Bollettino della Società Paleontologica Italiana, 46 (1), 2007, 1-31. Modena, 31 agosto 20071

Ammonites from the early Pliensbachian of the Furlo Pass (Marche, Italy): biostratigraphic and paleobiogeographic implications

Federico VENTURI, Carlo NANNARONE & Massimiliano BILOTTA

F. Venturi, Dipartimento di Scienze della Terra, Università degli Studi di Perugia, Piazza Università 1, I-06123 Perugia, Italy; [email protected] C. Nannarone, Dipartimento di Scienze della Terra, Università degli Studi di Perugia, Piazza Università 1, I-06123 Perugia, Italy. M. Bilotta, Dipartimento di Scienze della Terra, Università degli Studi di Perugia, Piazza Università 1, I-06123 Perugia, Italy; [email protected]

KEY WORDS - Ammonites, Taxonomy, Biostratigraphy, Paleobiogeography, Tethys, Early Jurassic.

ABSTRACT - The ammonite assemblages found in the spathic Fu3 shell beds (lumachellas) of the Grilli Quarry (Furlo Pass, Umbria- Marche Apennines, central Italy) supplement the previous studies on the early Pliensbachian (Carixian) in this area, allowing to obtain a quite varied taxonomic, biostratigraphic and paleobiogeographic framework. The abundant documentation of the three lumachellas forming the Fu3 fauna (Fu3a, Fu3b1 and Fu3b2) belongs to the second Apennine biozone of the early Pliensbachian: this unit was formerly indicated as Miltoceras sellae Taxon Range Biozone, but here is redefined in a formally more correct way as Miltoceras Interval Biozone. Among the several ammonites collected, many new taxa are described: the new species Miltoceras furlense (family Coeloceratidae, subfamily Coeloceratinae), the new genus Spiniclaviceras for the new species S. spirale (family Coeloceratidae, subfamily Dubariceratinae), the new genus Paramorphites with the new species P. acutiventris (family Polymorphitidae, subfamily Polymorphitinae), and the new genus Sphenoacanthites (family Sinuiceratidae) instituted for the Tunisian forms erroneously reported as Gorgheiceras costotuberculatum and G. tuberculatum. Moreover, the new Polymorphitidae subfamily Furlitinae is formalized, also to include (with some doubt) Gemmellaroceras. This latter genus has been often subject of taxonomic confusion, and therefore a precise definition is given for it, allowing to clarify its bio- and chronostratigraphic position. Since in the Apennines Gemmellaroceras is found only from the second early Pliensbachian biozone onwards, this genus cannot be considered as a representative of the basal part of the stage at issue. The diagnosis of Miltoceras is improved too, basing on an unpublished revision of the original material housed in the “G.G. Gemmellaro” Geological Museum of the Palermo University. In addition, three unnamed new forms are recognized: one ascribed to the Dubariceratinae, one to the nominal subfamily of the Tropidoceratidae, and one which position at a suprageneric level cannot be determined. Basing on the whole of the available data, phylogenetic and paleobiogeographic hypotheses for some Mediterranean Tethys ammonoids are discussed, and a quite wide taxonomic synthesis is proposed. The Apennine documentation allows considerations on the Sinuiceratidae and the earliest Tropidoceratidae, but seems also to testify the first evolutive phases of the Polymorphitidae. This latter group is deemed to be the possible ancestor of the Fanninoceratidae (genera Eoamaltheus and Fanninoceras) of the eastern Pacific area (Andean Province). From a paleobiogeographic point of view, the features of the Apennine lower Pliensbachian ammonite faunas suggest that a limited portion of the western Tethys can be considered as a “Peltolytoceratinae meso-Mediterranean paleobiogeographic unit”. This shallow and mid-depth marine region would have included Apennines, Tuscany, Sicily, Albania, North Africa (Morocco, Algeria, northern Tunisia) and perhaps also Betic Cordillera (Spain) and Austrian Alps. Its relations with other areas are discussed, as well as the possibility of westward faunal exchanges (although sometimes partial and discontinuous) with the Andean Province. Indeed, the available evidence suggests that the trans-Pangea seaway known as the “Hispanic Corridor” would have acted as a filter, allowing the migration only to some forms which probably lived in relatively shallow environments (e.g. Catriceras and Paramorphites), but not to those for which a more deep habitat can be inferred (e.g. Galaticeras).

RIASSUNTO - [Ammoniti del Pliensbachiano inferiore del Passo del Furlo (Marche, Italia): implicazioni biostratigrafiche e paleobiogeografiche] - Le associazioni ad ammoniti contenute nei livelli calcarei di lumachella spatica Fu3 della Cava Grilli (Passo del Furlo, Appennino umbro- marchigiano) permettono di integrare gli studi precedenti sul Pliensbachiano inferiore (Carixiano) di tale area, consentendo di ottenere un quadro tassonomico, biostratigrafico e paleobiogeografico piuttosto vario. Nelle tre lumachelle che complessivamente costituiscono la fauna Fu3 (Fu3a, Fu3b1 e Fu3b2) è stata rinvenuta abbondante documentazione della seconda biozona del Pliensbachiano inferiore: questa unità precedentemente era indicata come Biozona di Distribuzione a Miltoceras sellae, ma qui viene ridefinita in maniera formalmente più corretta come Biozona di Intervallo a Miltoceras. Fra i numerosi ammoniti trovati, sono stati descritti molti nuovi taxa, a cominciare dalla nuova specie Miltoceras furlense; con l’occasione è stata inoltre migliorata la diagnosi del genere a cui appartiene, basandosi su un inedito lavoro di revisione riguardante il materiale originale conservato presso il Museo Geologico “G.G. Gemmellaro” dell’Università di Palermo. Ad un altro sottogruppo di Coeloceratidae, i Dubariceratinae, è stato attribuito il nuovo genere Spiniclaviceras, qui istituito per la nuova specie S. spirale, caratterizzata da avvolgimento evoluto e tozze spine claviformi. Particolarmente importante è la documentazione dei Polymorphitidae, nella cui sottofamiglia nominale (Polymorphitinae) viene individuato il nuovo genere Paramorphites, con la nuova specie P. acutiventris. I dati disponibili suggeriscono di considerare tale forma come il capostipite del gruppo americano endemico dei Fanninoceratidae (generi Eoamaltheus e Fanninoceras). Rimanendo ancora nella famiglia Polymorphitidae, viene formalizzata la nuova sottofamiglia Furlitinae, alla quale è riferibile con qualche dubbio anche il genere Gemmellaroceras. Quest’ultimo è spesso stato oggetto di confusione tassonomica e ci è sembrato pertanto opportuno darne una definizione precisa. Ciò fra l’altro permette di chiarirne la posizione bio- e cronostratigrafica: poiché in Appennino Gemmellaroceras si ritrova solo a partire dalla seconda biozona del Pliensbachiano inferiore, esso non è un genere che si può ritenere rappresentativo della parte basale di tale piano.

ISSN 0375-7633 2 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Alla famiglia Sinuiceratidae viene ascritto il nuovo genere Sphenoacanthites, istituito per le specie tunisine erroneamente segnalate come Gorgheiceras costotuberculatum e G. tuberculatum. Il materiale del Passo del Furlo ha inoltre permesso di migliorare ulteriormente la diagnosi dei Sinuiceratidae, la cui posizione a livello gerarchico sopra-familiare rimane tuttora incerta. Per questo taxon le maggiori affinità si riscontrano con un nuovo genere inedito rinvenuto nel Calcare Massiccio di Monte Bove (Appennino umbro-marchigiano) probabilmente databile al Sinemuriano basale, che a sua volta sembra in qualche modo avvicinabile a Dudresnayiceras. In aggiunta a ciò, sono stati riconosciuti altri tre nuovi generi, lasciati privi di denominazione formale per la scarsità di dati: il primo è ascritto ai Dubariceratinae, il secondo alla sottofamiglia nominale dei Tropidoceratidae, mentre per il terzo la posizione a rango sopra- generico non è attualmente definibile. Nel loro complesso, i dati disponibili permettono di discutere ipotesi filogenetiche e paleobiogeografiche per alcune forme della Tetide mediterranea, e consentono inoltre di presentare una sintesi tassonomica piuttosto ampia. La ricchezza dell’associazione Fu3 ben rappresenta il rinnovamento faunistico degli ammonoidi del Pliensbachiano inferiore e la radiazione adattativa in seno alla quale si sono evoluti vari taxa inizialmente tipici dell’area mediterranea. In Appennino si possono riconoscere due fasi principali di questo processo: una è all’inizio della Zona a Catriceras, mentre l’altra è all’inizio della successiva Zona a Miltoceras, preceduta da una lacuna di documentazione. Durante la prima fase si ha la comparsa improvvisa dei Tropidoceratidae, la cui derivazione dagli Eoderoceratidae, per quanto plausibile, finora non è mai stata supportata in modo diretto. In ogni caso, il cambiamento morfologico assai consistente che avrebbe portato da forme non carenate a questi ammoniti carenati con coste flessuose si può considerare volto al miglioramento delle loro attitudini idrodinamiche, ma per la carenza di dati è ancora problematico trovare delle cause che spieghino la repentina comparsa di questo gruppo all’inizio del Pliensbachiano. Decisamente più consistenti sono invece le testimonianze appenniniche sulle prime fasi dell’evoluzione di altri gruppi, come ad esempio i Polymorphitidae: sembra infatti che almeno buona parte degli Eoderoceratoidea pliensbachiani con ornamentazione essenzialmente monospinata possano essere derivati da un ceppo comune di eoderoceratidi bispinati. Da queste forme deriverebbero due linee filetiche principali: la prima è quella dei Coeloceratidae, ammoniti monospinati che normalmente mostrano un’ornamentazione laterale e/o ventrale di tipo “ordinario”. La seconda è quella dei Polymorphitidae, fra i quali si riscontrano invece tendenze maggiormente “originali”, come ad esempio la conservazione di una conchiglia più o meno inornata con sutura semplificata (Furlites, Gemmellaroceras) o lo sviluppo di taxa ornati con area ventrale tettiforme (Paramorphites). Dal punto di vista paleobiogeografico, i caratteri delle faune ad ammoniti del Pliensbachiano inferiore in Appennino suggeriscono che una porzione limitata della Tetide occidentale può essere considerata come una “unità paleobiogeografica meso-mediterranea a Peltolytoceratinae”. Questa regione marina di bassa e media profondità avrebbe incluso Appennino, Toscana, Sicilia, Albania, Nordafrica (Marocco, Algeria, Tunisia settentrionale) e forse anche Cordigliera Betica (Spagna) ed Alpi Austriache. Vengono discusse le sue relazioni con altre aree, così come la possibilità di scambi faunistici (sebbene talora discontinui e parziali) ad ovest con la Provincia Andina. Tutto lascia in effetti pensare che il passaggio marino trans-Pangea detto “Corridoio Ispanico” abbia funzionato come un filtro, permettendo la migrazione solo ad alcune forme, probabilmente legate ad un ambiente di vita più superficiale (come Catriceras e Paramorphites), ma non a quelle per le quali si può supporre un habitat più profondo (come ad esempio Galaticeras).

FOREWORD Stratigraphy, all the zonal elements based on Jurassic ammonites (zones, subzones, biohorizons, zonules) Following the previous publications on the lower should be treated as chronostratigraphic units Pliensbachian ammonite faunas of the Umbria-Marche (chronozones, subchronozones, etc.) (see Page, 2003, p. Apennines (Venturi et al., 2004, 2005), here is studied 25-26 and references therein). If this methodology is the stratigraphically more recent of the three assemblages surely useful and necessary in the North-west Europe, found at the Grilli Quarry (Furlo Pass), named Fu3 (Fig. 1). The various recognized forms (including some new taxa) facilitate an accurate definition of the base of the second early Pliensbachian Apennine biozone (Miltoceras sellae Zone of Faraoni et al., 1996; that work regards the characterization of the middle and upper parts of the Zone itself). These data further improve the correlation outline between Apennines and standard zonations proposed by Venturi et al. (2004, 2005), supplementing studies on other localities (Venturi, 1978; Faraoni et al., 1996; Venturi & Bilotta, 2001). As a result, a better comparison between Mediterranean Tethys faunas (Apennines, Austroalpine, Sicily, Albania, Morocco, Algeria, northern Tunisia, etc.) and those from other areas is possible. This also facilitates the development of some themes concerning taxonomy, phylogeny and paleobiogeography: the latter subject is particularly significant, due to the considerable discrepancies in the available paleogeographic reconstructions.

THE EARLY PLIENSBACHIAN ZONATION IN THE MIDDLE-WESTERN TETHYS

According to the conventions followed by working Fig. 1 - Geographic location of the Furlo Pass section (Grilli Quarry), groups of the International Subcommission on Jurassic marked with an asterisk. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 3

Fig. 2 - Hypothesized correlation among the standard zonation and three different Mediterranean Tethys schemes for the early Pliensbachian. The scheme here presented (on the right) is a formal improvement of the zonation by Venturi et al. (2005). where the Stages were historically defined, we believe data lead to think that it can represent the basal portion that the correlation problems make hard the utilization of the biostratigraphic interval at issue, which in the of such an approach in the Mediterranean area. Bosso River section is lacking for the presence of a Therefore, we prefer to use the Apennine Zones (and barren interzone (about ten meters thick) between the last more in general those not belonging to the North-west beds of the Catriceras Zone and the first ones of the European standard scheme) considering them as Miltoceras Zone itself. biozones, in accordance with a practice which is Basing on the forms found in the Bosso River and widespread in the literature, although this is not a strictly Grilli Quarry sections, the most characteristic conventional methodology (Fig. 2). ammonoids that can be found associated with the index As formerly observed (Venturi et al., 2004, 2005), taxon of the Miltoceras biozone are: various monospinate the scheme elaborated by Faraoni et al. (1996) is the most coeloceratids, polymorphitids (both ornate or nearly suitable biostratigraphic reference for the study of the smooth, such as Gemmellaroceras Hyatt), and early Pliensbachian in the Apennines. Its basal part (i.e. Galaticeras Spath. In the lower portion of the Zone the the first biozone) was already refined by Venturi et al. Sinuiceratidae are fairly common, while the first forms (2005), while the second biozone is concerned here. This ascribable to Tropidoceras Hyatt typically appear in the unit was originally defined in the Bosso River section as middle-upper part. According to the most recent literature the Miltoceras sellae Taxon Range Biozone, but the index this biostratigraphic interval can also be recognized in species is not present for the entire interval. In reality, other sections of the Mediterranean Tethys, including the the authors intended to use the range of the genus Tunisia (Mines du Djebel Staa section; Rakús & Guex, Miltoceras Wiedenmayer, which in the reference section 2002). Due to the high ammonite diversification in the is found from the base (bed 82) to the upper part (bed Mediterranean areas, it is currently unknown an 116), but not until the top of the zone itself (whereas the unambiguous taxon which can be used to jointly and last bed, numbered 125, includes four Metaderoceras sp., adequately characterize the first two Apennine one Galaticeras sp. and one Tropidoceras gr. flandrini biostratigraphic subdivisions. It is therefore impossible (Dumortier)). With this kind of characterization, the to designate a single unit corresponding to the standard biostratigraphic unit at issue surely fits the current Jamesoni Zone, which chronological equivalent is made opinions, but some formal changes are deemed to be up by the sum of the Catriceras and Miltoceras biozones. convenient. In accordance with the recommendations of On the other hand, the use of the zonal scheme the International Stratigraphic Guide (Salvador, 1994), here proposed allows to at least partially overcome some here we propose to redefine the second Apennine correlation problems existing until recent years in the biozone of the early Pliensbachian as Miltoceras Interval Mediterranean Tethys. In particular, the studies on the Biozone. Its base is defined by the appearance of Apennine Pliensbachian faunas show that the second ammonites of the genus Miltoceras (such as those figured subdivision of our zonation (Miltoceras Zone) largely in Faraoni et al., 1996, pl. 6, figs. 3, 5-7), while its top is coincide with the Gemmellaroceras aenigmaticum Zone, determined by the first (mass) occurrence of which is the first biostratigraphic unit of the early Tropidoceras gr. mediterraneum (Gemmellaro) (as those Pliensbachian defined by Braga et al. (1982, 1984) for figured in Faraoni et al., 1996, pl. 7, figs. 5, 8). This the Betic Cordillera (southern Spain). The practical maintains the original concept of Faraoni et al. (1996), problems arose by the usage of this latter scheme have rectifying its formal imperfections. been noted for instance by Faraoni et al. (1996, p. 76) The Fu3 fauna subject of the present paper is exactly and Venturi et al. (2005, p. 112); actually, Braga et al. attributable to the Miltoceras Zone: indeed the current (1982, p. 228) themselves already couched some 4 Bollettino della Società Paleontologica Italiana, 46 (1), 2007 reservations on the complete reliability of the zonation constituting the lumachellas is very often fragmented, they proposed. Basically, lacking more significant taxa, without evident sorting or orientation, and never they adopted the appearance of Gemmellaroceras reworked. Probably, these shell beds came from an aenigmaticum (Gemmellaro) as a compromise to denote elevated portion of the sea-bottom, and were deposited the first Pliensbachian beds in the Betic Cordillera. Due on the slope after rather short transport, without the to this formal agreement, the first occurrence of G. contribution of waves or currents. aenigmaticum and the actual beginning of the The Fu3 assemblage here described is made up of three Pliensbachian Stage did not match, being separated by different lumachellas (Fu3a, Fu3b1 and Fu3b2), roughly an undetermined interval. Now, our data show that this superimposed on the same mountainside portion: their hiatus, indicated by Braga et al. (1984, fig. 5) with a faunas are not exactly the same (the two Fu3b seem question mark, coincides with the entire Catriceras Zone, slightly younger than the Fu3a), but anyway they are which in turn is correlatable with the Taylori Subzone of closely comparable. the standard scheme. As a matter of fact, the first The preservation of the ammonites is substantially the Apennines ammonites attributable to Gemmellaroceras same observed for Fu1 and Fu2 lumachellas (Venturi et are found in the Fu3 fauna from the Grilli Quarry and in al., 2005, p. 85-86) but, compared with the other two the bed 82 of the Bosso section, i.e. within the Miltoceras faunas (especially the first), most part of the Fu3 forms Zone (the two specimens from the Bosso bed 52 are middle- to small-sized and larger ammonites are erroneously mentioned as Gemmellaroceras sp. by found only as fragments. Similarly to the preceding Faraoni et al., 1996 are in fact Furlites Venturi & Ferri). assemblages, the bioclasts appear to float in an abundant Therefore, we do not think that Gemmellaroceras can be matrix, which is almost always recrystallized, and show considered a representative ammonoid for the basal part internal cavities frequently filled by druse cements, but of the early Pliensbachian, also because this taxon may without evident geopetal structures. Ammonites are often give rise to some problems of practical preserved as internal moulds composed of calcite identification (as already evidenced by Braga et al., 1982, crystals, but in the largest specimens the phragmocone p. 228), making it taxonomically “ambiguous” and thus can also be filled by micrite, and at times a pseudo-test not well suited to be an index species. Indeed, several is preserved, too. The suture line is often visible (at least early and middle Liassic forms are small-sized, evolute, in transparency), even when the mould is covered by one smooth or feebly ornamented, and for this general aspect or two of the innermost test layers. On other occasions, they might be mistook with Gemmellaroceras, but they calcite completely effaces the suture line, making differ from it for many characters: see for example the impossible to distinguish the body chamber from the ammonoids incorrectly named G. aff. aenigmaticum by phragmocone if morphologic peculiarities Dommergues et al. (1983; pl. 1, figs. 1-12); or those (ornamentation or else) are not present. Therefore, in erroneously figured as G. aenigmaticum, G. cortesei (Gemmellaro) and G. sp. by Smith & Tipper (1996; text- fig. 26e; pl. 6, figs. 12-14, 19-23; pl. 10, figs. 5-6). According to the above-explained point of view, the G. aenigmaticum Zone of Braga et al. (1982, 1984) seems to have a too much abstract significance, and we deem that its application to outcrops outside the Betic Cordillera (as for example the Tunisian sections of Rakús & Guex, 2002) is at least inadvisable.

