Bollettino della Società Paleontologica Italiana, 49 (3), 2010, 237-253. Modena, 15 dicembre 2010237

Silurian and lowermost Devonian conodonts from the Passo Volaia area (Carnic Alps, Italy)

Carlo Corradini & Maria G. Corriga

Carlo Corradini, Dipartimento di Scienze della Terra, Università di Cagliari, via Trentino 51, I-09127 Cagliari; [email protected] Maria G. Corriga, Dipartimento di Scienze della Terra, Università di Cagliari, via Trentino 51, I-09127 Cagliari; [email protected]

KEY WORDS - Silurian/Devonian boundary, Conodonts, Biostratigraphy, Taxonomy, Carnic Alps.

ABSTRACT - Two sections (Rifugio Lambertenghi Fontana - RLF - and Rifugio Lambertenghi Fontana III - RLF III) of the Orthoceras limestones that crop out just South of Passo Volaia in the Carnic Alps yielded a rich and diverse conodont fauna. Twenty-six taxa belonging to eleven genera (Belodella, Coryssognathus, Dapsilodus, Dvorakia, Icriodus, Oulodus, Ozarkodina, Panderodus, Pseudooneotodus, Wurmiella and Zieglerodina) were discriminated. Wurmiella alternata n. sp. is described, and Belodella coarctata, Dvorakia amsdeni and Zieglerodina zellmeri are reported for the first time from the Carnic Alps. The fauna allows recognition of five late Silurian-earliest Lochkovian conodont zones (snajdri, crispa, eosteinhornensis s.l., detortus and woschmidti). The Silurian/Devonian boundary is interpreted to occur in the upper part of the RLF III section.

RIASSUNTO - [Conodonti del Siluriano e Devoniano basale nell’area di Passo Volaia (Alpi Carniche, Italia)] - Nelle Alpi Carniche affiora una delle più complete sequenze paleozoiche pre-erciniche d’Italia, costituita da successioni sedimentarie debolmente metamorfiche di età compresa tra l’Ordoviciano Sup. e il Carbonifero. Le rocce del Siluriano e del Devoniano basale affiorano in modo discontinuo e, soprattutto nel versante italiano, gli affioramenti non sono molto estesi. Immediatamente a sud del Passo Volaia, situato nella parte occidentale delle Alpi Carniche, affiorano una quarantina di metri di calcari a Orthoceras depositatesi in un mare poco profondo. L’associazione faunistica è dominata da crinoidi, brachiopodi, cefalopodi, con associati più rari bivalvi e trilobiti. Qui sono state misurate e campionate due sezioni a conodonti, denominate rispettivamente “Rifugio Lambertenghi Fontana (RLF)” e “Rifugio Lambertenghi Fontana III (RLF III)”. La ricca fauna a conodonti raccolta (circa quattromila elementi) comprende ventisei taxa appartenenti a undici generi (Belodella, Coryssognathus, Dapsilodus, Dvorakia, Icriodus, Oulodus, Ozarkodina, Panderodus, Pseudooneotodus, Wurmiella e Zieglerodina), che hanno consentito di riconoscere le ultime quattro biozone del Siluriano (snajdri, crispa, eosteinhornensis s.l. e detortus) e la prima del Devoniano (woschmidti). Il limite Siluriano/Devoniano è localizzato nella parte alta della sezione RLF III. Tre specie (Belodella coarctata Barrick & Klapper, Dvorakia amsdeni Barrick & Klapper e Zieglerodina zellmeri Carls et al.) sono segnalate per la prima volta nelle Alpi Carniche; inoltre, viene descritta la nuova specie Wurmiella alternata n. sp.

INTRODUCTION of Passo Volaia (Fig. 1). Here about thirty meters of Orthoceras limestones of Pridoli and earliest Lochkovian In the Carnic Alps, one of the most complete Palaeozoic age are exposed, which are characterized by extremely sedimentary successions in Europe is exposed at the shallow-water sediments across the Silurian Devonian Italian-Austrian border. Deposition was almost continuous boundary. from the Late Ordovician into the Permian. Silurian and lowermost Devonian sediments are irregularly distributed within the Carnic Alps, from the Monte Cocco area at the THE SILURIAN AND LOWER DEVONIAN east, to Lake Wolayer at the west. In general, outcrops are IN THE CARNIC ALPS quite small, mainly on the Italian side, with the exception of the Mt. Cocco and La Valute areas. Silurian and Lower Devonian deposits are irregularly The sections presented in this paper are located just distributed within the Carnic Alps, and range from south of Lake Wolayer. The area is well known for the shallow water bioclastic limestones to nautiloid-bearing numerous outcrops of Upper Ordovician to Devonian limestones, interbedded shales and limestones to black sediments, which formed mainly in shallow water graptolitic shales and cherts. The overall thickness does environments. Several other sections across the Silurian/ not exceed 60 m. The Silurian transgression started at the Devonian boundary in the area have been studied: base of the Llandovery, and, owing to the disconformity Rauchkofel Boden (Ferretti et al., 1999, and references separating the Ordovician and the Silurian, a varying of therein), Costone Lambertenghi/Seekopf Sockel (Vai, sediments is locally missing, which corresponds to several 1963; Schönlaub, 1980), Valentin Torl (Vai, 1963; Histon conodont zones of Llandovery to Ludlow age (Histon & et al., 1999, and references therein), Seewarte (Suttner, Schönlaub, 1999). 2007). The famous Cellon section (Walliser, 1964), which The Silurian and lowermost Devonian of the Carnic can be considered the reference section for the Silurian, Alps is subdivided into four lithofacies associations is located only a few kilometers to the east. representing different depths of deposition and This paper reports on the conodont fauna from two hydrodynamic conditions (Wenzel, 1997). The Wolayer- new sections, Rifugio Lambertenghi Fontana and Rifugio facies is characterised by proximal shelf sediments and the Lambertenghi Fontana III, which crop out just south Bischofalm-facies by deep water deposits; the Plöcken-

ISSN 0375-7633 238 Bollettino della Società Paleontologica Italiana, 49 (3), 2010

Fig. 1 - Location map of the studied area (asterisk) within the Carnic Alps.

