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Volume 32 Issue 3
Jun.  2021
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Martyn Lee Golding. Early Anisian (Middle Triassic) Conodonts from Romania and China, with Comments on Their Role in the Recognition and Correlation of the Base of the Anisian. Journal of Earth Science, 2021, 32(3): 573-591. doi: 10.1007/s12583-020-1392-9
Citation: Martyn Lee Golding. Early Anisian (Middle Triassic) Conodonts from Romania and China, with Comments on Their Role in the Recognition and Correlation of the Base of the Anisian. Journal of Earth Science, 2021, 32(3): 573-591. doi: 10.1007/s12583-020-1392-9

Early Anisian (Middle Triassic) Conodonts from Romania and China, with Comments on Their Role in the Recognition and Correlation of the Base of the Anisian

doi: 10.1007/s12583-020-1392-9
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  • The Olenekian-Anisian Boundary (OAB) interval is an important time in Earth history, reflecting the last phase of marine ecosystem recovery in the aftermath of the end-Permian mass extinction. Despite this, the Global Stratotype Section and Point (GSSP) for the base of the Anisian remains undefined. The first appearance of the conodont Chiosella timorensis has been proposed as a potential index for the boundary; however, the discovery of this conodont with ammonoids traditionally considered to be Spathian has generated doubts about its suitability. The taxonomy and relationships of early Anisian conodonts, including species of Chiosella, remain understudied, which leads to difficulties in correlation. New species of Neogondolella (N. gradinarui) and Magnigondolella (M. n. sp. D) have been recognized from the leading GSSP candidate section for the OAB at Deşli Caira, and from an additional OAB section at Guandao. Furthermore, several species previously identified in Canada and the USA can be recognized from these sections, improving correlation between Tethys and North America. One of these species may serve as a suitable alternative proxy for the OAB; for instance, N. curva appears just below the first Anisian ammonoids in Deşli Caira, and just above the first appearance of C. timorensis in both Deşli Caira and Guandao. Continued work on sections other than the candidate sections, and on the taxonomy of species outside of those traditionally proposed as indices, is required.
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Early Anisian (Middle Triassic) Conodonts from Romania and China, with Comments on Their Role in the Recognition and Correlation of the Base of the Anisian

doi: 10.1007/s12583-020-1392-9

Abstract: The Olenekian-Anisian Boundary (OAB) interval is an important time in Earth history, reflecting the last phase of marine ecosystem recovery in the aftermath of the end-Permian mass extinction. Despite this, the Global Stratotype Section and Point (GSSP) for the base of the Anisian remains undefined. The first appearance of the conodont Chiosella timorensis has been proposed as a potential index for the boundary; however, the discovery of this conodont with ammonoids traditionally considered to be Spathian has generated doubts about its suitability. The taxonomy and relationships of early Anisian conodonts, including species of Chiosella, remain understudied, which leads to difficulties in correlation. New species of Neogondolella (N. gradinarui) and Magnigondolella (M. n. sp. D) have been recognized from the leading GSSP candidate section for the OAB at Deşli Caira, and from an additional OAB section at Guandao. Furthermore, several species previously identified in Canada and the USA can be recognized from these sections, improving correlation between Tethys and North America. One of these species may serve as a suitable alternative proxy for the OAB; for instance, N. curva appears just below the first Anisian ammonoids in Deşli Caira, and just above the first appearance of C. timorensis in both Deşli Caira and Guandao. Continued work on sections other than the candidate sections, and on the taxonomy of species outside of those traditionally proposed as indices, is required.

