib-index) occupied by different nominal species of Tornquistes Lemoine, 1910. Data taken from the literature and unpublished collects. The named “species” are all morphological variants of one paleospecies : Tornquistes helvetiae (Tornquist, 1894).

of the ornamentation and the width of the umbilicus 1808, and the Toarcian Osperleioceras Krimholtz, are more or less directly associated to the thickness of 1957 and Dactylioceras Hyatt, 1867. Examples are also the section by the expression of different mechanical known in the Oxfordian Cardioceratidae Hyatt, 1892 and biochemical constraints (Hammer & Bucher, (Marchand, 1977, 1986) and Gregoryceras Spath, 2005 ; Guex et al., 2003). In addition to the Bajocian 1924 (Bert et al., 2003 ; Bert, 2004 ; Bert & Enay, Sonninniidae studied by Westermann (1966), several 2004 ; Bert et al., 2009). The laws of covariation of the very demonstrative examples have been given by Guex characteristics are perfectly applicable to the case of et al. (2003), Morard & Guex (2003), and Morard Tornquistes Lemoine, 1910. (2006) for the Domerian Amaltheus de Montfort, The harvest of several very well dated Tornquistes in Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 479

the Cheiron Mountain and other nearby localities of the (3) the morphology with compressed section but with Alpes-Maritimes (southeastern France, Fig. 1) is spread fewer robust ribs (= “helvetiae” type). The first type from the Cordatum Subzone to the Antecedens Subzone. is connected with the two others by the “liesbergense” These collections were placed in parallel with specimens and “oxfordiense” morphotypes. The second and third of literature as well as those from different localities and types are connected by the “multicostatum nodosum” private collections (Poitou, Calvados, Burgundy, Alpes- morphotype which is figured here for comparison (Fig. de-Haute-Provence, Drôme, Hautes-Alpes) : first for the 5). Thus, although extreme morphologies seem very Lower Oxfordian (Arkell, 1946 [in 1934-1938] ; Gygi different at first sight (for exemple Fig. 5vs Pl. I, fig. 1a-b) et al., 1994 ; Marchand et al., 2002 ; Quereilhac in fact a large number of nominal species of Tornquistes et al., 2009) and secondly for the Middle Oxfordien actually correspond to different morphological variants (Bourseau, 1977 ; Branger et al., 1995 ; Quereilhac, of the same paleobiological species. This possibility 2000 ; Sequeiros, 1974 ; Thierry & Charpy, 1982 has been raised long ago by authors (de Loriol, 1896, pars). There are three main extreme morphologies p. 21-22 ; Douvillé, 1912, p. 53 ; Charpy, 1976, p. connected by all intermediaries in the case of the 86, 143 ; Thierry & Charpy, 1982, p. 646-647 ; Gygi Tornquistes of the Plicatilis Biozone (the only enough - et al., 1994, p. 465). In this context, several taxa were Fig. 4) : (1) the morphology with very thick section and incorporated by Charpy (1976) and Thierry & Charpy with a high average number of ribs (usually blunt) (= (1982) as morphotypes of other “species” (helvetiae/ “tornquisti” type) ; (2) the morphology with compressed kobyi and tornquisti/tuberculata). section and numerous thin ribs (= “romani” type) ; and On the other hand, comparisons between the Tornquistes

Fig. 5 : Tornquistes helvetiae (Tornquist, 1894), “multicostatum nodosum” type, specimen n°tal01 from Talant (Burgundy, France), C. Beaudoin’s collection. 480 D. Bert

of different age permit to consider the relative height of Prodrome (1850) a nomen oblitum. This article has been the primary ribs point of bifurcation as the best criterion changed in the 4th version of the ICZN (art. 23.2 and for differentiation between samples. In that case, at 23.9) but the Ammonites hermione d’Orbigny remains every time there was only one variable species and this unusable : this species (of no type specimen have ever criterion could potentially serves for a chronospecific been designed) is also species dubia. Most of the different differentiation (Fig. 6). The ribs point of bifurcation may specimens of the d’Orbigny’s collection classified under be located (1) relatively high between half and the upper Ammonites hermione d’Orbigny have now disappeared third of flanks (Praecordatum and Bukowskii subzones), and they are too small (10-25 mm) to ensure a reliable (2) between the first quarter and half part of the height of determination (Cottreau, 1927, p. 107-108, pl. 44, fig. flanks (Cordatum Subzone), or (3) around the base of the 6-7 et 8-9). They also belong from different levels and flanks (Vertebrale and Antecedens subzones). However, from different geographical origin localities. depending on the thickness of the ribs themselves and sometimes on their high attenuation in the lower part of The bifurcation point of the main ribs on the type- the flanks it is not always possible to be very precise in specimen of Tornquistes helvetiae (Tornquist, 1894) this positioning. is clearly located at the edge of the umbilical wall. The strong ornamentation and the compressed section are all features that plead for a synonymy with Tornquistes Discussion about species of Tornquistes Lemoine, nicolisi (Parona in Nicolis & Parona, 1885). The 1910 only difference between the two type specimens of these taxa is the presence of trifurcated ribs in the latter but it Ammonites hermione d’Orbigny, 1850 has been put into is a highly variable feature among the Tornquistes and it synonymy of Tornquistes romani (Douvillé, 1912) by can not be considered here to differentiate species. On Thierry & Charpy (1982) with reference to Article 23b the other hand, if considering the morphological changes of the International Code of Zoological Nomenclature associated with variation in thickness of the section as the (ICZN) that made the species of the d’Orbigny’s expression of intraspecific variability (see above) and the