facies and the Findenig-facies represent intermediate facies associations. The pattern of depositional lithofacies suggests an overall transgressive regime from the Llandovery through the Ludlow. Uniform limestone sedimentation during the Pridoli indicates that more stable conditions were developed at that time (Schönlaub, 1997). For a more detailed description of the Silurian of the Carnic Alps refer to Histon & Schönlaub (1999) and Schönlaub & Histon (2000). Fig. 2 - Aereal view (Immagine TerraItaly™ - © Blom CGR) of the Passo Volaia area with location of the studied sections. GEOLOGICAL SETTING STUDIED SECTIONS The region around Passo Volaia is one of the better studied area of the Carnic Alps because of the variety of Two sections were measured and sampled for facies represented in Upper Ordovician to Upper Devonian conodonts a few tens of meters south of Passo Volaia and strata, which were deposited either in relatively shallow the state boundary (Fig. 2). They have been designated or deep water environments, for the quality of the outcrop the Rifugio Lambertenghi Fontana (RLF) and Rifugio exposures, and the abundant fossils. Lambertenghi Fontana III (RLF III) sections, respectively. The Silurian and lowermost Devonian sequence Although the two sections are very close each other, in is represented here by shallow water sediments of the the field it is difficult to correlate them precisely because “Wolayer facies” (Wenzel, 1997). The sequence starts of the topography of the area, the dip of the strata and with about 15 m of middle Wenlock to Ludlow highly effects of trench construction from the First World War. fossiliferous neritic Orthoceras limestones (neritic Based on field correlations, they do not overlap for a few equivalent of the Kok Formation; Schönlaub, 1997), which tens of centimetres, with top of the RLF section slightly disconformably overlie the Upper Ordovician crinoidal older than the bas of the RLF III section. Conodont data Wolayer Limestone. Nautiloid cephalopods, bivalves, confirm this correlation. brachiopods and trilobites are abundant; in some levels microstromatolites are evident in the lower part of the unit (Histon & Schönlaub, 1999), as well as ooidal ironstones (Ferretti, 2005). The overlying Cardiola Formation (Ludlow) is represented by a very thin level of dark limestone rich in cephalopods and bivalves. The overlying sequence comprises up to 30 m of fine grey micritic limestone (Alticola limestone Auct. + Megaerella limestone Auct.) with abundant bioclasts and nautiloids and a fossiliferous content similar to the neritic Kok Formation (Histon & Schönlaub, 1999). In the Rauchkofel Boden section (Schönlaub, 1970; Ferretti et al., 1999 and references herein) the base of the Devonian is marked by a Scyphocrinites bed at the top of the unit. The lowermost Devonian is represented by more of 100 m of very shallow water sediments of the “neritic Fig. 3 - Panoramic view of the Rifugio Lambertenghi Fontana Rauchkofel Formation Auct.” (grey crinoidal limestone, Section, with location of samples. Samples from 7 to 10 have been rich of bioclasts) or deeper water well bedded dark grey collected in a World War I cave, where beds are well exposed and limestones of the “Pelagic Rauchkofel Formation”. precisely correlated with beds outside. C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps 239

The Rifugio Lambertenghi Fontana (RLF) section coordinates N 46°26’22.6” E 12°52’07.8”, more or less The Rifugio Lambertenghi Fontana section is located where a fountain is placed (Figs. 2-3). About 18 m of on along the path to Rifugio Lambertenghi Romanin, at Orthoceras limestone are here exposed (Fig. 4).

Fig. 4 - Stratigraphic log of the Rifugio Lambertenghi Fontana section, with occurrence of main conodont taxa and conodont abundance. 240 Bollettino della Società Paleontologica Italiana, 49 (3), 2010

The section starts with about three meters of highly fossiliferous reddish limestones, where fossil remains are mainly represented by crinoids, brachiopods, cephalopods and bivalves, often fragmented and packed together at the centimeter scale. A covered interval corresponding to a World War I trench is present in the lower part of the section. The central part of the section comprises grey micritic limestone rich in orthoceratid nautiloids; concentrations of small crinoidal debris are observable in some levels, as well as a few brachiopod casts. The fossiliferous content strongly decreases above sample RLF 6 and only a few poorly preserved cephalopods occur in the upper part of the section, where the colour of the rock frequently grades to red due to weathering. A mineralized horizon, bearing hematite and limonite, occurs just above sample RLF 9. Sixteen conodont samples were collected from the Rifugio Lambertenghi Fontana section.

The Rifugio Lambertenghi Fontana III (RLF III) section The Rifugio Lambertenghi Fontana III section is located along the path from Rifugio Lambertenghi Romanin to Mt. Capolago, at coordinates N 46°26’22.7”, E 12°52’05.4” (Figs. 2, 5). More than 15 meters of Fig 5 - a: Panoramic view of the Rifugio Lambertenghi Fontana III limestone crop out in a World War I trench, immediately Section, with approximate location of selected samples; b: detailed west of the path. The section is subdivided into two parts, view across the Silurian/Devonian Boundary. 5 and 10.5 m thick respectively, separated by a covered interval about 10 m thick (Figs. 5a, 6). The lower part of the section, up to sample RLF III 3A, It suddenly decreases to values of around 25, with a last is represented by grey micritic limestone, with a sparse peak of 73 elements/kg in sample RLF III 1N. Above this crinoid remnants and scattered rare brachiopods. level, abundance is very low with only a few elements/ The upper part is much more fossiliferous, and the kg up to the top of the section; samples RLF III 1R and fossil content increases toward the top of the section. RLF III 0 were barren. However, the state of preservation of the fauna is poor. Twenty-six taxa belonging to eleven genera (Belodel- Crinoids are always abundant and brachiopods often la, Coryssognathus, Dapsilodus, Dvorakia, Icriodus, present, in places concentrated in centimeter-thick shelly Oulodus, Ozarkodina, Panderodus, Pseudooneotodus, levels. The fauna includes bivalves, nautiloid cephalopods, Wurmiella and Zieglerodina) were identified. Among them rare trilobites and solitary corals. In the uppermost part Belodella coarctata Barrick & Klapper, Dvorakia amsdeni of the section, above sample RLF III 2, bedding planes Barrick & Klapper and Zieglerodina zellmeri Carls et al. are difficult to observe, due to heavy weathering and are reported for the first time from the Carnic Alps, and fracturing of the rocks. Wurmiella alternata n. sp. is described. Twenty-eight conodont samples were collected from Elements of ozarkodinids are abundant throughout the the Rifugio Lambertenghi Fontana III section, with greater sections, representing about two-thirds of the whole fauna. detail in the upper part of the section, across the S/D Coniforms (mainly Dapsilodus and Panderodus) and boundary (Fig. 5b-6). Belodella are constantly present and especially abundant in some samples of the snajdri Zone (i.e. RLF 3, RLF 5).

