Rivista Italiana di Paleontologia e Stratigrafia sorume IU) numero 1 nro'ne I)9-1la Aprile 1999 NOU BREW . SHORT NOTE DISCOVERY OF PARATIROLITES FROM THE BELLEROPHON FORMATION (UPPER PERMIAN, DOLOMITES, ITALY) RENATO POSENATO * & HERWIG PRINTOTH** ReceirLed September 10, 1998; accEted December 10, 1998 Key-uords: Ammonoids, ParatiroLites, Bellerophon Fm., Upper Permian, Dolomites. Riassunto. Viene descritto il ritrovamento, il primo della Teti de occidentale, di un esemplare di Paratirolites. L'ammonoide, raccol- to nel detrito della Fm. a Bellerophon nei pressi di Santa Cristina Valgardena (Bolzano, Dolomiti), è conrenuîo in una piccola lastrina di calcare marnoso, nerastro, della Facies Badiota, con una microbio- facies dorninata da ostracodi. Sulla base del litotipo e della biofacies si presume che esso possa derivare dai livelli dell'Associazìone ad Ostrà- codi, sìtuati pochi metri sotto a quelli dell'Associazìone a Cornelica- nia e Nanhinella. Non si può escludere tuttavia una provenienza da livelli più bassi, sempre comunque appartenenti alla Facies Badiota. Questo ritrovamento consente di stabilire, contrariamente a quanto sostenuto da alcuni autori, che l'Associazione a Comelicania e Nanbi- nella è ptù recente della Zont a Phisonites - Comelicania (:Gruntalli na) della Transcaucasia e che essa è correlabile o è pir\ giovane della Zona a Paratiro/ires del Dorashamiano suo. Abstract. The first discovery of Paratirolites in the western Tethys is here described. The ammonoid was collected in the debris of the Bellerophon Fm. near Santa Cristina Valgardena (Bolzano, Do- lornites). The specimen is contained in a small slab made of marly dark grey limestone with a biomicrofacies dominated by ostracods. It probably comes from the Ostracod Assemblage beds (Badiota Facies), which are situated few metres below the Comelicania beds. The oc- currence o[ Paratirolites allow us to dàte this segment of the upper Bellerophon Fm. to the late Dorashamian, and to deÍìne the Conteli cdni.l ànd Nankinella beds of the Dolomites as younger than rhe Pbí sonites - Comelicania (:Gruntallina) beds of the Transcaucasia (basal Dorashamian). These Dolomite beds are equivalent ro or younger than the Paratirolites Zone (ate Dorashamian). Introduction. In the Dolomites, the Upper Permian is repre- sented by the Bellerophon Formation which was formed in a shallow marine environment, mostly inhabited by benthic organisms. Ammonoids of the Bellerophon For- mation of the Dolomites are thus veÍy rare. To date, only few specimens of Paraceltites sextensis (Diener) have been found at the end of the last century in the Sesto (Sexten) area (Diener, 1897). IJnfortunatly, such an ende- mic species does not al1ow a direct correlation with the ammonoid standard zofiafion of the Late Permian. The chronological framework of the Bellerophon Fm. has therefore been made using other taxa, mainly forams and brachiopods, by means of which a correlarion with the ammonoid-bearing sequences has been artempted. How- ever, the ages obtained from these fossils are often appro- ximative and lack a general consensus, among different authors, on their precise chronostratigraphical posirion. The majority of authors consider the Bellerophon Fm. Dzhulfian/Changxingian in age, even if the posi- tion of the boundary between these two srages has not been detected, as most of the formation was deposited in a restricted shallow mr.rine environmenr in which fossils are rare, and represenred by long-ranging taxa. Only in the uppermost metres of the formation did more open marine conditions allow the presence of fu- sulinids and brachiopods, which have a grearer chrono- stratigraphical vaiue. Flowever, the ages inferred from these taxa are also uncertain. For instance, the age pro- posed for the Comelicania beds ranges from ropmost Dzhulfian-basal Changxingian (Kozur, 1.989), to iower Dorashamian (Assereto er à1., 1.973), ro upper Dorasha- mran (Broglio loriga et a1., 1988; Posenato, 1988; etc.). Stratigraphic position of the ammonoid. The ammonoid described here was discovered by one of us (H.P.) on the blocks of a large landslide which fell several tens of years ago from Pic }l4t. (Pizza Cuecena in the Ladinian language, Pitschberg in the German ian- guage). This locality (]muèia da Insom), about 2 km norths/ard of Santa Cristina Valgardena (Fig. 1), is the same as that in which the frsh Archaeolepidotus leonardii Accordi was found. 