Evolutionary Process from Mockina Bidentata to Parvigondolella Andrusovi: Evidence from the Pizzo Mondello Section, Sicily, Italy

Journal of Earth Science, Vol. 32, No. 3, p. 667–676, June 2021 ISSN 1674-487X Printed in China https://doi.org/10.1007/s12583-020-1362-2 Evolutionary Process from Mockina bidentata to Parvigondolella andrusovi: Evidence from the Pizzo Mondello Section, Sicily, Italy Yixing Du *1, Tetsuji Onoue 2, Viktor Karádi3, Ian S. Williams4, Manuel Rigo1, 5 1. Department of Geosciences, University of Padova, 35131 Padova, Italy 2. Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan 3. Department of Palaeontology, Eötvös Loránd University, Budapest 1117, Hungary 4. Research School of Earth Sciences, The Australian National University, ACT 2601 Canberra, Australia 5. Institute of Geosciences and Earth Resources, National Research Council of Italy, 35131 Padova, Italy Yixing Du: https://orcid.org/0000-0001-6397-1494 ABSTRACT: During their last phase of evolution, the pectiniform conodont elements manifested an evident trend of simplification and miniaturization. This phase started from the late Norian (Sevatian) in the Late Triassic and the evolutionary process of genus Mockina to Parvigondolella, in particular between Mockina bidentata and Parvigondolella andrusovi, is one of the most significant examples. Par- vigondolella has been reported worldwide since it was first described in the early 1970s. However, it has recently been suggested that genus Parvigondolella is an ecostratigraphic morphotype of genus Mockina, and thus a phenotype controlled by the environmental conditions, and not an independent taxon. In the Pizzo Mondello Section (Sicily, Italy), transitional forms between M. bidentata and P. andrusovi have been found at different evolutionary stages. We have investigated the oceanic conditions at the time by using redox-sensitive elements (Mn, Fe, V, Cr, and Ni) and seawater temperatures from biogenetic 18 δ Ophos to understand the possible environmental influences on the phylogenetic evolution between Mockina and Parvigondolella. The geochemical and isotope analyses indicate that the redox condition and temperature were stable during the evolution of genus Parvigondolella in Pizzo Mondello, confirm- ing that genus Parvigondolella is a real taxon and not a phenotype. A new conodont species named Par- vigondolella ciarapicae n. sp. is described here for the first time. KEY WORDS: conodont, Late Triassic, evolution, oxygen isotope, geochemistry. 0 INTRODUCTION taxa survived the second event, which corresponds to the Conodonts are calcium phosphate tooth-like elements from Carnian Pluvial Episode occurring from Julian 2 (late Carnian) an elaborate feeding apparatus of a marine vertebrate (e.g., to the Julian/Tuvalian boundary (mid-Carnian) (Mazza et al., Donoghue et al., 2000; Sansom et al., 1992) that became extinct 2012a; Rigo et al., 2007). Faunal turnovers occurred at the near the Triassic/Jurassic boundary (Du et al., 2020a). Conodonts Tuvalian/Lacian (Carnian/Norian) boundary (Mazza et al., are a significant tool for global biostratigraphic correlations in 2012a, b, 2010). This interval is characterized by the develop- particular to define the global boundary stratotypes (GSSPs) of ment of the genus Epigondolella (=Ancyrogondolella sensu the Upper Triassic stages (Mazza et al., 2018, 2011; Rigo et al., Orchard, 2018) and the mass emergence and, shortly afterwards, 2018, 2016; Bertinelli et al., 2016; Mietto et al., 2012). the sudden disappearance of the genus Metapolygnathus (with Conodonts suffered several extinctions and/or faunal the exception of Me. mazzai). turnovers from the Carnian to the end of Rhaetian before their Subsequently, conodonts evolved into two main phyloge- final extinction (e.g., Rigo et al., 2018). The first event was in netic trends: one was characterized by the absence of ornamen- the early Julian (early Carnian), when the ornamented budu- tation on the platform margins and free blade (i.e., Norigon- rovignathids disappeared. The simplified paragondolellids sur- dolella); the other was characterized by the development of vived beyond that event (Kozur, 1989). Only a few conodont nodes and then high denticles on the platform margins, such as Epigondolella and Mockina. A clear faunal turnover started in *Corresponding author: [email protected] the Lacian/Alaunian boundary interval with the appearance of © The Authors 2021. This article is published with open access the genus Mockina and the subsequent demise of the genus at Springerlink.com Epigondolella. The last event occurred over a long period, which started in the mid-Sevatian and led through several steps Manuscript received June 15, 2020. to the extinction of conodonts around the Triassic/Jurassic Manuscript accepted October 29, 2020. boundary (Du et al., 2020a; Karádi et al., 2020; Rigo et al., Du, Y. X., Onoue, T., Karádi, V., et al., 2021. Evolutionary Process from Mockina bidentata to Parvigondolella andrusovi: Evidence from the Pizzo Mondello Section, Sicily, Italy. Journal of Earth Science, 32(3): 667–676. https://doi.org/10.1007/s12583-020-1362-2. http://en.earth-science.net 