CONODONT DATA BIOSTRATIGRAPHY A total of forty-four samples from the two sections were processed with conventional formic acid technique. The biozonation schemes followed in this paper More than ninety kilograms of limestone yielded are those proposed by Corradini & Serpagli (1999) and about 3900 conodont elements (Tabs. 1-2). The state updated by Corriga & Corradini (2009) for the Silurian, of preservation is generally quite good, even if a few and by Carls & Weddige (1996) for the Lower Devonian. elements are broken. Conodont colour is dark brown, The conodont faunas allow recognition of five conodont corresponding to a Colour Alteration Index (CAI) of 4. zones in the Rifugio Lambertenghi Fontana and Rifugio The abundance is variable, from almost 200 elements/ Lambertenghi Fontana III sections: snajdri, crispa, kg to barren samples. In the lower part of the RLF section eosteinhornensis s.l. and detortus zones in the Silurian (snajdri and crispa zones), the average is around 30 and the woschmidti Zone in the Devonian. elements/kg and rises in the upper part up to 192 elements/ kg in sample RLF 9 (Fig. 4). Frequencies are high also The snajdri Interval Zone in the lower part of the RLF III section (Fig. 6), up to According to Corradini & Serpagli (1999), the lower sample RLF III 2B, with an average of 60 elements/kg. and upper boundary of this interval are defined by the C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps 241

LO (Last Occurrence) of Pe. latialata and the FO (First dominant in sample RLF 1, whereas Belodella is very Occurrence) of Oz. crispa, respectively. Therefore, it is abundant in sample RLF 3: similar abundances of these possible to attribute the lower part of the RLF section to taxa in the snajdri Zone occur also in Cellon and Monte the snajdri interval Zone. Dapsilodus obliquicostatus is Cocco II sections (Corriga & Corradini, 2009).

Fig. 6 - Stratigraphic log of the Rifugio Lambertenghi Fontana III section, with occurrence of main conodont taxa and conodont abundance. 242 Bollettino della Società Paleontologica Italiana, 49 (3), 2010

RLF 1 2 3 4 5 6 6A 6B 7 7A 8 8A 9 10 11 12 total S0 5 2 1 1 9 S1 2 2 Belodella anomalis S2 1 1 S3 1 1 2 T 1 1 S0 2 4 1 7 Belodella coarctata T 1 1 S1 1 1 22 23 2 1 2 2 54 Belodella resima S2 1 1 3 5 T 1 3 4 Dapsilodus obliquicostatus 52 2 8 5 7 10 1 2 4 1 5 2 1 1 101 S1 1 1 2 Dvorakia amsdeni S2 1 1 Dvorakia sp. 1 1 P1 1 4 5 M 1 1 Oulodus elegans elegans S0 1 1 2 S1 3 1 4 S2 1 2 2 2 7 Oulodus elegans detortus M 1 1 S1 1 1 Oulodus sp. S2 1 1 P1 1 2 1 1 5 Ozarkodina confluens P2 1 1 2 P1 3 3 Ozarkodina crispa P2 1 1 P1 1 3 5 4 11 5 29 P2 2 1 2 1 1 1 8 Ozarkodina eosteinhornensis s.l. S0 1 1 S1 1 1 S2 1 2 1 4 Panderodus recurvatus 2 1 3 2 2 8 2 2 3 7 4 3 39 Panderodus unicostatus 5 1 1 2 10 3 2 2 2 18 5 51 P1 2 1 14 1 18 P2 1 1 1 13 2 18 M 1 2 1 4 Wurmiella alternata S0 1 4 5 S1 1 3 1 5 S2 1 2 1 4 P1 3 6 10 19 12 4 61 4 67 187 19 148 33 38 40 651 P2 6 7 2 3 17 4 9 21 6 52 7 5 139 M 2 1 1 7 1 1 4 3 5 14 2 37 15 3 4 100 Wurmiella excavata S0 1 1 3 1 1 11 3 3 8 3 31 17 2 4 89 S1 1 1 8 1 2 6 3 8 41 9 63 36 5 2 186 S2 1 3 10 4 12 4 8 15 17 28 33 17 132 3 2 4 293 P1 1 1 2 Zieglerodina zellmeri P2 1 1 P1 3 3 Zieglerodina sp. P2 1 1 P1 1 1 3 1 1 1 8 Indetermined ozarkodinids P2 1 1 1 3 Indetermined ramiforms 1 1 1 3 Fragments 1 3 3 8 8 4 8 48 40 30 74 43 45 48 37 24 424 Total 67 24 66 37 119 53 33 180 88 174 421 111 589 172 90 90 2314 kg. rock 2,15 2,20 2,06 2,76 2,48 2,80 2,70 2,44 2,21 3,19 2,99 2,63 3,05 2,45 2,93 2,82 41,86 conodonts/kg 31,2 10,9 32,0 13,4 48,0 18,9 12,2 73,8 39,8 54,5 140,8 42,2 193,1 70,2 30,7 31,9 55,3 Tab. 1 - Distribution of conodonts in the Rifugio Lambertenghi Fontana section.

The crispa Zone section, from the base to around sample RLF III 1K. The Oz. crispa occurs in sample RLF 6 only. However, the lower boundary is defined by the FO ofOulodus elegans occurrence of Oz. eosteinhornensis s.l. in sample RLF 5 detortus, whereas the upper boundary is difficult to locate allows reference of this level to the crispa Zone. In fact, precisely because of the very low conodont abundance the latter species has its first occurrence within this zone in the upper part of the RLF III section. For notes on the (Corradini & Serpagli, 1999), or even at the base of the Silurian/Devonian boundary position (and of the upper zone together with Oz. crispa, like in Bohemia (Muslovska boundary of this zone) see the next chapter. Quarry and Kolednik Quarry; Chlupac et al., 1980). Wurmiella alternata occurs in the lower part of the zone, up to sample RLF III 3B; Oz. eosteinhonensis The eosteinhornensis s.l. Interval Zone s.s. is limited to sample RLF 4, where Oz. snajdri has The eosteinhornensis s.l. Interval Zone is distinguished its only occurrence at an unusually high stratigraphic in the upper part of the RLF section, from sample 6A to 10, level. Elements of Wurmiella excavata dominate, except because the lower boundary is defined by the LO of Oz. in samples from RLF III 2C to 2X, where Panderodus crispa, and the upper boundary by the FO of Oulodus el. unicostatus is very abundant, as does Belodella anomalis detortus. Wurmiella alternata n. sp. appears slightly above in sample RLF III 2B. the base of the zone. Elements of Wurmiella excavata dominate at all the levels of this interval. The woschmidti Zone The base of the zone is marked by the FO of Icriodus The detortus Zone woschmidti or Icr. hesperius. In the RLF III section Icr. The detortus Zone can be recognized in the upper hesperius occurs only in the uppermost part, in sample part of the RLF section and in the most of the RLF III RLF III 1. However, the lower boundary of the zone can C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps 243

