Bollettino della Società Paleontologica Italiana, 50 (1), 2011, 1-10. Modena, 1 luglio 20111

The teleost fishParavinciguerria praecursor Arambourg, 1954 in the Cenomanian of north-eastern

Giorgio Carnevale & Antonino Rindone

G. Carnevale, Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, I-10125 Torino, ; [email protected] A. Rindone, Liceo Scientifico “Archimede”, Viale Regina Margherita 3, I-98100 , Italy; [email protected]

KEY WORDS - Teleostei, Stomiiformes, Paravinciguerria praecursor, Cenomanian, Sicily.

ABSTRACT - Skeletal remains of the teleost fish species Paravinciguerria praecursor Arambourg, 1954 are described for the first time from the upper Cenomanian of the Peloritani and Nebrodi Mountains, north-eastern Sicily. Four partially articulated cranial fragments were collected from the bituminous shales of the Argille Varicolori succession outcropping near the towns of Floresta and Malvagna, in the . The upper Cenomanian fossil fish-rich bituminous shales of the Peloritani and Nebrodi Mountains were deposited on a distal ramp along the North African continental shelf and represent sediments related to the Oceanic Anoxic Event 2. The finding of Paravinciguerria praecursor, previously described from the upper Cenomanian-lower Turonian deposits of Morocco and northern Italy, constitutes the eighteenth fish taxon to be described from the upper Cenomanian of north-eastern Sicily. The phylogenetic affinities of Paravinciguerria are discussed in detail in the present study. The assignment of this genus to one of the recognized protacanthopterygian subgroups is excluded here on the basis of anatomical features. Based on the structure of the upper jaw and hyobranchial apparatus, it is suggested that Paravinciguerria may be interpreted as a stem stomiiform, thereby representing the earliest member of this lineage.

RIASSUNTO - [Il teleosteo Paravinciguerria praecursor Arambourg, 1954 nel Cenomaniano della Sicilia nord-orientale] - Resti scheletrici del teleosteo Paravinciguerria praecursor Arambourg, 1954 sono descritti per la prima volta nel Cenomaniano dei Monti Peloritani e dei Monti Nebrodi, nel settore nord-orientale della Sicilia. Sono stati esaminati quattro resti cranici parzialmente articolati raccolti negli scisti bituminosi delle Argille Varicolori affioranti nei pressi dei centri abitati di Floresta e Malvagna, in provincia di Messina. Gli scisti bituminosi ittiolitiferi tardo cenomaniani dei Monti Peloritani e dei Monti Nebrodi si originarono su una rampa distale lungo la piattaforma continentale nord-africana e costituiscono l’espressione sedimentaria del secondo evento anossico oceanico (OAE 2). Paravinciguerria praecursor, descritto in precedenza dai depositi del Cenomaniano superiore-Turoniano inferiore del Marocco e dell’Italia settentrionale, è il diciottesimo taxon ittico segnalato nei depositi tardo cenomaniani della Sicilia nord-orientale. Le possibili affinità filogenetiche diParavinciguerria sono descritte in dettaglio. L’attribuzione di Paravinciguerria ad uno dei sottogruppi noti di protacantopterigi (=salmoniformi) è esclusa sulla base di evidenze anatomiche. La struttura e la conformazione delle ossa della mascella e dell’apparato io-branchiale evidenziano una certa affinità con gli stomiiformi, dei quali Paravinciguerria costituirebbe il più antico rappresentante.

INTRODUCTION north-eastern Sicily increased even further thanks to the contributions of Rindone (1984, 1988, 2008). Articulated skeletal remains of Cretaceous teleost Here, we document, for the first time, the presence fishes are rather abundant in Italy (Dalla Vecchia et al., of the teleost Paravinciguerria praecursor Arambourg, 2005). A large amount of specimens have been collected 1954 from the black shales of north-eastern Sicily. Our from a number of localities densely distributed in northern study is based on four specimens collected in the nearby Italy and throughout the peninsula. As far as the Sicilian of Floresta and Malvagna. The systematic status and record is concerned, skeletal remains of teleost fishes possible phylogenetic affinities of Paravinciguerria are are known from some localities of the Monti Peloritani, also discussed in detail. in the Messina district. Fossil fishes from north-eastern Sicily were reported for the first time by Ponte (1923), who cursorily described fish and plant remains collected STRATIGRAPHY AND PALEOENVIRONMENT from the bituminous shales outcropping in the nearby of the town of Malvagna. Subsequently, Accordi (1960) Fossil fishes were collected from black shales published a short note, documenting the presence of outcropping in the nearby of the towns of Floresta and articulated fish remains in the territory surrounding the Malvagna (Fig. 1) in the Monti Nebrodi and Monti town of Floresta. A few years later, thanks to the efforts of Peloritani, respectively. Lithologically, the fossiliferous Prof. B. Accordi, Leonardi (1965) realized a monographic deposits consist of 20 meters thick inframillimetrically study on the fishes collected from the black shales of laminated organic-rich black shales rhythmically alternated north-eastern Sicily exposed close to Floresta and . with dark marlstone and claystone (Bellanca et al., 2000). Leonardi (1965) documented the presence of 14 taxa and The black shales contain abundant pyrite, a moderately recognized the strong faunal affinities existing between diverse microfossil assemblage (Scopelliti et al., 2008), the Sicilian assemblage and the Cenomanian-Turonian and, in certain horizons, abundant macrofossils (fishes, assemblage of Jbel Tselfat, Morocco, which was described ammonites, plant remains, coprolites) (see Leonardi, a few years earlier by the eminent French paleontologist 1965; Campisi, 1977). The fossiliferous deposits are part Camille Arambourg (1943, 1954). More recently, the of the Argille Varicolori, a mainly pelitic unit belonging known diversity of the Cretaceous fish assemblage of to the Peloritani Thrust Belt, which is exposed in Calabria