Fig. 6 : Evolution of the umbilicus width and of the position of the primary ribs bifurcation point through time for the genus Tornquistes Lemoine, 1910. Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 481

existence of many intermediaries between the extremes Tornquistes leckenbyi (Arkell, 1946) was doubtfully (Fig. 4), there is no reason to consider the nominal dated by Arkell (1946) of the Praecordatum Subzone. taxa of the Plicatilis Biozone as belonging to several Thierry & Charpy (1982) have replaced this species in species. Thus Tornquistes helvetiae (Tornquist, 1894), the Bukowskii Subzone. This new datation is consistent Tornquistes nicolisi (Parona in Nicolis & Parona, with the recent discovery of a specimen of the H. 1885), Tornquistes multicostatum nodosum Thierry & Châtelier’s collection (unpublished but visible to the Charpy, 1982, Tornquistes kobyi (de Loriol, 1896), URL : http ://www.ammonites.fr/Fiches/0492.htm) in the Tornquistes liesbergensis (de Loriol, 1896), Tornquistes level of ferruginous ooids (H15) at Villers-sur-Mer in the tornquisti tuberculatum Thierry & Charpy, 1982, Vaches Noires cliff outcrop-section (Calvados, North- Tornquistes tornquisti (de Loriol, 1896), Tornquistes West of France). The bed H15 is very characteristic oxfordiensis (Tornquist, 1894) and Tornquistes romani of the Bukowskii Biohorizon (see Bonnot, 1995, p. (Douvillé, 1912) are morphological representatives 53-54). Two other specimens of the same species were of a single paleospecies and are to be considered as discovered by Ch. Cornago in the Blieux area (Alpes- synonymous of Tornquistes helvetiae (Tornquist) (see de-Haute-Provence, southeastern France). The most above the remarks about synonymy for the taxonomic complete is an adult microconch of about 130 mm in choice). diameter (Fig. 7). Tornquistes leckenbyi (Arkell) is characterized by the primary ribs point of bifurcation