'r Dipanimento dj Scienze Geologiche psr@dns. unife.it 'r" Via Stu[rn 15, Oniser, Bolzano. e Paleontologiche, Università di Ferrara, Corso Ercole I d'Este 32, 44rcA Ferrara, Italy. e-mail: , 1Km . ÀNNAD,?* ORTISEI TESERO 1iu R. Posenato & H. Prinotb Fig. I - Geographical setting of the locality (asterisk) from which the ammonoid has been collected. The ammonoid occurs in a smail slab of blackish marly limestone, very rich in ostracods, belonging to the Badiota Facies (Fig. 2). This facies repiesents the up- per part of the Bellerophon Fm. in the Valgardena area, as weil as in all the western Dolomites. In his schematic description of the Pic Mt. section, Accordi (1955) descri- bed a unit (unit 6) made up of "Calcare argilloso a ostra- codi e a piccoli molluschi" (:marly limestone with ostra- cods and small molluscs"), from which probably the am- monoid derives. Flowever, Accordi (1955) did not report the thickness of this unit but only that of the whole Ba- diota facies, which is 35 m thick (from unit 3 to unit Z). In the Valgardena area, recent stratigraphic data on the Bellerophon Fm. are reported from the Seceda section (Massari et al., t994), located about 2 km NW of Pic Mt. In this section the Badiota Facies is about 35 m thick, as in the Pic section, and represents the 5'h and 6'h sequences of third order into which Massari et al. (1994) divided the Upper Permian of the Eastern Sout- hern Alps. The lower part of the 5'h sequence is a transgressi- ve segment made up of dominant subtidal fossiliferous limestones, rich in algae and forams (upper part of the Algae Assemblage of Broglio lnríga et al., 1988). The uppermost, regressive part of the sequence consists o{ silty dolomites and marly limestones, with a biofacies characterized by the mass occurrence of ostracods (Ostracod Assemblage of Broglio Loriga et al., 1988). The sequence ends with vuggy dolomite with root tra- ces which suggest subaereal exposures (Massari et a1., 1994). This regionally regressive event is about 10-12 m thick (Fig 3) The uDDermost Bellero-"rr"_'_""' nhnn Fm ehorrt 1 5 m thick inrrr,t evvs( r,J r the Seceda section, records the transgressive event of the sixth sequence which is mainly repre- sented by the basal -Werfen Fm. ('fesero Florizon and Mazzrn Member). The top of the Belle- Ostracod biofacies of the m"- trix containing the ammo- noid. Negative print from acetate peel (x 40). t32 R. Posenato & H. Prinoth tains three Dorashamian genera: Paratirolites Stoyanoq Dzhulfites Shevyrev and Abichites Shevyrev. The latter two genera have been considered by Teichert et al. (1973) as synonyms o[ Paratirolites. Because Dzhuffites is slightly older than the other two genera (Paratirolites and Abichites are associated in the Paratirolites beds), a comparison with the genera proposed by Shevyrev (1965) is necessary. Dzbulfites is characterized by an ovoidal-subrectan- gular, slightly compressed whorl secrion and a ventral lobe which is simple-pronged and non-denticulated. The Dolomites specimen has a whorl section which is sli ghtly depressed, scarcely subpentagonal, with a small denticle on the last adoral ventral lobe as occurs in Para- tirolites and Abichites. Fig. 4 - Paratirolites sp., lateral (a) and ventral (b) views; Jmuèia da Insom, Santa Cristina Valgardena (Bolzano), x 2. (.