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10 (25-10) DALLA VECCHIA 128-135_GEOLOGIA 18/02/11 09.27 Pagina 128

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Ital.J.Geosci. (Boll.Soc.Geol.It.), Vol. 130, No. 1 (2011), pp. 128-135, 5 figs. (DOI: 10.3301/IJG.2011.02)

Ceratodontoid (Dipnoi) calvarial bones from the Triassic of Fusea, Carnic Alps: The first Italian lungfish FABIO M. DALLA VECCHIA (*) & GIORGIO CARNEVALE (**)

ABSTRACT Four calvarial (=skull roof) bones from the Fusea vertebratebearing site (uppermost Ladinian or lowermost Carnian), near Tolmezzo (Udine Province, northeastern Italy) provide the first unambiguous record of lungfish (Dipnoi) in Italy. The preservation of the specimens does not allow a detailed taxonomic interpretation and for this reason they are referred to the lungfish suborder Ceratodontoidei, leaving indeterminate their familial and generic attribution. Dipnoans constitute an additional taxon to be added to the diverse vertebrate assemblage discovered in the Fusea site, formed by nothosauroids, cyamodontoid placodonts, the protorosaurian Tanystropheus, small archosaurians, and elasmobranchian and actinopterygian fishes. These fishes provide evidence of freshwater influence in the sedimentary environment of this important paleontological site occurring at the boundary between two prevailing marine units (the Schlern/Sciliar Dolostone and the Val Degano Formation).

KEY WORDS: Ceratodontoidei, Dipnoi, bone beds, Ladinian/Carnian boundary, Triassic, Carnic Alps, northeastern Italy.

INTRODUCTION

A rich Triassic fossiliferous site characterized by abundant vertebrate remains is located in the southern Carnic Alps, in the vicinity of the village of Fusea, municipality of Tolmezzo (Friuli Venezia Giulia Region; northeastern Italy) (ZUCCHI STOLFA, 1975; PINNA & ZUCCHI STOLFA, 1979; DALLA VECCHIA, 1994, 2000, 2008; RIEPPEL & DALLA VECCHIA, 2001; RIEPPEL & NOSOTTI, 2002) (fig. 1). The site was discovered in the early 1970s by Dr. Mario Cuder during the preparation of its master thesis at the Università di Trieste; however, the site has not been exploited systematically until 1990 when excavations and researches started thanks to the efforts of the senior author and the Museo Friulano di Storia Naturale, Udine (MFSN). The goal of this note is to document four dipnoan bones from the Fusea site, two of which (MFSN 19187; MFSN 19188) collected by the senior author in the early 1990s, one (MFSN 15699) collected by Dr. Mario Cuder in the early 1970s, and one (MFSN 27294) found during the 2001 field work of the MFSN; these specimens represent the only dipnoan remains discovered in this site.

(*) Institut Català de Paleontologia (ICP), Edifici ICP, Campus de la Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain - [email protected]. (**) Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso, 35 - I-10125 Torino, Italia [email protected].

Dipnoans, or lungfishes, constitute a well-defined clade of sarcopterygian fishes known by a moderately rich fossil record dating back to the Devonian. The early diversification of these fishes occurred in shallow marine environments (see CAMPBELL & BARWICK, 1987) and was quickly followed by a rapid ecological and geographical dispersion in all the aquatic environments. The analysis of the fossil record of the dipnoans evidences a dramatic shift from a rapid to a very slow rate of evolutionary change (WESTOLL, 1949; SCHULTZE, 2004). Some dozens of genera occurred in the Devonian, while only three genera are living today (THOMSON, 1969; MILES, 1977; SCHULTZE, 1992). The phylogenetic relationships of lungfish genera have been discussed by several authors (e.g., BERTMAR, 1968; MILES, 1977; SCHULTZE, 1981, 2001, 2004; MARSHALL, 1987; ANTUNES et alii, 1990; CAMPBELL & BARWICK, 1990; SCHULTZE & MARSHALL, 1993; SCHULTZE & CHORN, 1997). The Mesozoic history of these fishes is characterized by peaks of diversity in the Early and Late Triassic (SCHULTZE, 2004). Most Mesozoic and Cenozoic lungfishes are known only by their tooth plates, while skull roofing bones or articulated specimens are rather rare. Post-Paleozoic dipnoans exhibit a broad reduction of calvarial (=skull roof) ossification that together with many other cranial and postcranial features of the skeleton seem to be related to paedomorphosis (e.g., BEMIS, 1984; ARRATIA et alii, 2001). All the extant dipnoans are able to survive long periods in subaerial conditions and the species of the genera Lepidosiren and Protopterus display aestivation capability. Paleoecological consideration suggests that some other Paleozoic, Mesozoic and Cenozoic dipnoans possibly possessed the physiological machinery necessary to aestivate or, at least, to survive in ephemeral freshwater biotopes dry spells in burrows (BERMAN, 1976; CAVIN et alii, 2007).