Fig. 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. Bert

highly positioned between half and the upper third of possibly be a Tornquistes. This species was interpreted the flanks. This criterion does not occur in the Middle as a Rasenia Salfeld, 1913 (Eurasenia Geyer, 1961), Oxfordian Tornquistes (Fig. 6). The shell is usually more a Lower Kimmeridgian Aulacostephanidae Spath, evolute in Tornquistes leckenbyi (Arkell) regardless to 1924, by Oloriz in the Revision of the Gemmellaro’s the scaphitoïde coiling of adult microconchs or variations collection (in Pavia & Cresta, 2002, p. 377-378). In due to the covariation laws of characteristics. The fact, this species is only known with its type specimen specimen of the H. Châtelier’s collection has the further which is from an unknown level of Sicily (Trapani), out of interest to present parabolic structures on the ribs like in the habitual biogeographical of Rasenia (Hantzpergue, Tornquistes greppini (de Loriol, 1900) (Preacordatum 1989). The shape of the ornamentation, the whorl section Subzone, see Marchand et al., 2002). and the uncoiling of the body-chamber are all features Four specimens of the Tornquistes represented by of Tornquistes. In this hypothesis, the type specimen of Thierry & Charpy (1982, pl. 2, fig. 1b ; pl. 3, fig. 1 ; pl. Persiphinctes pancerii Gemmellaro should probably of 12, fig. 1 ; pl. 13, fig. 1) have the same type of morphology an Oxfordian age, but further data are still necessary to and ornamentation than Tornquistes leckenbyi (Arkell) statute. with the bifurcation points located fairly high on the flanks. They have almost all been attributed to different species and placed with doubts in the Plicatilis Biozone. Origin and evolution of the Tornquistes lineage But in accordance with this ornamental parameter these specimens may actually come from the Cordatum Since a long time ago it is universally recognized that Biozone (Costicardia or Bukowskii subzone) especially the origin of the Oxfordian Tornquistes Lemoine, 1910 because their localities of origin include concentrated/ is from the Callovian genus Pachyceras Bayle, 1875. condensed levels (Thierry, 1966, p. 649 ; Marchand Although some differences in the sutural line, both & Pascal, 1979, p. 110 ; Thierry & Charpy, 1982, genus have a very strong morphological and ornamental p. 634 ; Courville & Colin, 1997 ; Collin et al., convergence as the common uncoiling of the last whorl 1999). This is particularly true with the type specimen in the microconchs (Douvillé, 1912, p. 51 ; Charpy, of Tornquistes multicostatum multicostatum ( hierry T & 1976, p. 84). The presence of parabolic structures and Charpy, 1982) (pl. 10, fig. 3 ; pl. 11, fig. 3) and some the high position of the main ribs bifurcation point of the others specimens of this taxon cited by Thierry & oldest Tornquistes are clearly of Perisphinctacea type. Charpy (1982). This identity would results in placing But additional researches at the top of the Callovian and Tornquistes multicostatum multicostatum (Thierry in the Mariae Biozone are still required to consider all & Charpy) in synonymy with Tornquistes leckenbyi evolutionary trends related to the origin of the genus (Arkell) which both have already been close together Tornquistes Lemoine. by Thierry & Charpy (1982, p. 637). The remaining Depending to the age of the samples of the genus specimens of the Plicatilis Biozone are more akin to Tornquistes Lemoine it is possible to recognize a Tornquistes helvetiae (Tornquist, 1894) as designed in stratigraphical polarity for the primary ribs bifurcation this work : they represent the slender morphotype with compressed section (“multicostatum nodosum” type in point position. From Lower Oxfordian to Middle Fig. 4). Oxfordian the evolution of the Tornquistes gradually proceeds in the relative decline of this point on the flanks Tornquistes helveticus (Jeannet, 1951) of the Cordatum and a discrete narrowing of the umbilicus (Fig. 6). Thus Subzone of Aargau (Switzerland) was revised by Gygi it is possible to define three, maybe four, successive et al. (1994) ; it is also known in the Cordatum Subzone chronospecies : of the Cheiron Mountain (Alpes-Maritimes, southeastern 1(?) - Tornquistes greppini (de Loriol, 1900) in the France - unpublished data). From its general appearance Praecordatum and Costicardia subzones (Mariae and and the shape of the section, Gygi et al. (1994, p. 465) Cordatum biozones) ; have considered the possibility of an eventual synonymy 2 - Tornquistes leckenbyi (Arkell, 1946) at least in of this species with the Tornquistes helvetiae-kobyi- the Bukowskii Subzone (Cordatum Biozone of the oxfordiense group [= Tornquistes helvetiae (Tornquist, Lower Oxfordian). These species have the primary ribs 1894), this work]. However, according to the stratigraphic bifurcation point located between half and the upper third level and the position of the primary ribs bifurcation point of the flanks ; between the first quarter to the mid-flanks theJ eannet’s 3 - Tornquistes helveticus (Jeannet, 1951) which species (1951) is located between Tornquistes leckenbyi the bifurcation point is located between half and the (Arkell, 1946) and Tornquiste helvetiae (Tornquist, lower quarter of the flanks. This species is ranged in 1894) as designed in this work (Fig. 6). This position the Cordatum Subzone (Cordatum Biozone, Lower confirms its status as independent species. Oxfordien) ; 4 - Tornquistes helvetiae (Tornquist, 1894) of the In view of R. Enay (personal communication), Plicatilis Biozone which the bifurcation point is located Perisphinctes pancerii Gemmellaro, 1878 could around the base of the flanks. Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 483

IV. Is Protophites Ebray, 1860 a same order of diameter known in the Middle Oxfordian Pachyceratidae ? samples (Fig. 7) ; (2) the length of the body-chamber is only a half whorl in “Sphaeroceras” chapuisi de Loriol The strictly Oxfordian genus Protophites Ebray, 1860 whereas for the microconchs of Tornquistes (of any age) is not related to the Callovian genus Oechoptychius it is about three-quarters of a whorl ; (3) the existence of a Neumayr, 1878 with which it presents a morphological preapertural constriction (Marchand et al., 2002, p. 472) (peristome) and stratigraphical relatively large hiatus. is totally unknown in Tornquistes ; and (4) there are clear Moreover, according to Schweigert & Dietze differences in the sutural line at the same diameter (de (1998) Oechoptychius Neumayr would be a possible Loriol, 1900, fig. 10 vs Thierry & Charpy, 1982, fig. microconch of Phlycticeras Hyatt, 1900 so Protophites 2a). In particular the external saddle of “Sphaeroceras” Ebray can not be included in the family Oechoptychiidae chapuisi de Loriol is clearly incised in the middle by a Arkell, 1957 (= Strigoceratidae Buckman, 1924). small accessory lobe and it is much broader and shallower Because of some morphological convergences, Enay than in Tornquistes Lemoine. Similarly the internal (1977) then Bourseau (1977) have considered the saddle of “Sphaeroceras” chapuisi de Loriol is wide possibility of a dimorphism between Tornquistes and incised in the middle by a small accessory lobe while