-_) " Abichites has a compressed, rectangular or subqua- drate whorl section; the venrer is slightiy convex in the inner whorls, while it becomes flattened in the body chamber. This genus differs from Paratirolites by a sharp dorsal shoulder and the absence of ventral nodes on the adult whorl. Since our specimen is smaller by half with respect to the smallesr specimen of Abichites illustrated by Shevyrev (1965), the ontogenetic changes of the whorl shape cannot be used here as an element of com- parison even if the lacking of ventral nodes in A. abtchi Shevyrev and A. stoyanorai (Kiparisova) (see Shevyrev, 1965, pl. 34, [ig. 2-4), seems to occur already in the in- ner phragmocone whorls, a character in common with the Dolomites specimen. Flowever, Abichttes has sharp dorsal and ventral shoulders whereas they are rounded in the Dolomites ammonoid, as occurs in some Paratiro- /lres species (e.g. P. waageni). The Dolomites specimen has a slightly depressed whorl section and a low-arched venter with a low crest. A depressed whorl is common among Paratirolites spe- cies, but a ventral ridge is nor present in the specimens figured by Shevyrev (1965). However, according ro To- zer (1979), the lack of a ventral ridge in many Dzhulfi- tid species of the type area may be related to an imper- fect preservation of the material, as specimens of Parati- rolites aediensls Shevyrev from Kuh-e-Ali Bashi (Iran) have one. Paratirolites has lrtero-ventral nodes; these are ab- sent in the Dolomites specimen, in which only ribs oc- cur. The difference could be related to the differenr on- togeneîic stages of the confronted material illustrated by Shevyrev (1.965), as these Transcaucasian specimens have sizes which are three or four times larger. F{owever, the lectotype of P. kittli figured by Spath (1934, {ig. 135 a, b) has ventral nodes already 19 mm in diameter. The lack of ventral nodes in the Dolomites specimen thus raises some doubts as to its attribution to the gen. Para- t iro I it e s s en s u Shetry rev. The specimen described here thus belongs to the fam. Dzhulfitidae but, following the Shevyrev's classifica- tion, it is impossible to determine its precise generlc po- sition as it is too sma1i, with morphological characters in common with different genera^ The lack of ventral nodes is a character of Abichttes, whrle the well rounded ventrai shoulder, slightly depressed whorl and 1ow, smooth ven- tral crest are taxonomicai features of Paratirolites. Since it shares more characters with Paratirolttes than those in common with Abichttes, the specimen resembles the for- mer genus more than any other Late Permian ammonoid. A different classification of the Transcaucasian Dzhulfitidae was proposed by Teichert et a1. (1973), who interpreted a large morphological variability among them regarding whorl section and ornamenta- tion, even if they did not analyse them in detail on ac- count of the incompleteness of the specimens. For this \.f\ Shell section (a, x 2) and last (end of phragmocone) suture lines at a whorl height of 7.1 rnm ft, x 7) of Paratirolites sp.; Jmuéia da Insom, Santa Cristrna Valgardena (Bolzano). l. (-r f r , z l'r ì fY . rTì B o Oc () :lo 0) U) c iO z 'F frì ì ì I'r ì (/, .c) O o lJ_ o+ .oo o oo Discoaery of Paratirolites 1,31 <- FO I isarcica <- FO H. parvus (B) <- FO l/. parws (A) <- FO l{ latidentatus a- Comelicaniabeds +Paratirolìtes sp. Fig. 3 - Probable stratigraphical position of Paratirolites sp. Litho- strarigraphical unirs are nor to scale, as their thickness changes according to the different secrions (e.g. Tesero Ho- rizon in the Bulla and Tesero sections) from which data on conodonts are available flVignall at al., 1996; Farabegoli & Perri, 1998). Abbreviations: C.