MATERIALS AND METHODS

The studied ammonites were found in the biosparites belonging to the informal lithostratigraphic unit called “Corniola”, and were included in the highest of the three (Fu1, Fu2 and Fu3) main spathic shell beds (lumachellas) recognized at the Furlo Pass (Grilli Quarry), as already explained in Venturi et al. (2005, p. 85-86). These lumachellas come from a side of the Mount Pietralata where the Corniola outcrops in “massive” facies, lack an evident stratification (except for some sporadic instances), and they appear as sub-lenticular Fig. 3 - Schematic section depicting the relations of the bodies probably resulting from episodic inputs. These lithostratigraphic units on the side of the Mount Pietralata, as they bodies are placed side by side or alternated one another, were observed in the valley (the background is in dark grey, the with not much clear lateral and sometimes vertical mountainside is white). Above the Corniola in “massive” facies relations (Fig. 3). (without fossils; lower part of the scheme) there are four fossiliferous The setting is characteristic of reduced or condensed lumachellas: the first one (Fu1) contains bivalve molluscs, ammonites, nautiloids, belemnites, brachiopods and crinoids; the successions (ramp depositional environment), with second one (Fu3a) yielded ammonites, bivalves and gastropods, while sedimentation due to discontinuous and markedly in the two Fu3b lumachellas (Fu3b1 and Fu3b2) only ammonites canalized gravitative deposits (debrites). The material were found. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 5 general we are not able to ascertain if the smallest Subclass AMMONOIDEA Zittel, 1884 individuals are juveniles or simply nuclei, and the data Order PHYLLOCERATIDA Arkell, 1950 do not allow to state whether they are microconchs Family PHYLLOCERATIDAE Zittel, 1884 (dimorphs) or not. On the other hand, we are inclined Subfamily PHYLLOCERATINAE Zittel, 1884 to exclude that the small-sized specimens can be micromorphs, since we believe that such dwarf forms are Genus Phylloceras Suess, 1865 more related to “stressed” environments, while the assemblages at issue evoke a tropical scenario, with great Type species - Ammonites heterophyllus Sowerby, 1820 competition and high faunal diversity. As a rule, we adopt a “restrictive” taxonomic approach Phylloceras sp. (Venturi et al., 2004, p. 365). For practical purposes we prefer, in fact, (except in very well-documented cases, Material - Four small-sized specimens (nuclei). for instance with precise stratigraphic references) to keep not excessive ranges of variability, especially for taxa Measurements - See Tab. 1. whose assigned ranks are genus and species. With this method, the differences (both in morphology and in Description - Decidedly involute shell, smooth, quite geographic-stratigraphic distribution) are markedly broad. High elliptic whorl section, with rounded and not underlined, thus having a precise characterization for the much narrow ventral area. The whorl overlapping is formally named groups. Sedimentation and fossil record conspicuous (nearly 2/3). are often episodic or very discontinuous, thus causing Suture line with phylloid saddle endings; E lobe many uncertainties: therefore, to perform biostratigraphic (possessing the characteristic phylloceratine median comparisons between different areas as well as septum) a little shorter than L, which is trifid and paleobiogeographic studies we believe that taxa with apparently symmetric; four umbilical lobes, the first of clearly defined morphology and stratigraphic-geographic which (U2) is almost as long as L; diphyllic ES and LS1 distribution are far more useful. Such groups are easily saddles. recognizable, independently from their possible biological value. Remarks - The coiling, the lack of ornamentation, the To obtain greater completeness in the systematic whorl section and the aspect of the suture line do not distinctions, all the available elements are jointly leave much doubts on the generic identification; however, examined: morphology (coiling, shell shape, the documentation is not enough to allow detailed ornamentation), structure (conformation of the suture comparisons, which are necessary for an adequate line), stratigraphic and geographic localization. specific assignment.

Stratigraphic distribution - Three specimens were SYSTEMATIC DESCRIPTIONS found in the Fu3a lumachella, while the fourth one comes from the Fu3b2 lumachella; both are datable to the early The ammonite fauna of the three Fu3 lumachellas from Pliensbachian (base of the Miltoceras Zone). the Furlo Pass is highly diversified, and from them over than 430 individuals were recovered, including more or Family JURAPHYLLITIDAE Arkell, 1950 less complete specimens and fragments. For about forty small- or very small-sized exemplars (with a diameter Genus Juraphyllites Müller, 1939 from 8-9 mm to about 4 mm) an adequate taxonomic identification was impossible, while in at least a pair of Type species - Phylloceras diopsis Gemmellaro, other instances the high cementation degree prevented 1884 the extraction from the lumachella and thus hampered a careful study. Juraphyllites sp. For the terminology used in the descriptions of this paper, see Venturi et al. (2004) and references therein. Material - At least four small-sized specimens, For a selected number of specimens of most species including one nucleus. the following biometric parameters are given, in millimetres (for linear measurements) or as adimensional Remarks - Most of the specimens show feeble striae, numbers (for ratios): diameter (d), umbilical diameter due to the presence of the test which apparently effaces (u), whorl height (h), whorl width (w), umbilical ratio or the suture lines. Sometimes not much deep constrictions involution index (u/d), whorl shape or flattening index are visible, too: they are characterized by a straight (w/h), height ratio (h/d), width ratio (w/d). Estimated pattern, just like that of the striae. values are preceded by the symbol ~. The attribution to the genus Juraphyllites is based on the general “phylloceratine” aspect, with striae and not flexuose constrictions, and more evolute coiling than that observable in the forms ascribed to Phylloceras.

Stratigraphic distribution - The specimens were collected from the Fu3a lumachella, datable to the early Tab. 1 - Measurements for three Phylloceras sp. specimens from the Fu3a and Fu3b lumachellas. Pliensbachian (base of the Miltoceras Zone). 6 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Order PSILOCERATIDA Houša, 1965 Genus Galaticeras Spath, 1938 Family LYTOCERATIDAE Neumayr, 1815 Type species - Amphiceras harpoceroides Genus Lytoceras Suess, 1856 Gemmellaro, 1884

Type species - Ammonites fimbriatus J. Sowerby, 1817 Galaticeras sp.

Lytoceras sp. Material - Nine small-sized specimens, most of which are nuclei. Material - One fragmentary small-sized specimen. Measurements - See Tab. 2. Description - Evolute shell, with roundish whorl section, slightly broader than high, and rounded ventral Remarks - The studied specimens show weak area. constrictions, and for this reason they do not seem to Whorls apparently do not overlap much; they are belong to the species G. canavarii (Fucini) found in the smooth or present only feeble striae. Fu2 lumachella, which instead is characterized by evident The suture line is only partially visible, and it is constrictions, already visible at a small diameter. In any indented, with a seemingly trifid or bi-trifid and case, the overall morphology (coiling, aspect of whorl asymmetric L lobe. section and ventral area, amount of whorl overlapping) and the few observable portions of the suture do not leave Remarks - The observable characters seem sufficient much doubts on the fact that also the Fu3 specimens are to ascribe this form to the genus Lytoceras, but they do to be attributed to Galaticeras. not allow a definite specific assignment. As already noted (Venturi & Bilotta, 2001; Venturi et al., 2005), this genus has a chronostratigraphic range Stratigraphic distribution - The specimen was found from the basal (Catriceras Zone) to the middle part in the Fu3a lumachella, datable to the early Pliensbachian (Metaderoceras gemmellaroi Zone) of the early (base of the Miltoceras Zone). Pliensbachian, and its geographic distribution is restricted as well. In particular, it is found only in the Apennines (where it is very frequent; Venturi & Bilotta, 2001; Family HOLCOLYTOCERATIDAE Venturi, Nannarone & Venturi et al., 2005), Tuscany (Venturi & Bilotta, 2001; Bilotta, 2005 Venturi et al., 2005), Sicily (Gemmellaro, 1884; Venturi & Bilotta, 2001), Morocco (Lachkar et al., 1998), Genus Aegolytoceras Spath, 1924 northern Tunisia (Rakús & Guex, 2002), Albania (Dommergues et al., 2000), southern Turkey Type species - Audaxlytoceras fucinii Fantini Sestini, (Dommergues et al., 2005), perhaps also southern Alps 1973 (Lytoceras serorugatum Fucini, 1901, non Stur in and some Austrian Austroalpine units (Dommergues, Geyer, 1886) personal communication), while it is completely absent for instance in Hungary and northern Turkey, and as far as Aegolytoceras sp. we know, specimens correctly ascribable to this taxon were never found in extra-Mediterranean areas. For Material - Two fragmentary small-sized specimens. instance the English upper Sinemurian forms (Obtusum Zone) originally called Galaticeras jacksoni Howarth Remarks - Despite its fragmentary nature, the material & Donovan (1964, p. 289-290; text-fig. 1b-c; pl. 48, figs. can be referred with good confidence to this genus for 1-4) show characters (chiefly aspect of the suture line the evolute form, with whorl section as high as wide and and presence of a keel) and a stratigraphic position which rounded ventral area, the presence of evident are incompatible with those of the genus to which they constrictions followed by expansions (varices), and the were assigned, as already noted by Venturi & Bilotta rather simple suture line which seems to have a trifid L (2001). The geographic isolation of Galaticeras may lobe. be due to many reasons, beginning from paleoecologic

Stratigraphic distribution - The specimens were found in the Fu3a lumachella, datable to the early Pliensbachian (base of the Miltoceras Zone).

Family ANALYTOCERATIDAE Spath, 1927 Subfamily PELTOLYTOCERATINAE Venturi & Bilotta, 2001

Remarks - Venturi et al. (2005, p. 93) expressed some doubts on the original placement of this subfamily within the Ectocentritidae, suggesting as an alternative a possible affinity with the group represented by Analytoceras Hyatt. Now this choice is deemed to be preferable, and Tab. 2 - Measurements for nine Galaticeras sp. specimens from the therefore it is adopted here. Fu3a lumachella. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 7 causes. Actually, shell morphology, ornamentation with The whorl is ornated by poorly relieved primary striae and indenting of the suture line of this form seem ribs, almost straight or slightly proverse; on the inner to agree with a mode of life more related to the lower third of the flank they end in small spines, which are photic zone (approximatively between a depth of 100 and nearly orthogonal to the coiling plane. From them, thin 200 m), and this may imply a lesser tendency to the and dense secondary ribs arise, crossing the ventral dispersal in different environments. However, one must area without interruption. not exclude also paleogeographic factors, since this is The suture line is rather indented, with E lobe longer not the only endemic taxon in the early Pliensbachian and, (sometimes only a little) than L, which is enlarged and in fact, the partial provincialism of the Apennine fauna trifid or asymmetric tetrafid; inclined ES saddle split in compared to those more or less coeval from other areas two uneven parts by an inside-shifted A lobe; slightly has been noticed more than once (Venturi & Bilotta, 2001; suspensive umbilical lobes (placed on an oblique line), Venturi et al., 2004, 2005). This can be observed during with U2 more developed than U3; both are nearly parallel an interval from the early Sinemurian to most part of the to L, and are inserted at different heights (not much early Pliensbachian, a time corresponding to the retracted sutural lobe). stratigraphic range of the Peltolytoceratinae. Therefore, the basically qualitative datum of the Remarks - The original diagnosis of Miltoceras given presence (or absence) of Sinemurian or Pliensbachian by Wiedenmayer (1980) has some lacking points and does Peltolytoceratinae (respectively Peltolytoceras Spath and not seems to us completely shareable: the emended one Exomiloceras Wiedenmayer; Galaticeras and here presented derives from the unpublished revision Castanyiceras Rakús & Guex), as well as other associated work of the original Gemmellaro (1884) material drafted forms has, in our opinion, a remarkable by one of us (Venturi) between 1998 and 1999. paleo(bio)geographic significance, characterizing a As already designated by Smith & Tipper (1996, p. branch of the western Tethys with an essentially East- 42), the lectotype of the type species Miltoceras sellae West extension, from southern Turkey to Morocco. The (Gemmellaro) is the specimen no. 27/1 of the original discrepancies among the various available Gemmellaro (1884, pl. 3, figs. 1-2) collection, housed paleogeographic reconstructions do not allow to precise in the “G.G. Gemmellaro” Geologic Museum, Geology in detail its boundaries, but we believe it is possible and Geodesy Department of the Palermo University. This depicting from early Sinemurian to at least early specimen is preserved with the test, which makes Pliensbachian times the existence of a limited portion impossibile to observe the internal mould, and the of the Mediterranean Province of Page (1996), sutures here figured (Fig. 4) were drawn from two distinguished as a “Peltolytoceratinae meso- Mediterranean paleobiogeographic unit”. Its relations with some parts of the Province are uncertain, while in other cases (for instance Hungary and northern Turkey) a clear separation might be legitimately supposed. Indeed, it is characterized by several peculiar taxa, from the Peltolytoceratinae to Gemmellaroceras. Since many of these forms are chiefly endemic, we deem that any reference to them made outside this area (whether as taxonomic attribution or as biostratigraphic correlation), must be very cautiously considered, and that it cannot be accepted if not supported by a safe identification, based both on the morphology and (when the information is available) on the suture line.

Stratigraphic distribution - The specimens were found in the Fu3a lumachella, datable to the early Pliensbachian (base of the Miltoceras Zone).