STRATIGRAPHIC NOTES

The stratigraphic section of the Fusea site was described in detail by DALLA VECCHIA (2000) (fig. 2). The specimens MFSN 19187, MFSN 19188, and MFSN 27294 were collected from the top surface of the layer D, a thin conglomerate lens. MFSN 19187 and MFSN 19188 were found closely associated to each other. The maximum thickness of the conglomerate layer equals about 5 centimeters and the maximum size of the carbonate clasts reaches up to 3 or 4 centimeters even though their size is highly variable and the clasts are sparsely distributed within the level. This conglomerate level origi-


CERATODONTOID (DIPNOI) CALVARIAL BONES FROM THE TRIASSIC OF FUSEA, CARNIC ALPS

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Fig. 1 - Location of the Fusea vertebrate-bearing site.

nated in a high energy environment and the fossil remains – primarily teeth and fragmentary bones – are scattered since were possibly hydraulically transported as clasts. Small fish teeth (main axis < 5 mm) are by far the most common fossils; fragments of variable size of the armor of cyamodontoid placodonts are also present, as well as scattered and usually incomplete bones of nothosauroidean eusauropterygians (e.g., vertebral centra). The specimen MFSN 15699 was collected from the top of the overlying layer E, a coarsely laminated black limestone rich in organic matter with plant remains and thin-shelled bivalves, ostracods and rare benthic foraminifers (Aulotortus cf. planidiscoides, Glomospirella sp., Ophtalmidium sp.). MFSN 15699 was found closely associated to a element of the pelvic girdle of a cyamodontoid placodont; both bones are affected by a long exposure to recent weathering. Layer E is the richest in vertebrate macroremains, which in this case consist of several scattered bones and teeth of the nothosaurid eusauropterygian Nothosaurus, remains of a cyamodontoid placodont, and a cervical vertebra of the protorosaurian Tanystropheus (DALLA VECCHIA, 2000). The fossiliferous section is placed at the passage between the top of the Schlern/Sciliar Dolostone (fig. 3), representing an 800 meters thick carbonate platform sequence, and the Val Degano Formation, a sequence of black limestone up to 800 meters thick, deposited in a marine basin relatively deep in its depocentral area located between Trava and Buttea (VENTURINI, 2006, 2009). The base of the Val Degano Formation is characterized by the presence of coal levels and carbonate conglomerate and breccia lenses (lithofacies Dega of VENTURINI, 2009, p. 116). According to the definition of the Val Degano Formation provided by VENTURINI (2009), the vertebrate-bearing section represents the base of Val Degano Formation (see also the geological map in VENTURINI, 2009). The Val Degano Formation was once considered as ‘middle’ Carnian in age [Val Degano Formation = ‘black

Fig. 2 - The stratigraphic section of the Fusea vertebrate-bearing site. A-G = stratigraphic layers. Lithology: 1) black limestone; 2) coquina with coarse calcarenite matrix and coal fragments at the top; 3) conglomerate with carbonate clasts; 4) whitish dolomitic limestone with intraformational breccia lenses. Scale bar = 10 cm.

limestone’ and ‘well-bedded black limestone’, T4c, and T4c–T4t of PISA in BRAGA et alii (1971) and FRASCARI in BRAGA et alii (1971), respectively] because of the presence of the bivalve Myophoria kefersteini and the alga Clypeina besici, at that time considered as indicative of the ‘middle’ Carnian. The thick carbonate platform sequence of the Schlern/Sciliar Dolostone was interpreted to as late Ladinian-‘middle’ Carnian in age (PISA in BRAGA et alii, 1971). Based on a detailed comparison