Lemoine, 1910 and Protophites Ebray therefore in Tornquistes Lemoine the lobe U2 is directly broad and proposing it as a Pachyceratidae Buckman, 1918 deep. All this suggests that “Sphaeroceras” chapuisi de as Arkell (1957, p. L.298) then Callomon (in Loriol is neither the microconch of Tornquistes greppini Donovan et al., 1981, p. 181) did. But Charpy (1976) (de Loriol) nor a Tornquistes. However, in agreement then Thierry & Charpy (1982) were the first to with G. Schweigert (in Marchand et al., 2002) all convincingly demonstrate the existence of a dimorphism these peculiar characteristics compare “Sphaeroceras” in the genus Tornquistes Lemoine. They were also the chapuisi de Loriol with the genus Protophites Ebray, first to have described and figured the macroconch of this 1860 of which this species would be the currently genus which can grow quite large (D=300 mm) ; all the oldest known representative. In this regard some of the previous depictions of literature are regarded as those Protophites represented by Jeannet (1951, pl. 31, fig. 10 of microconchs (120>D>160 mm). This dimorphism is and 11) show a very similar morphology of the uncoiled also well documented in the Cheiron Mountain sample body chamber that is not completely folded-down onto of the Arkelli Biohorizon (this work). Moreover, the the inner whorls. Note that this gradual “fold-down” of relative height of the ribs bifurcation point is different the body chamber is one of the main evolutionary features between the two genera : in Protophites Ebray it evolves of the genus Protophites Ebray over time (Bert, 2003). during growth (but remains substantially around half of Even if Protophites Ebray is not the microconch of the flanks – Bert, 2003) unlike in Tornquistes Lemoine Tornquistes Lemoine there are certain morphological where it shows a stratigraphic polarity (this work). convergences between the both genera, so in waiting of “Macrocephalites” greppini de Loriol 1900 (non more data Protophites Ebray should be placed in the 1898) and “Sphaeroceras” chapuisi de Loriol, 1900 Pachyceratidae Buckman, 1918 in which it could have were recently revised by Marchand et al. (2002) and its origin (?). But this position remains to be confirmed. were both considered as dimorphs of the same species of In particular, the presence of parabolic nodes on the ribs Tornquistes Lemoine. Tornquistes greppini (de Loriol, is a feature of Perisphictaceae Steinmann, 1890. 1900) is from the Mariae Biozone (Praecordatum Subzone), making it the oldest Tornquistes known to date. As in Tornquistes leckenbyi (Arkell, 1946) the V. Conclusions ribs bifurcation point is fairly high on the flanks and there are parabolic nodes on some ribs (cf. Marchand et al., Even if the genus Tornquistes Lemoine, 1910 is still 2002). It would have been tempting to consider the both very rare the study of the sample collected in the Cheiron species as synonym on these criteria alone ; inasmuch Mountain (Alpes-Maritimes, southeastern France) is a the de Loriol’s species has also been reported in the new contribution to knowledge of the Arkelli Biohorizon Costicardia Subzone (Enay, 1966, p. 142, 244 ; Charpy, Subtethyan ammonite-fauna at the top of the Vertebrale 1976, p. 137, pl. 3, fig. 5). But it still seems a bit premature Subzone (Plicatilis Biozone, Middle Oxfordian). The because Tornquistes greppini (de Loriol) is only known deposits of this age are indeed uncommon in Western as nuclei of small size. This fact is accentuated by the Europe and the top of the Vertebrale Subzone (Arkelli special preservation in the Renggeri marls where large Biohorizon) is still paleontologicaly relatively unknown. fossils are usually absent. In contrast, complete adults On the other hand, this sample of Tornquistes Lemoine of “Sphaeroceras” chapuisi de Loriol do not seems was collected in a single level and it has revealed its exceed 20 mm in diameter. In fact a number of features homogeneity whereas its morphology is located between separates the latter from the genus Tornquistes Lemoine : two nominal and classical species of literature : Tornquistes (1) a very much less size while the barely more recent tornquisti (de Loriol, 1896) and Tornquistes oxfordiense Tornquistes leckenbyi (Arkell) [m] are already of the (Tornquist, 1894). The study of the bibliography 484 D. Bert