ISSN 0375-7633 2 Bollettino della Società Paleontologica Italiana, 50 (1), 2011

lucida drawing arm. Type and other specimens of Paravinciguerria praecursor from the Jbel Tselfat, Morocco, in the collection of the Muséum National d’Histoire Naturelle, Paris (MNHN-F DTS 74, holotype; MNHN-F DTS 200, paratype; MNHN-F DTS 201; MNHN-F DTS 202; MNHN-F DTS 203; MNHN-F DTS 221) were examined for comparative purposes. Anatomical abbreviations: br, branchiostegal rays; ctb, ceratobranchial; cth, ceratohyal; d, dentary; gr, gill rakers; h, hyomandibula; mx, maxilla; pas, parasphenoid; pmx, premaxilla; q, quadrate; smx, supramaxilla; v, vertebra.

SYSTEMATICS

Subdivision TELEOSTEI sensu Patterson & Rosen, 1977 Order STOMIIFORMES Fink & Weitzman, 1982

Genus Paravinciguerria Arambourg, 1954 Paravinciguerria praecursor Arambourg, 1954 Fig. 1 - Sketch map of north-eastern Sicily. The asterisks indicate (Figs 2-4) the location of the outcrops of the ichthyolitiferous organic-rich black shales of the Argille Varicolori. Scale bar = 5 km. 1954 Paravinciguerria praecursor Arambourg, p. 83-90, text-fig. 40; pl. 9, figs 3-4; pl. 10, figs 1-2. 1976 Paravinciguerria praecursor Arambourg - Sorbini, p. 503- 505, text-fig. 12, pl. 20-21b. and eastern Sicily (Amodio-Morelli et al., 1976), also 1994 Paravinciguerria praecursor Arambourg - Taverne, p. 56-69, known as Argille Scagliose (Campisi, 1977), Complesso text-figs 1-3. Antisicilide (Ogniben, 1969) and, more recently, Argille Scagliose Antisicilidi (Lentini et al., 2000). The black Material - Four (partially) articulated head skeletons. shales of the Argille Varicolori originated on a distal ramp DSTM FLV1, incomplete head skeleton (Figs 2a-b), located along the North African continental shelf (see Floresta; DSTM FLV2, largely incomplete head skeleton Giunta & Nigro, 1999), possibly not far from the present (Fig. 2c), Floresta; DSTM FLV3 and DSTM FLV4, part Tunisia (Scopelliti et al., 2008). Micropaleontological and counterpart of a largely incomplete head skeleton analyses and isotope and organic geochemistry (Scopelliti (Figs 3c-d), Floresta; DSTM MAL11 and DSTM MAL12, et al., 2008; Rindone, 2010a, b) concur to indicate that part and counterpart of an incomplete head skeleton (Figs the deposition of the organic-rich black shales occurred 3a-b), Malvagna. in a highly stressed paleobiotope, characterized by low oxygen and nutrient rich waters. More generally, the black Occurrence - Upper Cenomanian to lower Turonian, shales of the Argille Varicolori represent the sedimentary western Tethys. expression of the Oceanic Anoxic Event 2 (OAE 2) that occurred close to the Cenomanian-Turonian boundary, Remarks - Despite their incompleteness, the specimens leading to the world-wide sedimentation of organic-rich exhibit several characters that fit well the definition of deposits (Schlanger & Jenkyns, 1976; Jenkyns, 1980). Paravinciguerria praecursor as given by Arambourg In Italy, deposits related to this event, also known as (1954) and, subsequently, by Taverne (1994), including: Bonarelli-level equivalents, are frequently exposed in general physiognomy of the head, structure and southern Alps, Apennines and Sicily, often characterized configuration of the upper jaws (morphology of the by fossil fish remains (Bonarelli, 1891; Leonardi, 1965; maxilla and supramaxilla and upper jaw dentition), general Sorbini, 1976; Bizzarini & Coccioni, 1990; Avanzini outline of the dentary, orientation and structure of the & Luciani, 2001; Gomez et al., 2002). High resolution hyomandibula, and morphology of the gill rakers. stratigraphic analyses suggest that the organic-rich black shales of the Argille Varicolori of north-eastern Sicily Description - All the available specimens consist of mostly record the lower portion of the OAE 2, dating partially disarticulated skeletons, exclusively represented back to the uppermost part of the Cenomanian (Scopelliti by head bones (Figs 2-3). The bones are mostly et al., 2008). preserved as impression only. The neurocranium is low and moderately elongate. The parasphenoid is the only distinctly recognizable element of the neurocranium, METHODS exclusively observable in the specimens DSTM FLV1 (Fig. 2a), DSTM MAL11 and DSTM MAL12 (Figs 3a-b); The specimens are deposited in the collection of the it is a robust bone that passes through the lower third of Dipartimento di Scienze della Terra of the Università the orbit; the basipterygoid process of the parasphenoid di Messina (DSTM). These were examined using a appears to be absent (see also Taverne, 1994). The eyeball Leica MS5 stereomicroscope equipped with a camera is relatively small (less than one fourth the recognizable G. Carnevale, A. Rindone - Paravinciguerria praecursor from the Cenomanian of Sicily 3