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stone 2 of late Julian estimated age (i.e, late early Carnian in the bipartite subdivision of this stage in Julian and Tuvalian). However, recent studies in the Dogna Valley (Julian Alps), approximately 25 kilometers north of Fusea, revealed that the top of the thick carbonate platform that preceded the carbonate platform of the Dolomia Principale is latest Ladinian in age (JADOUL & NICORA, 2000; JADOUL et alii, 2002). The top of that platform shows pockets of bauxite-laterites that testify the emersion of the platform under a humid climate (see MUTTI & WEISSERT, 1995). Above, 29 meters of well-bedded dolostone [‘Dolomia di Rio Terra Rossa’; JADOUL et alii (2002)] are found; a monospecific conodont fauna with Pseudofornishius murcianus murcianus has been reported in the middle part of that dolostone (JADOUL & NICORA, 2000; JADOUL et alii, 2002), which is indicative of a latest Ladinian-earliest Carnian age (NICORA, 1981; KOZUR, 1993; BROGLIO LORIGA et alii, 1999). The ‘Dolomia del Rio di Terra Rossa’ is in turn covered by the early Carnian Rio del Lago Formation, which contains Myophoria kefersteini and ammonoids indicative of the Aonoides Ammonoid Subzone in its lower part (PRETO et alii, 2005). Unfortunately, the vertebrate-bearing section of Fusea only provides few useful fossils for biostratigraphic purposes. The sauropterygians Nothosaurus giganteus and Cyamodus, both possibly present in the site, are characterized by a Middle Triassic range and have not been reported from the Carnian (RIEPPEL, 2000). Tanystropheus is common in the Middle Triassic and very rare in the Upper Triassic (DALLA VECCHIA, 2006). The foraminifer Trocholina cf. cordevolica, indicative of a late LadinianCarnian age (SANDRO VENTURINI, pers. comm.) was found in the basal layer A that is the uppermost bed of the Schlern/Sciliar Dolostone (fig. 2). Sampling for palynomorphs in the overlying black limestones of the basal part of the Val Degano Formation gave no results (GUIDO ROGHI, pers. comm.). However, the base of this formation near Muina (about 10 km NW of Fusea) has recently yielded the conodont Pseudofornishius murcianus murcianus (see VENTURINI, 2009). In summary, several physical stratigraphic and paleontological evidences concur to indicate a latest Ladinian or earliest Carnian age for the vertebrate-bearing section of Fusea.

METHODS Fig. 3 - The Ladinian-Carnian lithostratigraphy in the Fusea (southern Carnic Alps) and Dogna (Julian Alps) areas. The asterisk indicates the position of the Fusea site.

with the stratigraphic architecture of the Dolomites (see DE ZANCHE et alii, 1993), DALLA VECCHIA (2000) suggested that the stratigraphic position of the Fusea vertebrate-bearing section might be placed in the middle part of the Carnian (uppermost Julian). Such hypothesis was justified by the stratigraphic position of the carbonate platform just underlying the Fusea section, which is the last thick carbonate platform preceding the latest Tuvalian-Rhaetian carbonate platform of the Dolomia Principale; in the Dolomites, the last carbonate platform preceding the Dolomia Principale is the Cassian Dolo-

Dipnoans show a unique pattern of calvarial bones. The homology of these bony elements within the order Dipnoi is still unresolved, as well as the comparison with those of other bony fishes. For this reason, several systems, primarily based on topographical position and lateral-line grooves patterns, have been developed using letters and numbers in order to interpret the identity of the skull roofing ossifications (e.g., FORSTER-COOPER, 1937; WHITE, 1965; THOMSON & CAMPBELL, 1971; MARTIN, 1981; SCHULTZE, 1981; BEMIS, 1987; ANTUNES et alii, 1990; KEMP, 1998). CAVIN et alii (2007) proposed a nomenclature that refers to topographic locations only. Such a method, which is tentatively used herein, is really useful for comparing the simplified skull roof patterns typical of post-Paleozoic dipnoans.



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Fig. 4 - Ceratodontoidei indet., Triassic, Fusea, northeastern Italy: A) MFSN 15699, dorsal view; B) MFSN 19187, dorsal view; C) MFSN 19187, internal view; D) MFSN 27294; E) MFSN 19188, dorsal view; F) MFSN 19188, internal view. Scale bars = 10 mm.