-N. A. - ComeLicania and Nanhinella Assemblage. Third order sequences from Mas- sari et al. (1994); biostratigraphic units from Broglio Lori- ga et al. (1988). FO H. latidmtatus (?: Hind,eodus n. sp. X of Orchard, 1996): at 0.3 m above the base of the Tesero Florizon (Bulla section, Farabegoli 6c Perri, 1998). FO 1-1. parvus (A) (?: H. latilentatils prdepdreus oÍKozv, 1996, 1998): at 1.30 m above the base of Tesero Hor. (Bulla sec- tion; Farabegoli Ec Perri, 1998); FO H. panus (B): at about 14 m above the base of Tesero Hor. (Tesero secrion, Wi- gnall et al., 1996); FO I. isarcica: ar 7 m above the FO of H. parous (B) (Tesero section, \lignall et al., 1996). rophon Fm. yields the Cornelicania beds, which are made up of bioclastic wackestone and marls conraining a well diversified assemblage with forams and algae, and brachiopods represented by Comelicania haueri (Stache) and C. rnegalotis (Stache) (Comelicania and Nanhinella Assemblage of Broglio Ioriga et a1., 1988). The upper- most 10-20 cm of the Bellerophon Fm., characrerizedby the appearance of ooids, are made up of packsto- nelgrainstones containing C. merlai Posenato, Janiceps spp., Ombonia canevai Merla and Orthothetina ,uentild- brum (Leonardi). According to Massari et al. (1994), the- se beds are separated from the C. haueri and C. rnegalotis beds by a slight erosional contact. On the basis of the litho- and biofacies of the ma- trix, the ammonoid probably derives from the regressive segment (Ostracod Assemblage) of the 5'h sequence (Fig. 3). However, a iower position inside the Badiota Facies cannot be entirely excluded, as ostracod lenses occur also in the lower part of the Algae Assemblage belon- ging to the 4'h sequence of Massari et al. (tll+) (cf. Seres section, Cirilli et aI., 1998, fig. 5). Flowever, in the Pic and Seceda sections the 4th sequence is mostly repre- sented by marl, marly dolomite and dolomite belonging to the Fiammazza Facies. Systematic description * Supra-generic classification according to Shevyrev, 1986 Ord. Ceratitida Hyatt, 1884 Suborder Paraceltitina Shevyrev, 1968 Superfam. X e n o d i s c a c e a e Frech, l9O2 Fam. Dzhwlfitidae Shevyrev, 1965 Gen. Paratirollres Stoyanornr. 1910 Paratirolites so. (Fis. 4, s) Description. The specimen is an evolute sheii of small size, incomplete, consisring of the outer whorl of phragmocone and part of the aboral dorsal region of the body chamber. It has a diameter of 19.6 mm, whorl width of 8.5 mm, whorl height of 7.2 mm and an um- bilical diamerer of 7.8 mm. The whorl is slightly de- pressed, and has flanks converging very slightly toward the dorsal shouider; the venter is broadly arched with a hardly perceptible, smoothed crest; rhe venrral and dor- sal shoulders are rounded. The lateral areas bear coarse ribs which, in the last half whod of phragmocone, are distant and rectiradiate. The last two ribs, near the ven- tral shoulder, seem to curve forward. In the umbilical fragment of body chamber the ribs appeaî closer roget- her, while they become lateral nodes in the inner umbi- lical whods. The ribs are most prominent on rhe flanks, and they disappear towards the venter, which is smooth; ribs protude siightly on the dorsal shoulder. Suture is ceratitic with two denticuiated lateral lo- bes; the auxiliary lobe on umbilical seam and ventral lobe are slightly denticulated. The lateral saddle is lower than ventral and auxiliary saddles; the ventral (argest) and auxiliary saddles are asymmetrical; the latter projec- ting slightly toward the umbilical seam (Fig. 5b). Comparison. The classification in the Fam. Dzhulfitidae is mainly based on the suture which has a low lateral, depressed saddle, separated from adjacent ventral and auxiliary saddles by two denticulated lobes. According to Sheryrev (1965; 1986), this family con- Discooery of Paratiro lites r33 reason, as already quoted, these authors considered,4Al- cbites synonymous of Paratírolites, down-grading Shevy- rev's genera to a specific level. Since we have only one, very small and incomplete specimen, making it difficult to use Shevyrev's classification, we prefer to adopt that nf Tciehcrr "r 'l (1973), according to whom the Dolo-- -- *-' \^-' mites