Superfamily EODEROCERATOIDEA Spath, 1927 Family COELOCERATIDAE Haug, 1910 Subfamily COELOCERATINAE Haug, 1910 Fig. 4 - Miltoceras sellae (Gemmellaro), showing the characteristics of the genus, drawn on the material of the original Gemmellaro Genus Miltoceras Wiedenmayer, 1980 collection, housed in the “G.G. Gemmellaro” Geologic Museum, Geology and Geodesy Department of the Palermo University; a) Type species - Aegoceras sellae Gemmellaro, 1884 lateral view of the young specimen n. 27/2 (paralectotype); magnified about x 1.5; b) whorl section of the same specimen, magnified about Emended diagnosis - Moderately evolute or x 2; c) suture line of the same specimen, drawn at a diameter of moderately involute shell, with high elliptic whorl about 200-300 mm; magnified about x 1.5; d) suture line of the specimen n. 27/3 (originally unfigured paralectotype) drawn at a section; rounded elevated ventral area. diameter of about 200-300 mm; magnified about x 1.5 (drawings by F. Venturi). 8 Bollettino della Società Paleontologica Italiana, 46 (1), 2007 out of the four paralectotypes identified in the material Holotype description - Moderately evolute shell, with at issue: one of them is the young no. 27/2 of roundish and a little wider than high whorl section; Gemmellaro (1884, pl. 3, figs. 3-4). On the other hand rounded and elevated ventral area. The last whorl overlaps it was not possible to find the individual or the fragment about 1/4 of the preceding one. (probably a large-sized one) from which the suture The inner whorls are not well preserved, and the reproduced in Gemmellaro (1884, pl. 3, fig. 5) has been ornamentation is visible only from a diameter of about 6 taken. In any case, these suture lines have a mm: it is formed by primary ribs which nearly on the half coeloceratine aspect, differing from those of Coeloceras of the flank end with a short spine. Starting from the Hyatt chiefly for the conformation of the LS1 saddle diameter of about 14-15 mm thin and close secondary and for the distance between U2 and U3 lobes. ribs originating from the spines and crossing the ventral According to the available data, Miltoceras is area can be noted as well. typically found especially in the lower part of the The suture line is observable only for its lateral portion homonym Apennine Zone, and anyway we do not think (chiefly on the last stretch of phragmocone, at a diameter that forms correctly ascribable to it may belong to earlier of about 15 mm), and is rather indented: the L lobe is time intervals. In particular we believe that the species slender and trifid; the ES saddle has a well developed A called Miltoceras gruenae Blau (1998, text-fig. 27; pl. lobe in its inner portion; the umbilical lobes are slightly 13, fig. 3), coming from the upper Sinemurian beds inclined, with a relatively large U2 and a shorter (but not (Raricostatum Zone, Macdonnelli Subzone) of the tooth-like) U3. Lienzer Dolomiten (south-western Austria) is to be attributed to another genus. In fact, it shows intercalated Diagnosis - Moderately evolute shell, with whorl lateral ribs (which in true Miltoceras are lacking) and section from roundish in the inner whorls to pentagonal very different ontogenetic development, with an inner or high elliptic in the outer ones; rounded or sub-roof- stage possessing very coarse ribs and spines (the author shaped ventral area, always very elevated. Each whorl himself notices that this prolonged “Coeloceras-type” overlaps about 1/3 or 1/4 of the preceding one. stage differentiates his species from all the Miltoceras The innermost whorls of the nucleus have an involute known): in our opinion this form is probably referable to and “inflated” aspect, and are smooth until a diameter of Paramicroderoceras Dommergues, Ferretti & Meister. about 3-4 mm, when ribs appear: they involve the inner For the same kind of reasons we do not feel able to half of the flank, and at first they are not very relieved support the original ideas expressed by Wiedenmayer (sometimes they are weakly flexuose); from the diameter (1980, p. 172), who reported the presence of Miltoceras of about 5 mm onwards, the ribs end in short and small from the base of the Jamesoni Zone to at least the Davoei spines, while the outer part of the flank and the ventral Zone or probably even in the Margaritatus Zone. area show thin secondary ribs, which are evident as far as Therefore, as far as we know, there is not a remarkable the body chamber. At times the spines are quite large, but overlapping with the stratigraphic range of Coeloceras. other times they are very small, and in some instances they even seem to be absent; in any case they are placed about on the half of the flank (or a little higher) and Miltoceras furlense nov. sp. perpendicular to it. Figs. 5a-m, 16a-c, g

Name derivation - From Furlo, with reference to the provenance locality.

Holotype - Fu3C00N, specimen with the initial part of the body chamber (Figs. 5c, 16b), housed in the Earth Sciences Department, Università degli Studi di Perugia.

Paratypes - Fu3C02, specimen with part of the body chamber (Fig. 16a); Fu3C01, specimen with the initial part of the body chamber (Figs. 5d, 16c); both are housed in the Earth Sciences Department, Università degli Studi di Perugia.

Type locality - Furlo Pass (Umbria-Marche Apennines).

Type section - Grilli Quarry (Furlo Pass), Fu3a lumachella.

Material - About one hundred and seven different- sized specimens (mostly mid- to small-sized; many of them are fragments). Tab. 3 - Measurements for twenty-one Miltoceras furlense nov. sp. specimens from the Fu3a lumachella. Measurements - See Tab. 3. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 9

Fig. 5 - Miltoceras furlense nov. sp.; a) lateral view and whorl section of the fragment Fu3C10; magnified about x 1.5; b) lateral view and whorl section of the nucleus Fu3C35; magnified about x 1.5; c) ventral profile and lateral view of the holotype Fu3C00N (the innermost whorl is restored); magnified about x 1.5; d) suture line of the specimen Fu3C01, drawn at a diameter of about 14.5 mm; e) lateral view and ventral profile of the nucleus Fu3C06; magnified about x 1.5; f) lateral view and ventral profile of the nucleus Fu3C21; magnified about x 1.5; g) ventral profile and lateral view of the young individual or nucleus Fu3C38; magnified about x 1.5; h) ventral profile, lateral view and whorl section of the young individual or nucleus Fu3C39; magnified about x 1.5; i) ventral profile, whorl section and lateral view of a restored specimen (chiefly based on the fragment Fu3C00); magnified about x 1.5; j) lateral view and whorl section of the fragment Fu3C62; magnified about x 1.5; k) suture line of the same specimen, drawn at a diameter of about 11 mm; l) whorl section and lateral view of the nucleus Fu3CP06; magnified about x 1.5; m) whorl section and lateral view of the fragment Fu3C49; magnified about x 1.5 (drawings by F. Venturi).

The suture line, starting from the diameter of about The stratigraphic situation of the Grilli Quarry does 7.5 mm or less, is rather indented, and it is characterized not allow to have a continuous chronologic range for by slender lobes: E remarkably longer than L, which is these forms, and indeed it is hard to establish with trifid; ES saddle with two well developed A lobes (the confidence whether they are co-specific variants with innermost one is larger than the outermost one); LS1 a taxonomic value (subspecies) or not. In any case we saddle narrower than ES; the U2 lobe is large, while U3 think that, as a whole, the Miltoceras of the Fu3 is shorter (but not tooth-like) and slightly inclined (or assemblage can be well differentiated from the other suspensive). forms attributed to this genus, and the observed variability strengthens the idea that it is a separated Remarks and comparisons - Within the same species, species. the variability of the Fu3 material allows to recognize at In particular, compared to Miltoceras sellae least three morphotypes (i.e. minor intraspecific varieties (Gemmellaro) at the same diameter, the Grilli Quarry which cannot be taxonomically formalized). The first one specimens have more “inflated” inner whorls, an always (represented by at least five specimens) is characterized more elevated venter, thinner and thicker ribs, their spines by relatively evolute coiling and slightly raised (sub-roof- are placed lower on the flank, the suture line apparently shaped) ventral area, which give the whorl section a has more spaced lobes, and the stratigraphic position is pentagonal aspect; the ornamentation is formed by large lower. The same kind of differences can be observed also primary ribs, thin secondary ribs crossing the venter in relation to M. seguenzae (Gemmellaro), which is (already evident in the nucleus, which is typically broad) normally more evolute, with broader whorls, less elevated and rather robust spines (Figs. 5a-b). The second ventral area, coarser and more sparse ribs, spines placed morphotype is definitely more frequent, and can be higher on the flank, and has a higher stratigraphic position. considered the most representative of the species; compared to the first one it has more involute coiling, Stratigraphic distribution - Early Pliensbachian (base with high elliptic whorl section and smaller spines (Figs. of the Miltoceras Zone). 5c-k). The third morphotype (to which at least about twenty specimens can be attributed), is characterized by a very high whorl section and by a tendentially weaker ornamentation, with flexuose ribs on the nucleus and Subfamily DUBARICERATINAE Dommergues & Meister, subsequently very small or apparently absent spines 1999 (nomen translatum nov., ex Dubariceratidae (Figs. 5l-m). Dommergues & Meister, 1999) 10 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Genus new undetermined 1) usually more sigmoidal and broader ribs; Figs. 16d-f 2) slightly larger spines, which do not stand out clearly from to the ribs, appearing as the endings of the ribs 2006 Dubariceras silviesi (Hertlein) - VENTURI, BILOTTA & RICCI, themselves in the internal moulds; fig. 2f. 3) depressed ventral area, not elevated. Material - About twenty-one different-sized The lack of data on the suture line for the Fu3b1 specimens, which in almost all cases are fragmentary. lumachella specimens (and as far as we know also for the eastern Pacific ones) does not allow to adequately Description - Moderately evolute shell, with poor appraise the taxonomic meaning of such differences, nor whorl overlapping. enables us to evaluate how much the similarities do reflect Whorl section higher than wide, sub-rectangular affinity or are due to convergence. elliptic, with rounded and elevated ventral area. From a purely morphologic standpoint, the Furlo The whorl is smooth and moderately involute up to a Pass forms can be considered a kind of “forerunners” diameter of at least 8-9 mm; subsequently it is ornated of Dubariceras and the like, that is a variant of the by evident ribs, which are proverse and nearly straight, same stock from which these monospinate taxa but sometimes slightly flexuose near the umbilical edge. originated (Fig. 18). Hypothesizing a relationship (and As a rule they are rather thin and dense up to a diameter in particular, an ancestor-descendant relation) between of about 14-18 mm, then they tend to become broader the Apennine forms (more ancient) and the already- and more spaced. On the ventro-lateral edge the ribs mentioned American ammonites (more recent), we think always show punctiform and sharp spines, after which it permissible to imagine that the latter lack a prolonged they considerably weaken, crossing the venter. Here, smooth inner stage because the ornamentation has especially at a medium-large diameter, they form a feeble established also in the innermost whorls. This idea is and slightly proverse arch. compatible with the data suggesting an intermittent The preservation of the calcitic specimens does not paleo(bio)geographic connection between the western allow to observe the suture line. Tethys and the American Pacific coast already active by late Sinemurian-early Pliensbachian times, as more Remarks and comparisons - The general aspect as widely discussed by Venturi et al. (2006). per coiling, ornamentation and whorl section resemble those of the ammonites ascribed to Dubariceras Stratigraphic distribution - The specimens were found Dommergues, Mouterde & Rivas. In particular, the in the Fu3b1 lumachella, datable to the early specimens from the Furlo Pass show similarities with Pliensbachian (base of the Miltoceras Zone). the American forms called by Smith & Tipper (1996, p. 43; pl. 15, figs. 3-4) D. silviesi (Hertlein), a species in which these same Authors include also the Argentine Genus Spiniclaviceras nov. gen. material originally referred by Hillebrandt (1987; pl. 2, figs. 1, 5) as Uptonia cf. obsoleta (Simpson). These Type species - Spiniclaviceras spirale nov. sp. specimens differ from the Apennine ones chiefly because they have a shorter smooth inner stage (for Name derivation - From the Latin spina (= spine) instance, the South American forms are ornated since a and clavus (term coming from clava = club, to indicate a diameter of about 3.5 mm), at the same size their whorl tubercle or spine elongated in direction of coiling) and is a little more evolute and normally they have sparser from the Greek kéras (= horn, due to the resemblance ribs, with spines placed slightly higher. Furthermore, their with the ram horns of the ancient god Zeus Ammon, stratigraphic position is higher, as they are found in an traditionally adopted as suffix in many ammonite names). interval which is essentially correlatable with the Ibex and Davoei Zones of the standard scheme (respectively Type locality - Furlo Pass (Umbria-Marche Apennines). Whiteavesi Zone and lowest part of the Freboldi Zone for the North American specimens; Eoamaltheus Typical beds - Spathic lumachella of the “Corniola” meridianus Zone for the South American ones). in “massive” facies (Fu3a lumachella); early Notwithstanding these differences, the remarkable Pliensbachian. similarities lead us to think that the lumachella Fu3b1 material, the Canadian specimens of Smith & Tipper Material - Fourteen small-sized specimens, including (1996) and the Argentine specimen of Hillebrandt (1987) some fragments and two nuclei, all attributed to the same may represent species of the same genus. Anyway, we species, preserved as spathic internal moulds. have to note that, in our opinion, ascribing these forms to Dubariceras is not completely appropriate, and Diagnosis - Evolute shell, with poorly-overlapping actually Dommergues & Meister (1999) already whorls. Trapezoidal whorl section with nearly straight considered the American Pacific taxa as convergent, but flanks and flat (sub-tabulated) ventral area. not really congeneric, with the true Mediterranean The inner whorls are more involute, with an high Dubariceras. trapezoidal section and slightly rounded venter, and are The main characters of D. dubari Dommergues, smooth until a diameter of about 4 mm. Later on, the Mouterde & Rivas (type species of the genus) which whorl shows depressed, broad and poorly reliefing ribs, differentiate it from the Apennine forms as well from which at first are hinted and evanescent, and usually the American ones are the following: become evident only at a diameter of about 5-6 mm. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 11

These ribs are more accentuated on the ventro-lateral 80, fig. 3) figure cannot be considered as completely edge, where they end with short clavus-like structures, representative of the suture line of Metaderoceras. On not much prominent but well developed, formed by squat the contrary, many subsequent pictures are definitely reliefs, very lengthened at their base (long and narrow), accurate and complete, as those of Faraoni et al. (1996, and outwards directed obliquely at 45°. pl. 10, figs.10, 13) and Venturi & Ferri (2001, p. 121, At diameters larger than about 13 mm ribs weaken, 128): this makes sure that serious characterization leaving only a kind of lateral bulge, while the clavus- problems for the genus do not exist, even if it would like spines remain quite clearly evident, especially when be clearly desirable to have more adequate figures for observed in ventral view. the type material. The ventral area never shows traces of secondary ribs. A superficial resemblance as per coiling, flattening The suture line has a rather large E lobe, narrow and of the venter, shape of the whorl section and in part not much indented, characterized by long lateral branches ornamentation can be observed with the specimen figured at its base and by a deep median saddle involving more as Apoderoceras ferox Buckman (1925, pl. 651), which than half of the lobe itself; the L lobe, much shorter than attribution to Apoderoceras Buckman seems to us at least E, is lengthened, trifid, tendentially thin and nearly uncertain for the absence of secondary ribs and the not symmetric; the ES saddle is inclined outwards, and has rounded ventral area. In any case, the English ammonite an accessory lobe which splits it in two almost equally has an aspect comparable with that of Spiniclaviceras wide parts (but the outer one is more advanced than the only at a large diameter (about 300-500 mm), and it does inner one); the LS1 saddle is wide about half of ES, and it not seem to have a similar morphology at the same size is placed at the same height of the inner part of ES itself; of the Fu3 specimens (maximum diameter of about 18- the umbilical lobes are rather close, with a poorly- 20 mm). Furthermore, the species called A. ferox has denticulate U2, not much developed, shorter than L and higher whorl section, slightly less flattened flanks, and moderately inclined, just like U3 (hint of suspensive its spines are not clavus-like. lobe), which is even smaller. Included species - Spiniclaviceras spirale nov. sp. Remarks and comparisons - The whole of the (type species by original designation) characters concerning the overall shell aspect and suture relate this new genus to the Dubariceratinae as conceived in the present paper (that is the totality of the genera Spiniclaviceras spirale nov. sp. Crucilobiceras Buckman, Metaderoceras Spath, and Figs. 6a-k, 16i Dubariceras, included by Dommergues & Meister, 1999 in the family Dubariceratidae). Name derivation - From the Latin spiralis (= coiled), The flattening of the flanks and the evolute coiling adjectival form of spira (= coil, spiral), with reference might recall those of several species ascribed to to the typically evolute aspect of the shell. Metaderoceras, which however, at the same diameter always show a less flattened whorl, narrower and more Holotype - Fu3Sp01 (Figs. 6a, 16i), nearly complete marked primary ribs, lateral and ventral secondary ribs specimen, with a whorl of body chamber, housed in the and long, non-clavus-like spines; moreover, the suture line Earth Sciences Department, Università degli Studi di is a little less indented, with E lobe as long as L or a little Perugia. more, and more developed U2 lobe, and never shows the typical inclination of the ES saddle observable in Paratypes - Fu3Sp05, specimen with phragmocone Spiniclaviceras. These differences can be noticed for and beginning of the body chamber (Fig. 6g); Fu3Sp07, instance in relation to the M. beirense Mouterde figured specimen with a third of whorl of body chamber (Fig. by Faraoni et al. (1996, pl. 8, figs. 6, 9), the M. 6b); both are housed in the Earth Sciences Department, gemmellaroi (Levi) of Ferretti (1975, pl. 24, fig. 4) and Università degli Studi di Perugia. Faraoni et al. (1996, pl. 8, fig. 10; pl. 10, figs.10-14), the M. venarense (Oppel) of Dommergues & Mouterde Type locality - As for the genus. (1982, pl.1, figs. 12-13), the M. evolutum (Fucini), M. mouterdei (Frebold), M. talkeetnaense Thomson & Type section - Grilli Quarry (Furlo Pass), Fu3a Smith presented by Smith & Tipper (1996; respectively lumachella. pl. 16, figs. 3-5, 7, text-fig. 33c; pl. 19, fig. 3; pl. 17, figs. 2-3, text-figs. 33a, 34c), all of which, besides, are Material - As for the genus. more recent forms compared to those of the Fu3 fauna. Incidentally, we note that the original description and figure of the suture presented by d’Orbigny (1844, p. 274; pl. 80, fig. 3) for the type species of Metaderoceras have some characters (such as the E lobe shorter than L) which disagree with those of the several specimens ascribed in the literature to this genus. As reported by Dommergues & Mouterde in their revision given in Fischer (1994, p. 71-72), the drawing at issue must be a sort of restoration, only partially inspired to a fragment of the Tab. 4 - Measurements for eight Spiniclaviceras spirale nov. sp. original collection, and therefore d’Orbigny (1844, pl. specimens from the Fu3a lumachella. 12 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

The inner whorls are well preserved only from the diameter of about 3 mm onwards, and they appear smooth; starting from the diameter of about 4 mm weak depressed ribs can be noted, ending in well developed short clavus- like elements. This ornamentation is clearly visible from the diameter of about 6-7 mm. The phragmocone ends at the diameter of about 8 mm, and the body chamber is preserved for an entire whorl; at about 13 mm ribs weaken appearing as lateral bulges. The aspect of the peristome cannot be observed. Concerning the suture line, only a very small part of that at the end of the phragmocone is visible, and shows a lengthened, trifid L lobe.

Diagnosis - As for the genus.

Remarks - The base structure of the suture line with E lobe longer than L and ES saddle inclined outwards is found both in the Dubariceratinae and in the Coeloceratinae, and indeed we think that probably it has been inherited by the common ancestor of these monospinate forms (Fig. 18). The relations with other ammonites are more difficult to ascertain, as in the case of Farinaccites clavatus Faraoni, Marini, Pallini & Venturi, a taxon which is doubtfully referable to the Dubariceratinae, and is found in the upper part of the Miltoceras Zone. It could be interpreted as an “extreme” variant of Spiniclaviceras, but the vertical direction of the clavi, the aspect of the ribs and some traits of the suture line do not seem to support this idea.