and of new specimens now allows completing our as observed in other forms suddenly emerged by processes understanding of the variability of this group for the of progenesis type. The oldest species of Protophites now Plicatilis Biozone (Middle Oxfordian). It appears that the recognized is Protophites chapuisi (de Loriol, 1900) at features usually taken into account to establish specific the top of the Mariae Biozone (Praecordatum Subzone). denominations (section thickness, strength and density The apparent hiatus at the base of the Cordatum Biozone of the ornamentation, widening of the umbilicus) are in is probably due to a lack of observation of these forms fact interrelated and are manifestations of the “normal” which are still very rare. variability in a single species of Tornquistes (laws of covariation of characteristics) taken throughout its paleogeographical range. However, this variability seems Acknowledgments not necessarily uniform from one area to another and paleoecological factors could be envisaged to explain the I would especially like to thank Mrs. Chantal Cornago, absence of certain morphological type in certain places at Mr. Jean Arbault, Cyril Beaudoin, Pierre-Yves certain times. Thus the absence of the morphology with Boursicot, Patrick Branger, Gérard Delanoy, Jean- compressed section at the top of the Vertebrale Subzone Louis Latil and Albert Magnin for the help they have in the Cheiron Mountain could possibly be the result of a provided and/or for the loan of their specimens. Mr. Abel more distal environment than in the Burgundy platform Prieur gave me broad access to the collections of the at the same age, or at the base of the Antecedens Subzone Faculty of Science of Lyon which he is responsible, he in other localities of the Alpes-Maritimes where this is warmly thanked. I also express my thanks to Raymond type of morphology is more frequent. Specific collects Enay for his constructive remarks on the manuscript. are 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 nominal References taxa described in the literature in the Plicatilis Biozone as a single paleobiological species : Tornquistes helvetiae Arkell, W.J. (1934-1948) - A monograph of the English (Tornquist, 1894). Corallian Beds. Paleontological Society, London : 420 pp. On the other hand, the stratigraphic polarity of a hitherto Arkell, W.J. (1950) - A classification of the Jurassic character seldom considered by the authors (the position ammonites. Journal of Palaeontology, London, 24(3) : 354-364. of the primary ribs bifurcation point) now allows defining Arkell, W.J. (1952) - Jurassic ammonites from Jebel Tuwaiq, at least three, maybe four, successive chronospecies from Central Arabia. Philosophical Transaction of the Royal Lower to Middle Oxfordian : (?) Tornquistes greppini (de Society of London, Series B, Biological Sciences, 236, B. Loriol, 1900), Tornquistes leckenbyi (Arkell, 1946), 633 : 231-313. Tornquistes helveticus (Jeannet, 1951) and Tornquistes Arkell, W.J., B. Kummel & C.W. Wright (1957) - helvetiae (Tornquist, 1894). Mesozoic Ammonoidea. In : Moore, R.C. (Ed.), Treatise Finally, the study of the sample of Tornquistes from the on Invertebrate Paleontology. Part L, Mollusca 4, Cheiron Mountain confirms the findings of Charpy Cephalopoda, Ammonoidea. The Geological Society of America and the University of Kansas Press (1976) and Thierry & Charpy (1982) concerning , New York and Lawrence : 80-437. the dimorphism in this genus. Although Protophites Bert, D. (2003) - Etude de Protophites vannii sp. nov. bray E has often been regarded as a microconch, it (Ammonoidea), sous-zone à Cardioceras vertebrale, is clearly not the one of Tornquistes Lemoine. Note Oxfordien moyen, et évolution du genre Protophites that this micromorphic genus has perhaps simply not Ebray, 1860. Riviéra Scientifique, Nice, 87 : 69-84. enough visible differences between its dimorphs to be Bert, D. (2004) - Révision, étude systématique et évolution differentiable only on the basis of the fossilized shell just du genre Gregoryceras Spath, 1924 (Ammonoidea,

Plate I

All 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 Cheiron Mountain (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 I