Fig. 2 - Paravinciguerria praecursor Arambourg, 1954 from the Cenomanian of north-eastern Sicily. a, DSTM FLV1, left side, lateral view, scale bar = 2 mm; b, partially preserved head skeleton drawn from specimen in a; c, DSTM FLV2, coated with ammonium chloride, scale bar = 5 mm. Photo 2c courtesy of Andrea Tintori. 4 Bollettino della Società Paleontologica Italiana, 50 (1), 2011 length of the neurocranium) and preserved as a thin carbon posteriorly up to the distal termination of the bone. Of the film in DSTM FLV1 (Fig. 2a). lower jaw only the dentary is clearly recognizable. The There is no evidence of the bones of the infraorbital dentaries form most of the ventral border of the mouth. series in the examined specimens. Each dentary is well developed and elongate. The dorsal The gape of the mouth is very large (Fig. 2b). The border of these bones is straight and linear and bears small premaxillae are reduced in size and greatly resemble those teeth of subequal length. of the extant stomiiform genera Cyclothone, Gonostoma The suspensorium is scarcely preserved except for and Vinciguerria (see Weitzman, 1967; Harold, 1998). the hyomandibula, which can be observed in DSTM Each premaxilla has a relatively short ascending process. FLV1 (see Figs 2a-b) and DSTM MAL12, the thick These toothed bones are relatively broad anteriorly and articular facet of the quadrate and what appears to be the taper to a blunt point posteriorly. Posterior to the ascending posterior border of the ectopterygoid (in DSTM FLV4). process, a concave facet representing an articulatory point The hyomandibula possesses a moderately large and flat for the maxilla seems to be present. An indefinite number articular head. The main shaft of this bone is slender and of closely spaced subequal teeth apparently arranged in a vertically oriented and bears small and laminar anteriorly single row can be observed ankylosed along the alveolar projecting process, and a short and stout opercular process. process of this bone. The maxillae form the dorsal and The preopercle is the sole distinguishable bone of postero-dorsal border of the mouth. These bones are the opercular series (Fig. 2b). It is a moderately curved extremely elongate. The anterior condyle is thick with bone that articulates anteriorly with the posterior border rounded profile. For a very short anterior part of its length, of the hyomandibula. The main body of the preopercle is the maxilla articulates with the dorso-medial surface of an enclosed bony sensory canal with an approximately the premaxilla and it is toothless. Towards the beginning vertical axis. A roughly triangular flange emerges centrally of the second eighth of its length, the ventral border of the along the posterior margin of the main axis of this bone. maxilla angles ventralward becoming gently convex up The hyoid apparatus is partially preserved in the to its rounded posterior border. There are about 70 small specimens DSTM FLV1, DSTM FLV2, DSTM FLV3/4 closely spaced teeth of subequal length along the ventral and DSTM MAL11. The hyoid bar is very elongate border of this bone. Only one supramaxilla (corresponding (see Fig. 2b). Due to the inadequate preservation, it is to the posterior one) is present on each side of the upper not possible to properly define the structure and extent jaws. Each supramaxilla is an elongate, thin and slender of its constituent bones. The general shape of the bar is bone. The dorsal border of each supramaxilla is convex approximately rectangular with nearly linear and regularly