RLF III 5 4 3D 3C 3B 3A 3 2C 2B 2Y 2X 2A 2 1N 1W 1M 1K 1L 1B 1P 1X 1A 1R 1Y 1S 1Z 1 0 total S0 1 3 23 3 1 2 1 1 5 10 1 2 53 S1 2 2 Belodella anomalis S2 5 3 8 S3 13 1 1 1 16 T 1 1 Belodella coarctata S0 1 4 1 6 S0 1 1 Belodella resima S1 1 1 9 4 2 3 1 2 23 S2 1 1 S0/S1 3 3 Coryssognathus dubius S2 1 1 2 Dvorakia amsdeni S3 4 4 Dvorakia sp. 3 2 1 1 7 Dapsilodus obliquicostatus 1 1 4 2 1 1 10 P1 1 1 Icriodus hesperius M 1 1 P1 1 1 1 3 P2 1 1 2 M 1 1 Oulodus elegans elegans S0 1 1 1 1 1 5 S1 1 1 1 1 2 1 1 8 S2 2 1 1 1 1 1 7 Pa 1 1 Oulodus greilingi hirpex Sc 1 1 P1 1 1 M 1 1 Oulodus siluricus S0 1 1 S1 1 1 S0 1 1 2 Oulodus sp. S2 1 1 P1 1 1 1 3 Ozarkodina confluens P2 2 2 Ozarkodina eosteinhornensis s.s. P1 1 1 P1 5 1 1 1 5 1 2 1 1 18 Ozarkodina eosteinhornensis s.l. P2 1 1 S2 1 1 2 Ozarkodina planilingua P1 1 1 2 1 5 Ozarkodina snajdri P1 3 3 Ozarkodina sp. P1 1 1 1 1 4 Panderodus recurvatus 4 1 3 1 7 1 3 1 2 4 27 Panderodus unicostatus 3 7 8 5 7 22 6 3 35 20 23 18 21 29 3 31 2 3 6 252 Pseudooneotodus beckmanni 1 2 1 4 P1 4 4 P2 1 6 7 M 4 4 Wurmiella alternata S0 1 1 S1 4 4 S2 5 5 P1 35 119 5 40 27 46 135 2 6 2 1 10 18 6 452 P2 12 29 14 6 10 45 1 1 1 4 123 M 3 19 1 3 1 2 32 2 3 8 4 1 79 Wurmiella excavata S0 5 15 2 1 2 3 23 2 1 1 3 58 S1 1 26 2 5 5 11 31 1 1 2 7 3 1 96 S2 8 28 4 6 7 35 2 1 3 7 15 11 1 128 Wurmiella sp. P1 1 1 2 P1 1 2 3 2 3 2 3 4 2 22 P2 3 1 3 4 11 M 1 1 Zieglerodina remscheidensis S0 1 1 2 S1 1 1 2 4 S2 1 1 1 3 Indetermined ramiforms 1 1 1 1 4 Fragments 11 20 9 9 8 12 36 1 7 2 2 5 2 2 1 1 3 2 6 2 1 1 8 151 Total 83 283 35 92 93 124 352 11 113 38 30 56 81 88 2 5 2 51 20 6 7 34 0 2 9 7 33 0 1657 kg. rock 1,33 2,93 1,20 2,20 1,70 1,78 3,20 1,40 1,60 1,80 1,30 2,20 2,76 1,20 2,80 1,80 2,00 2,90 2,28 1,85 1,80 2,67 1,39 1,30 1,60 1,60 2,48 1,80 51,74 conodonts/kg 62,4 96,6 29,2 41,8 54,7 69,7 110 7,9 70,6 21,1 23,1 25,5 29,3 73,3 0,7 2,8 1,0 17,6 8,8 3,2 3,9 12,7 0,0 1,5 5,6 4,4 13,3 0,0 32,0 Tab. 2 - Distribution of conodonts in the Rifugio Lambertenghi Fontana III section.

be placed around sample RLF III 1K, just above the first (= Oz. typica sensu Murphy et al., 2004), which is limited occurrence of Zieglerodina remscheidensis (see below for to Silurian, and the first occurrence ofIcriodus hesperius, comments). As already pointed out, conodonts are quite an index taxon for the basal Devonian, which occurs only rare in this part of the section. at very top of the section. However, other taxa can be of help, especially Zieglerodina remscheidensis. Genus Zieglerodina was recently proposed by COMMENTS ON THE POSITION OF THE Murphy et al. (2004) to include the ozarkodinids of the SILURIAN/DEVONIAN BOUNDARY “remscheidensis Group” and included several different forms previously put together in only one species It is difficult to precisely locate the Silurian/Devonian (Ozarkodina remscheidensis Ziegler). In their revision Boundary in the Rifugio Lambertenghi Fontana III Murphy et al. (2004) restricted the diagnosis of Z. section, owing to the scarcity of the fauna in the upper remscheidensis to morphs very similar to the holotype part of the section. In fact, there is a wide biostratigraphic of Ziegler (1960, pl. 13, fig. 4) and Carls et al. (2007) gap between the last occurrence of Ozarkodina confluens introduced three new species to discriminate forms from 244 Bollettino della Società Paleontologica Italiana, 49 (3), 2010 the Pridoli (Z. klonkensis, Z. ivochlupaci and Z. zellmeri). in the latest Pridoli and the position of the S/D boundary We agree on this approach and we believe that other within the rising limb of the carbon peak is documented species of Zieglerodina are still to be described from the from different peri-Gondwana locations (Buggisch & latest Silurian. Murphy et al. (2004) and Carls et al. (2007) Mann, 2004), Laurentia (Saltzman, 2002; Jacobi et al., claim that Z. remscheidensis is limited to lowermost 2009) and south Baltica (Malkowski et al., 2009). Devonian, on the basis of the occurrence of the species in the type locality (Ziegler, 1960), but it is present at the very top of the Pridoli either in other Carnic Alps sections SYSTEMATIC PALAEONTOLOGY (i.e. Monte Cocco II section; Corriga & Corradini, 2009) or in other palaeogeographic regions (Sardinia; Corriga Systematic notes are restricted to necessary taxonomic et al., 2009a). remarks and to taxa newly documented from the Carnic In the RLF III section, Z. remscheidensis enters Alps. For suprageneric classification, the scheme proposed in sample RLF III 1M, just above the last occurrence by Sweet (1988) is followed. Synonymy lists are limited of Oz. confluens. Wurmiella excavata is present up to to main captions and previous illustrations of specimens sample RLF III 1L. This species is usually abundant from the Carnic Alps. The entire fauna is housed in in the Silurian, but suddenly disappears just below the the Earth Sciences Department, University of Cagliari S/D boundary in the Monte Cocco II section (Corriga & (DSTC), under numbers 30000-30115. Horizon and Corradini, 2009), where the facies is similar to that of the catalogue numbers of figured specimens are given in the Rifugio Lambertenghi Fontana III section. Therefore, on plate captions. the basis of conodont occurrences, the S/D boundary can tentatively be placed around sample RLF III 1L. This is supported also by preliminary Carbon isotope Phylum Chordata Bateson, 1886 data (Corriga et al., 2009b), which suggest to locate the Class Cavidonti Sweet, 1988 S/D boundary in the upper part of the prominent δ13C shift, Order Belodellida Sweet, 1988 and just before the δ13C values reach their maximum (Fig. Family Belodellidae Khodalevich & Chernikh, 1973 7). This basal Devonian “plateau”-like peak in the carbon curve is known also from the Prague Basin (Buggisch & Genus Belodella Ethington, 1959 Mann, 2004, fig. 2). The characteristic shift in 13δ C starts Type species - Belodus devonicus (Stauffer, 1940)