Martyn Lee Golding. Early Anisian (Middle Triassic) Conodonts from Romania and China, with Comments on Their Role in the Recognition and Correlation of the Base of the Anisian. Journal of Earth Science, 2021, 32(3): 573-591. doi: 10.1007/s12583-020-1392-9
Citation: Martyn Lee Golding. Early Anisian (Middle Triassic) Conodonts from Romania and China, with Comments on Their Role in the Recognition and Correlation of the Base of the Anisian. Journal of Earth Science, 2021, 32(3): 573-591. doi: 10.1007/s12583-020-1392-9
  • The Olenekian-Anisian Boundary (OAB) is currently undefined, with no accepted Global Stratotype Section and Point (GSSP) for the base of the Anisian stage (early Middle Triassic). This can be attributed to several factors, including: varying philosophies on the historical placement of the boundary; disagreements on the occurrence, suitability and correlation of various stratigraphic markers; the rarity of good OAB sections due to a widespread hiatus at the boundary; and the perceived lesser importance of the boundary in comparison with others such as the Permian-Triassic Boundary (Tong et al., 2019; Ogg et al., 2014; Hounslow et al., 2007). The need to define this boundary has become more acute in recent years, as the OAB interval has come to be recognized as an important time. The boundary encompasses the last phase of recovery of marine organisms from the end-Permian mass extinction, and the re-establishment of normal oceanographic and climatic conditions, and of complex marine ecosystems (e.g., Pietsch and Mosqueda, 2019; Liang et al., 2016; Song et al., 2015; Wignall, 2015; Chen and Benton, 2012; Sun et al., 2012).

    The original stratotype for the Anisian stage was based on limestone belonging to the Gutensteinerkalk at Großreifling in Austria (Summesberger and Wagner, 1972; Assereto, 1971; Arthaber, 1896; Waagen and Diener, 1895). The scope of the Anisian was subsequently expanded and re-defined by Arthaber (1906) and Pia (1930), with the original Anisian of Waagen and Diener (1895) being regarded as the upper Anisian, and the beds below being included in the lower Anisian (Hydaspian of Pia, 1930). As the type region lacked ammonoids in the lower part of the Anisian, the basal part of the stage was later further refined in Greece and Turkey, where ammonoids were more abundant (Assereto, 1974). The sections at Marathovouno on Chios Island in Greece, and the Kocaeli Peninsula in Turkey, become the stratotypes for the Aegean and Bithynian sub-stages, respectively. Additional studies at Chios on the ammonoid and conodont faunas, as well as chemostratigraphy and magnetostratigraphy, have been published, both prior to and after the designation of the Aegean stage (Mertmann and Jacobshagen, 2003; Muttoni et al., 1995, 1994; Muttoni and Rettori, 1994; Jacobshagen et al., 1993; Gaetani et al., 1992; Bender, 1970). The sections on this island remain important for understanding the OAB.

    The base of the Aegean sub-stage, and consequently the base of the Anisian stage, was initially recognized on the basis of the first occurrence of the ammonoid genus Paracrochordiceras (Assereto, 1974). Other ammonoid genera have been used to recognize the boundary in different regions, including Aegeiceras, Japonites, and Paradanubites (Ogg et al., 2014; Balini et al., 2010; Gaetani, 1993). Other potential markers that have been proposed to aid recognition of the OAB include the first appearance of the conodont Chiosella timorensis (Orchard, 2010; Grădinaru et al., 2007, 2006; Orchard et al., 2007a, b; Orchard and Tozer, 1997; Assereto et al., 1980), a peak in the δ13C values (Grădinaru et al., 2007), and the shift from reversed-polarity to normal-polarity magnetozones (the base of magnetozone MT1n; Hounslow and Muttoni, 2010; Hounslow et al., 2007).

    Thus far, the most thoroughly studied candidate for the base-Anisian GSSP is the section at Deşli Caira, North Dobrogea, Romania (Grădinaru et al., 2007, 2006). The first appearance of the ammonoid genus Japonites was originally proposed as the marker index at Deşli Caira (Grădinaru et al., 2007). In addition to the section at Deşli Caira, research is ongoing at two other possible candidate sections at Wantou in South China (Chen et al., 2020; Ogg, 2019; Ovtcharova et al., 2015, 2006; Galfetti et al., 2008, 2007; Wang et al., 2005) and at Kçira in Albania (Muttoni et al., 2019, 1996; Meço, 2010, 1999; Germani, 1997). Other important regions for the characterization of the upper Spathian and lower Anisian include Guandao, Guizhou Province, South China (Li et al., 2018; Lehrmann et al., 2015; Orchard et al., 2007b); Milne Edwardsfjellet, Svalbard (Nakrem et al., 2008); Ogama, Japan (Muto et al., 2018); Mt. Lilu, Timor (Nogami, 1968); Wadi Alwa, Oman (Orchard, 1995; Tozer and Calon, 1990); Siberia (Dagys, 1988); and Primorye, eastern Russia (Zakharov et al., 2005). Of these, the section at Guandao is particularly informative, for although it lacks an ammonoid fauna, it contains abundant conodonts and several radiometrically-dated ash layers.