Fig. 3 - Paravinciguerria praecursor Arambourg, 1954 from the Cenomanian of north-eastern Sicily. a: DSTM MAL11; b: DSTM MAL12; c: DSTM FLV3; d: DSTM FLV4. Specimens coated with ammonium chloride. Scale bar = 5 mm. Photos courtesy of Andrea Tintori. G. Carnevale, A. Rindone - Paravinciguerria praecursor from the Cenomanian of Sicily 5

Fig. 4 - Paravinciguerria praecursor Arambourg, 1954 from the Cenomanian-Turonian of Jbel Tselfat, Morocco. Paratype, MNHN-F DTS 201G, right lateral view. Scale bar = 20 mm. Photo courtesy of Bouziane Khalloufi.

straight dorsal and ventral borders. It is not possible to Sorbini (1976) documented the presence of estimate the original number of branchiostegal rays. Paravinciguerria praecursor in the Cenomanian-Turonian The posterior elements of the series are not exposed laminated bituminous shale of Cinto Euganeo, north- in the examined specimens. The branchiostegals are eastern Italy, based on four cranial remains; he reaffirmed thin, slender, with a gently sigmoid outline (Fig. 2b). the gonostomatid affinities ofParavinciguerria based on The anterior branchiostegal rays articulate with the the structure of the jaws and general weak ossification of anteriormost portion of the ventral margin of the bar (Fig. the head skeleton. 2b), in a region possibly corresponding to the boundary Taverne (1994) restudied the Moroccan and Italian between the ventral hypohyal and the anterior ceratohyal material assigned to Paravinciguerria praecursor and or to the posterior sector of the ventral hypohyal. concluded that it cannot be considered as a stomiiform, The gill apparatus is partially preserved in DSTM but it should be interpreted as a protacanthopterygian FLV1, represented by a long, elongate and linear possibly belonging to the Salmonoidei. The exclusion ceratobranchial that carries at least six strongly developed of Paravinciguerria from the gonostomatids, and more and robust gill rakers; some of these are characterized by generally from stomiiforms, was justified by Taverne a denticulate dorsal margin (Fig. 2b). (1994) based on the absence of a remarkably enlarged The axial skeleton is exclusively testified by some posterior branchiostegal ray. thoracic quadrangular delicate vertebral centra exposed More recently, Prokofiev (2005) critically rediscussed in the specimens DSTM FLV1 (Figs 2a-b) and DSTM the possible phylogenetic relationships of Paravinciguerria MAL12 (Fig. 3b). and concluded that it should be retained within the Stomiiformes representing a “…form close to a group ancestral to this order…”. THE AFFINITIES OF Therefore, the analysis of the literature concerning PARAVINCIGUERRIA PRAECURSOR Paravinciguerria has revealed a confusing scenario characterized by different contrasting hypotheses of Paravinciguerria praecursor has so far proved to be a phylogenetic relationships. difficult taxon to be placed in a phylogenetic context. The As discussed above, the specimens documented affinities of this Cretaceous teleost have been extensively herein, as well as the material from Moroccan type discussed since its original description provided by localities referred to Paravinciguerria praecursor, Arambourg (1954) in his monograph on the Moroccan are poorly preserved, often represented by impression ichthyofauna from the Jbel Tselfat. Arambourg (1954) only, with negative implications for the observation considered Paravinciguerria as the earliest unquestionable and interpretation of certain structures. In particular, member of the stomiiform family Gonostomatidae. Such the structure and configuration of the caudal skeleton attribution was supported by a set of morphological cannot be unambiguously defined in any of the studied characters, including the structure of the jaw bones, specimens. In his original description, Arambourg (1954) neurocranial reduction, position and orientation of the did not present any character of the caudal skeleton hyobranchial apparatus, lack of postcleithrum, relative of Paravinciguerria, except for the possible presence position of the fins, and general configuration of the axial of an urostylar vertebra. Taverne (1994) considered skeleton. Based on these features, as well as on meristic Paravinciguerria as a member of the protacanthopterygian similarities, Arambourg (1954) emphasized the existence suborder Salmonoidei (thereby excluding the possibility of a possible relationship between Paravinciguerria and of an assignment to the Stomiiformes) mostly based the extant phosichthyid Vinciguerria. on the structure of its caudal skeleton (first preural and Weitzman (1967) proposed that Paravinciguerria first and second ural vertebrae not fused; presence of a may be related to the ancestor of Recent stomiiforms, large uroneural; neural spine of the first preural vertebra apparently excluding any definitive assignment to the reduced in size; neural spines of the ural vertebrae order Stomiiformes pending the availability of additional absent; neural spine of the second preural vertebra only comparative information. slightly shortened) and, subordinately, of the upper jaws 6 Bollettino della Società Paleontologica Italiana, 50 (1), 2011