Stratigraphic distribution - Early Pliensbachian (base of the Miltoceras Zone). Fig. 6 - Spiniclaviceras spirale nov. gen. et nov. sp.; a) lateral view and whorl section of the holotype Fu3Sp01; magnified about x 1.5; b) ventral profile and lateral view of the nucleus Fu3Sp07; magnified about x 1.5; c) suture line of the fragment Fu3Sp04, drawn at a Family POLYMORPHITIDAE Haug, 1887 diameter of about 15.5 mm; d) lateral view of the same specimen; magnified about x 1.5; e) lateral view, whorl section and ventral Remarks - As far as we know, the ammonites which profile of the fragment Fu3Sp02; magnified about x 1.5; f) suture can be considered the more ancient representatives of line of the same specimen, drawn at a diameter of about 13 mm; g) this group pertain exclusively to the Apennines, and appear lateral view of the young individual Fu3Sp05; magnified about x in the Catriceras Zone (Venturi et al., 2005): they are 1.5; h) suture line of the same specimen, drawn at a diameter of Caleites Venturi & Ferri (a monospinate genus ascribable about 9.5 mm; i) ventral and lateral view of the fragment Fu3Sp04, clearly showing the aspect of the clavus-like spines (an arrow to the nominal subfamily) and Furlites (a smooth genus, indicates the anterior direction for the ventral view); about natural member of a distinct subgroup here formalized). The size; j) whorl section of the fragment Fu3Sp03; magnified about x most known Polymorphitidae as for instance 2.75; k) suture line of the same specimen, drawn at a diameter of Polymorphites Haug, Platypleuroceras Hyatt, Uptonia about 15 mm; magnified about x 8 (oblique segments are the radial Buckman, instead, are typically found in the North-west lines; note the extent of the suture portion developed on the ventral European Province, and only starting from a time interval area) (drawings by F. Venturi). correlatable with the Miltoceras Zone. These taxa differ from the Mediterranean ones first of all for their paleobiogeographic distribution (as already noted by Dommergues et al., 1984) and partially chrono- stratigraphic range. Moreover, they have the distinctive Measurements - See Tab. 4. morphologic traits of the family already well established in the inner whorls (which have a very short initial smooth Holotype description - Evolute shell, with poorly- stage, in contrast with the Mediterranean forms), and the overlapping whorls. Whorl with nearly straight flanks and ornamentation develops some peculiar features, absent flat (sub-tabulated) ventral area; the shape of the whorl in the Apennine faunas, such as ribs crossing the venter section cannot be clearly observed due to the rock which without interruption. partially incorporates the specimen, and from which it The available data, as a whole, indirectly suggest cannot be separated unless seriously compromising its that the Apennine Polymorphitidae are derived from the integrity. same bispinate eoderoceratid stock among which the F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 13

Coeloceratidae would have originated (Fig. 18). It more accentuated, and in some specimen they seem to seems that the acquisition of a monospinate reach the false keel, albeit they are very weakened. ornamentation in these groups initially involved the The peristome has a collar-like constriction and a sort transition through small smooth forms (“regressive” of cuneiform ventral “lappet”, nearly resembling a evolution, with a more or less extensive innovation in rostrum, formed by the continuation of the false keel. the inner whorls); subsequently an outer whorls Near the aperture ribs become slightly thicker, apparently innovation took place, noticeable several times over and forming more accentuated projections. at various degrees in some taxa, starting from the lower The suture, as in other typical Polymorphitidae, is part of the Catriceras Zone. This is widely documented not much arborescent; broad E lobe, a little more larger in the lower Pliensbachian Apennine sections, where it than L, which is trifid; ES saddle with a characteristic is registered the occurrence of many forms with nuclei oblique A lobe (markedly shifted towards L) splitting it possessing transitional characters between the bispinate in two parts, the outermost of which is broader and eoderoceratids, the monospinate ones and the first more advanced; LS1 saddle narrower than ES; U2 large smooth polymorphitids (furthermore, all these about half of L; very small and tooth-like U3. ammonite groups share some base sutural characters). Remarks and comparisons - The middle- and mid- large-sized Paramorphites specimens can be quite easily Subfamily POLYMORPHITINAE Haug, 1887 distinguished from most of the coeval forms; on the contrary, the individuals with a diameter less than 10 mm Genus Paramorphites nov. gen. are more difficult to discriminate from some Miltoceras furlense at the same size, although these latter have always Type species - Paramorphites acutiventris nov. sp. slightly broader whorls. Similar inner whorls are found also in Caleites, which Name derivation - From the Greek pará (= nearby) however has a more compressed nucleus, a different and morphé (= form), with the termination -ites for ventral area (never acute nor bearing a false keel), suture analogy with the name of several ammonites, including line with a larger E lobe, which is shifted from the middle Polymorphites. of the ventral area, and a more ancient chronostratigraphic position (lower-middle part of the Catriceras Zone). Type locality - Furlo Pass (Umbria-Marche Some characters comparable with those of Apennines). Paramorphites concerning presence of a false keel, coiling, type and development of the ornamentation, can Typical beds - Spathic lumachella of the “Corniola” be observed in the Tunisian species Zamaiceras in “massive” facies (Fu3a lumachella); early carinatum Rakús & Guex (2002, p. 116; pl. 32, figs. 21, Pliensbachian. 26; text-fig. 93a-d). However, the latter is more compressed, has more sigmoidal ribs, always clearly Material - One hundred and fourteen different-sized crossing the ventral area, has a different and later false specimens (many of them are fragments), all attributed keel, and its suture line has at least a differently-shaped to the same species, preserved as spathic internal moulds. ES saddle; furthermore, its stratigraphic position is more recent, since it comes from beds correlatable with the Diagnosis - Moderately evolute shell, compressed, standard Ibex Zone. Even more marked differences can with poorly-overlapping whorls. be noted with respect to Z. mangoldi Rakús & Guex Sub-quadrate roundish inner whorl section, high as (2002, p. 116; pl. 32, figs. 13, 19, 23; text-fig. 92a-d), wide, but in the smaller specimens the width is quite type species of the genus: in fact its ventral area is variable. Subsequently the whorl becomes higher than rounded, and it seems to us that its suture (known only wide, at first with an ogival section, then sub-pentagonal. for the umbilical portion) does not show evident Initially the ventral area is roundish or slightly similarities neither with Z. carinatum, nor with that of subacute, then decidedly acute and roof-shaped; on the Fu3 specimens. body chamber, with a gradual transition, a siphonal relief The general aspect and especially the ribs ending (false keel) is formed. by small ventro-lateral spines, more or less distinctly The ornamentation is absent on the first whorls, and continuing on the venter recall those of various the shell is smooth until a diameter variable between ammonoids ascribed (sometimes not properly) to about 1 mm and 3.5 mm, when small and pointed spines Polymorphites. In particular, we note a remarkable can be noted near the ventral edge. Between the diameter similarity between the Grilli Quarry specimens and the of about 2-2.5 mm and 4.5 mm regular and narrow ribs early Pliensbachian (Eoamaltheus meridianus Zone, appear, too: at first they are simply rectiradiate and end more or less corresponding to the standard Ibex Zone) by the ventral spines; afterwards, they become well Argentine exemplars initially figured by Hillebrandt reliefing and sharp, forming a weak ventral projection after (1987, pl. 2, figs. 6-10) as Polymorphites (?) sp., and the spines which usually greatly fades before arriving to now attributed by him to a new, densely-ribbed species the middle of the ventral area. The whorl height increase of Eoamaltheus Hillebrandt (personal communication). is rather conspicuous throughout the ontogenesis, but by However, we think that, for their sinuous ribs which do the beginning of the body chamber (which length is not reach the medial relief of the venter, these South from half a whorl to about three-quarter of whorl) it American specimens are more correctly identifiable as seems to stop. Here, moreover, the rib projections look a species of Paramorphites which is more involute and 14 Bollettino della Società Paleontologica Italiana, 46 (1), 2007 recent than that of the Fu3 fauna, although this 16q); all are housed in the Earth Sciences Department, assignment is not completely sure due to the absence Università degli Studi di Perugia. of data concerning the suture line of the eastern Pacific material. Type locality - As for the genus. The forms from the British Columbia (Canada) called by Smith & Tipper (1996, pl. 6, figs.15-18; text-fig. 32c) Type section -Grilli Quarry (Furlo Pass), Fu3a Polymorphites confusus (Quenstedt) differ more lumachella. substantially from the Apennine ones, especially for their coarser and sometimes thicker ornamentation, their Material - As for the genus. broader whorl with a faster height increase, the lack of a medial relief on the body chamber and the progressive Measurements - See Tab. 5. flattening of the venter during the growth. Some elements which can superficially recall Holotype description - Moderately evolute shell, Paramorphites (particularly the suture, which, albeit even compressed, with poorly-overlapping whorls. more simplified, has the same base structure and the Outer whorls with sub-pentagonal section, higher than typical A lobe in the ES saddle) are found in wide. “Polymorphites” appenninicus Faraoni, Marini, Pallini The ventral area is acute roof-shaped until the diameter & Venturi (1996, p. 97; pl. 3, figs. 3-6; pl. 9, figs. 6-8). of about 9.5 mm; afterwards it tends to form a false keel, However, it is younger (upper part of the Miltoceras clearly distinguishable from the diameter of 10.2 mm. Zone), has much thinner and thicker ribs, which are The inner whorls are visible only from a diameter of sinuous and proverse, sometimes tend to fasciculate and about 3 mm, and they seem to already have rectiradiate always join the middle of the venter; moreover, it never and not much reliefing ribs, ending with a small spine presents a false keel (but rather an acute ventral area) or near the ventral edge. From the diameter of about 5.5 mm ventral spines, and the whorl section is decidedly sub- onwards, ribs become decidedly more evident and triangular ovoidal (not sub-pentagonal). The peculiar reliefing; between the diameter of 9.5 mm and 10.2 mm characters of the form of Faraoni et al. (1996) make its they clearly develop also a slight ventral projection. original generic attribution certainly disputable (for this The suture is not visible. reason here we placed the name in inverted commas), but its differences from the Fu3 samples lead us to think that Diagnosis - As for the genus. it cannot be referred to Paramorphites, either. Finally, compared to more “genuine” species of Remarks - The new species Paramorphites Polymorphites, as for instance the P. polymorphus acutiventris is very abundant in the Fu3 fauna, but has (Quenstedt) and the P. bronni (Roemer) figured by never been found in the Apennine section where the Schlatter (1980), the new genus Paramorphites has more middle-upper part of the Miltoceras Zone is documented involute inner whorls and is less evolute in the outer ones. (Bosso and Stirpeto), nor in outcrops representing Moreover, it has much smaller and less reliefing ribs, subsequent time intervals. On the other hand, as already which do not end very near to the ventral relief, nor they noted, some forms which we deem ascribable to the same cross the venter forming a chevron; its whorl section is genus might be present on the South American Pacific pentagonal (rather than sub-quadrate) and the suture is coast, in rocks correlatable with the standard Ibex Zone. more indented, with less spaced lobes and a typical The current data suggest that the eastern Pacific taxon inclined A lobe in the ES saddle, absent in the aforementioned taxa.

Included species - Paramorphites acutiventris nov. sp. (type species by original designation)

Paramorphites acutiventris nov. sp. Figs. 7a-j, 16l-m, o-q

Name derivation - From the Latin acutus (= acute, sharp) and venter (= venter), with reference to the characteristic aspect of the ventral area.

Holotype - Fu3P09 (Fig. 16l), specimen with part of the body chamber, housed in the Earth Sciences Department, Università degli Studi di Perugia.

Paratypes - Fu3P13, specimen with only phragmocone (Fig. 16m); Fu3P03, specimen with part of the body chamber (Fig. 16o); Fu3P89, specimen with nucleus and part of the body chamber (Figs. 7g, 16p); Tab. 5 - Measurements for twenty Paramorphites acutiventris nov. Fu3P11, specimen with part of the body chamber (Fig. sp. specimens from the Fu3a lumachella. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 15

Fig. 7 - Paramorphites acutiventris nov. gen. et nov. sp.; a) lateral view and whorl section of the specimen Fu3P01N; magnified about x 1.5; b) suture line of the same specimen, drawn at a diameter of about 11-12 mm; magnified about x 7; c) lateral view with restored outline of the missing portion and whorl section of the fragment Fu3P70; magnified about x 1.5; d) lateral view and whorl section of the fragment with nucleus Fu3P91; magnified about x 1.5; e) ventral profile and lateral view of the nucleus Fu3C25; magnified about x 1.5; f) lateral view, whorl section and upper ventral view of the nucleus of the complete specimen Fu3P64 (note the peristome); magnified about x 2; g) lateral view with restored outline of the missing portion and ventral profile of the paratype Fu3P89; magnified about x 1.5; h) lateral view and ventral profile of an Argentine specimen (Puesto Araya section) redrawn from the photographs in Hillebrandt (1987); magnified about x 1.15; i) lateral view of the nucleus Fu3C22-2; magnified about x 1.5; j) lateral view, whorl section (both magnified about x 1.5) and suture line (drawn at a diameter of about 8 mm; magnified about x 4) of the specimen Fu3P57 (drawings by F. Venturi).

(younger) descends from the Apennine one (older), the shifting of the A lobe towards the external portion which can be considered the ancestor of the endemic of the ES saddle (Venturi et al., 2006; see also the sutures American group formed by the genera Eoamaltheus and figured in Donovan, 1994, figs. 5a-b and Smith & Tipper, Fanninoceras McLearn. As explained by Venturi et al. 1996, text-fig. 31). (2006), this phylogenetic hypothesis is mainly based on All this, besides having important the fact that Paramorphites, Eoamaltheus, and paleo(bio)geographic implications (in particular Fanninoceras share a similarly structured suture line, concerning the trans-Pangea seaway known as “Hispanic with a large and broad E lobe, and a peculiarly shifted A Corridor”, as discussed by Venturi et al., 2006), means lobe in the ES saddle, which is more or less advanced that Eoamaltheus and Fanninoceras would not have in regards to LS1 saddle. On the other hand, shell shape close relations with Metaderoceras and Dubariceras (as, and ornamentation are different but it seems possible on the contrary, was hypothesized by Dommergues & to recognize a clear transition from Paramorphites Meister, 1999), and they would be rather regarded as the acutiventris to its direct congeneric South American sole two representatives of a taxon derived from the descendant (Hillebrandt, 1987, pl. 2, figs. 6-10), and from Polymorphitidae. This group is the equivalent of the it to Eoamaltheus and Fanninoceras, in a rather subfamily Fanninoceratinae of Dommergues & Meister reasonable chronologic sequence. The relationship (1999), but we think it more appropriate to raise it at the between the latter two genera, already supported by family rank, and therefore to indicate it as Dommergues & Meister (1999, and references cited Fanninoceratidae (nomen translatum nov. ex therein), is particularly evident observing the inner whorls Fanninoceratinae Dommergues & Meister, 1999). of Eoamaltheus meridianus Hillebrandt (1981, pl. 5, figs. 6-12, pl. 9, figs. 6-8) and those of the Fanninoceras Stratigraphic distribution - Early Pliensbachian (base behrendseni (Jaworski) figured in Hillebrandt (1987, pl. of the Miltoceras Zone). 3, figs. 8-12): in fact they have an ornamentation which can be considered as progressively derived from that of Paramorphites, and a ventral area always preserving its Subfamily FURLITINAE nov. subfam. typical roof-shaped aspect. The modifications occurred along this phyletic lineage highlight the tendency to an Type genus - Furlites Venturi & Ferri, 2001 increase in shell involution and rib flexuosity, with acquisition of a more streamlined and hydrodynamically Diagnosis - Small-sized platycone shells, involute in efficient morphology. During the entire process the basic the inner whorls, then evolute. structure of the suture line remains essentially constant, The whorl section is subogival or elliptic, with ventral although, especially in later representatives of area mostly rounded or weakly subacute. Fanninoceras, an increase in indenting and complexity The ornamentation is absent or very poorly can be observed, with the addition of umbilical lobes and developed: when present it should be clearly visible only 16 Bollettino della Società Paleontologica Italiana, 46 (1), 2007 on the test, with slightly flexuose striae tending to fasciculate. Suture line with spaced and poorly indented lobes: E usually as long as L or a little less; L is essentially bi- trifid; at times the simplification of the suture is quite accentuated, and the E lobe can be shifted from the middle of the ventral area. All the taxa of this group are exclusively known in the early Pliensbachian of the Mediterranean Tethys.