    The conodont Chiosella timorensis was proposed as a possible index for the OAB at the Chios Section by Assereto et al. (1980), and this species has been recognized in OAB sections at Deşli Caira (Grădinaru et al., 2007, 2006; Orchard et al., 2007a), Guandao (Orchard et al., 2007b), Wantou (Chen et al., 2020) and Kçira (Muttoni et al., 2019). However, Mirăuţă (2000, 1974) considered the first occurrence of C. timorensis to be in the Olenekian, and subsequently this conodont has been recorded in Nevada occurring together with ammonoids of the Haugi Zone (Neopopanoceras haugi, Keyserlingites pacificus, Subhungarites yatesi, and Pseudacrochordiceras inyoense; Goudemand et al., 2012). This ammonoid zone is Spathian in age, and therefore the suitability of C. timorensis as an indicator for the base of the Anisian has been called into question (Goudemand et al., 2012). Recent re-evaluation of the ammonoid record in the Kçira-A Section also suggests that the first occurrence of C. timorensis is in the same stratigraphic interval as the Spathian ammonoid Procarnites kokeni (Eugen Grădinaru, personal communication), suggesting that Spathian occurrences of this species are more widespread than previously thought. Additional issues with C. timorensis center on the definition of the species, and its differentiation from related species such as C. gondolelloides, C. n. sp. A and C. n. sp. B (see discussion in Goudemand et al., 2012). This taxonomic difficulty has not been resolved thus far in the most recent study of the conodont fauna at Kçira (Muttoni et al., 2019). At Wantou Chen et al. (2020) recognized the new species of Chiosella identified by Goudemand et al. (2012), but retained the name C. gondolelloides for several specimens considered to be C. timorensis by Goudemand et al. (2012), making correlation of the Chiosella faunas between Wantou, Deşli Caira and Guandao difficult at this time. In the sections at both Kçira and Wantou, the first appearance of C. timorensis is still considered to be the most suitable proxy for the OAB (Chen et al., 2020; Muttoni et al., 2019; Yan et al., 2015).

    In light of the aforementioned issues with Chiosella timorensis, it is appropriate to consider whether other conodont species from the boundary interval may also be suitable as alternative proxies for recognizing the OAB. In particular, the first occurrence of Gladigondolella tethydis has been highlighted by several workers as an important datum in the vicinity of OAB (e.g., Muttoni et al., 2019; Goudemand et al., 2012; Orchard et al., 2007b). This species generally occurs slightly above the first occurrence of C. timorensis in most sections; however, specimens of G. tethydis have been documented from below C. timorensis at Kçira (Meço, 1999, fig. 5; Muttoni et al., 2019, fig. 4), where they appear to occur with Spathian ammonoids (Eugen Grădinaru, personal communication). Additional specimens of G. tethydis have also been identified from the Smithian of Oman (Marc Leu, personal communication). The taxonomy of this species is less well-advanced than that of C. timorensis, and it is clear that specimens referred to G. tethydis show a wide variation in morphology and may represent different species in different sections (for example, compare fig. 5, parts 29–30 of Orchard et al., 2007a with fig. 5, parts 5a–5c of Chen et al., 2020).

    Most OAB sections also include significant numbers of Neogondolellins, particularly the genera Neogondolella and Magnigondolella; however, the taxonomy of the early Anisian species of these genera in Tethys is poorly understood, and occurrences are commonly reported as Neogondolella sp. or N. ex gr. regalis (a poorly defined species group now encompassed by several species within the genus Magnigondolella). New species of conodont belonging to Neogondolella and Magnigondolella were recently described from the Anisian of British Columbia in Canada, and Nevada in the USA (Welteri Zone and Caurus Zone and younger; Golding and Orchard, 2018, 2016). Some of these species have subsequently been recognized more widely in western Canada (Henderson et al., 2018). In light of the updated taxonomy of Anisian Neogondolellins, existing collections from the OAB sections at both Guandao (Orchard et al., 2007b) and Deşli Caira (Orchard et al., 2007a) have been re-examined to assess the range of diversity of Neogondolella and Magnigondolella in the samples. In spite of continued studies of the geochronology and stratigraphy of the section at Guandao (e.g., Li et al., 2018; Lehrmann et al., 2015), and paleontology at Deşli Caira (e.g., Grădinaru and Gaetani, 2019) there has been little new work on the Olenekian and Anisian conodont faunas at either section since the study of Goudemand et al. (2012), who utilized materials from both Deşli Caira and Guandao in their re-assessment of Chiosella.