specimen belongs to the gen. Paratirolites. As concerns the determination at specific level, some small-sized specimens of P kittli figured by Tei- cherr et aL (1,973, pl.6, fig. 7, 1,0, 1,I) have a sculpture and a venter morphology very close to ours. They have ribs without ventrai nodes and a venter decidedly ar- ched, at a she1l diameter of about 45 mm. FIowever, the- se specimens are about twice our own in size, and have a slightly compressed whorl (figs. 10, 11): such differen- ces do not aliow us a specific determination of our am- monoid. Therefore, adopting the classification of Tei- chert et al. (1.973), the specimen is here determined as Paratirolites sp. Age. The finding of Paratirolitpr sensu Teichert et aI. (1973) in the upper Bellerophon Fm. permits us to recognize here the upper Dorashamian Paratirolites Zone: the last ammonoid zone of the Dorashamian, ac- cording to the original definition of this stage (Rosto- vtsev Ec A.zaryan, 1971 1973). The same correlation can also be proposed following Shevyrev's classification (Pa- ratirolites ? sp.), since the Dolomites specimen has char- acters in common with Paratirolites and Abichites, which, in Transcaucasia, are associated rn the Paratiroli- res beds; besides, it is different from Dzbuffites, a marker of an older Dorashamian biozone placed between lrani- tes and Sher.ryreaites zones. Llowever, in Transcaucasia, a younger Permian ammonoid zone has since been recognized: this is the Pleuronodoceras occidentale Zone, which occurs above the Paratirolites Zone (Akhura Suite) in a unit made up of red clays and marls, belonging to the base of the Ka- rabagljar Suite (Zakharov, 1988). The P occidenale Zone is correlated to the upper Changxingian of South China (e.g. Yang &. Lí, 1992), while the Dorashamian, from Phisonites to Paratirolites Zones, is considered equivalent to the lower Changxingian (Kozur, 1989; Yin 6c Tong, 1998). An alternative opinion is expressed by Sweet et al. (1992) and Tozer (1979), who correlate the upper Changxingian with the Dorashamian. According to To- zer (1979) the occurrence of Paratirolites ìn the lower Changxingian of Chrna is questionable, and Plewronodo- ceras and Pseudotiro/ites, markers of the upper Chan- gxingian, are associated with Paratirolites in the Ali Bas- hi Formation of Transcaucasia. Comelicania and laniceps beds of the uppermost Bellerophon Fm. are thus younger than the Pbisonites- "Comelicania" beds of the basal Dorashamian or lower Changxingian to which they have so far been correlated (e.g. Yin & Tong, 1998). Unfortunately, no zonal mar- ker has been found among conodonts in the uppermost Bellerophon Fm., making it impossible to define the age of this segment with precision. Conodont zonal mar- kers such as Hindeodus latidentatus and H. paruus, the latter of which has been proposed (Yin, 1993) as the marker of the base of Triassic, only appear in the lower 'W'erfen Fm. (Tesero Horizon andMazzin Member), but taxonomical problems on the classification of these spe- cies impede us from objectively determining the posi- tion of the P/Tr boundary (for the taxonomical pro- blems and chronostratigraphical significance of these co- nodonts see Schònlaub, 1991.; Kozur, 1,996; 1,998; Or- chard, 7996; Orchard & Krystyn, 1998; Vignail et al., 1.996;Farabegoli & Perri, 1998, etc.). AcknowLedgeruents. \We rre grateful to Maurizio Gaetani, Carmen Loriga Broglio, Brian Glenister, Edward T.'fozer and Yuri Zachtrov for their critical review, useful comments and suggestions on an eady version o{ manuscript. This work was supponed by grants of Murst, funds 40olo (C. Loriga Broglio). REFERENCES Accordi B. (1955) - Archaeolepidotus leonardii n. gen. n. sp. e altri pesci permo-werfeniani delle Dolomiti. Mem. Sci. Geol. Univ. Padova, v. 19, pp. 1-29,Paàova. Assereto R., Boseliini A., Fantini Sestini N. & Sweet '\1.C. 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