1b 1a

2 cm

2a 2b 486 D. Bert

Oxfordien). Annales du Muséum d’Histoire naturelle de Nouvelles Archives du Muséum d’Histoire Naturelle de Nice 19 : 1-183. Lyon, 15 : 116 p. Bert, D. (2006) - Sur quelques Céphalopodes de la collection Bourseau, J.-P., J. Charvet & R. Enay (1979) - Faune Sipp. Minéraux et Fossiles, Cedim, Paris, 350 : 24-39. oxfordienne dans les Dinarides internes au nord de Bert, D. (2008) - Etude de Paraspidoceras colloti Zeiss, 1962 Sarajevo (Bosnie orientale, Yougoslavie). Géobios, (Aspidoceratidae Zittel, 1895, Ammonitina) au sommet Villeurbanne, 12(1) : 123-131. de la sous-zone à Vertebrale (Oxfordien moyen, zone à Branger, P., P. Nicolleau & A. Vadet (1995) - Les Plicatilis) du Sud-Est de la France. Revue de Paléobiologie, ammonites et les oursins de l’Oxfordien du Poitou. Musée Genève, 27(2) : 335-356. de Niort et APGP Poitou-Charentes-Vendée : 1-149. Bert, D. & A. Bonnot (2004) - Etude paléobiologique Buckman, S.S. (1887-1907) - A monograph of the ammonites d’une population d’Euaspidoceras davouxi sp. nov. of the Inferior Oolite Series. Palaeontological Society, (Apidoceratidae Zittel, 1895, Ammonitina) du sommet London : 1-456. de la sous-zone à Vertebrale (Oxfordien moyen, zone Callomon, J.H. (1981) - Dimorphism in ammonoids. In : à Plicatilis) dans le sud-est de la France. Revue de House M. R. & Senior J. R. (Eds.). The Ammonoidea. Paléobiologie, Genève, 23(1) : 81-98. The Systematics Association, Academic Press, Spec. Publ., Bert, D. & R. Enay, (2004) - Les Gregoryceras (Ammonitina, 18 : 257-273. Oxfordien moyen) de la Cluse de Chabrières (sud- Cariou, E., R. Enay, F. Atrops, P. Hantzpergue, D. est de la France) : étude paléobiologique et nouvelles Marchand & M. Rioult (1997) - Oxfordien. In : interprétations. Revue de Paléobiologie, Genève, 23 : 441- Cariou, E. & P. Hantzpergue (Coords). Biostratigraphie 461. du Jurassique Ouest-Européen et Méditerranéen : zonations Bert D., R. Enay & F. Atrops (2009) - Les Gregoryceras parallèles et distribution des invertébrés et microfossiles. (Ammonitina) de l’Oxfordien moyen terminal et supérieur Bulletin du Centre de Recherche Elf Exploration- téthysien : révision systématique, biostratigraphie et Production, 17 : 79-86. évolution. Géobios, Villeurbanne, 42 (4) : 451-493. Charpy, N. (1976) - Le genre Pachyceras (Ammonitina, Bert, D., D. Marchand, R.A. Gygi & G. Delanoy Pachyceratidae, Callovien supérieur à Oxfordien moyen) (2003) - Gregoryceras defayi sp. nov. et Gregoryceras – Systématique, phylogénie, paléobiologie, stratigraphie. tenuisculptum Gygi, 1977 : deux espèces successives Thèse de Doctorat, Université de Bourgogne (unpublished), de la sous-famille des Peltoceratinae Spath, 1924 Dijon : 160 p. (Ammonitinae, Aspidoceratidae Zittel, 1895) de Charpy, N. & J. Thierry (1977) - Dimorphisme et l’Oxfordien moyen. Eclogae geologicae Helvetiae, Basel, polymorphisme chez Pachyceras Bayle (Ammonitina, 96 : 475-493. Stephanocerataceae) du Callovien supérieur (Jurassique Besnosov, N.V. & I.A. Michailova (1983) - The evolution moyen). Haliotis, 6 : 185-218. of the Jurassic-Cretaceous ammonoids. Doklady Akademii Colin, P.-Y., Ph. Courville, J.-P. Loreau, D. Marchand Nauk SSSR, 269 : 733-737 [in russian]. & J. Thierry (1999) - Séries condensées et indice de Besnosov, N.V. & I.A. Michailova (1991) - The higher taxa préservation d’unité biostratigraphique : exemple de of Jurassic and Cretaceous Ammonitida. Paleontological l’ennoiement de la plate-forme nord-bourguignonne Journal, 25 : 1-19. (France) au Callovo-Oxfordien. Comptes Rendus à Bonnot, A. (1995) - Les Aspidoceratidae d’Europe occidentale l’Académie des Sciences, Paris, Sciences de la Terre et des au Callovien supérieur et à l’Oxfordien inférieur. Thèse 3e planètes, 328 : 105-111. cycle, Dijon (unpublished) : 537 p. Cottreau, J. (1927) - Types du prodrome de paléontologie Bourseau, J.-P. (1977) - L’Oxfordien moyen à nodules des stratigraphique universelle de d’Orbigny - II. Annales de “Terres Noires” de Beauvoisin (Drôme) (Ammonitina Paléontologie, Paris, 16(2-3) : 101-132. de la zone à Plicatilis, paléontologie et biostratigraphie ; Courville, Ph. & P.-Y. Colin (1997) - La série du Callovien milieu de sédimentation et genèse des nodules carbonatés). et de l’Oxfordien de Veuxhaulles (Châtillonais, Côte