  • The section at Deşli Caira Hill is located in southeastern Romania near the coast of the Black Sea (Fig. 1a), with the base of the section at 28°48'08"E, 45°04'27"N (Grădinaru et al., 2007). The section consists of a thick sequence of massive-bedded limestone, termed the Agighiol Limestone (Grădinaru et al., 2007). These rocks were part of a carbonate platform developed on the central-eastern part of the Tulcea Unit, a major tectonostratigraphic unit of the North Dobrogean Orogen, which was formed by subduction of the Paleo-Tethys Ocean prior to being thrust over Eurasia during the Cimmerian Orogeny (Grădinaru, 2000, 1995).

    Figure 1.  Maps showing the locations of the two sections discussed in this study. (a) Location of the Deşli Caira Section (marked by red star) in the North Dobrogean Orogen of eastern Romania; location with respect to the Black Sea is shown inset (modified from Grădinaru et al., 2007); (b) location of the Guandao Section (GD, marked by red star) in the Nanpanjiang Basin on the northern margin of the Great Bank of Guizhou; location of the basin in South China is shown inset (modified from Orchard et al., 2007b); (c) schematic cross-section of Great Bank of Guizhou, showing the approximate position and stratigraphy of the upper (UGD) and lower (LGD) sections at Guandao (modified from Orchard et al., 2007b).

  • The Guandao Section is located in Guizhou Province, South China (Figs. 1b, 1c), at 106°38'00"E, 25°36'46"N (Wang et al., 2005). The section consists of more than 700 m of limestone and shale, and the OAB is located in carbonates belonging to the Luolou Formation (Lehrmann et al., 2015). These rocks were formed at the edge of the northern margin of the Great Bank of Guizhou, an isolated carbonate platform within the Nanpanjiang Basin, formed after inundation of the Yangtze Platform began in the Late Permian (Lehrmann et al., 2005, 1998). The majority of samples utilized in the this study come from the upper section (OU), with fewer from the lower section (O).

  • Samples from Romania utilized in this study were previously collected by Michael J. Orchard in 2000 during a field trip to Deşli Caira as part of a workshop on the Lower-Middle Triassic (Olenekian-Anisian) Boundary (Grădinaru, 2000); specimens from some of these samples were subsequently described and illustrated in Orchard et al. (2007a). These samples are currently located in the archival collections of the Geological Survey of Canada in Vancouver. Additional conodont samples from the Deşli Caira Section have been collected previously and reported in preliminary papers by Mirăuţă (2000, 1974), and Grădinaru et al.(2006, 2002). Some of these specimens were re-studied by Michael J. Orchard and Alda Nicora, and included in the publications by Grădinaru et al.(2007, 2006) and Orchard et al. (2007a). Additional conodont samples are reposited in the collections of the University of Bucharest, and new bed-by-bed conodont sampling, closely tied to a recent high-resolution ammonoid biostratigraphy around the OAB, is in progress (Eugen Grădinaru, personal communication); these samples were not able to be utilized for the present study. A total of 12 samples from the Deşli Caira Section contain specimens of Magnigondolella and Neogondolella (Table 1).