SYSTEMATICS Infraclass DIPNOIFORMES CLOUTIER & AHLBERG, 1995 Order DIPNOI MÜLLER, 1845 Suborder CERATODONTOIDEI NIKOLSKI, 1954 Ceratodontoidei indet. (fig. 4)

Description MFSN 15699 – The dorsal side of this element is exposed (fig. 4A); it is moderately preserved, with a partial erosion of its surface, which appears ornamented by radial striations that produced a fringed texture all along the margins. This flat element is roughly ovoid in outline, with a width approximately equal throughout its length. Its length measures 53 mm, whereas it maximum width equals about 34 mm. There is no evidence of sensory line grooves. The inadequate preservation of this element makes it impossible to properly interpret its anatomical identity. MFSN 19187 – This thick element is partially complete, lacking the anteromedial corner (figs 4B-C). The margins of this bone are irregularly eroded, making it as subelliptical in outline (maximum length 46 mm; maximum width 35 mm) and widest across its anterior half. The dorsal side (fig. 4B) is nearly smooth, while the ventral one (fig. 4C) has a scaber texture, devoid of any kind of ventral process. However, despite its incompleteness the general outline seems to be indicative of a bilateral symmetry, thereby suggesting that this specimen represents a medial element of the skull roof. A shallow and irregular groove appears to be partially preserved on the anterolateral sector of this element; a short and straight linear groove can be observed in the posteromedial sector of the bone; however, the sensorial nature of this groove cannot be definitely established. The general morphology of the element, its symmetric appearance, and absence of

vertical processes along its internal surface concur to suggest that it may be interpreted as a bone of the medial series. MFSN 19188 – This element appears to be nearly complete (figs 4E-F). It has a roughly pentagonal shape (maximum length 38 mm; minimum width 37 mm) with posterocentral corner distinctly angular and anterior margin nearly straight. The internal side (fig. 4F) of the bone is flat while the dorsal one (fig. 4E) is markedly concave in its posterior third; such a concavity may be interpreted as a deep groove that extends transversely across the width of the bone. The overall morphology of this bone suggests that it possibly represents a left posterior mediolateral element. MFSN 27294 – Only the dorsal side of the element is exposed (fig. 4D); it is largely incomplete and moderately preserved (maximum length 41 mm; maximum width 26 mm). The bone is ornamented by radial striations while sensory line grooves appear to be absent. Because of its incompleteness, the description of its original morphology is not possible, as well as the interpretation of its original position on the skull. Remarks The structure and morphology of the calvarial bones are really important in dipnoan classification (SCHULTZE & MARSHALL, 1993). Characters related to the general aspects (sensory line patterns, ornamentation, attenuation or emargination, fusion patterns, etc.) of these bony elements are often chosen for generic diagnoses of postPaleozoic dipnoans (KEMP, 1998; CAVIN et alii, 2007). The inadequate preservation of the specimens documented herein unfortunately does not allow a careful comparative analysis with calvarial bones of other Mesozoic lungfishes. For this reason, it is not possible to unquestionably define the anatomical identity of each


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bony element, as well as their taxonomic assignment at the generic level. The general outline and texture of the skull bones exhibit a certain degree of similarity with those of the ceratodontoid families Arganodontidae and Ceratodontidae, particularly the genera Arganodus and Ptychoceratodus (see, e.g., MARTIN, 1981; SCHULTZE, 1981, 2004; KEMP, 1998; CAVIN et alii, 2007), even though much more comparative information would be necessary to conclusively demonstrate their affinities to one of these taxa. The general structure of the bones may indicate that all these belong to a single taxon. Moreover, the specimen MFSN 19187 and MFSN 19188 apparently belong to the same individual as suggested by their close association on the same stratigraphic layer, where these were found mutually associated in a very restricted surface. Therefore, we tentatively refer these specimens to the lungfish suborder Ceratodontoidei as defined by SCHULTZE (2004), leaving indeterminate their familial and generic attribution until better preserved specimens will be available.