(premaxilla and maxilla densely toothed; possession of a classically included within the protacanthopterygians. single thin and pointed supramaxilla). Despite the efforts Taverne (1994) did not describe the morphology of the to interpret the morphology of the constitutive elements intermuscular bones of Paravinciguerria. Our cursory of the caudal skeleton, we were unable to unambiguously analysis of the Moroccan material led to the observation recognize any structure of the urophore complex in the of simple, thin and slender epineurals, consistent with available specimens of Paravinciguerria praecursor; those recognizable in the reconstruction by Taverne therefore, our observations are not consistent with those (1994, Fig. 1). The absence of proximally forked of Taverne (1994). Such opinion was also discussed by epineurals might be considered as a valid argument Prokofiev (2005), who pointed out that the caudal skeleton to support the alignment of Paravinciguerria with the of Paravinciguerria is “…always preserved highly protacanthopterygian fishes. However, as also described incompletely…”. Moreover, some of the characters of the by Patterson & Johnson (1995) and Johnson & Patterson caudal skeleton used by Taverne (1994) to demonstrate (1996), the absence of proximally forked intermusculars the protacanthopterygian affinities of Paravinciguerria is also shared by stomiiforms, and certain aulopiforms. (e.g., second ural vertebra not fused to the first one; neural Therefore, the possession of simple not proximally spine of the second preural vertebra shortened) can also be forked epineurals in Paravinciguerria cannot contribute observed in stomiiforms (see, e.g., Fink & Weitzman, 1982). to the unambiguous definition of its potential affinities The inclusion of Paravinciguerria within the with the protacanthopterygian fishes. Considering the salmoniform (=protacanthopterygian) fishes discussed by constituent members of the Protacanthopterygii (in the Taverne (1994) was not supported by the observation of sense of Johnson & Patterson, 1996), the argentinoids specific characters; moreover, he did not recognize any differ from Paravinciguerria for the small terminal apomorphic feature of the main teleost lineages and by mouth, absence of supramaxilla and upper jaw dentition, mutual exclusion concluded that Paravinciguerria should and possession of epipleurals (see Greenwood & Rosen, be considered as a protacanthopterygian fish, possibly 1971; Begle, 1991a; Patterson & Johnson, 1995; Johnson belonging to the Salmonoidei. Our observations, however, & Patterson, 1996). Paravinciguerria cannot be placed have not revealed any of the diagnostic features of the within the alepocephaloid fishes since these fishes are Salmonoidei, and more generally of the salmoniforms characterized by having two supramaxillae, epipleural (=protacanthopterygians). bones, and dorsal fin inserted well back on the body The superorder Protacanthopterygii was created by (Gosline, 1969; Greenwood & Rosen, 1971; Patterson Greenwood et al. (1966) in order to allocate a greatly & Johnson, 1995). Moreover, many alepocephaloids heterogeneous assemblage of fish groups, which included lack maxillary teeth (e.g., Matsui & Rosenblatt, 1987; the salmoniforms, stomiiforms, alepocephaloids, Begle, 1991a) and possess a basipterygoid process of the myctophiforms and, at least questionably, the parasphenoid (see Gosline, 1969; Johnson & Patterson, ostariophysans. Because of the amazing heterogeneity 1996). Based on the definitions of the salmonoids of the constituent members, the Protacanthopterygii was provided by Rosen (1974) and Sanford (1990) (e.g., not satisfactorily defined (see Patterson, 1970). Since arrangement of the prominent basihyal teeth; peg- its original establishment several groups have been and-socket arrangement of the posterior haemal arch progressively removed from the Protacanthopterygii elements of the caudal region), it is possible to exclude (see Rosen & Patterson, 1969; Rosen & Greenwood, the possibility that Paravinciguerria could be related to 1970; Rosen, 1973, 1974). In particular, Rosen (1974) this group, as suggested by Taverne (1994). Regarding the considered the Protacanthopterygii coextensive with the possibility of an osmeroid affinity of Paravinciguerria, Salmoniformes (as did Taverne, 1994), representing a most of the characters used to define this group (e.g., monophyletic assemblage defined by few characters of the Roberts, 1984; Howes & Sanford, 1987; Begle, 1991b; branchial skeleton. Subsequently to the publication of Rosen Johnson & Patterson, 1996) cannot be checked on the (1974) paper, the monophyly of the protacanthopterygian fossils because of their inadequate preservation. The fishes has been discussed by many authors (e.g., Fink & configuration of the upper jaw provides strong support Weitzman, 1982; Rosen, 1982; Lauder & Liem, 1983; for the exclusion of Paravinciguerria from the osmeroid Fink, 1984; Sanford, 1990). More recently, in an extensive