    Sample Height (m) Magnigondolella aff. dilacerata Magnigondolella n. sp. D Magnigondolella sp. Neogondolella cf. bifurcata Neogondolella curva Neogondolella hastata Neogondolella cf. prava Neogondolella gradinarui Neogondolella n. sp. A Neogondolella n. sp. B Neogondolella ex. gr. constricta Neogondolella sp. Total Other fauna
    Deşli Caira
    607 -1.50 - - - - - - - - - - - 4 4 Chiosella timorensis
    9042 -1.25 - - - - - - - - - - - 1 1 Triassospathodus ex gr. homeri, Cratognathus sp. A, Gen. et sp. nov. A, Chiosella sp. A, Chiosella timorensis
    204/5 0.25 - - - - 1 - - - - - - 4 5 Cratognathus sp. B, Gen. et sp. nov. A, Chiosella timorensis, Gladigondolella tethydis
    9043 1.00 - - - - - - - 1 - - - 2 3 Gladigondolella tethydis, Gen. et sp. nov. A, Chiosella timorensis
    9044 2.25 - - - - - - - 1 - - 5 15 21 Cratognathus sp. A, Gen. et sp. nov. A, Chiosella n. sp. B, Chiosella timorensis
    609 2.75 - - - - - - - - - - - 15 15 Chiosella timorensis, Chiosella n. sp. B
    9045 3.25 - - - - 1 - - - - 1 2 4 Cratognathus sp. A, Gen. et sp. nov. A
    9046 8.00 - - - - - - - - - - 1 5 6 Cratognathus sp. A, Gen. et sp. nov. A, Chiosella timorensis
    612 14.25 - - - - - 2 - 2 - - - 4 8 Cratognathus sp. A, Chiosella timorensis, Gladigondolella tethydis
    9048 14.50 - - - - - 3 - - - 1 6 8 18 Cratognathus sp. A, Gen. et sp. nov. A, Chiosella timorensis, Gladigondolella tethydis
    9049 16.75 - - - - - 2 - 1 - - - - 3 Cratognathus sp. A, Cratognathus sp. B., Gen. et sp. nov. A, Chiosella timorensis, Chiosella sp., Gladigondolella tethydis
    615b 18.50 - - - - - 1 - - - - - 1 2 Chiosella timorensis, Gladigondolella tethydis
    DC total 0 0 0 0 1 9 0 5 0 1 13 61 90
    Guandao -
    UGD-21 243.70 (O) - 1 - - - - - - - - - - 1 Chiosella timorensis
    WG-131 248.20 (O) - - - - - - - - - - - 1 1 Chiosella timorensis
    GDL-50 248.70 (O) - 1 - - - - - - - - - - 1 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis, Gen. et sp. nov. A
    GQC-166 248.80 (O) - - - - - - - - - - - 1 1 Chiosella timorensis
    OU-8 10.90 (OU) - 2 - - - - - - - - - 1 3 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis, Triassospathodus ex gr. homeri
    OU-9 11.05 (OU) 1 1 82 - - - - - - - - - 84 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Gladigondolella tethydis, Cratognathus sp. A, Cratognathussp. B, Triassospathodus ex gr. homeri
    OU-10 11.15 (OU) - - 22 - - - - - - 1 - 6 29 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis
    OU-11 11.30 (OU) - - - - 2 - - - - - - 29 31 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B
    OU-13 11.60 (OU) - - 9 - 1 - - - - - - 5 15 Chiosella timorensis, Chiosella n. sp. A, Gladigondolella tethydis
    OU-14 11.70 (OU) - - 2 - - - - - - - 3 5 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B, Gen. et sp. nov. A
    OU-15 11.80 (OU) - - - - - - - - - - - 3 3 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. A, Cratognathus sp. B, Gen. et sp. nov. A
    OU-18 12.25 (OU) - - - - - - - - - - - 8 8 Chiosella timorensis, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis, Gen. et sp. nov. A
    OU-19 12.35 (OU) - - - - - - 1 - - - - 11 12 Chiosella timorensis, Cratognathus sp. A, Triassospathodus ex gr. homeri
    OU-20 12.40 (OU) - - - - - - - - - - - 7 7 Chiosella timorensis, Gladigondolella tethydis
    OU-21 12.50 (OU) - - - - 1 - - - 3 - 22 26 Chiosella timorensis, Chiosella n. sp. B, Cratognathus sp. A
    OU-22 12.65 (OU) - - - - 1 - - - - - - 6 7 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. B
    OU-23 12.85 (OU) - - - - - - - 1 - - 2 11 14 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis, Gen. et sp. nov. A
    OU-24 12.95 (OU) - - - - 2 - - - - - - 12 14 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B, Gen. et sp. nov. A
    OU-25 13.05 (OU) - - - - - - - - - - - 23 23 Chiosella timorensis, Chiosella n. sp. A, Chiosella n. sp. B, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis, Gen. et sp. nov. A
    OU-26 13.15 (OU) - - - - - - - - - - - 3 3 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis, Gen. et sp. nov. A
    OU-27 13.25 (OU) - - - - 1 - - - - - - 9 10 Chiosella timorensis, Cratognathus sp. A, Gladigondolella tethydis, Gen. et sp. nov. A
    OU-28 13.35 (OU) - - - - 1 - - - - - - 5 6 Chiosella timorensis, Chiosella n. sp. B, Cratognathus sp. A, Gladigondolella tethydis
    OU-29 14.10 (OU) - - - - - 1 - 11 - - - 60 72 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. A
    OU-30 15.10 (OU) - - - - - 3 - 5 - - - 36 44 Chiosella timorensis, Gladigondolella tethydis
    OU-31 15.50 (OU) - - - 1 - 1 - 3 - - 1 75 81 Chiosella timorensis, Chiosella n. sp. A, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis
    OU-32 16.00 (OU) - - - - - - - - - - - 2 2 Chiosella timorensis, Cratognathus sp. A, Cratognathus sp. B, Gladigondolella tethydis
    G total 1 4 115 1 9 5 1 20 3 1 3 339 502
    Total 1 4 115 1 10 14 1 25 3 2 16 400 592