Plate II

All 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 II

2 cm

4b 4c 488 D. Bert

d’Or) : problèmes de datation, de géométrie et de Lominadzé, T.A. (1982) - Les Ammonitidae calloviennes paléoenvironnements dans une série condensée. Bulletin du Caucase. Académie des Sciences de Géorgie, SSR, Scientifique de Bourgogne, Dijon, 49 : 29-43. Tbilissi : 272 p. [in russian]. Courville, Ph., J. Thierry & E. Cariou (1998) - Modalités Loriol, Ch. de (1896) - Etude sur les mollusques et évolutives du genre Bullatimorphites (Ammonitina) brachiopodes de l’Oxfordien supérieur et moyen du Jura au Bathonien-Callovien (Jurassique moyen) en Europe Bernois. Mémoires de la Société Paléontologique Suisse, occidentale. Comptes Rendus à l’Académie des Sciences, Genève, 23 : 97 p. Paris, Sciences de la Terre et des planètes, 328 : 59-65. Mangold, Ch. (1988) - Les Pachyerymnoceras (Pachyceratidae, Donovan, D.T., J.H. Callomon & M.K. Howarth (1981) - Perisphictaceae, Ammonites) du Callovien moyen et Classification of the Jurassic Ammonitina. In : House, supérieur de la région de Saida (Algérie occidentale). M. R. & J. R. Senior (Eds.). The Ammonoidea. The Origine phylétique et biogéographique des Pachyceratidae. Systematics Association, Academic Press, Spec. Publ. 18 : Géobios, Villeurbanne, 21(5) : 567-609. 101-155. Marchand, D. (1977) - Quelques précisions sur le Douvillé, R. (1912) - Etudes sur les Cardiocératidés de Dive, polymorphisme dans la famille des Cardioceratidae Villers-sur-Mer et quelques autres gisements. Mémoires de Douvillé (Ammonoidea). Haliotis, Dijon, 6 : 119-140. la Société Géologique de France, Paris, 45 : 89 pp. Marchand, D. (1986) - L’évolution des Cardioceratinae Enay, R. (1966) - L’Oxfordien dans la moitié sud du Jura d’Europe occidentale dans leur contexte paléobiologique français. Etude stratigraphique. Nouvelles Archives du (Callovien supérieur-Oxfordien moyen). Thèse de Muséum d’Histoire Naturelle, Lyon, 8(2) : 323 p. Doctorat, Université de Bourgogne (unpublished), Dijon : Enay, R. (1977) - A propos du dimorphisme chez les 603 p. ammonites jurassiques. Quelques réflexions. Colloque Marchand, D. & A. Pascal (1979) - Précisions sur le Polymorphisme chez les Invertébrés, Dijon, 1975. stratigraphiques et sédimentologiques sur la limite Dogger- Haliotis 6 (1976), 96-118. Malm en Haute-Marne (région de Latrecey). Bulletin de Gil, G.A., J. Thierry & H. Tintant (1985) - Ammonites la Société des Sciences Naturelle et d’Archéologie de la calloviennes du Sud d’Israël : systématique, biostratigraphie Haute-Marne, 21(5) : 101-112. et paléobiogéographie. Géobios, Villeurbanne, 18(6) : 705- Marchand, D., Ph. Courville, A. Bonnot, J. Rossi & 751. Qu. Scoufflaire (2002) - Very small Ammonites Głowniak, E. (2000) - The Platysphinctes immigration event (Micromorphs) from Lower Oxfordien Marls (Mariae in the Middle Oxfordian of the Polish Jura Chain (Central Zone). In : Summesberger, H., K. Histon & A. Daurer Poland). Acta Geologica Polonica, 50(1) : 143-160. (Eds). Cephalopods - Present and Past. Abhandlungen der Guex, J., A. Koch, L. O’Dogherty & H. Bucher (2003) - Geologischen Bundesandstalt, Wien, 57 : 467-478. A morphogenetic explanation of Buckman’s law of ayr Hermann covariation. Bulletin de la Société Géologique de France, M , E. (1974) - Populations, espèces et évolution. , Paris, 174(6) : 603-606. Paris : 496 p. Morard, A. (2006) - Covariation patterns in ammonoids : Gygi, R.A., D. Marchand & J. Thierry (1994) - Tornquistes helveticus (Jeannet, 1951) (Ammonitina, Pachyceratidae) observations, models, and open questions. 4th Swiss de l’Oxfordien inférieur du Jura Suisse ; Nom. nov. pro Geoscience Meeting, Bern 2006. « Herznachites » helveticus Jeannet, 1951. Géobios, Morard, A. & J. Guex (2003) - Ontogeny and covariation Villeurbanne, 27(4) : 459-466. in the Toarcian genus Osperleioceras (Ammonoidea). Hahn, W. (1971) - Die Tulitidae S. Buckman, Sphaeroceratide Bulletin de la Société géologique de France, 174, 607-615. S. Buckman und Clydoniceratidae S. Buckman Nicolis, E. & C.F. Parona (1885) - Note stratigrafiche e (Ammonoidea) des Bathoniums (Brauner-Jura epsilon) paleontologiche sul Giura superiore della Provincia di im südwestdeutschen Jura. Jahreshefte des Geologischen Verona. Bolletino della Società Geologica Italiana, 4 : 105 Landesamt Baden-Würtemberg, 14 : 55-122. p. Hammer, Ø. & H. Bucher (2005) - Buckman’s first law of Orbigny, A. d’ (1850) - Prodrome de paléontologie covariation – a case of proportionality. Lethaia, Oslo, 38 : stratigraphique universelle des animaux mollusques et 67-72. rayonnés. Masson, Paris : 432 p. I.C.Z.N. (International Commission on Zoological Page, K.N. (1993) - Mollusca : Cephalopoda (Ammonoidea, Nomenclature) (1999) - International Code of Zoological Ancyloceratina). In : Benton, J.M. (Ed.). Fossil Record 2. Nomenclature, 4th ed. International Trust for Zoological Chapman & Hall : 213-228. Nomenclature, London, 29 : 306 p. Page, K.N. (1996) - Mesozoic ammonoids in space and time. Hantzpergue, P. (1989) - Les ammonites kimmeridgiennes In : Landman, N. H., K. Tanabe & R. A. Davis (Eds). du haut-fond d’Europe occidentale. Biochronologie, Ammonoid Paleobiology. Plenum Press : 755-794. systématique, paléobiogéographie. Cahiers de Pavia, G. & S. Cresta (2002) - Revision of Jurassic Paléontologie, CNRS, Paris : 428 p. Ammonites of the Gemmellaro Collections. Quaderni Jeannet, A. (1951) - Stratigraphie und palaeontologie del Museo Geologico “G. G. Gemmellaro”. Dipartimento des oolithischen Eisenerzlagers von Herznach und di Geologia e Geodesia, Università di Palermo : 401 p. seiner Umgebung. Beiträge zur Geologie der Schweiz Quereilhac, Ph. (2000) - … A propos de quelques ammonites Geotechnische, Berne, 13(5) : 354 p. récoltées dans l’Oxfordien du Poitou. Ph. Quereilhac Ed., Krishna, J. & J. Thierry (1987) - Discovery of the genus Poitier : 207 p. Erymnoceras from the Middle Callovian of Kachchh, Quereilhac, Ph., D. Marchand, R. Jardat, A. Bonnot, Western India : paleontological, stratigraphical and D. Fortwengler & Ph. Courville (2009) - La faune paleobiogeographical implications. Newsletter on ammonitique des marnes à fossiles ferrugineux de la région Stratigraphy, Berlin, Stuttgart, 17(2) : 71-78. de Niort, France (Oxfordien inférieur, Zone à Cordatum, Discussion, evolution and new interpretation of the Tornquistes Lemoine, 1910 489