Belodella coarctata Barrick & Klapper, 1992 (Pl. 1, fig. 6)

1992 Belodella coarctata n. sp. Barrick & Klapper, p. 42-43, Pl. 2, figs. 3-4, 8-9, 12-14 (cum syn.).

Remarks - The specimens referred to this species fits perfectly the original diagnosis. This is the first report of B. coarctata from the Carnic Alps.

Stratigraphic distribution - The species is documented from the Ludlow (Jeppsson, 1989) to the Pridoli (Barrick & Klapper, 1992). In Klonk it is very abundant just below the S/D boundary (Jeppsson, 1989). One of our specimens comes from the very base of Devonian.

Studied material - 13 S0 and 1 T elements from samples RLF 2, 5, 8, 9 and RLF III 2C, 1L, 1S.

Genus Dvorakia Klapper & Barrick 1983

Type species - Dvorakia chattertoni Klapper & Barrick 1983

Dvorakia amsdeni Barrick & Klapper, 1992 (Pl. 1 fig. 12-13)

1992 Dvorakia amsdeni n. sp. Barrick & Klapper, p. 43-44, Pl. Fig. 7 - Detail of the stratigraphic log of the RLF III section around 2, figs. 11, 15-19. the Silurian/Devonian boundary, with Carbon isotope data (after Corriga et al., 2009b) and occurrence of conodont taxa useful to Remarks - The specimens referred to this species fit locate the Silurian/Devonian boundary. the original description by Barrick & Klapper (1992) from C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps 245 the south-central U.S.A. The lack of ornamentation on the with an evident shoulder in both side of the process. The surfaces, the broad keel and the inner anterolateral costa cusp is high, prominent, strong, posteriorly inclined and distinguish D. amsdeni from the other species of the genus. with a triangular outline. The anterior process is short This is the first report ofD. amsdeni from the Carnic Alps. and decreases in height towards the distal end; it bears three well spaced triangular denticles of equal size. The Stratigraphic distribution - The species is documented posterior process bears five triangular discrete denticles; in the Pridoli (Barrick & Klapper, 1992). the last three slightly larger than the others. The basal cavity is deep and wide under the cusp, where is laterally Studied material - 2 S1, 1 S2 and 4 S3 elements from limited by a prominent rim, and progressively tapers up samples RLF 9, 12 and RLF III 2B. to the distal end of processes.

Remarks - The apparatus of Oz. crispa is still unknown, Class Conodonti Branson, 1938 and was tentatively reconstructed by Helfrich (1975) as Order Ozarkodinida Dzik, 1976 “Group X”, and by Wang & Aldridge (2010). Both these Family Spathognathodontodae Hass, 1959 reconstructions were done on the basis of joint occurrence of elements in some samples, but it looks that the various Genus Ozarkodina Branson & Mehl, 1933 specimens figured as representative of the same element in the apparatus are different and, therefore, may belong Type species - Ozarkodina confluens Branson & Mehl, to different taxa. The P2 element here described is from 1933 a sample (RLF 6) where, beside P1 elements of Oz. crispa, the only other ozarkodinids are W. excavata and Remarks - The Genus Ozarkodina was recently Oz. confluens. subdivided in several new genera by Murphy et al. (2004) Walliser & Wang (1989) distinguished four morpho- and Carls et al. (2005). We agree that in the previous types of the Pa element, based on the occurrence and meaning Ozarkodina included several different groups morphology of a furrow at the oral margin. The Pa that may represent separate genera, but in our opinion elements from RLF section belongs to β morphotype. not everything fits well in their scheme. Wurmiella was proposed to include taxa related to “excavata Group”, Stratigraphic distribution - The species is the marker while Zieglerodina is the new generic name for the of the crispa Zone and is limited to this interval (Corradini “remscheidensis Group”. These subdivisions seem to be & Serpagli, 1999). valid and the names are accepted, apart from some possible nomenclature problems highlighted by Donoghue et al. Studied material - 3 P1, 1 P2, from sample RLF III 6. (2008). For notes on the “eosteinhornensis Group” see the remarks on genus Zieglerodina. Murphy et al. (2004) and Carls et al. (2005) restricted the diagnosis of Ozarkodina, based on Oz. confluens Branson & Mehl (= Oz. typica Genus Wurmiella Murphy, Valenzuela-Rios sensu Murphy et al., 2004), including some Silurian & Carls, 2004 taxa, but left several other species without a generic assignment. We do not accept this restricted diagnosis, at Type species - Ozarkodina excavata tuma Murphy & least until a comprehensive revision of the ozarkodinids Matti, 1983 has been completed, in order not to expand the taxonomic uncertainty generated by their partial revision. We Remarks - Genus Wurmiella was recently proposed recognize that Ozarkodina remains a polyphyletic genus, by Murphy et al. (2004) to include the ozarkodinids of but we believe that stability in nomenclature should be the “excavata Group”. maintained until a revision will be concluded. Wurmiella alternata n. sp. Ozarkodina crispa (Walliser, 1964) (Pl. 2, figs. 1-8) (Pl. 3, fig. 20-21) 1986 Ozarkodina excavata excavata (Branson & Mehl) - Mawson, pl. 4, figs. 3, 5-7, 12, 16, 19, 21-22 (only). 1964 Spathognathodus crispus Walliser, p. 74-75, Pl. 9, fig. 3; 1994 Ozarkodina excavata excavata (Branson & Mehl) - Mawson Pl. 21, figs. 7-13. & Talent, figs. 13 E, G-H (only). 1989 Ozarkodina crispa (Walliser) - Walliser & Wang, p. 114-119, 2004 Ozarkodina excavata (Branson & Mehl) - Farrell, pl. 9, figs. Pl. 1, figs. 1-16; text-fig. 1. 3. 2003 Ozarkodina crispa (Walliser) - Corradini et al., pl. 1, figs. 2007 Ozarkodina excavata ssp. Suttner, p. 37, pl. 12, fig. 2. 6-7. 2007 Unassigned specimen Suttner, pl. 12, fig. 4. 2009 Ozarkodina crispa (Walliser) - Corriga & Corradini, p. 114-119, figs. 4 G-H. 2010 Ozarkodina crispa (Walliser) - Wang & Aldridge, p. 88, Pl. Holotype - DSTC 30000/1-6 figured in Pl. 2, figs. 1-6. 22, figs. 9-10, 13-14 (only). 2010 Ozarkodina crispa (Walliser) - Corradini et al., fig. 3g. Paratypes - Figured specimens DSTC 30001 and DSTC 30002; not figured specimens DSTC 30003/1-3, Description - For the Pa element, see Walliser & 30004/1-3, 30005/1-4, 30006/1-30, 30007/1-5, 30008, Wang (1989). Pb element ozarkodiniform very stout, 30009, 30010/1-24. 246 Bollettino della Società Paleontologica Italiana, 49 (3), 2010