    Table 1.  Sample table showing the number of specimens of Neogondolella and Magnigondolella recovered from the sections at Deşli Caira and Guandao, together with the composition of the accompanying conodont fauna. Sample heights measured from stratigraphic columns in Orchard et al.(2007a, b) and Goudmenad et al. (2012); datum for Deşli Caira is the first occurrence of Aegiceras ugra, for Guandao it is the base of the measured section (O or OU).

    Conodont samples from Guandao were collected and processed by Daniel J. Lehrmann, Jiayong Wei and Chinese collaborators, and the residues sent to Michael J. Orchard for study, with initial results published by Orchard et al. (2007b). These samples are now stored in the archival collections at the Geological Survey of Canada in Vancouver. Additional conodont samples from the Guandao Section reported in Lehrmann et al. (2015) are located in the collections of Trinity University, and have not been included in the present study. A total of 26 samples from the Guandao Section contain specimens of Magnigondolella and Neogondolella (Table 1).

    The conodont samples were processed at the Geological Survey of Canada using standard techniques as outlined in Stone (1987) and Jeppsson et al. (1999). More than 500 specimens of Magnigondolella and Neogondolella were identified in the 38 samples utilized in this study (Table 1).

  • The present taxonomic re-appraisal has led to the recognition of several species of Neogondolella and Magnigondolella first identified in North America, as well as five new species that have thus far been identified in only the Deşli Caira and Guandao sections. This is the first record of these species outside of North America, and their recognition allows improved correlations to be made between Tethys and North America in the OAB interval. The complete conodont faunas from samples containing specimens of Magnigondolella or Neogondolella from Deşli Caira and Guandao are shown in Table 1.

    In Guandao, the oldest identifiable species of Neogondolellin is Magnigondolella n. sp. D, which appears in the Spathian of British Columbia (Subrobustus Zone) and occurs in sample OU-8, together with specimens of Chiosella timorensis, Cratognathus sp. A and sp. B, Triassospathodus ex gr. homeri, and Gladigondolella tethydis (Fig. 2). The early Anisian Magnigondolella aff. dilacerata, previously recognized in British Columbia and Nevada (Caurus and Americanum zones), is identified in sample OU-9, where it occurs with a diverse fauna of Magnigondolella spp. Above this level, Neogondolella curva occurs in samples OU-11 and OU-21, as well as in sample 204/5 in Deşli Caira (Figs. 2, 3). In both sections, N. curva occurs with C. timorensis and G. tethydis, and allows correlation of the two sections (Figs. 2, 3). At Deşli Caira, N. curva is the oldest identifiable species of Neogondolella, although fragmentary specimens of this genus can be found in samples 607 and 9042. N. n. sp. A is recognised in sample OU-21 at Guandao, whereas N. gradinarui occurs in both sections, in samples OU-23, OU-29, OU-30 and OU-31 at Guandao, as well as samples 9043, 9044, 612 and 9049 at Deşli Caira (Figs. 2, 3). N. n. sp. B occurs in one sample, 9048, at Deşli Caira, and in one sample at Guandao, OU-10 (Figs. 2, 3). Specimens of N. ex gr. constricta occur in samples 9044, 9045, 9046 and 9048 at Deşli Caira, but are much rarer at Guandao, only occurring in samples OU-23 and OU-31 (Figs. 2, 3). Specimens referred to N. cf. prava are identified in sample OU-19 at Guandao (Fig. 2); these early Anisian specimens resemble the younger N. prava that is typical of the Germanic Basin and western Tethys. Near the top of the studied parts of both sections, the late early Anisian to late Anisian conodont N. hastata occurs, in sample OU-30 at Guandao, and samples 9045, 612, 9048, and 615b at Deşli Caira (Figs. 2, 3). In both sections, N. hastata occurs with C. timorensis and G. tethydis. One of the youngest species found at the Guandao Section in this study is N. cf. bifurcata in sample OU-31 (Fig. 2). The specimen is fragmentary and so the identification is uncertain; however, the presence of this species could indicate the lowermost part of the Bithynian (middle Anisian).