Sous-Zone à Cordatum). Carnets de Géologie / Notebooks Thierry, J. (1966) - Analyse stratigraphique de la série on Geology, Brest, Article 2009/05 (CG2009_A05). Bathonien-Oxfordien du Châtillonnais. Bulletin de la Roman, F. (1938) - Les ammonites jurassiques et crétacées. Société Géologique de France, Paris, (7), 8 : 642-651. Essai de Généra. Masson et Cie., Paris : 607 p. Thierry, J. & N. Charpy (1982) - Le genre Tornquistes Schindewolf, O. (1923) - Über die Ausgestaltung der (Ammonitina, Pachyceratidae) à l’Oxfordien inférieur Lobenlinie bei den Neoammonoidea. Centralbl. für et moyen en Europe occidentale. Géobios, Villeurbanne, Mineralogie, Geologie und Paläontologie : 337-370. 15(5) : 619-677. Schindewolf, O. (1963) - Studien zur Stammesgeschichte Tornquist, A. (1894) - Ueber Macrocephaliten im Terrain- der Ammoniten. III. Abhandlungen der Matematish- à-Chailles. Abhandlungen der Schweizerischen Naturwissenschaftlichen Klasse Jahrgang, Wiesbaden, 6 : paläontologischen Gesellshaft, Zürich, 21 : 31 p. 147 pp. Westermann, G.E.G. (1956) - Philogenie der Schweigert, G. & V. Dietze (1998) - Revision der dimorphen Stephanocerataceae und Perisphinctaceae des Dogger. Ammonitengattung Phlycticeras Hyatt - Oechoptychius Neues Jahrbuch für Geologie und Paläontologie Neumayr (Strigoceratidae, MittelJura). Stuttgarter Abhandlungen, Stuttgart, 103 : 233-279. Beiträge zur Naturkunde, Serie B, 269 : 60 p. Westermann, G.E.G. (1966) - Covariation and taxonomy of Sequeiros, L. (1974) - Paleobiogeografía del Calloviense y the Jurassic ammonite Soninia adicra (Waagen). Neues Oxfordiense en el sector central de la Zona Subetica II. Jahrbuch für Geologie und Paläontologie Abhandlungen, Tesis Doctorales, Universidad de Granada : 361 p. Stuttgart : 124 : 289-312. Sturani, C. (1967) - Ammonites and stratigraphy of the Bathonian in the Digne-Barrême area (South-eastern Accepté décembre 2009 France, dept. Basses-Alpes). Bolletino della Società Paleontologica Italiana. 5(1) : 3-57.