Locus Typicus - Rifugio Lambertenghi Fontana section, subtriangular, laterally compressed and posteriorly just south of Passo Volaia and Rifugio Lambertenghi reclined, with a well developed keel on its anterior margin. Romanin, Carnic Alps, Italy. The strong anterior process bears up to ten closely spaced denticles of different size. The posterior process is longer Stratum Typicum - Bed of sample RLF 9. and thinner and bears up to nineteen small and closely spaced denticles. The basal cavity is larger under the cusp Derivatio nominis - From Latin alternatus, because of and becomes thinner below the processes. the characteristic denticulation pattern. M element neoprioniodiform. The cusp is high, robust laterally compressed. The posterior process is bent Diagnosis - A species of Wurmiella with some adjacent downward and bears small, normally alternated, denticles. denticles of different size in all elements of the apparatus. A single denticle could be present anterior of the cusp. The basal cavity is wider beneath the cusp on the inner side Description – Apparatus composed by six elements: an continues as a groove towards the posterior margin. P1, P2, M, S0, S1, S2. S0 element trichonodelliform with an angle of about P1 element spathognathodiform, straight and thin 160° between the symmetrical lateral processes. Processes with upper and lower margins more or less parallel. The bear small closely spaced denticles. The cusp is high and subtriangular cusp is only slightly larger than the denticles; strong. The basal cavity is narrow under and anterior of denticles are closely spaced and of different size on both the cusp and continues as a groove below the processes. processes, with smaller denticles intercalated within larger S1 element plectospathodiform, with two asymmetrical ones. Usually the posterior process bears 4 or 5 denticles processes. The posterior process has an undulating lower and the anterior process bears 8 or 9 denticles. The small margin and bears several denticles alternating in size; basal cavity is located slightly posterior. denticles close to the cusp are smaller than the others. P2 element ozarkodiniform with an angle of about The anterior process is shorter and bears up to ten closely 120° between the processes. The cusp is large, high, spaced equal denticles. The cusp is high, strongly reclined

EXPLANATION OF PLATE 1

Figs. 1-3, 5 - Belodella anomalis Cooper, 1974. 1 - DSTC 30028; lateral view of S0 element; sample RLF III 2B, detortus Zone; 2 - DSTC 30029; lateral view of S3 element; sample RLF III 2B, detortus Zone; 3 - DSTC 30030; lateral view of S2 element; sample RLF III 2B, detortus Zone; 5 - DSTC 30032; lateral view of S0 element; sample RLF III 3A, detortus Zone.

Fig. 4 - Belodella resima (Philip, 1956). DSTC 30031; lateral view of S1 element; sample RLF III 2B, detortus Zone.

Fig. 6 - Belodella coarctata Barrick & Klapper, 1992. DSTC 30033; lateral view of S0 element; sample RLF III 1L, woschmidti Zone.

Fig. 7 - Dapsilodus obliquicostatus (Branson & Mehl, 1933). DSTC 30034; lateral view; sample RLF 1, woschmidti Zone.

Figs. 8-11 - Coryssognathus dubius (Rhodes, 1953). 8 - DSTC 30035; lateral view of S2 element; sample RLF III 2B, detortus Zone; 9 - DSTC 30036; lateral view of S0/S1 element ; sample RLF III 2B, detortus Zone; 10 - DSTC 30037; lateral view of S0/S1 element; sample RLF III 2B, detortus Zone; 11 - DSTC 30038; lateral view of S0/S1 element; sample RLF III 2B, detortus Zone.

Figs. 12-14 - Dvorakia amsdeni Barrick & Klapper, 1992. 12 - DSTC 30039; lateral view of S3 element; sample RLF III 2B, detortus Zone; 13 - DSTC 30040; lateral view of S2 element; sample RLF 9, eosteinhornensis s.l. Zone; 14 - DSTC 30041; lateral view of element S1; sample RLF 10, eosteinhornensis s.l. Zone.

Figs. 15-18 - Panderodus recurvatus (Branson & Mehl, 1933). 15 - DSTC 30043; lateral view;sample RLF 2B, detortus Zone; 16 - DSTC 30044; lateral view; sample RLF 2Y, detortus Zone; 17 - DSTC 30042; lateral view; sample RLF 2X, detortus Zone; 18 - DSTC 30045; lateral view; sample RLF 7, eosteinhornensis s.l. Zone.

Figs. 19-20 - Panderodus unicostatus (Branson & Mehl, 1933). 19 - DSTC 30046; lateral view; sample RLF 9, eosteinhornensis s.l. Zone; 20 - DSTC 30047; lateral view; sample RLF 7, eosteinhornensis s.l. Zone.

Fig. 21 - Pseudooneotodus beckmanni (Bischoff & Sannemann, 1958). DSTC 30048; lateral view; sample RLF III 2B, detortus Zone.

Fig. 22 - Icriodus hesperius? Klapper & Murphy, 1975. DSTC 30049; upper view of a broken P1 element; sample RLF III 1, woschmidti Zone.