? Subfamily FURLITINAE nov. subfam. Genus Gemmellaroceras Hyatt, 1900 Type species - Aegoceras aenigmaticum Gemmellaro, 1884 Emended diagnosis - Small-sized platycone shells, involute in the inner whorls, then evolute. The whorl section is subogival or elliptic higher than wide, with rounded ventral area. The ornamentation consists of irregular and slightly flexuose radial striae, forming a weak proverse angle on the venter, where they are often fading. At times (especially when the test is preserved) the fasciculation of the striae gives rise to ribs, which in some rare instance end with small ventro-lateral spines. The suture line is not much indented, with spaced lobes: E usually broad, as long as L or shorter, and Fig. 8 - Gemmellaroceras aenigmaticum (Gemmellaro), drawn on sometimes shifted from the middle of the ventral area; the material of the original Gemmellaro collection, housed in the “G.G. Gemmellaro” Geologic Museum, Geology and Geodesy L enlarged, bi-trifid, with a deep ventral cavity; two Department of the Palermo University; a) ventral profile and lateral umbilical lobes in the outer suture and one in the inner view of the specimen n. 30/1 (lectotype); magnified about x 1.5; b) one; not much evident sutural lobe. suture line of the same specimen; magnified about x 4.5 (drawings by F. Venturi). Remarks - The emended diagnosis here presented is based on the already mentioned unpublished revision of the original Gemmellaro (1884) material. During that work it was noted that the whole of the species originally from the Mediterranean Tethys and from other areas), described as Aegoceras aenigmaticum Gemmellaro often more or less unduly referred to Gemmellaroceras (1884, pl. 3, figs. 12, 14-15, pl. 4, fig. 10, pl. 7, fig. 20), for their evolute coiling, with smooth whorls or A. cortesei Gemmellaro (1884, pl. 3, figs. 17-18, pl. 4, ornamentation consisting in weak, flexuose pseudo-ribs figs. 7-9), A. n. sp. indet. gr. cortesei Gemmellaro (1884, sometimes well reproduced also in the internal moulds, pl. 3, fig. 16), A. mazzettii Gemmellaro (1884, pl. 3, fig. has already been noted (in part also by Dommergues et 13, pl. 4, figs. 1-2) and A. circumcrispatum Gemmellaro al., 1994). Now it seems no longer acceptable to regard (1884, pl. 4, figs. 11-14, pl. 7, fig. 21) allows to identify Leptonotoceras Spath as a synonym or a subgenus of a rather precise morphologic ambit for Gemmellaroceras, Gemmellaroceras (as, on the contrary, was thought for genus to which now they are normally attributed. A instance by Arkell et al., 1957; Donovan, 1958; Bremer, different treatment must be deserved to the forms 1965; Donovan & Forsey, 1973; Géczy 1976; originally called Aegoceras granuliferum Gemmellaro Wiedenmayer, 1977; Donovan et al., 1981; Smith & (1884, pl. 3, fig. 19, pl. 4, figs. 3-6) and A. alloplocum Tipper, 1996; Howarth, 2002): the two taxa do not have Gemmellaro (1884, pl. 4, figs. 17-20, pl. 7, fig. 22), direct phyletic relations and show differences both in the which show a more marked ornamentation and other morphologic characters (e.g. in their coiling), and in the features which are not completely consistent with those stratigraphic distribution (which for Leptonotoceras is of the above-mentioned species. In particular, the first restricted to the late Sinemurian), as observed by seem more close to the Polymorphitinae, so much so Dommergues et al. (1983), Rakús (1994) and Rakús & that its interpretation is still disputed, and it is not evident Guex (2002). The same kind of considerations also whether it must be ascribed to Gemmellaroceras, or to applies to the synonymy between Tubellites Buckman and Polymorphites (as done by Ferretti, 1975), or it must be Gemmellaroceras proposed for instance by Arkell et al. considered a further, different genus (Dommergues et al., (1957), Donovan et al. (1981) and Smith & Tipper (1996). 1994). The second form at issue, instead, has a subacute In accordance with an interpretation of the ventral area (described by Gemmellaro, 1884, as a morphologic variability based on the features presented sometimes crenulated keel), and a suture line which at by the type material, Gemmellaroceras is ornated by least has a differently developed L lobe. striae which bundle to form pseudo- or fading ribs, well The taxonomic confusion concerning various early visible only on the test and perfunctorily reproduced in and middle Liassic small platycone ammonites (both the internal mould: this can be clearly observed on the F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 17 lectotype photo in Venturi & Ferri (2001), as well as on its drawing here presented (Fig. 8). Moreover, the inner whorls are smooth, involute and rather broad: this might lead to think that these weakly ornated polymorphitids originated by a more or less complete spoliation (i.e. loss of ornamentation) of the early Pliensbachian bispinate Eoderoceratoidea. This hypothesis seems supported by the apparently “transitional” characters showed by species as G. Fig. 9 - Gemmellaroceras sp. from the Fu3b2 lumachella; all magnified cortesei, as well as by some undetermined smooth about x 1.5; a) whorl section and lateral view of the specimen forms with a relatively indented suture found in the Fu3b2Ge01 (nucleus partially restored, also basing on the fragment Fu3b2Ge02); b) whorl section and lateral view of the fragment Fu3b2 lumachella. Fu3b2Ge03; c) ventral profile and lateral view of the nucleus Some traits (chiefly the overall aspect of shell and Fu3b2Ge06h; d) lateral view and ventral profile of the specimen suture line) suggest to include this genus in the new Fu3b2Ge05h (drawings by F. Venturi). subfamily Furlitinae. However, it is hard to ascertain if its similarities with Furlites are actually homologous (and therefore they reflect the belonging to a same group) or if they are rather due to analogy: for this reason, the The whorl section is ellipsoidal, higher than wide, classification of Gemmellaroceras in the Furlitinae is with rounded ventral area. Usually each whorl overlaps not completely sure, and here it is indicated dubitatively. the preceding one for about 1/3 or less. From a paleobiogeographic point of view, The inner whorls are smooth and quite involute; Gemmellaroceras is confined within the already from the diameter of about 4 mm irregular striae, straight mentioned “Peltolytoceratinae meso-Mediterranean unit” or slightly sinuous, can be noted. They tend to bundle, and, as far as we know, outside this area there is no and are clearly visible when the test is preserved, evidence of the presence of specimens of this genus. For whereas on the internal moulds they mostly appear as example we believe that none of the Turkish forms figured weak reliefs. In any case, this ornamentation is relatively by Bremer (1965, pl. 16, figs. 3, 6, 8, text-fig. 4f) and marked only on the flank, while it considerably fades Cope (1991, pl. 1, fig. 3) as Gemmellaroceras can be or even stops a little before reaching the ventro-lateral correctly referred to this genus, since they show edge. remarkable differences as per coiling, shell compression The suture line is only partially visible, and it is poorly and sometimes also ornamentation. Similar indented, with a large and broad E lobe, shaped in a considerations apply to the Hungarian species called G. characteristic way. gemmellaroi Géczy (1976, p. 74; text-fig. 45; pl. 14, fig. 7), which characters are incompatible with those of true Remarks and comparisons - Most part of the Fu3 Gemmellaroceras: the very reliefing and regular ribs and samples are so much cemented in the lumachella that they the ventral keel lead to think that they are young cannot be separated unless compromising their integrity. Tropidoceras, an alternative proposed by Géczy (1976) Anyway, this material as a whole is characterized by himself. Finally, we do not deem reliable the assignments variability in the degree of shell compression and partially to Gemmellaroceras reported by Smith et al. (1988) and also whorl overlapping, but clearly identifiable Smith & Tipper (1996) for their British Columbia morphotypes cannot be recognized. We do not know if (Canada) specimens. this can be interpreted as the presence of two or more congeneric species, and due to the impossibility of a complete study, we prefer to abstain from formal Gemmellaroceras sp. designations. Figs. 9a-d Concerning the comparison with other known Gemmellaroceras forms, the most similar species seems Material - At least twenty-four specimens, eighteen to be G. mazzettii, but the original Sicilian exemplars have of which cannot be separated by the incorporating rock. a slightly more accentuated ornamentation and are more evolute. Measurements - See Tab. 6. Similarities do exist also with G. cortesei, in which, however, the bundled up striae form evident ventral Description - Evolute and moderately compressed projections and very small ventro-lateral spines, absent shell. in the Fu3 specimens. Compared to G. aenigmaticum, the Furlo Pass forms are more involute, usually less compressed, and have less sparse striae. Finally, G. circumcrispatum is much more compressed, and has a more reliefing ventral area, crossed by striae which rise and give to the last whorl a “serrated” outline.

Stratigraphic distribution - The specimens were found Tab. 6 - Measurements for four Gemmellaroceras sp. specimens in the Fu3b2 lumachella, datable to the early from the Fu3b2 lumachella. Pliensbachian (base of the Miltoceras Zone). 18 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

base structure of the suture line make this form comparable with Catriceras Venturi. However, this latter genus shows, at the same diameter, more evident ribs, an higher keel and a suture with more indented L lobe, less markedly differing in length from E; moreover, both ribs and keel appear earlier during the ontogenetic development. Actually, these differences do not exclude some affinity, and one can think that the Fu3 ammonites may represent a late (and somehow “degenerated”) relative of Catriceras. Fig. 10 - New undetermined Tropidoceratinae; a) restored lateral The material, despite its quite good abundance, does view based on several fragments; magnified about x 1.5; b) whorl not seem sufficient to establish a formal taxon: in fact, it section of the fragment Fu3T09; magnified about x 1.5; c) suture largely consists of fragments and does not supply line of the specimen Fu3T02, drawn at a diameter of about 13 mm detailed informations on the ontogenetic development. (drawings by F. Venturi). Stratigraphic distribution - The specimens were found in the Fu3a lumachella, datable to the early Pliensbachian (base of the Miltoceras Zone).

Family TROPIDOCERATIDAE Hyatt, 1900 (= ACANTHOPLEUROCERATIDAE Arkell, 1950) Order to be specified Subfamily TROPIDOCERATINAE Hyatt, 1900 Family SINUICERATIDAE Venturi, Nannarone & Bilotta, 2005 Genus new undetermined Figs. 10a-c, 16h Emended diagnosis - Platycone shells, compressed, with evolute inner whorls and from involute to moderately Material - Fifteen mostly fragmentary specimens. involute outer whorls. Sub-elliptic whorl section, higher than wide. Measurements - See Tab. 7. Smooth phragmocone; body chamber often ornated by sinuous biconcave constrictions, and in some forms Description - Compressed and moderately evolute also by thin hemi-ribs (due to the bundling of striae) shell, with sub-ogival higher than wide whorl section. ending with short cuneiform tubercle-spines. Near the ventral area the flanks slope just like a roof, Quite simple suture line: the L lobe is long about as extending to form a medial relief, which results as an twice as E or a little more; large U2 lobe, as long as L or acute and well formed (but not very high) keel. a little less; the remaining umbilical lobes are simple and The inner whorls are smooth, with rounded umbilical placed on an oblique line (appearing slightly suspensive); edge, and have round ventral area until a diameter of about LS1 saddle much more advanced and wide than ES; sub- 9 mm; afterwards it become acute. lituid and embracing I lobe. The ornamentation is very weak, consisting in broad and low ribs, very depressed, which present a forward Remarks - The diagnosis here presented improves projection near the ventral edge. the original one, but does not change the already noted The suture is very simple, with enlarged lobes: E doubts (Venturi et al., 2005, p. 111) on the suprafamiliar shorter than L, which is bifid (or, at greater diameters, attribution of this group. The sutural characters, which trifid); ES saddle with only one A lobe, which is very small, we deem decisive from this point of view, give somehow tooth-like, and parallel to E. conflicting indications: the E lobe has a medial saddle with a transversal cut resembling that of some Remarks - The presence of a keel, the general “lytoceratines” (albeit with a different shape), whereas ornamentation style, the rounded umbilical edge and the the I lobe would have a lituid aspect recalling that typical of the Phylloceratida (Venturi & Bilotta, 2001; Venturi & Ferri, 2001). Indeed, this latter datum has never been directly observed in the Apennine specimens, none of which enabled us to to see the inner lobe, and was obtained from what Rakús & Guex (2002) report for their Tunisian species erroneously attributed to Gorgheiceras Venturi & Ferri. The inner lobe of these forms is described as generally provided of basal enlargements, and is indicated as I”S” or IS. Originally this notation properly refers to an embracing lobe with well developed septal terminations: since in the figures by Rakús & Guex (2002) these branches cannot be seen at all, we suppose Tab. 7 - Measurements for eight specimens of a new undetermined that the authors meant to point out only a sort of Tropidoceratinae from the Fu3a lumachella. embracement as from I. In the Phylloceratida inner lobes F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 19 lacks septal branches, and seem to be “laid” one above another in a manner which can simulate an embracement. This is quite close to that figured by Rakús & Guex (2002): therefore we are inclined to think that these are lituid or sub-lituid lobes, and we note that the suture never has an even vaguely phylloid aspect (at no stage of the development) either in the Tunisian specimen or in the Apennine ones.

Fig. 12 - Suture line of Sinuiceras planulatum Venturi & Ferri, drawn from the holotype Fu2S01 (provenance: Fu2 lumachella, Furlo Pass) at a diameter of about 12 mm; magnified about x 4.5. It shows the features typical of the family Sinuiceratidae: the E lobe has a transversal cut, and it is slightly shifted from the middle of the ventral area; the LS1 saddle is advanced compared to ad ES; U2 is much larger than the remaining three umbilical lobes, which are placed on an oblique line. Oblique segments represents the radial lines (drawings by F. Venturi).

Concerning the overall shell aspect (coiling, whorl section, ornamentation, etc.), the Sinuiceratidae have some elements which can superficially recall groups such as the Juraphyllitidae (as suggested by Donovan, personal communication), the Analytoceratidae or the Ectocentritidae (as hypothesized by Rakús & Guex, 2002), but the whole of the characters is combined in a very peculiar way, and considerably differentiate these forms from all the Jurassic ammonoids known in the literature. According to the evidence we have, the greatest affinities lay with a new genus (Fig. 11) abundantly found in a rich, unpublished fauna from the Calcare Massiccio of Monte Bove (Umbria-Marche Apennines), which, due to the association with Arietitidae similar to Coroniceras Hyatt or Megarietites Spath is probably datable to the basal Sinemurian. It resembles the Sinuiceratidae as per inner whorl aspect, coiling, shell compression, presence of bundling striae which end in cuneiform tubercles, and for the base characters of the suture (advancement of the LS1 saddle, aspect and sizes of L and U2 lobes), which however is more simplified and less developed in its umbilical portion. This form, in turn, seems to show Fig. 11 - New genus from Monte Bove (Umbria-Marche Apennines), similarities as per structure and proportions of the suture found in a rich, unpublished fauna of the Calcare Massiccio, probably line, whorl section and partially coiling with the datable to the basal Sinemurian. The morphological traits (inner whorl Ammonites suessi Hauer (1854, pl. 1, figs. 1-6), aspect, coiling, shell compression, presence of bundling striae which subsequently chosen as type species of Dudresnayiceras end in cuneiform tubercles) as well as the structure of the suture line anticipate those of the early Pliensbachian Sinuiceratidae. Mainly Rakús (1994, p. 303). As far as we know, the new genus basing on this reason (but also because both taxa are exclusively from Monte Bove lacks evident forerunners in the earliest known in the Mediterranean Tethys) we deem these forms to be the Jurassic and, hypothesizing an origin in the Hettangian (a only ammonoids which can be considered as the forerunners (or very scarcely represented period in the Mediterranean ancestors) of the Sinuiceratidae. a) lateral view of the specimen Tethys successions) within the Phylloceratida or the very MB-A00; magnified about x 2; b) lateral view (magnified about x 2) first Psiloceratida, one must admit extreme sutural and suture line (drawn at a diameter of about 8 mm) of the specimen MB-A03; c) lateral view (magnified about x 2) and suture line (drawn modifications, which at present are not documented. For at a diameter of about 6 mm; magnified about x 5.5) of the nucleus instance, no kind of relation with the psiloceratid MB-A04; d) lateral view and ventral profile of the specimen MB- Neophyllites Lange can be demonstrated, although for A01 (note the striae and the small cuneiform spines on the final some general characters (size, coiling, simplified suture, tract of the shell); magnified about x 2; e) suture line of the specimen etc.) it might superficially resembles the Monte Bove MB-A05, drawn at a diameter of about 7.5 mm; f) suture line of the forms. Alternatively, we do not feel to completely rule specimen MB-A06, drawn at a diameter of about 7.8 mm; g) lateral out a direct origin from the Triassic Ceratitida (albeit this view and whorl section of the specimen MB-A08; magnified about x 4.5 to show the coiling since the protoconch: note the stage (from is surely a “non-orthodox” eventuality), as can be a diameter of about 5 mm to about 8.2 mm) with feeble reliefs and suggested by the pseudoceratitic aspect of the suture line; depressions which can resemble tubercles (drawings by F. Venturi). but at present this possibility is not verifiable, either. 20 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Genus Sphenoacanthites nov. gen.

Type species - Gorgheiceras costotuberculatum Rakús & Guex, 2002

Name derivation - From the Greek sphén (= wedge) and ákantha (= spine), with reference to the presence of peculiar cuneiform tubercle-spines on the body chamber.

Type locality - Djebel Zaghouan (north-eastern Tunisia).

Typical beds - Mines du Djebel Staa, layer 5 (light grey glauconitic organo-detritic limestones); early Pliensbachian.