superfamily Galaxioidea, in which the maxilla is nearly and extremely detailed morphological study, Johnson & completely edentulous and largely excluded from the gape Patterson (1996) demonstrated the monophyletic status (McDowall, 1969). The skeleton and general outline of of the Protacanthopterygii, constituted by argentinoids, Paravinciguerria are in some ways reminiscent of those alepocephaloids, osmeroids and salmonoids, which is characteristic of osmerid fishes (see, e.g., Weitzman, supported by epicentral cartilages and lack of proximal 1967). Despite this only superficial similarity, however, forking in the intermuscular bones. However, such the head skeleton of Paravinciguerria notably differs hypothesis has not been confirmed by recent molecular from those of osmerid taxa in having an horizontal (rather studies (e.g., Ishiguro et al., 2003; Alfaro et al., 2009; than notched or emarginated) anterodorsal border of the Santini et al., 2009; Li et al., 2010). In summary, opercle (see, e.g., Taverne, 1994; Johnson & Patterson, there is no general consensus about the status of the 1996), and anterior branchiostegal ray articulating on the Protacanthopterygii and the interrelationships between hyoid bar below the anterior margin of the orbit (rather its constituent members, which are now more correctly than at the level of the posterior margin of the orbit; referred to as basal euteleosts. see, e.g., Weitzman, 1967). In conclusion, based on the In order to test the euteleostean relationships of vast array of arguments discussed above it is possible to Paravinciguerria outside the stomiiforms, therefore, it is conclude that Paravinciguerria cannot be confidently necessary to discuss its possible affinities with the groups assigned to any of the clades of euteleosts classically G. Carnevale, A. Rindone - Paravinciguerria praecursor from the Cenomanian of Sicily 7 included in the Protacanthopterygii (or Salmoniformes), As far as the development of the posterior namely the salmonoids, alepocephaloids, argentinoids, branchiostegal rays is concerned, as also described and galaxioids and osmeroids. figured by Taverne (1994), the posterior branchiostegal The stomiiform affinities of Paravinciguerria rays of Paravinciguerria are considerably enlarged with proposed by Arambourg (1954) and subsequently respect to the preceding elements. Extant stomiiforms reiterated by Sorbini (1976) and Prokofiev (2005) usually exhibit an abrupt expansion of the posterior have never been discussed in detail. Both Arambourg branchiostegal(s) (see, e.g., Weitzman, 1974; Fink & (1954) and Sorbini (1976) considered Paravinciguerria Weitzman, 1982), which is usually greater than that praecursor as gonostomatid, based on its general characteristic of Paravinciguerria. However, some similarity with the extant phosichthyid genus Vinciguerria exceptions to this pattern are known in Idiacanthus and (at that time included in the family Gonostomatidae). Photostomias, which possess unmodified and slender On the contrary, Weitzman (1967) and Prokofiev (2005) posterior branchiostegal rays (see McAllister, 1968; tentatively interpreted it as a stomiiform. Unfortunately, Fink & Weitzman, 1982). Taverne (1994) justified the inadequate preservation of the fossils referred to the exclusion of Paravinciguerria from stomiiforms Paravinciguerria makes it really problematic to properly exclusively based on the absence of a notably expanded evaluate its possible stomiiform affinities. However, posterior branchiostegal ray. Considering the considerable some cranial characters, which can also be observed in enlargement of the two posterior branchiostegal rays the Sicilian specimens documented herein, appear to be characteristic of Paravinciguerria, as well as of the strongly indicative of a stomiiform relationship. existence of exceptions within extant stomiiforms, it The first reasonable definition of the stomiiform clade seems to be ambiguous to evaluate the possible assignment was presented by Rosen (1973) who recognized two of this Cretaceous teleost fish to the stomiiforms solely features of the branchial skeleton (modified alignment based on a different degree of relative expansion of the of the second and third pharyngobranchials, specialized posterior branchiostegal ray. double articular surface of the second epibranchial) as The last potentially diagnostic feature - branchiostegals apomorphic of the order. Such a diagnosis was extended articulating with the ventral hypohyals - also represents by Fink & Weitzman (1982) that listed eight derived a problematic issue for the evaluation of the possible characters: (1) photophores with a structure unlike that phylogenetic relationships of Paravinciguerria. This is of other teleosts, (2) type 3 mode of tooth attachment mostly due to the poor preservation of the hyoid bar in (see Fink, 1981), (3) presence of a medial division of the which it is difficult to recognize the limits between the adductor mandibulae muscle which is subdivided