Fig. 23 - Icriodus hesperius Klapper & Murphy, 1975. DSTC 30050; lateral view of M element; sample RLF III 1, woschmidti Zone. C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps Pl.247 1 248 Bollettino della Società Paleontologica Italiana, 49 (3), 2010 and laterally compressed. The small basal cavity slightly In the Walliser collection from the Cellon section rises on the inner side of the cusp and tapers as a groove (Walliser, 1964), which C.C. had the possibility to study under the processes. a few years ago during a visit in Göttingen, W. alternata S2 element hindeodelliform. The posterior process n. sp. occurs in all samples from 32B to 34 (lower part it long and slightly arched with discrete and alternate of the eosteinhornensis s.l. Zone) and more rarely up to denticles. The anterior process is shorter and strongly sample 46 (detortus Zone). bowed inward. The prominent cusp is inclined slightly posteriorly. The basal cavity is narrow and extends as a Stratigraphic distribution - Our material comes from groove up to the posterior end. the eosteinhornensis s.l. i.Z. and the lower part of the detortus Zone. The range of the species in the Cellon Remarks - The most characteristic and easiest to section is the same. The P1 element figured by Farrell recognize element of W. alternata n. sp. is the P2 element, (2004) is from the lower Pridoli, too, whereas all the for the obvious denticulation on the anterior process, other specimens reported in the synonymy list are from where large and robust denticles alternate with small and the upper Lochkovian (delta Zone). Therefore, the range thin ones (Pl. 2, figs. 2, 7-8). of the species seems to cover most of the Pridoli and the The general morphology of elements of W. alternata Lochkovian, even if it is not documented up to now close n. sp. is similar to that of W. excavata, from which it to the S/D boundary and in the lower Lochkovian. differs only by the peculiar alternating denticulation. This supports the attribution of W. alternata n. sp. to this Studied material - 22 P1, 25 P2, 8 M, 6 S0, 9 S1 and genus, even if according to the diagnosis of Wurmiella 9 S2 elements from samples RLF 6B, 8, 8A, 9, 10, 12 (Murphy et al., 2004, p. 8), representatives of the genus and RLF III 3C-3B. have “processes without strong size variation of adjacent denticles”. S1 and S2 elements of Wurmiella alternata n. sp. Wurmiella excavata (Branson & Mehl, 1933) differ from the equivalent elements of Ozarkodina (Pl. 2, figs. 9-25) eosteinhornensis because are thinner. Furthermore, the S1 element differs by the undulating lower margin of the 1995 Ozarkodina excavata excavata (Branson & Mehl) - Simpson posterior process and the S2 element by its less regular & Talent, p.147-153, Pl.8, figs. 16-25; Pl. 9, figs. 1-24 (cum denticulation pattern. The S2 element is different from that syn). 2003 Ozarkodina excavata excavata (Branson & Mehl) - Corradini of Zieglerodina because of the more pronounced angle et al., Pl. 1 fig. 1. within the processes and the less developed alternating 2004 Wurmiella excavata (Branson & Mehl) - Murphy et al., figs. denticulation. 2.29-2.36

EXPLANATION OF PLATE 2

Figs. 1-8 - Wurmiella alternata n. sp. 1 - holotype DSTC 30000/1; lateral view of P1 element; sample RLF 9, eosteinhornensis s.l. Zone; 2 - holotype DSTC 30000/2; lateral view of P2 element; sample RLF 9, eosteinhornensis s.l. Zone; 3 - holotype DSTC 30000/3; lateral view of M element; sample RLF 9, eosteinhornensis s.l. Zone; 4 - holotype DSTC 30000/4; lateral view of S0 element; sample RLF 9, eosteinhornensis s.l. Zone; 5 - holotype DSTC 30000/5; lateral view of S1 element; sample RLF 9, eosteinhornensis s.l. Zone; 6 - holotype DSTC 30000/6; lateral view of S2 element; sample RLF 9, eosteinhornensis s.l. Zone; 7 - paratype DSTC 30001; lateral view of a broken P2 element showing the characteristic denticulation pattern on the anterior process; sample RLF 9, eosteinhornensis s.l. Zone; 8 - paratype DSTC 30002; lateral view of a broken P2 element showing the characteristic denticulation pattern on the anterior process; sample RLF 9, eosteinhornensis s.l. Zone.

Figs. 9-25 - Wurmiella excavata (Branson & Mehl, 1933). 9 - DSTC 30011; lateral view of P1 element resembling W. tuma; sample RLF 9, eosteinhornensis s.l. Zone; 10 - DSTC 30012; lateral view of P1 element resembling W. tuma; sample RLF III 3B, detortus Zone; 11 - DSTC 30013; lateral view of P1 element; sample RLF 6B, eosteinhornensis s.l. Zone; 12 - DSTC 30014; lateral view of P1element; sample RLF 9, eosteinhornensis s.l. Zone; 13 - DSTC 30015; lateral view of P1 element; sample RLF 9, eosteinhornensis s.l. Zone; 14 - DSTC 30016; lateral view of P1 element; sample RLF III 4, detortus Zone; 15 - DSTC 30017; lateral view of P1 element; sample RLF 9, eosteinhornensis s.l. Zone; 16 - DSTC 30018; lateral view of P2 element; sample RLF 9, eosteinhornensis s.l. Zone; 17 - DSTC 30019; lateral view of P2 element; sample RLF 9, eosteinhornensis s.l. Zone; 18 - DSTC 30020; lateral view of M element; sample RLF 9, eosteinhornensis s.l. Zone; 19 - DSTC 30021; lateral view of M element; sample RLF 9, eosteinhornensis s.l. Zone; 20 - DSTC 30022; lateral view of S0 element; sample RLF 9, eosteinhornensis s.l. Zone, 21 - DSTC 30023; lateral view of S0 element; sample RLF III 4, detortus Zone; 22 - DSTC 30024; lateral view of S1 element; sample RLF III 4, detortus Zone; 23 - DSTC 30025; lateral view of S0 element; sample RLF 9, eosteinhornensis s.l. Zone; 24 - DSTC 30026; lateral view of S2 element; sample RLF 9, eosteinhornensis s.l. Zone; 25 - DSTC 30027; lateral view of S2 element; sample RLF III 4, detortus Zone. C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps Pl.249 2 250 Bollettino della Società Paleontologica Italiana, 49 (3), 2010