Diagnosis - Small-sized compressed forms, with evolute and smooth inner whorls. The inner whorl section is at first as high as wide, then it become high elliptic, with considerable overlapping (greater than 1/ 3). The subsequent whorls of the phragmocone are still smooth, but less evolute, because the whorl tends to have a great increase in its height. Rounded ventral area, narrow and very elevated. The ornamentation consists in striae, well visible when the test is preserved; on the body chamber they tend to bundle, and on the flank they can sometimes form thin, Fig. 13 - New Sinuiceras species from Le Gorghe section (middle very reliefing ribs, distinctly reproduced in the internal part of the early Pliensbachian, Metaderoceras gemmellaroi Zone); moulds. When present, these ribs form a short, oblique a) lateral view and ventral profiles of the specimen Go-S03; magnified and pointed element with a triangular outline (cuneiform about x 1.5; b) suture line of the same specimen, drawn at a diameter tubercle-spine), placed near the ventral edge and of about 22 mm; magnified about x 4. Oblique segments represents symmetrically arranged on the two sides of the whorl. the radial lines (drawings by F. Venturi). After this element, the ribs originate projections which tend to fade before reaching the middle of the venter. Quite simple suture line, typical of the family, with a large U2 lobe, similar as per size to L, and placed together with the subsequent ones on an oblique line; very advanced LS1 saddle, broader than ES; sub-lituid embracing I lobe. Admitting that the Sinuiceratidae are actually related with the Monte Bove form, the incertitudes in the Remarks - In their recent monograph on the early suprafamiliar attribution may therefore imply the Jurassic ammonoids from the Tunisia, Rakús & Guex existence of an high-ranked group separated early from (2002) describe many new species, among which those the Phylloceratida or the Psiloceratida, for which an called Gorgheiceras tuberculatum Rakús & Guex (2002, origin in the basal Jurassic or even in the Triassic can p. 48; text-fig. 39a-e; pl. 25, figs. 4-7, 10), G. be assumed. The members of this hypothetical taxon, costotuberculatum Rakús & Guex (2002, p. 50; text-figs. which could suitably include various forms lacking an 40-41; pl. 24, figs. 5, 10, 12-13; pl. 25, figs. 1-3.) and G. adequate position as Dudresnayiceras, would have planatum Rakús & Guex (2002, p. 51; text-fig. 42a-c; preserved the pseudoceratitic suture until the pl. 24, fig. 2; pl. 25, figs. 8-9). These forms were found Sinemurian (genus from Monte Bove and also in the Apennines, but their characters are Dudresnayiceras), and only by early Pliensbachian times incompatible with those of the type species of the genus, they would have been involved by an increase in the G. gorghense Venturi & Ferri (2001, p. 136; pl. 13e). indenting and in the number of umbilical lobes, also for This latter taxon differs remarkably from the above-cited the greater shell involution (Sinuiceratidae). The ammonites for its more evolute coiling, the ammonites ascribable to a species of Sinuiceras Venturi ornamentation formed by spines and faint striae (not & Ferri found in the Le Gorghe section (middle part of bundled up) present both on the body chamber and on the the early Pliensbachian, Metaderoceras gemmellaroi phragmocone (which lacks constrictions), and suture line Zone) are the latest Apennine representatives of this (more indented, with E lobe much more larger and longer lineage: they emphasize the typical characters of the than L; very developed A lobe in the ES saddle, which is suture, such as the length difference between E and L broader than LS1 and does not have a different lobe and the development of the umbilical portion, while advancement compared to it; umbilical lobes not placed the ornamentation tends to almost completely disappear on an oblique line). Therefore, we exclude that the (Fig. 13). specimens at issue can be ascribed to Gorgheiceras, F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 21 and on the contrary we note that they exhibit the distinctive traits of the Sinuiceratidae. More in particular, the species originally indicated as Gorgheiceras planatum is correctly interpretable as a late representative of Sinuiceras (Fig. 13), while for the other two we deemed it necessary to establish the new genus Sphenoacanthites. It shares with Sinuiceras the base characters of the suture (e.g. the LS1 advancement), but can be distinguished chiefly because the umbilical lobes are placed on a less sloping line, the shell is more evolute since the inner whorls (a difference perceptible starting from the diameter of at least 8 mm), the constrictions appear slightly more precociously (about a half whorl before) and on the body chamber it has the typical cuneiform tubercle-spines. This new genus has some elements (coiling and shell compression; partially also ornamentation and different advancement of ES and LS1 saddles) which might recall Tragophylloceras Hyatt and relatives, as for example the already mentioned English Sinemurian species improperly called Galaticeras jacksoni, which original generic attribution is undoubtedly incorrect. In any case, these ammonites are always more involute compared to Sphenoacanthites, their lateral and ventral ornamentation is usually more developed, the constrictions never seem to involve the body chamber, the suture has phylloid saddle endings and the geographic and stratigraphic distribution is different.

Included species - Sphenoacanthites costotuberculatum (Rakús & Guex, 2002) (type species by original designation), Sphenoacanthites tuberculatum (Rakús & Guex, 2002).

Fig. 14 - Sphenoacanthites costotuberculatum (Rakús & Guex, 2002); a) lateral view, ventral profile and whorl section of the specimen Fu3S01N; magnified about x 1.5; b) lateral view and whorl section of the fragment Fu3S22; about natural size; c) lateral view and ventral profile of the specimen Fu3S02N; magnified about x 1.2; d) suture line of the same specimen, drawn at a diameter of about 14-15 mm; e) lateral view, upper ventral profile and oblique view of the fragment Fu3S08; magnified about x 2 (drawings by F. Venturi).

Sphenoacanthites costotuberculatum (Rakús & Guex, 2002) Figs. 14a-e, 16j, n, r

2002 Gorgheiceras costotuberculatum RAKÚS & GUEX, p. 50, Text-fig. 40a-c; pl. 24, figs. 5, 12-13; pl. 25, figs. 1-3. 2002 Gorgheiceras costotuberculatum subcarinatum RAKÚS & GUEX, p. 50, Text-fig. 41a-c; pl. 24, fig. 10.

Material - At least ninety-six specimens, most of which are fragmentary.

Measurements - See Tab. 8.

Tab. 8 - Measurements for nineteen Sphenoacanthites Diagnosis - Small-sized compressed shell, very costotuberculatum (Rakús & Guex, 2002) specimens from the Fu3a evolute in the inner whorls, then relatively more involute. lumachella. 22 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

The phragmocone is smooth, with an high elliptic section and rounded but narrow and very elevated ventral area. The body chamber is long at least 3/4 of whorl, and has a subacute ventral area; with flanks ornated by sinuous constrictions (well reproduced in the internal moulds) and striae. These latter tend to bundle as thin but rather vigorous hemi-ribs, forming near the ventral edge a cuneiform tubercle-spine, after which they Fig. 15 - New undetermined genus (order and family uncertain); a) project on the venter and usually disappear before suture line of the specimen Fu3Xa08, drawn at a diameter of about reaching the middle, but sometimes they can originate 5 mm (dashed lines mark the extent of the ventral area); b) suture a sort of rounded chevron with proverse convexity. line of the specimen Fu3Xa01, drawn at a diameter of about 10 mm The suture is typical of the family, with E lobe shorter (drawings by F. Venturi). than L; rather developed U2, followed by three or four umbilical lobes placed on an oblique line and separated by very small saddles; LS1 saddle much more advanced Description - Moderately involute shell with a very than ES. fast increase of the whorl, which is moderately compressed. Remarks - Judging from the associated fauna, the The whorl overlapping is poor, and the section is Tunisian specimens seem to be more recent than the slightly higher than wide, rounded sub-quadrate or sub- Apennine ones, although the sections studied by Rakús oval. The ventral area is rounded. & Guex (2002) are often highly condensed; anyway, there The phragmocone (until the diameter of about 10 mm) are not many doubts on the fact that in both cases we is smooth, with some not very deep constrictions; the are dealing with the same species. body chamber, long at least a quarter of whorl, is ornated by striae, which are intercalated to evident and weakly Stratigraphic distribution - In the type locality flexuose varices; both these elements cross the ventral (Djebel Zaghouan, layer 5 of Mines du Djebel Staa) this area, where varices swell up to form a sort of large node. species was found in highly condensed beds, referred by It seems that these thickenings are due to the presence Rakús & Guex (2002) to the Tropidoceras demonense of test, while on the corresponding internal mould they Zone, which is correlatable with the upper part of the appear as constrictions or weak reliefs. Apennine Miltoceras Zone (early Pliensbachian) or with The suture is very poorly indented, with E longer the lower part of the Metaderoceras gemmellaroi Zone. than L, which is very simple; U2 equally simple, shorter The material from the Furlo Pass comes from the than L; tooth-like U3; ES and LS1 saddles without Fu3a lumachella, datable to the early Pliensbachian (base indentations. of the Miltoceras Zone). Remarks - The characters of this form, especially those concerning ornamentation and suture, make very Order uncertain difficult to establish its relationships. The Pliensbachian Family uncertain taxon which shows greatest similarities for its overall aspect seems to be Galaticeras, which however differs Genus new undetermined remarkably for ventral area and development of the suture Figs. 15a-b, 16k line, and never presents the typical swollen up varices. Some traits as per coiling and whorl section make Material - Seven small-sized specimens (two of the Fu3a specimens superficially comparable also with which are nearly complete). the young forms of Bouhamidoceras Dubar. However, this genus is known only in the late Sinemurian, and at Measurements - See Tab. 9. the same diameter has more evolute inner whorls (with an articulate stage and small parabolic nodes in the shape of lunules), deeper constrictions, higher whorl section, much more indented suture (with E lobe shorter than L). These differences can be observed for instance in relation to the B. zizense Dubar figured by Rakús (1994; pl. 1, figs. 1-2) and the small B. sp. of Dommergues et al. (1994; text-fig. 6; pl. 1, fig. 7). Chiefly basing on the peculiar suture line, we think that the Grilli Quarry material cannot be properly referred to any already-know genus: by now we prefer to omit any formal designation, also because its position at a suprageneric level cannot be still determined.

Stratigraphic distribution - The specimens were found Tab. 9 - Measurements for five specimens of a new undetermined in the Fu3a lumachella, datable to the early Pliensbachian genus (order and family uncertain) from the Fu3a lumachella. (base of the Miltoceras Zone). F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 23

Fig. 16 - Various ammonoids coming from the Fu3 lumachellas (Furlo Pass). All specimens at natural size. A black triangle marks the beginning of the body chamber, when it can be distinguished. a) Ventral and lateral view of Miltoceras furlense nov. sp. (paratype, Fu3C02; provenance: Fu3a); b) ventral and lateral view of Miltoceras furlense nov. sp. (holotype, Fu3C00N; provenance: Fu3a); c) ventral and lateral view of Miltoceras furlense nov. sp. (paratype, Fu3C01; provenance: Fu3a); d) lateral view and whorl section of a new undetermined Dubariceratinae (Fu3bCx15; provenance: Fu3b1); e) whorl section of a new undetermined Dubariceratinae (Fu3bCx02; only phragmocone; provenance: Fu3b1); f) ventral and lateral view of the same specimen; g) ventral and lateral view of Miltoceras furlense nov. sp. (Fu3C39; provenance: Fu3a); h) lateral and ventral views of a new undetermined Tropidoceratinae (Fu3T15; provenance: Fu3a); i) lateral view and whorl section of Spiniclaviceras spirale nov. gen. et nov. sp. (holotype, Fu3Sp01; provenance: Fu3a); j) lateral and ventral view of Sphenoacanthites costotuberculatum (Rakús & Guex) (Fu3S04; provenance: Fu3a); k) lateral and ventral views of a new undetermined genus (order and family uncertain) (Fu3Xa01; provenance: Fu3a); l) ventral and lateral view of Paramorphites acutiventris nov. gen. et nov. sp. (holotype, Fu3P09; provenance: Fu3a); m) lateral and ventral view of Paramorphites acutiventris nov. gen. et nov. sp. (paratype, Fu3P13; only phragmocone; provenance: Fu3a); n) lateral and ventral view of Sphenoacanthites costotuberculatum (Rakús & Guex) (Fu3S06; provenance: Fu3a); o) lateral view of Paramorphites acutiventris nov. gen. et nov. sp. (paratype, Fu3P03; provenance: Fu3a); p) ventral and lateral view of Paramorphites acutiventris nov. gen. et nov. sp. (paratype, Fu3P89; provenance: Fu3a); q) whorl section and lateral view of Paramorphites acutiventris nov. gen. et nov. sp. (paratype, Fu3P11; provenance: Fu3a); r) ventral and lateral view of Sphenoacanthites costotuberculatum (Rakús & Guex) (Fu3S08; only body chamber; provenance: Fu3a) (whorl sections and ventral profiles drawings by F. Venturi).

THE APENNINE TAXA DIVERSIFICATION IN documentation (Fig. 17). Substantially, for the entire THE EARLY PLIENSBACHIAN lower part of the early Pliensbachian in the Apennines the first occurrence of most new taxa is recorded, such The ammonite faunas which characterize the as the families Holcolytoceratidae (this might be already Sinemurian-Pliensbachian transition and the early present in the late Sinemurian, even if with some Pliensbachian show a remarkable change at a global doubts) and Sinuiceratidae. scale, which usually is exemplified by the diversification This applies also to the Tropidoceratidae and the of the Eoderoceratoidea (Dommergues & Meister, Polymorphitidae, which appearance seems to be related 1992; Dommergues et al., 1996; Meister & Stampfli, to the beginning of an adaptive radiation. In the first case 2000; Meister et al., 2003). Indeed, the studies on the the origin is sudden, and probably happened at the Apennine assemblages of this time interval demonstrated Sinemurian-Pliensbachian transition; subsequently the that the renewal involves several other groups (Venturi family diversified, acquiring great importance in the lower et al., 2004, 2005), and that for it two main phases and middle part of the early Pliensbachian. It is generally can be recognized: one is at the beginning of the assumed that the Tropidoceratidae derived from the Catriceras Zone corresponding both to stable isotopes Eoderoceratidae: actually, this is plausible, but as far as variations (positive for ä18O, negative for ä13C) we know the direct evidence of this transition has never and to radiation/extinctions episodes of calcareous been found in any place (Venturi et al., 2004, p. 380), and nannoplankton (Speranza & Parisi, 2007), while the forerunners of Catriceras, which is the most ancient the other one is at the beginning of the subsequent representative of the group, still remain unknown. In any Miltoceras Zone, preceded by a gap in the case, the appearance of the Tropidoceratidae required 24 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Fig. 17 - Biostratigraphic range of various Apennine ammonoid genera in the basal part of the early Pliensbachian (Catriceras and Miltoceras Zones). For sake of completeness, the final portion of the late Sinemurian and the beginning of the Metaderoceras gemmellaroi Zone are showed as well. Capital letters nearby the vertical black bars representing the genera indicate the group to which they belong; from left to right: H, Holcolytoceratidae; A, Analytoceratidae (Peltolytoceratinae); C, Coeloceratidae (Coeloceratinae, Dubariceratinae); E, Eoderoceratidae (Paramicroderoceratinae, etc.); P, Polymorphitidae (Polymorphitinae and Furlitinae); T, Tropidoceratidae (Tropidoceratinae); S, Sinuiceratidae. Note the gap in the documentation (hiatus) separating the Fu2 fauna from the Fu3 assemblage and evidencing the faunal turnover which marks the beginning of the Miltoceras Zone. This renewal is exemplified by the loose of ornamentation of the eoderoceratoids, occurred at various degrees: in forms as Gemmellaroceras it is nearly complete, while in others (e.g. Miltoceras) it is only partial (ammonite drawings by F. Venturi).

a substantial morphologic change, leading to forms with Souissi & Abdallah (2004, p. 470; text-fig. 6a-d; pl. 1, adaptations such as flexuose ribs and a ventral keel figs. 1-2) are difficult to interpret: this Tunisian species which can be considered directed to improve the has a strange oxynoceratid aspect, and at present we hydrodynamic capabilities. These modifications, think that its membership to the Tropidoceratidae already well developed in the basal Pliensbachian with proposed by Dommergues et al. (2004b) is not Catriceras, probably allowed the exploitation of new shareable. As a whole, however, it is hard to find the ecologic niches, and were further accentuated in the causes to explain the sudden appearance of this keeled topmost part of the early Pliensbachian (middle-upper ammonite group at the beginning of the Pliensbachian. portion of the Miltoceras Zone) with the appearance By now in the Mediterranean area there is no evidence of the first Tropidoceras. The derivation of this latter of an environmental crisis between Sinemurian and genus from Catriceras is surely a reasonable possibility, Pliensbachian: the nearly systematic absence (both in but transitional forms documenting it are not known Tethyan sections and elsewhere) of fossiliferous beds (Venturi et al., 2005, p. 101). Although chronologically at the transition between the two stages, combined to intermediate between Catriceras and Tropidoceras, the the frequent presence of tectonic “noises”, leads to the new undetermined Tropidoceratinae described above extreme scarcity or complete lack of data on the in the present paper is probably a lateral and somehow evolutive derivations in this time interval. This leaves “degenerated” branch of this phyletic lineage. The open the speculation to several, not verifiable, alternative subsequent evolutive history of the family (middle part scenarios (Venturi et al., 2004, p. 380): for instance one of the early Pliensbachian) is relatively better known, can imagine that the Tropidoceratidae originated in an since the ancestor-descendant tie between Tropidoceras extra-Apennine area during the late Sinemurian, and and Acanthopleuroceras Hyatt has been reported by subsequently migrated in this region at the beginning of Dommergues & Mouterde (1978) and Dommergues the Pliensbachian due to the opening of one or more (1987). On the other hand, the relationships of marine connections formerly closed, but this hypothesis Paratropidoceras numidianum Dommergues, Meister, simply shifts the problem of the first appearance of the F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 25