into two constituent bones. However, even if it is not possible to sectors, a dorsal one inserting directly onto the maxilla, definitively establish the exact location of the insertion and a ventral one inserting onto the primordial ligament, of the anterior branchiostegal ray(s) along the ventral (4) unique ethmoid-contralateral premaxilla ligament- margin of the hyoid bar, the branchiostegal series of crossing pattern, (5) a single, broad dorsal termination Paravinciguerria originates in the anterior fifth of the bar of the second epibranchial that articulates with both just below the anterior margin of the orbit, similarly to the second and third pharyngobranchials, (6) posterior the condition typical of stomiiforms. The potential value branchiostegal rays conspicuously enlarged, (7) some of the topographical relationship between branchiostegal branchiostegals articulating with the ventral hypohyals, rays and hyoid bar as an indicator of possible phylogenetic and (8) rete mirabilia and associated blood vessels located relationships between Paravinciguerria and stomiiforms at the posterior of the swim bladder. Later, Lauder & Liem seems to be corroborated by the configuration characteristic (1983) identified a peculiar configuration of the retractor of several sternoptychids (Araiophos, Argyripnus, dorsalis muscle as diagnostic of the stomiiforms and, Argyropelecus, Polyipnus, Sonoda, Sternoptyx, Thorophos) more recently, Harold & Weitzman (1996) confirmed and malacosteine stomiids (Aristostomias, Malacosteus, the validity of the diagnostic characters listed by Fink Photostomias) in which there are no branchiostegal & Weitzman (1982), except for the broad termination of rays on the ventral hypohyals (Weitzman, 1974; Fink & the second epibranchial (character #5) that appears to be Weitzman, 1982; Fink, 1985). present also in myctophiforms (see Paxton, 1972). Of all of Therefore, the survey of the stomiiform synapomorphies these characters, only four (unique photophore structure; as defined by Fink & Weitzman (1982) and Harold & type 3 mode of tooth attachment; posterior branchiostegal Weitzman (1996) has not provided an unquestionable ray remarkably enlarged; anterior branchiostegal(s) evidence of the possible stomiiform relationships of articulating on the ventral hypohyal) may be potentially Paravinciguerria. Such relationships were classically recognizable in fossils. (Arambourg, 1954; Sorbini, 1976) supported by the The possible presence of photophores and the mode structure of the upper jaws, which certainly represents of tooth attachment cannot be confidently checked in the most striking evidence relating Paravinciguerria to Paravinciguerria. Squamation pattern and other dermal the stomiiforms. In particular, the very short premaxilla structures are generally poorly preserved in fishes from with a reduced ascending process, the elongate maxilla the Bonarelli-level equivalents in Italy and Morocco (Figs with a rounded and gently curved profile, the small closely 2-4); in particular, in tiny and poorly ossified specimens spaced maxillary teeth of subequal length, and the single (including Paravinciguerria) the dermal cover is usually pointed and elongate (posterior) supramaxilla are identical absent (see Arambourg, 1954; Sorbini, 1976; Khalloufi et to those of certain gonostomatids and phosichthyids (see al., 2010). Moreover, the inadequate preservation of the Weitzman, 1967; Harold, 1998) and, more generally, available material does not allow a proper observation of consistent with those of a large number of stomiiforms the tooth attachment region. (e.g., Weitzman, 1967, 1974). Outside stomiiforms, a 8 Bollettino della Società Paleontologica Italiana, 50 (1), 2011 somewhat similar configuration of the upper jaw can Alfaro M.E., Santini F., Brock C., Alamillo H., Dornburg A., be observed only in certain osmerids (see Weitzman, Rabovsky D.L., Carnevale G. & Harmon L.J. (2009). Nine 1967). It is really difficult to believe that the similarities exceptional radiations plus high turnover explain species diversity in jawed vertebrates. Proceedings of the National existing between the upper jaws of Paravinciguerria Academy of Sciences of the United States of America, 106: and certain extant stomiiforms simply represents the 13410-13414. product of parallel or convergent evolution. The structure Amodio-Morelli L., Bonari G., Colonna V., Dietrich D., Giunta G., of the upper jaws, of the hyoid apparatus, and more Ippolito F., Liguori V., Lorenzoni S., Paglionico A., Perrone V., generally the general physiognomy of the skeleton of Piccaretta G., Russo M., Scandone P., Zanettin Lorenzoni E. Paravinciguerria concur to suggest a stomiiform affinity. & Zappetta A. (1976). L’arco Calabro-Peloritano nell’orogene appenninico-maghrebide. Memorie della Società Geologica That of Paravinciguerria possibly represents the primitive Italiana, 17: 1-60. stomiiform body plan and for this reason we tentatively Arambourg C. (1943). Note préliminaire sur quelques