PALEOENVIRONMENTAL IMPLICATIONS

Triassic dipnoans are known from several localities of Europe (e.g., VOROBYEVA & MINIKH, 1968; SCHULTZE, 1981), Africa (MARTIN, 1979, 1981; ANTUNES et alii, 1990; KEMP, 1996), Madagascar (LEHMAN et alii, 1959; BELTAN, 1968; MARTIN et alii, 1999), Arabian Peninsula (KEAR et alii, 2010), Australia (KEMP, 1994, 1997, 1998), India (JAIN, 1968; MARTIN et alii, 1999), Antarctica (DZIEWA, 1980; YOUNG, 1991), North America (CASE, 1921), South America (RICHTER & TOLEDO, 2008), and eastern Asia (MARTIN & INGARAVAT, 1982). As far as concerns the Late Triassic European record, several species of the genera Ceratodus and Ptychoceratodus have been documented in deposits of Austria (TELLER, 1891; LEHMAN, 1976), France (MARTIN et alii, 1981), Germany (AGASSIZ, 1838; PLIENINGER, 1844; VOLLRATH, 1923; SCHMIDT, 1928; LINCK, 1936; 1962; MARTIN, 1980; SCHULTZE, 1981), Great Britain (AGASSIZ, 1838) and Switzerland (AGASSIZ, 1838), whereas coeval species of the genus Arganodus have been reported from Morocco (MARTIN, 1979, 1981, 1984), and a single species of Ptychoceratodus was described from the Late Triassic Cenger Formation, Turkey (MONOD et alii, 1983). To the best of our knowledge, a single specimen from Italy has been referred to the Dipnoi (D’ERASMO, 1922; SIRNA et alii, 1994; BONFIGLIO, 2005). BIZZARINI & ROTTONARA (1997, p. 312, pl. 1, fig. 4) assigned to Ceratodus a fragmentary bone from the Santa Croce/Heiligkreuz Formation (lower to upper Carnian boundary) near Santa Croce/Heiligkreuz (Val Badia, Bolzano/Bozen, Alto Adige/Süd Tirol, northeastern Italy). The specimen is figured but not described, lacking any indication of the inventory number and repository institution. According to the authors, such a thick specimen «is composed of two cranial bones and their suture». The degree of fusion of calvarial ossifications in dipnoans is usually greatly reduced with respect to the complete fusion exhibited by the specimen (see, e.g., K EMP, 1998). The Santa Croce/Heiligkreuz Formation also yielded armor fragments of cyamodontoid placodonts (SIRNA et alii, 1994), which are characterized by an overall structure similar to that observed in the presumed dipnoan specimen, and metoposaurid tem-

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nospondyls as well. Therefore, it is our opinion that the specimen from Santa Croce/Heiligkreuz cannot be considered as an unquestionable evidence of the presence of dipnoans, thereby implying that the material from Fusea documented herein represent the first unambiguous lungfish remains reported in Italy. In the Fusea site, vertebrate remains occur, in order of decreasing frequency, mainly in the layers E, F and D, whereas they are very rare in layers A and C (DALLA VECCHIA, 2008). Layers E, F and possibly also D can be considered as multitaxic bone beds according to the definition by BEHRENSMEYER (2007). Relatively common in layers E, F, and D are the armour remains of a cyamodontoid placodont (fig. 5B), with rare vertebrae and girdle bones (DALLA VECCHIA, 1994, 2008; RIEPPEL & DALLA VECCHIA, 2001); moreover, a skull (fig. 5A) formerly described by ZUCCHI STOLFA (1975) and subsequently referred to Cyamodus by RIEPPEL & NOSOTTI (2002), was collected at the top of layer E. Abundant disarticulated elements of Nothosaurus (fig. 5C, E), some of which attributed to N. cf. giganteus because of their large size (suggesting the presence of individuals up to four metres long) and vertebral features (figs. 5C-G), were collected in the layers E and F (RIEPPEL & DALLA VECCHIA, 2001). A cervical vertebra of the peculiar prolacertiform Tanystropheus (fig. 5H) was also collected at the top of layer E (DALLA VECCHIA, 2000). Archosaurs are represented by a few, but morphologically diversified, small isolated teeth (figs. 5I-J) from layers E and F, and cynodont synapsids are possibly testified by a single tooth (fig. 5K) from layer F or top E (DALLA VECCHIA, 2008). Isolated and scattered teeth of the durophagous elasmobranchian Paleobates angustissimus (figs. 5L-M) are common in layers D-F, as also those rounded and molariform of durophagous or semidurophagous actinopterygian fishes (?Sphaerodus, figs. 5N-O; DALLA VECCHIA, 2008); instead, conical teeth of predatory actinopterygian fishes (fig. 5P) are less frequent. In their paleoecological analysis of post-Paleozoic lungfishes, CAVIN et alii (2007) evidenced that both Mesozoic and Cenozoic dipnoans were probably characterized by an exclusively freshwater mode of life and that rare occurrences from rocks of marine origin should be considered as products of reworking (see also MARTIN, 1984). The freshwater adaptation of the Triassic lungfishes therefore provides new paleoenvironmental information about the latest Ladinian or earliest Carnian Fusea site. VENTURINI (2009, p. 120) considers the basal conglomerates of the Val Degano Formation as fluvio-deltaic deposits; furthermore, a coal level occurs at the base of the Val Degano Formation (a stratigraphic equivalent of the vertebrate-bearing section) along the Luchiat creek, only one hundred meters north of the Fusea fossil site. The top of the layer F also contains small coal fragments, while plants remains are common in the upper part of layer E. However, the presence of benthic foraminifers in the layers A and E suggests a marine influence; moreover, placodonts, nothosaurids, and Tanystropheus are usually considered as shallow sea dwellers (RIEPPEL, 2000; NOSOTTI, 2007), and the elasmobranch Paleobates angustissimus occurs in unquestionably marine facies of the Rio del Lago Formation near Dogna, although represented by notably larger specimens (DALLA VECCHIA, 2008). Therefore, it seems to be reasonable to indicate that the vertebrate-