the first one is the Coeloceratidae, monospinate forms which usually have an “ordinary” lateral and/or ventral ornamentation. The second lineage is that of the Polymorphitidae, among which more “original” tendencies can be observed, such as the preservation of a more or less inornated shell with simplified suture (Furlites, Gemmellaroceras) or the development of ornated taxa with roof-shaped ventral area. Afterwards, the latter morphologies would have lead to lenticular forms as the Fanninoceratidae of the eastern Pacific area, which derivation apparently involved a westward migration of the Apennine Paramorphites. These hypotheses are based on: shell morphology (coiling, ornamentation, shape of the whorl section, aspect of the ventral area, etc.), ontogenetic development (essentially aspect of inner whorls and their relations with the outer ones), suture lines (general structure, shape of lobes and saddles and their proportions, etc.) and chronologic relations among taxa. Although the interpretations of such data can be no more than hardly verifiable conjectures, they are grounded on a documentation that we deem sufficient, and, among the several possibilities, these scenarios seems to better Fig. 18 - Interpretation of the phyletic relations among some early Pliensbachian eoderoceratoids in the Apennines (Catriceras and explain the available evidence. Miltoceras Zones, corresponding to the standard Jamesoni Zone). These hypotheses are based on shell morphology, ontogenetic development, suture lines and biostratigraphy, and seem to TAXONOMIC SYNTHESIS consistently relate most of the available evidence, although some transitions remain particularly dubious (as evidenced by question The whole of the available data (some of which marks and arrows with dashed lines). According to the ideas here presented, the bispinate eoderoceratids (basal part of the scheme) unpublished or in preparation for the publication) enables would have give rise to new taxa passing through small smooth to put forward hypothesis on the phyletic relations of forms (“regressive” evolution). From them, two main linages would several taxa characteristic of the Apennines and more have originated: the Coeloceratidae (left part of the scheme) and the in general of the Mediterranean Tethys: on this base a Polymorphitidae (right part of the scheme). Among the latter group, quite wide taxonomic synthesis is proposed. in turn, two tendencies can be observed: the preservation of a more Following, a synoptic hierarchic scheme of the or less inornated shell (Furlites and Gemmellaroceras) or the major early and middle Liassic ammonoid groups is development of monospinate ornamentation. This case includes forms with a roof-shaped ventral area as Paramorphites, which presented, with particular attention to the early through a migration would have lead to the lenticular Fanninoceratidae Pliensbachian forms. For most families and subfamilies of the eastern Pacific area (ammonite drawings by F. Venturi). the included genera are reported, starting from the nominal one; an exception is made by Psiloceratidae, Schlotheimiidae, Cymbitidae, Arietitidae and Echioceratidae, for which this information is omitted. In various instances the list of genera is not exhaustive, and this is evidenced by an “etc.”; however, within family to a still unknown area, which paleogeographic every family and subfamily the enumeration location is hard to establish. arrangement of the genera mostly lacks a particular On the other hand, the Apennine documentation meaning (in other words, the fact that a genus is concerning the first phases of the evolution of the mentioned before another does not necessarily imply Polymorphitidae is decidedly more abundant: as that it is more ancient). To simplify matters, the new evidenced more than once in the present paper, it would undetermined taxa without formal denomination seem that at least most part of the Pliensbachian described in Venturi et al. (2005) and in the present Eoderoceratoidea with an essentially monospinate paper are left out. Genera doubtfully placed in a family ornamentation can be derived from a common stock or subfamily are preceded by a question mark; when of bispinate eoderoceratids (Fig. 18). During the basal the doubts are even more marked there are two question Pliensbachian (lower part of the Catriceras Zone) these marks. latter show a great morphologic “malleability”, Taxa chiefly or exclusively pertaining to the displaying the tendency to loose the umbilical row of Mediterranean area, which often are directly dealt with spines and sometimes also the remaining ornamentation in our recent papers, are marked by an asterisk. (Venturi et al., 2004). Undergoing an innovation in the inner whorls they would have originated new taxa Order PHYLLOCERATIDA Arkell, 1950 passing through small smooth forms (“regressive” Family PHYLLOCERATIDAE Zittel, 1884 evolution). From them, two main phyletic linages initially Subfamily PHYLLOCERATINAE Zittel, 1884 typical of the Mediterranean Tethys would be derived: 26 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Genera: Phylloceras Suess*, Partschiceras Subfamily COELOCERATINAE Haug, 1910 Fucini*, Zetoceras Kovacs, Geyeroceras Hyatt, Genera: Coeloceras Hyatt, Apoderoceras etc. Buckman, Hyperderoceras Spath, Miltoceras Subfamily CALLIPHYLLOCERATINAE Spath, 1927 Wiedenmayer*, Pseudoskirroceras Genera: Calliphylloceras Spath*, Calaiceras Wiedenmayer, Zamaiceras Rakús & Guex, etc. Kovacs, etc. Subfamily DUBARICERATINAE Dommergues & Family JURAPHYLLITIDAE Arkell, 1950 Meister, 1999 (nom. transl. nov. ex Genera: Juraphyllites Müller*, Paradasyceras Dubariceratidae Dommergues & Meister, 1999) Spath, Tragophylloceras Hyatt, etc. Genera: Dubariceras Dommergues, Mouterde & Order PSILOCERATIDA Houša, 1965 Rivas, Genera: Metaderoceras Spath, Family PLEUROACANTHITIDAE Hyatt, 1900 Crucilobiceras Buckman, Spiniclaviceras nov., Genus: Pleuroacanthites Canavari ? Farinaccites Faraoni, Marini, Pallini & Family ANALYTOCERATIDAE Spath, 1927 Venturi*, ? Baltzerites Rakús & Guex, etc. Subfamily ANALYTOCERATINAE Spath, 1927 Family LIPAROCERATIDAE Hyatt, 1867 Genera: Analytoceras Hyatt, Tragolytoceras Genera: Liparoceras Hyatt, Tetraspidoceras Spath, ? Trachyphyllites Arthaber, etc. Spath, Vicinodiceras Trueman, Becheiceras Subfamily PELTOLYTOCERATINAE Venturi & Bilotta, Trueman, Beaniceras Buckman, Aegoceras 2001* Waagen, Oistoceras Buckman, Amaltheus De Genera: Peltolytoceras Spath, Exomiloceras Montfort, Pleuroceras Hyatt Wiedenmayer, Galaticeras Spath, Family POLYMORPHITIDAE Haug, 1887 Castanyiceras Rakús & Guex Subfamily POLYMORPHITINAE Haug, 1887 Family ECTOCENTRITIDAE Spath, 1926 Genera: Polymorphites Haug, Platypleuroceras Subfamily ECTOCENTRITINAE Spath, 1926 (nom. Hyatt, Uptonia Buckman, Caleites Venturi & transl. Venturi & Bilotta, 2001) Ferri*, Paramorphites nov.*, ? Gorgheiceras Genera: Ectocentrites Canavari, Lytotropites Venturi & Ferri*, etc. Spath, ?? Eolytoceras Frebold Subfamily FURLITINAE nov. Subfamily FUCINITINAE Venturi & Nannarone, 2002 Genera: Furlites Venturi & Ferri, ? Genus: Fucinites Gugenberger Gemmellaroceras Hyatt ?Subfamily BOUHAMIDOCERATINAE Rakús, 1999 Family FANNINOCERATIDAE Dommergues & Meister, Genus: Bouhamidoceras Dubar 1999 (nom. transl. nov. ex Fanninoceratinae Family HOLCOLYTOCERATIDAE Venturi, Nannarone & Dommergues & Meister, 1999) Bilotta, 2005* Genera: Fanninoceras McLearn, Eoamaltheus Genera: Holcolytoceras Spath, Aegolytoceras Hillebrandt Spath Family TROPIDOCERATIDAE Hyatt, 1900 Family LYTOCERATIDAE Neumayr, 1815 Subfamily TROPIDOCERATINAE Hyatt, 1900 (nom. Genera: Lytoceras Suess*, (Derolytoceras transl. Venturi, 1985) Rosenberg), Zaghouanites Rakús & Guex, etc. Genera: Tropidoceras Hyatt, Catriceras Venturi* Family NANNOLYTOCERATIDAE Spath, 1927 Subfamily ACANTHOPLEUROCERATINAE Arkell, 1950 Genera: Nannolytoceras Buckman, ? Genus: Acanthopleuroceras Hyatt Audaxlytoceras Fucini Superfamily PSILOCERATOIDEA Hyatt, 1867 Family to be specified Family PSILOCERATIDAE Hyatt, 1867 Genus: Lytoconites Wiedmann Family SCHLOTHEIMIIDAE Spath, 1923 Superfamily EODEROCERATOIDEA Spath, 1929 Superfamily CYMBITOIDEA Buckman, 1919 Family EODEROCERATIDAE Spath, 1929 Family CYMBITIDAE Buckman, 1919 Subfamily EODEROCERATINAE Spath, 1929 Superfamily ARIETITOIDEA Hyatt, 1875 Genera: Eoderoceras Spath, Xipheroceras Family ARIETITIDAE Hyatt, 1875 Buckman, Microderoceras Hyatt, Bifericeras Family OXYNOTICERATIDAE Hyatt, 1875 Buckman, etc. Genera: Oxynoticeras Hyatt, Gleviceras Subfamily PARAMICRODEROCERATINAE Venturi, Buckman, Radstockiceras Buckman*, etc. Nannarone & Bilotta, 2004* Family ECHIOCERATIDAE Buckman, 1913 Genera: Paramicroderoceras Dommergues, Superfamily uncertain Ferretti & Meister, Paraderoceras Venturi, Family uncertain Nannarone & Bilotta, Omoderoceras Venturi, Genus: Paratropidoceras Dommergues, Meister, Nannarone & Bilotta, ? Foetterleiceras Rakús Souissi & Abdallah & Guex Order to be specified Subfamily EPIDEROCERATINAE Dommergues & Family SINUICERATIDAE Venturi, Nannarone & Meister, 1999 (nom. transl. Venturi, Nannarone Bilotta, 2005* & Bilotta, 2004) Genera: Sinuiceras Venturi & Ferri, Genera: Epideroceras Spath, Coeloderoceras Sphenoacanthites nov. Spath, Pseuduptonia Bremer, Villania Till, ?? Family to be defined Pseudophricodoceras Dommergues, Mouterde Genera: new genus from Monte Bove*, & Rocha; ? Capreoliceras Alkaya & Meister Dudresnayiceras Rakús, etc. Family COELOCERATIDAE Haug, 1910 Order uncertain F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 27

Family to be specified 4) Peri-Gondwanian way, bordering the whole Genus: Pelingoceras Venturi, Nannarone & Gondwana (Arabia, India, Australia, Antarctica) as far as Bilotta* the South America; Order uncertain 5) pantropical distribution, with a dispersal in the Superfamily uncertain entire tropical belt of the proto-Pacific Ocean, unrelated Family uncertain to the proximity of the continental edges. Genus: Tunisiceras Dommergues, Meister, Among all these options, the first one (“Hispanic Souissi & Abdallah Corridor”) seems the only that can provide a sufficiently consistent explanation for the presence of the The present scheme, albeit not exhaustive, allows to aforementioned Apennine taxa on the Pacific South outline a quite rich and complex taxonomic picture: the American coasts. As far as we know, these forms are presence of several forms with a doubtful or uncertain exclusively recorded in these two areas, and they have position indicate the need for new researches aimed to never been found elsewhere. Since it is reasonable to understand the phyletic relationships among the various suppose the existence of at least one Tethyan equatorial groups and within them. This is especially true for the westward surface current (similar to its modern Pacific Mediterranean Tethys successions, which proved to be counterpart at comparable latitudes), it seems permissible very important for the studies on the Jurassic ammonoid to think that Catriceras, Paramorphites, Miltoceras and systematics and evolution. the undetermined dubariceratins could have “used” this kind of circulation, following an E-W route to migrate from the western Tethys to the Andean area (Venturi et PALEOBIOGEOGRAPHIC IMPLICATIONS al., 2006). Such a route, through an intermittent and temporary From a paleobiogeographic point of view, the lower seaway acting like a filter, seems to agree with the Pliensbachian ammonite faunas of the Apennines show phylogenetic development hypothesized for a partial isolation with respect to other areas of the Paramorphites: the ancestral form occurs only in the Mediterranean Province, as evidenced by several Apennines, preceding the taxa interpreted as its apparently endemic taxa such as the Peltolytoceratinae descendants, which are found exclusively on the western (but also other forms, as Gemmellaroceras). This seems American border (moreover, this would explain the to suggest that a limited portion of the western Tethys absence of forerunners for the lineage of Eoamaltheus can be considered as a “Peltolytoceratinae meso- in that area). The precariousness of the proto-Atlantic Mediterranean unit”, a matter already discussed above. marine connection during the early Pliensbachian would Basing on some paleogeographic reconstructions (e.g. account for the sharp chronologic and geographic those presented by Stampfli et al., 2002 and Dommergues separation between the initial form of the phyletic lineage et al., 2005), this area would have been clearly separated and its successors; furthermore, the forms involved from the North-western European regions, being rather would have had enough time and evolutive pressures to connected to the East Mediterranean Ocean and its modify their shell. continuation to the Apulian and Apennine platforms: this On the other hand, we think that the remaining faunal seems to agree with a faunal isolation compared to the transit ways do not fit to explain the case at issue: in fact, northernmost portions of the Mediterranean Province they would imply an areal distribution (e.g. the pantropical during the basal part of the early Pliensbachian. one) which is not proved for Catriceras, Paramorphites On the other hand, interesting similarities with the and the other mentioned taxa, or they would involve more or less coeval faunas of the western coasts of the crossing of environments placed at very high the South America (Andean Province of Page, 1996) northern and southern latitudes (“Viking Corridor”, Peri- can be noted (Venturi et al., 2005, 2006). In particular, Asiatic way, Peri-Gondwanian way). To oppose these this concerns Catriceras, Paramorphites, Miltoceras, interpretations, one can raise several objections: for and the Dubariceratinae here considered as a new instance it is not sure whether some tropical Tethyan undetermined genus. Generally speaking, the presence of ammonoid would have tolerated the high latitude north Mediterranean taxa on the American Pacific coasts during Asian and south Antarctic environments or not, but there the Lias can be explained by five possible faunal transit is no evidence that the taxa at issue occurred in areas ways (Smith, 1983; Newton, 1988; Westermann, 1993; such as Greenland, Scandinavia, Asia, Arabia, India, Dommergues, 1994; Dommergues et al., 2004a): Australia, Antarctica (i.e. along the various routes 1) trans-Pangea marine connection (“Hispanic substitutive to the “Hispanic Corridor”; for the lack of a Corridor” or proto-Atlantic seaway), formed by the general paleontological support for these ways see also western continuation of the Tethys between Africa and Iturralde-Vinent, 2006, p. 798 and references cited the Central and South American areas, in relation to the therein). Furthermore, as far as we know, there is no early opening phases of the future Atlantic Ocean; grounded proof of a pantropical distribution for the 2) “Viking Corridor”, which passes to the north examined ammonoid forms: on the contrary, their between Greenland and Scandinavia, then goes through absence in Hungary and northern Turkey seem to highlight the Arctic seas, and afterwards runs along the western a rather restricted geographic distribution. coast of the North America; Indeed, in agreement with Dommergues et al. 3) Peri-Asiatic way, with a transit along the north- (2004a) and Meister et al. (2005), we think that it is eastern edge of the continental masses corresponding to always better to be prudent concerning the the modern Asia; paleobiogeographic interpretations, because different 28 Bollettino della Società Paleontologica Italiana, 46 (1), 2007 taxonomic sensibilities may lead to divergent opinions that taxa with marked morphological differences lived about the actual affinities of geographically distant in different ways, with different reproductive strategies faunas. Furthermore, there is not a sufficiently clear and dispersal mechanisms, similarly to the modern comprehensive view of these matters, chiefly for the cephalopods (nautilus, cuttlefishes, squids, octopuses, lack of reliable successions in many areas. Also for etc.). Consequently, we suppose that the migration these reasons, we believe that the problem cannot be through the proto-Atlantic seaway is the most suitable currently discussed with general models, and that it to explain the presence of Catriceras, Paramorphites, must be preferable to deal only with specific data sets Miltoceras and the undetermined dubariceratins on the (ad hoc hypotheses). In the study of a highly diversified American Pacific coasts, but this may not be necessarily group such as the ammonoids, it is reasonable to think valid with other taxa. Indeed, we do not exclude that