668 Yixing Du, Tetsuji Onoue, Viktor Karádi, Ian S. Williams and Manuel Rigo 2020; Kozur and Mock, 1991; Orchard, 1983). Parvigondolella might be interpreted as an ecostratigraphic The diversity of Mockina species decreased during the morphotype of M. bidentata in an unfavourable environment Sevatian (Late Triassic) and the rise of atavistic homeomorphs (Gallet et al., 2007; Krystyn et al., 2007a, b), or should be con- (i.e., genus Parvigondolella and genus Misikella) is observed sidered as an independent taxon. through evident simplifications of the pectiniform elements (Karádi et al., 2020; Giordano et al., 2010). These two different 1 GEOLOGICAL SETTING phylogenetic trends were considered to have evolved from the The Pizzo Mondello Section (Fig. 1) is located in the same common species Mockina bidentata, both by the loss of southern Sicani Basin in western-central Sicily (Italy) (e.g., the platform and a decrease in size (Karádi et al., 2020; Rigo et Mazza et al., 2010; Muttoni et al., 2004, 2001; Gullo, 1996; al., 2018). These morphological trends have been observed by Bellanca et al., 1995). It is one of the longest continuous and several researchers working on different stratigraphic sections well-exposed successions for the study of the Upper Triassic worldwide (Du et al., 2020b; Karádi et al., 2020; Rigo et al., biostratigraphy, chemostratigraphy, magnetostratigraphy of the 2018, 2005; Mazza and Martínez-Pérez, 2015; Mazza et al., Tethyan realm, and it has been proposed as a GSSP candidate 2012b; Orchard et al., 2007a, b; Kozur and Mock, 1991). Thus, for the base of the Norian Stage (Mazza et al., 2018; Balini et M. bidentata has been regarded as the common ancestor of the al., 2010; Nicora et al., 2007). genus Parvigondolella (e.g., Karádi et al., 2020; Rigo et al., The 430 m lower part of the section consists of Upper Tri- 2018; Moix et al., 2007; Kozur and Mock, 1991) and recently assic Mufara Formation and overlying Scillato Formation. The of Misikella (Karádi et al., 2020; Rigo et al., 2018, 2005). Mufara Formation consists of Carnian marly limestone and Although Parvigondolella was reported both in Tethys and dark grey marl (Onoue et al., 2018), whereas the Scillato For- Panthalassa after its definition by Kozur and Mock (1972), mation consists of late Carnian to early Rhaetian (Mazza et al., there is still controversy about whether this genus is a real ge- 2012b; Muttoni et al., 2004, 2001; Gullo, 1996), evenly-bedded nus or not (Gallet et al., 2007; Krystyn et al., 2007a, b). How- to nodular Halobia-bearing cherty calcilutites, the Calcari con ever, the Parvigondolella is commonly found worldwide, such Selce (or cherty limestone) sensu Muttoni et al. (2004, 2001). as in Italy, Austria, Hungary, Slovenia, Canada, America, Mex- The section is characterized by almost uniform facies and high ico, Russia and Japan (Zhang et al., 2019; Rigo et al., 2018, sedimentation rates of 22–30 m/Ma (Mazza et al., 2012b, 2010; 2005; Mazza and Martínez-Pérez, 2015; Gale et al., 2012; Balini et al., 2010; Guaiumi et al., 2007; Muttoni et al., 2004, Carter and Orchard, 2007; Krystyn et al., 2007a; Moix et al., 2001). Overlying the thick Scillato succession is a thin (20 m) 2007; Orchard et al., 2007a, b; Pálfy et al., 2007; Bragin, 1991; lower to middle Rhaetian succession of calcilutites, marls, and Kozur, 1989; Kunihiro et al., 1984; Kozur and Mostler, 1971), the Portella Gebbia Limestone, that is locally covered uncon- especially for the species P. andrusovi. At present, there seems formably by Jurassic strata (Preto et al., 2013, 2012; Guaiumi to be a general consensus that Parvigondolella is the descen- et al., 2007; Gullo, 1996). dant of M. bidentata, and it has been recently proved by inte- The lower succession of the Pizzo Mondello Section is grating phylogenetic and biostratigraphic approaches with nu- well exposed in the abandoned La Cava quarry (Mazza et al., merical cladistic analyses (e.g., Karádi et al., 2020). In this 2018, 2010; Onoue et al., 2018; Muttoni et al., 2004, 2001). paper, we report morphoclines between Mockina bidentata and The samples for this study were collected from the uppermost Parvigondolella andrusovi collected from the Pizzo Mondello part of the section, between 349 and 369 m (Fig. 2). That part is Section. We document the ocean conditions during this evolu- characterized by almost uniform facies and yields large tion by using redox-sensitive elements (e.g., Mn, Fe, Cr, V, and amounts of conodonts, including different growth stages, such Ni) and the oxygen isotope profile of conodont apatite to test if as juvenile, adult and transitional forms, thus making Pizzo Figure 1. Sketch maps showing the location (a) and geological characteristics (b) of the Pizzo Mondello Section in Sicily, Italy (modified after Onoue et al., 2018). Evolutionary Process from Mockina bidentata to Parvigondolella andrusovi: Evidence from the Pizzo Mondello Section 669 Figure 2. Studied portion of the Pizzo Mondello Section, between 349 and 369 m from Onoue et al. (2018). The uniform lithology consists of light lime mud- 18 stones.

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