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Fig. 5 - The vertebrate assemblage, Triassic, Fusea, northeastern Italy: A) MFSN 26830, skull of the placodont Cyamodus sp., top layer E; B) MFSN 15700, armour of a cyamodontoid placodont, layer E; C) MFSN 19183, tooth crown of the nothosaurid Nothosaurus sp., layer E; D) MFSN 19866, partial skull of the nothosaurid Nothosaurus cf. N. giganteus, layer E; E) MFSN 19288, partial skull of the nothosaurid Nothosaurus sp., top layer E; F) MFSN 16849, cervical vertebrae of the nothosaurid Nothosaurus cf. N. giganteus, top layer E; G) MFSN 16851, dorsal vertebra of the nothosaurid Nothosaurus cf. N. giganteus, top layer E; H) MFSN 25760, cervical vertebra of the protorosaur Tanystropheus sp., top layer E; I) MFSN 31609, tooth crown of an indeterminate archosaur diapsid, layer F; J) MFSN (uncatalogued), tooth crown of an indeterminate archosaur diapsid, layer F; K) MFSN (uncatalogued), possible tooth crown of an indeterminate cynodont synapsid, layer F; L) MFSN (uncatalogued), tooth of the chondrichthyan fish Paleobates angustissimus, layer F; M) MFSN (uncatalogued), tooth of the chondrichthyan fish Paleobates angustissimus, layer F; N) MFSN (uncatalogued), tooth of an osteichthyan fish (?Sphaerodus), layer F; O) MFSN (uncatalogued), tooth of an osteichthyan fish (?Sphaerodus), layer F; P) MFSN (uncatalogued), tooth of an osteichthyan predatory fish, layer F. Scale bars = 50 mm for A, B, D, E, and H; 10 mm for C, F, G, and I; 1 mm for J to P.

bearing section of Fusea originated in a transitional depositional environment (e.g., a lagoon or a coastal marsh) subject to freshwater influence and oscillating salinity. This accounts for the presence of terrestrial (plants, archosaurs), freshwater (dipnoans) and shallow marine organisms. The section represents the initial stage of a marine transgression over the emergent and locally karstified Schlern/Sciliar carbonate platform (see VENTURINI, 2006).

CONCLUSION

The four calvarial bones from the Fusea site documented herein provide the first unambiguous evidence of fossil dipnoans in Italy. These specimens increase the diversity of a relevant faunal assemblage that has been only object of a preliminary analysis (see RIEPPEL, 2000), and often neglected in the regional geological synopses of the area (see for example VENTURINI, 2006, 2009). The


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study of the bony remains deposited at the Museo Friulano di Storia Naturale, Udine, will make this site as a reference point for the knowledge of the paralic or coastal vertebrates at the Ladinian/Carnian boundary. ACKNOWLEDGEMENTS We thank Dr. Sandro Venturini for the information about the microfossils preserved in the thin sections obtained from the samples collected in the site, and Dr. Guido Roghi for the information about the palynological investigation of the section. We are grateful to Dr. Giuseppe Muscio, Director of the Museo Friulano di Storia Naturale, Udine, for allowing the study of the material under his care. Many thanks go to Prof. Hans-Peter Schultze, who discussed affinities of our specimens, to Prof. Walter Landini for useful suggestions, and to Federica Giudice for improvement of the English. Thanks are also due to Drs. Gaël Clement and Lionel Cavin for constructive advice on improving the manuscript.

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Manuscript received 20 September 2010; accepted 14 January 2011; editorial responsability and handling by E. Erba.