Fig. 19 - Simplified early Pliensbachian paleogeographic reconstructions, evidencing the approximate extent of the “Peltolytoceratinae meso- Mediterranean paleobiogeographic unit” (a restricted portion of the Mediterranean Province). Both settings, albeit differing in several details, are compatible with the ammonite distribution, as well as with the faunal differences between the Mediterranean Tethys area and other regions; a) based on the scheme presented by Dommergues et al. (2005), with modifications; b) based on the scheme presented by Stampfli et al. (2002), with modifications. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 29 other cases could have different paleobiogeographic Concluding, issues emerged from our researches explanations. as a whole permit to have a quite varied survey on a portion of the early Jurassic which formerly was poorly known. The major prospect for the present study, CONCLUSIONS already hinted by other recent papers on the ammonites (Venturi et al., 2004, 2005), is the paleo(bio)geographic The features of Apennine early Pliensbachian theme. In particular, we note that the relations between ammonite faunas, as exemplified by the taxa found in the Mediterranean area and other regions such as the the Furlo Pass Fu3 lumachellas, suggest that a shallow eastern North Africa are still nearly unknown, as and mid-depth branch of the western Tethys in the Early testified by the sudden appearance without direct Jurassic extended from the present-day southern Turkey forerunners of many groups in the early Pliensbachian to the Morocco. This restricted portion of the (e.g. the Tropidoceratidae), and also in the subsequent Mediterranean Province would represent a meso- parts of the Lias (e.g. the Hildoceratidae and the Mediterranean paleobiogeographic unit including Hammatoceratidae). Apennines, Tuscany, Sicily, Albania, North Africa (Morocco, Algeria, northern Tunisia) and perhaps other regions such as the Betic Cordillera (Spain) and Austrian Alps. As far as we know, it would have the value of ACKNOWLEDGEMENTS separated unit for nearly the entire Lias, from late We would like to thank Prof. Leonsevero Passeri and Prof. Hettangian-early Sinemurian times to most part of the Gloria Ciarapica (Università degli Studi di Perugia) for the useful Toarcian. As testified by the dissimilar ammonite discussion and indications on the paleogeographic reconstructions assemblages, its paleoecologic features seem very of our area. different from those of the North-west European areas, A grateful acknowledgment to Dr. Jean-Louis Dommergues and besides, direct relations with the North-west (Université de Bourgogne) for his review of the manuscript and the interesting discussion about the paleobiogeographic value of European Province of Page (1996) can be basically Galaticeras, as well as to Dr. Kevin N. Page (University of ruled out for the existence of conspicuous barriers (Fig. Plymouth, UK) for his review of the manuscript. 19). The current data on the middle Liassic ammonites Thanks also to Mr. Giorgio Lucarini for the fine photographs show that neither eastward pantropical connections he took of our material. through the proto-Pacific are to be considered much, This paper was funded with the heading “Ricerca di Base” of and the same also apply to the southward the Dipartimento di Scienze della Terra, Università degli studi di Perugia. communications with Arabian areas: in both cases one can hypothesize that the faunal exchanges were mostly obstructed by a broad southern branch of the Tethys REFERENCES (East Mediterranean Ocean) which represented an insuperable barrier for various ammonites as the Arkell W.J., Furnish W.M., Kummel B., Miller A.K., Moore R.C., Peltolytoceratinae. On the contrary, it seems that the Schindewolf O.H., Sylvester-Bradley P.C. & Wright C.W. (1957). Mesozoic Ammonoidea. In Moore R.C. (ed.), Treatise Mediterranean Province might have had westward on Invertebrate Paleontology Part L: Mollusca 4, Cephalopoda, faunal exchanges (although sometimes partial and Geological Society of America and University of Kansas Press: discontinuous) with the Andean Province. The available L80-L465. evidence suggests that the trans-Pangea seaway known Blau J. (1998). Monographie der Ammoniten des Obersinemuriums as the “Hispanic Corridor” would have acted as a filter (Lotharingium, Lias) der Lienzer Dolomiten (Österreich): (Venturi et al., 2006), allowing the migration only to Biostratigraphie, Systematik und Paläobiogeographie. Revue de some forms which probably lived in relatively shallow Paléobiologie, 17 (1): 177-285. Braga J.C., Comas-Rengifo M.J., Goy A. & Rivas P. (1982). environments (e.g. Catriceras and Paramorphites), but Comparaciones faunísticas y correlaciones en el Pliensbachiense not to those for which a more deep habitat can be de la Zona Subbética y Cordillera Ibérica. Bolétin de la Real inferred (e.g. Galaticeras). Sociedad Española de Historia Natural (Sección Geologia), Other subjects are closely connected to the 80: 221-244. paleo(bio)geographic themes, as for instance the Braga J.C., Rivas P., Comas-Rengifo M.J. & Goy A. (1984). The biostratigraphic, taxonomic and phylogenetic ones. From Pliensbachian of Spain: Ammonite successions, boundaries and correlations. In Michelson O. & Zeiss A. (eds.), International the latter point of view, the Fu3 assemblage represents Symposium on Jurassic Stratigraphy - Erlangen, September 1- an adaptive radiation phase during which various taxa 8, 1984. Symposium Volume I: 159-176. initially typical of the Mediterranean area evolved. For Bremer H. (1965). Zur Ammonitenfauna und Stratigraphie des unteren some of them the origin seems to be sufficiently and Lias (Sinemurium bis Carixium) in der Umgebung von Ankara reasonably documented (e.g. Polymorphitidae and (Türkei). Neues Jahrbuch für Geologie und Paläontologie Coeloceratidae), while in other cases evidence is still Abhandlungen, 122 (2): 127-221. Buckman S.S. (1919-1930). Type Ammonites: Vol. III-VII, 358 pp., very scarce (as for the Sinuiceratidae, which by now Wheldon & Wesley, London. cannot be placed at a suprafamiliar rank, or the Cope J.C.W. (1991). Ammonite faunas of the Ammonitico Rosso of Tropidoceratidae). the Pontide Mountains, Northern Anatolia. In Farinacci A., Ager Regarding biostratigraphy, the studies on the early D.V. & Nicosia U. (eds.), Geology and Paleontology of Western Pliensbachian Apennine faunas allow to reach a rather Pontides, Turkey. Jurassic-Early Cretaceous stratigraphy, accurate local biozonation, with reliable short- and tectonics and paleogeographic evolution. Geologica Romana, middle-range correlations. 27: 303-325. 30 Bollettino della Società Paleontologica Italiana, 46 (1), 2007

Dommergues J.-L. (1987). Les Acanthopleuroceras, un genre Donovan D.T., Callomon H.J. & Howarth M.K. (1981). endémique euro-occidental issu d’une famille téthysienne; étude Classification of the Jurassic Ammonitina. In House M.R. & de leur divergence évolutive. In L’evolution chez les ammonitina Senior J.R. (eds.), The Ammonoidea. The Evolution, du Lias moyen (Carixien, Domerien basal) en Europe occidentale. Classification, Mode of Life and Geological Usefulness of a Major Documents des Laboratoires de géologie, Lyon, 98: 156-173. Fossil Group. The Systematic Association Special Volume, 18: Dommergues J.-L. (1994). Les faunes d’ammonites pandémiques 101-155. et téthysiennes du Lias confrontées à un modèle de distribution Faraoni P., Marini A., Pallini G. & Venturi F. (1996). New Carixian pantropicale. In Pallini G. (ed.), Proceeding of the III Pergola ammonite assemblages of Central Apennines (Italy), and their International Symposium “Fossili, Evoluzione, Ambiente” Pergola, impact on Mediterranean Jurassic biostratigraphy. Paleopelagos, 25-30 October 1990. Paleopelagos Special Publication, 1: 93- 6: 75-122. 107. Ferretti A. (1975). Ricerche biostratigrafiche sul Sinemuriano- Dommergues J.-L. & Meister C. (1992). Late Sinemurian and Early Pliensbachiano nella Gola del Fiume Bosso (Appennino Carixian ammonites in Europe with cladistic analysis of sutural marchigiano). Rivista Italiana di Paleontologia e Stratigrafia, characters. Neues Jahrbuch für Geologie und Paläontologie 81 (2): 161-194. Abhandlungen, 185 (2): 211-237. Fischer J.-C., director (1994). Révision critique de la Paléontologie Dommergues J.-L. & Meister C. (1999). Cladistic formalisation of Française d’Alcide d’Orbigny icluant la réédition de l’original. relationships within a superfamily of Lower Jurassic Ammonitina: Vol. 1, Céphalopodes Jurassiques: xii + 340 pp. Masson, Paris. Eoderocerataceae Spath, 1929. Revue de Paléobiologie, 18 (1): Géczy B. (1976). Les Ammonitines du Carixien de la Montagne du 273-286. Bakony: 225 pp. Akadémiai Kiadó, Budapest. Dommergues J.-L. & Mouterde R. (1978). Les faunes Gemmellaro G.G. (1884). Sui fossili degli strati a Terebratula d’ammonites du Carixien inférieur et moyen du gisement de aspasia della contrada Rocche Rosse presso Galati Cottards (Cher). Geobios, 11 (3): 345-365. (Messina). Giornale di Scienze Naturali ed Economiche Dommergues J.-L. & Mouterde R. (1982). Reynesocoeloceras Palermo, 16 (4): 3-48. praeincertum nov. sp. (Ammonitina, Carixen moyen). Remarques Hauer M.F.R. von (1854). Über einige unsymmetrische Ammoniten sur l’origine du genre Reynesocoeloceras. Geobios, 15 (5): aus dem Hierlatz-Schichten. Sitzungsberichte der Kaiserlichen 757-763. Akademie der Wissenschaften. Mathematisch- Dommergues J.-L., Ferretti A., Géczy B. & Mouterde R. (1983). Naturwissenschaftliche Classe, Abteilung I, 13 (2): 401-410. Eléments de correlation entre faunes d’Ammonites mésogéennes Hillebrandt A. von (1981). Faunas de ammonites del liásico (Hongrie, Italie) et subboréales (France, Portugal) au Carixien inferior y medio (Hettangiano hasta Pliensbachiano) de et au Domérien inférieur. Précisions sur la limite Carixien/ América del Sur (excluyendo Argentina). In Volkheimer W. & Domérien Mésogée. Geobios, 16 (4): 471-484. Musacchio E.A. (eds.), Cuencas sedimentarias del Jurásico Dommergues J.-L., Mouterde R. & Rivas P. (1984). Un faux y Cretácico de América del Sur, Comité Sudamericano del polymorphitiné: Dubariceras, nouveau genre d’ammonitina du Jurásico y Cretácico, 2: 499-538. Carixien mésogéen. Geobios, 17 (1): 831-839. Hillebrandt A. von (1987). Liassic ammonite zones of South Dommergues J.-L., Ferretti A. & Meister C. (1994). Les faunes America and correlations with other provinces. With d’ammonites du Sinémurien de l’Apenin Central (Marches et description of new genera and species of ammonites. In Toscane, Italie). Bollettino della Società Paleontologica Italiana, Volkheimer W. (ed.), Bioestratigrafía de los Sistemas 33 (1): 13-42. Regionales del Jurásico y Cretácico en América del Sur. Dommergues J.-L., Laurin B. & Meister C. (1996). Evolution of Contribution to I.G.C.P. # 171 Circum-Pacific Jurassic, ammonoid morphospace during the Early Jurassic radiation. Mendoza, 1: 111-157. Paleobiology, 22 (2): 219-240. Howarth M.K. (2002). The Lower Lias of Robin Hood’s Bay, Dommergues J.-L., Meister C., Bonneau M., Cadet J.-P. & Fili I. Yorkshire, and the work of Leslie Bairstow. Bulletin of the British (2000). Les Ammonites du Sinémurien supérieur et du Carixien Museum (Natural History), Geology., 58 (2): 81-152. inférieur à moyen du gisement de Lefterochori (Albanie Howarth M.K. & Donovan T.D. (1964). Ammonites of the Liassic méridionale). Témoin exceptionnel des faunes de la Téthys family Juraphyllitidae in Britain. Palaeontology, 7, (2): 286-305. méditerranéenne orientale. Geobios, 33 (3): 329-358. Iturralde-Vinent M.A. (2006). Meso-Cenozoic Caribbean Dommergues J.-L., Meister C. & Jaillard E. (2004a). Ammonites de Paleogeography: Implications for the Historical Biogeography la formation Santiago de la zone subandine du S-E de l’Équateur of the Region. International Geology Review, 48: 791-827. (Jurassique inférieur, Sinémurien). Revue de Paléobiologie, 23 Lachkar N., Dommergues J.-L., Meister C., Neige P., Izart A. & (1): 355-371. Lang J. (1998). Les ammonites du Sinémurien supérieur du Jebel- Dommergues J.-L., Meister C., Souissi F. & Abdallah H. (2004b). Bou-Hamid (Haut-Atlas central, Rich, Maroc). Approches Paratropidoceras nov. gen. numidianum nov. sp. et Tunisiceras paléontologique et biostratigraphique. Geobios, 31 (5): 587-619. nov. gen. insolitus nov. sp., deux nouveaux genres et deux Meister C. & Stampfli G. (2000). Les ammonites du Lias moyen nouvelles espèces d’ammonites du Carixien de la Téthys (Pliensbachien) de la Néotéthys et de ses confins; composition méditerranéenne (Pliensbachien, Tunisie). Revue de fauniques, affinités paléogéographiques et biodiversité. Revue Paléobiologie, 23 (2): 463-475. de Paléobiologie, 19 (1): 227-292. Dommergues J.-L., Meister C., Bonneau M., Poisson A. & Vrielinck Meister C., Blau J., Dommergues J.-L., Feist-Burkhardt S., Hart B. (2005). Les ammonites pliensbachiennes des nappes M., Hesselbo S.P., Hylton M., Page K. & Price G. (2003). A Lyciennes (Turquie méridionale). Description de faunes proposal for the Global Boundary Stratotype Section and Point nouvelles, implications biostratigraphiques et (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic). paléobiogéographiques. Geobios, 38 (4): 407-435. Eclogae geologicae Helvetiae, 96 (2): 275-297. Donovan D.T. (1958). The Lower Liassic Ammonite Fauna from Meister C., Blau J., Dommergues J.-L., Schlatter R., Schmidt-Effing the Fossil Bed at Langeneckgrat, near Thun (Median Prealps). R. & Burk K. (2005). Ammonites from the Lower Jurassic Schweizerische Paläontologische Abhandlungen, 74 (2): 1-58. (Sinemurian) of Tenango de Doria (Sierra Madre Oriental, Donovan D.T. (1994). Evolution in some early Jurassic ammonites: Mexico). Part IV: Biostratigraphy, palaeobiogeography and Asteroceratinae, Oxynoticeratidae and related forms. In Pallini taxonomic addendum. Revue de Paléobiologie, 24 (1): 365-384. G. (ed.), Proceeding of the III Pergola International Symposium Newton C.R. (1988). Significance of “Tethyan” Fossils in the “Fossili, Evoluzione, Ambiente” Pergola, 25-30 October 1990. American Cordillera. Science, 242 (4877): 385-391. Paleopelagos Special Publication, 1: 383-396. Page K.N. (1996). Mesozoic Ammonoids in Space and Time. In Donovan D.T. & Forsey G.F. (1973). Systematics of Lower Liassic Landman N.H., Tanabe K. & Davis R.A. (eds.), Ammonoid Ammonitina. The University of Kansas Paleontological Paleobiology. Topics in Geobiology, 13, Plenum Press: 755-794. Contributions, 64: 1-18. F. Venturi, C. Nannarone, M. Bilotta - Pliensbachian ammonites from Marche (Italy) 31

Page K.N. (2003). The Lower Jurassic of Europe: its subdivision Reconstruction of the evolution of the Alpine-Himalayan and correlation. Geological Survey of Denmark and orogeny. Journal of the Virtual Explorer, 8. Greenland Bulletin, 1: 23-59. Venturi F. (1978). Ammoniti della “Corniola” del Monte Catria Orbigny A. d’ (1842-1851). Paléontologie Française. Terrains (Appennino Marchigiano). Un orizzonte fossilifero attribuibile jurassiques. I. Céphalopodes: 642 pp. + Atlas, 234 pl. Masson, all’intervallo Lotharingiano sup.-Carixiano inf. Bollettino della Paris. Società Paleontologica Italiana, 17 (1): 99-117. Rakús M. (1994). Les ammonites Lotharingiennes du Jebel Bou Hamid Venturi F. & Bilotta M. (2001). Posizione tassonomica di (Haut-Atlas de Rich, Maroc). In Pallini G. (ed.), Proceeding of Galaticeras (Ammonoidea): un genere medio-liassico della the III Pergola International Symposium “Fossili, Evoluzione, Tetide mediterranea. Bollettino della Società Paleontologica Ambiente” Pergola, 25-30 October 1990. Paleopelagos Special Italiana, 40 (3): 325-337. Publication, 1: 299-316. Venturi F. & Ferri R. (2001). Ammoniti Liassici dell’Appennino Rakús M. & Guex J. (2002). Les ammonites du Jurassique Centrale. 269 pp. Città di Castello (PG). inférieur et moyen de la dorsale tunisienne. Mémoires de Venturi F., Nannarone C. & Bilotta M. (2004). Eoderoceratidae Géologie (Lausanne), 39: 217 pp. (Mollusca, Ammonoidea) from the “Corniola” of the Central Salvador A., ed. (1994). International Stratigraphic Guide: a guide Apennines, related to the Sinemurian-Pliensbachian boundary in to stratigraphic classification, terminology, and procedure. the Mediterranean area. Bollettino della Società Paleontologica Second Edition. 1-214+i-xix pp. The International union of Italiana, 43 (3): 361-382. Geological Sciences & The Geological Society of America. Venturi F., Nannarone C. & Bilotta M. (2005). Early Pliensbachian Schlatter R. (1980). Biostratigraphie und Ammonitenfauna des Unter- ammonites from the Furlo Pass (Marche, Italy): two new Pliensbachium im Typusgebiet (Pliensbach, Holzmaden und faunas for the middle-western Tethys. Bollettino della Società Nürtingen; Württemberg, SW-Deutschland). Stuttgarter Paleontologica Italiana, 44 (2): 80-115. Beiträge zur Naturkunde, Serie B, 65: 1-261. Venturi F., Bilotta M. & Ricci C. (2006). Comparison between Smith P.L. (1983). The Pliensbachian ammonite Dayiceras western Tethys and eastern Pacific ammonites: further evidence dayiceroides and Early Jurassic paleogeography. Canadian for a possible late Sinemurian-early Pliensbachian trans-Pangaean Journal of Earth Sciences, 20 (1): 86-91. marine connection. Geological Magazine, 143 (5): 699-711. Smith P.L. & Tipper H.W. (1996). Pliensbachian (Lower Jurassic) Westermann G.E.G. (1993). Global bio-events in mid-Jurassic Ammonites of the Queen Charlotte Islands, British ammonites controlled by seaways. In House M.R. (ed.), The Columbia. Bulletins of American Paleontology, 108 (348): Ammonoidea. Environment, Ecology, and Evolutionary Change. 122 pp. The Systematic Association Special Volume, 47: 187-226. Smith P.L., Tipper H.W., Taylor D.G. & Guex J. (1988). An Wiedenmayer F. (1977). Die Ammoniten des Besazio-Kalks ammonite zonation for the Lower Jurassic of Canada and the (Pliensbachian, Südtessin). Mémoires Suisses de United States: the Pliensbachian. Canadian Journal of Earth Paléontologie, 98: 1-169. Sciences, 25: 1053-1523. Wiedenmayer F. (1980). Die Ammoniten der mediterranen Provinz Speranza F. & Parisi G. (2007). High-resolution magnetic im Pliensbachian und unteren Toarcian aufgrund. Neuer stratigraphy at Bosso Stirpeto (Marche, Italy): anomalous Untersuchungen im Generoso-Becken (Lombardische Alpen). geomagnetic field behaviour during early Pliensbachian (early 262 pp. Birkhäuser Verlag, Basel. Jurassic) times? Earth and Planetary science Letters, 256: 344-359. Stampfli G.M., Borel G.D., Marchant R. & Mosar J. (2002). Western Alps geological constraints on western Tethyan Manuscript received 03 October 2006 reconstructions. In Rosenbaum G. & Lister G.S. (eds.), Revised manuscript accepted 09 January 2007 32 Bollettino della Società Paleontologica Italiana, 46 (1), 2007