2007 Ozarkodina excavata excavata (Branson & Mehl) - Suttner, denticles (Pl. 2, figs. 9-10). These specimens reminds p. 33-36, Pl. 1, fig. 3; Pl. 12, figs. 1-7; Pl. 13, figs. 3, 5, 8-9; one of W. tuma; however, the latter species, which is Pl. 14, figs. 2-11; Pl. 16, figs. 1-7, 9; Pl. 17, figs. 1-3, 5. the type species of Genus Wurmiella, has a higher short 2009 Wurmiella excavata (Branson & Mehl) - Corriga & stratigraphic range limited to middle Lochkovian (Murphy Corradini, fig. 4C. 2009 Wurmiella excavata (Branson & Mehl) - Corradini et al., fig. et al., 2004). 3e. Stratigraphic distribution - The species is documented Remarks - Wurmiella excavata is by long the more from lower Silurian to Lower Devonian. abundant taxon in many Silurian collections. This elements occur also in the studied sections, where they Studied material - 1103 P1, 262 P2, 179 M, 147 S0, are dominant in Silurian samples, but disappear close to 282 S1 and 421 S2 elements from samples RLF 1-12 and the S/D boundary. However, there are several different RLF III 5-2Y, 2A-1W, 1L. morphologies of the P1 element, differing by the length of the element, its general shape (straight and slightly arched forms), presence of the cusp, size and numbers of Genus Zieglerodina Murphy, Valenzuela-Rios & denticles. In the studied sections, several samples from Carls, 2004 the eosteinhorensis s.l. and the lower part of the detortus zones yielded some P1 elements of W. excavata very long, Type species - Spathognathodus remscheidensis slightly arched towards the extremities and bearing many Ziegler, 1960

EXPLANATION OF PLATE 3

Fig. 1 - Oulodus siluricus (Branson & Mehl, 1933). DSTC 30051; lateral view of P1 element; sample RLF III 4, detortus Zone.

Fig. 2 - Oulodus elegans detortus (Walliser, 1964). DSTC 30052; lateral view of M element; sample RLF 11, detortus Zone.

Fig. 3 - Ozarkodina snajdri (Walliser, 1964). DSTC 30053; upper view of P1 element; sample RLF III 4, detortus Zone.

Fig. 4 - Ozarkodina sp. DSTC 30054; lower lateral (a) and lateral (b) views of P1 element; sample RLF III 2A, detortus Zone.

Figs. 5-6, 18 - Oulodus elegans elegans (Walliser, 1964). 5 - DSTC 30055; lateral view of S1 element; sample RLF III 2A, detortus Zone; 6 - DSTC 30056; lateral view of S2 element; sample RLF III 4, detortus Zone; 18 - DSTC 30068; oblique-lateral view of S0 element; sample RLF III 2, detortus Zone.

Figs. 7-8 - Ozarkodina eosteinhornensis s.l. (Walliser, 1964). 7 - DSTC 30057 upper view of P1 element; sample RLF III 2X, detortus Zone; 8 - DSTC 30058 lateral view of P1 element; sample RLF III 1B, woschmidti Zone.

Fig. 9 - Ozarkodina eosteinhornensis s.s. (Walliser, 1964). DSTC 30059 upper view of P1 element; sample RLF III 4, detortus Zone.

Figs. 10-13 - Zieglerodina remscheidensis (Ziegler, 1960). 10 - DSTC 30060 lateral view of P1 element; sample RLF III 1A, woschmidti Zone; 11 - DSTC 30061 lateral view of P1 element; sample RLF III 1A, woschmidti Zone; 12 - DSTC 30062 lateral view of P1 element; sample RLF III 1Z, woschmidti Zone; 13 - DSTC 30063; lateral view of P1 element; sample RLF III 1X, woschmidti Zone.

Figs. 14-16 - Ozarkodina planilingua Murphy & Valenzuela-Rios, 1999. 14 - DSTC 30064; upper (a) and lower lateral (b) views of P1 element; sample RLF III 1X, woschmidti Zone; 15 - DSTC 30065; upper view of P1 element; sample RLF III 1, woschmidti Zone; 16 - DSTC 30066; upper view of P1 element; sample RLF III 1A, woschmidti Zone.

Fig. 17 - Oulodus sp. DSTC 30067; lateral view of an anomalous S1 element bearing a branched anterior process; sample RLF III 1A, woschmidti Zone.

Fig. 19 - Zieglerodina zellmeri Carls et al., 2007. DSTC 30069; lateral view of P1 element; sample RLF 8, eosteinhornensis s.l. Zone.

Figs. 20-21 - Ozarkodina crispa (Walliser, 1964). 20 - DSTC 30071; upper view of P1 element; sample RLF 6, crispa Zone; 21 - DSTC 30070; lateral view of P2 element; sample RLF 6, crispa Zone.

Figs. 22-23 - Ozarkodina confluens (Branson & Mehl, 1933). 22 - DSTC 30072; lateral view of P2 element; sample RLF 8, eosteinhornensis s.l. Zone; 23 - DSTC 30073; lateral view of P1 element; sample RLF 8, eosteinhornensis s.l. Zone.

Upper scale bar valid for figures 1-16; lower scale bar for figures 17-23. C. Corradini, M.G. Corriga - Silurian and Lower Devonian conodonts from the Carnic Alps Pl.251 3 252 Bollettino della Società Paleontologica Italiana, 49 (3), 2010

Remarks - Genus Zieglerodina was recently proposed This paper benefits from the opportunity that Prof. Otto Walliser by Murphy et al. (2004) to include the ozarkodinids of the (Göttingen) gave to C.C. to study his collection from the Cellon “remscheidensis Group”. Taxa of the “eosteinhornensis section. Luca Simonetto (Udine) and Monica Pondrelli (Pescara) are deeply acknowledged for help in the field work and discussions Group” have a very similar morphology of all the apparatus on the geology of the area. The authors thank Dick Aldridge elements, but the authors consider them belonging to a (Leicester) for information on the apparatus of Oz. crispa and for different genus (not yet established according to the discussion on the generic attribution of W. alternata n. sp. Elisa IZNC rules) because of differences in the P1 element. Zedda (Cagliari) helped with the conodont samples preparation, The opportunity to establish two different genera very and Claudio Gentilini (Modena) and Gabriele Cruciani (Cagliari) similar each other, or to place the two groups together in took SEM microphotographs. “Immagini TerraItaly™ - © Blom Compagnia Generale Riprese aeree S.p.A. - Parma (www.terraitaly. the same genus should be carefully evaluated and is not it)” allowed the reproduction of the aerial view of the Passo Volaia the topic of this paper. area. The authors thank R. Mawson (Sydney) and J.E. Barrick (Texas Tech) for the detailed and useful comments which made stronger this manuscript; the latter is acknowledged also and for correcting Zieglerodina zellmeri Carls et al., 2007 the English language. (Pl. 3 fig. 19) This research was supported by grants “ex-60%” University of Cagliari (resp. C. Corradini).

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