poissons interpret this Cretaceous teleost as a stem stomiiform, fossiles nouveaux. I. Les poissons du Jebel Tselfat (Maroc). thereby representing the earliest member of this lineage. Bulletin de la Société Géologique de France, 13: 281-288. Such a tentative assignment fits well with the current ideas Arambourg C. (1954). Les poissons crétacés du Jebel Tselfat on the phylogeny of teleosts that predict that stomiiforms (Maroc). Notes et Mémoires du Service Géologique du Maroc, should be present at least in the Albian (Forey & Patterson, 118: 1-188. Avanzini M. & Luciani V. (2001). Tselfatia formosa Arambourg, 2006). Up to date, the earliest undoubted members of this 1943 (Pisces, Actinopterygii) del Cretaceo Superiore del order known by articulated skeletal remains are from the Trentino (Italia Settentrionale). Studi Trentini di Scienze Middle Eocene of Georgia where representatives of all Naturali. Acta Geologica, 76: 195-201. the extant families (Gonostomatidae, Phosichthyidae, Begle D.P. (1991a). Monophyly and relationships of the argentinoid Sternoptychidae, Stomiidae) are present (Prokofiev, fishes. Copeia, 1991: 350-366. 2001, 2002a, b, 2005; Carnevale, 2002, 2008; Prokofiev Begle D.P. (1991b). Relationships of the osmeroid fishes and the use of reductive characters in phylogenetic analysis. Systematic & Bannikov, 2002). Zoology, 40: 33-53. As evidenced above, the comparative analysis Bellanca A., Neri R., Scopelliti G. & Sprovieri M. (2000). of selected relevant morphological features of Geochimica e petrografia di black shales del Livello Bonarelli, Paravinciguerria hints at the possible existence of close sezione di (Monti Peloritani), Sicilia nord- phylogenetic affinities between this Cretaceous genus orientale: implicazioni paleoambientali. Mineralogica et (and, therefore, the stomiiforms) and the osmerids. This Petrographica Acta, 43: 123-141. Bizzarini F. & Coccioni R. (1990). I livelli Selli e Bonarelli hypothesis was explored and discussed in great detail by nell’area Umbro-Marchigiana e gli scisti neri coevi nelle Alpi Weitzman (1967, 1974), rejected by subsequent authors Meridionali. In Tintori A., Muscio G. & Bizzarini F. (eds.), (e.g., Johnson & Patterson, 1996) and recently reaffirmed Pesci Fossili Italiani: Scoperte e Riscoperte, New Interlitho, by molecular studies (Alfaro et al., 2009; Santini et al., Trezzano sul Naviglio: 75-80. 2009; Li et al., 2010). Bonarelli G. (1891). Il territorio di Gubbio. Notizie Geologiche. As a final note, the description of Paravinciguerria Tipografia Economica, Roma: 1-38. praecursor documented herein brings the number of fish Campisi B. (1977). Le argille scagliose di Moio e Floresta (Sicilia Nordorientale). Geologica Romana, 16: 113-130. taxa from the upper Cenomanian of north-eastern Sicily to Carnevale G. (2002). A new barbeled dragonfish (Teleostei: 18 (see Rindone, 2008) and further increases the amount Stomiiformes: Stomiidae) from the Miocene of Torricella of taxa shared with the coeval localities of the Bonarelli- Peligna, Italy: Abruzzoichthys erminioi gen. & sp. nov. Eclogae level equivalents of north-eastern Italy (Sorbini, 1976) Geologicae Helvetiae, 95: 471-479. and Morocco (see Khalloufi et al., 2010). Carnevale G. (2008). Miniature deep-sea hatchetfish (Teleostei: Stomiiformes) from the Miocene of Italy. Geological Magazine, 145: 73-84. ACKNOWLEDGEMENTS Dalla Vecchia F.M., Barbera C., Bizzarini F., Bravi S., Delfino M., Giusberti L., Guidotti G., Mietto P., Papazzoni C.A., Roghi The authors thank Walter Landini (Dipartimento di Scienze della G., Signore M. & Simone O. (2005). Il Cretaceo marino. Terra, Università di Pisa) and Christopher P. Kenaley (School of In Bonfiglio L. (ed.), Paleontologia dei Vertebrati in Italia. Aquatic and Fishery Sciences, University of Washington, Seattle) Memorie del Museo Civico di Storia Naturale di Verona, Sez. for their suggestions and critical review of an early draft of the text. Scienze della Terra, 6: 101-112. Laura Bonfiglio (Dipartimento di Scienze della Terra, Università Fink W.L. (1981). Ontogeny and phylogeny of tooth attachment di Messina), Gaël Clement, Monette Véran, Bouziane Khalloufi modes in actinopterygian fishes. Journal of Morphology, 167: (Departement Histoire de la Terre, Muséum National d’Histoire 167-184. Naturelle, Paris), Italo Di Geronimo, Antonietta Rosso and Fink W.L. (1984). Basal euteleosts: relationships. In Moser H.G., Francesco Sciuto (Dipartimento di Scienze Geologiche, Università Richards W.J., Cohen D.M., Fahay M.P., Kendall Jr. A.W. & di Catania) are thanked for permission to examine material under Richardson S.L. (eds.), Ontogeny and Systematics of Fishes. their care. Thanks are also due to Federica Giudice for improvement American Society of Ichthyologists and Herpetologists Special of our English. The manuscript was much improved by the reviews Publication, 1: 202-206. of Bouziane Khalloufi and Francesco Santini (Department of Fink W.L. (1985). 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