    Figure 2.  Conodont biostratigraphy of the upper section (OU) at Guandao, showing the occurrences of newly identified species of Neogondolella and Magnigondolella, together with previously recognized occurrences of other species belonging to Chiosella, Gladigondolella, Cratognathus, Triassospathodus, and Spathicuspus. The OAB interval is indicated by the first occurrence of C. timorensis, and the first occurrence of N. curva. Modified from Orchard et al. (2007b) and Goudemand et al. (2012).

    Figure 3.  Conodont biostratigraphy of the section at Deşli Caira, showing the occurrences of newly identified species of Neogondolella and Magnigondolella, together with previously recognized occurrences of other species belonging to Chiosella, Gladigondolella, Cratognathus, Neospathodus, Triassospathodus, and Spathicuspus. The position of the OAB is marked at the first occurrence of the Anisian ammonoid Aegeiceras ugra. Modified from Orchard et al. (2007a), Goudemand et al. (2012) and Grădinaru and Gaetani (2019).

  • All of the species of Neogondolella and Magnigondolella described herein are early Anisian in age on the basis of their co-occurrence with ammonoids (Golding and Orchard, 2018, 2016; Grădinaru et al., 2007), and thus allow a more refined division of this sub-stage. They also allow greater precision in correlation of the Tethyan sections with those in North America and higher latitudes, where species such as Chiosella timorensis and Gladigondolella tethydis are rare or absent. For example, Fig. 4 shows a possible correlation of the early Anisian between Deşli Caira, Guandao, and the Mile Post 375 East Section in British Columbia. In particular, the recognition of N. curva and N. hastata in the the Deşli Caira and Guandao sections provides means for correlation with the Mile Post 375 East Section; both of these species have also been recognized in several sections throughout North America (Henderson et al., 2018; Golding and Orchard, 2016).

    Figure 4.  Possible correlation between sections at Deşli Caira and Guandao, and with Mile Post 375 East in British Columbia, based on conodonts. Stratigraphic columns are hung from the first occurrence of Neogondolella curva in each section; however, it is likely that the OAB occurs lower in the Mile Post 375 East Section as Anisian ammonoids occur below this level. Only some stratigraphically useful species of Neogondolella and Magnigondolella are shown. See Golding and Orchard(2018, 2016) for description of conodont faunas at Mile Post 375 East.

    The oldest species of Neogondolella recognized in the Deşli Caira and Guandao sections is N. curva, and it occurs above the first appearance of Chiosella timorensis in both sections. If C. timorensis is considered to be unsuitable as an index for the base of the Anisian due to its co-occurrence with Spathian (Haugi Zone) ammonoids, then one of the younger Neogondolella species may provide a suitable alternative. It is possible that N. curva would make an appropriate index fossil, as it is present in Deşli Caira, Guandao, and several sections in North America. Placement of the OAB at the FO of this species would situate it just below the first Aegean ammonoids at Deşli Caira, Aegeiceras ugra, Paracrochordiceras sp., Japonites sp., Stenopopanoceras sp., and Lenotropites sp. (Grădinaru and Gaetani, 2019), and just below the carbon isotope excursion recorded at this section (Grădinaru et al., 2007). This placement would be within magnetozone MT3 at Deşli Caira (Grădinaru et al., 2007); however, at Guandao, this would place the OAB just below the base of magnetozone MT3 (Li et al., 2018). In British Columbia, N. curva first occurs in the Caurus Zone. Therefore, the suitability of this species for recognition of the OAB appears promising at Deşli Caria, but additional study would be required.

    Alternatively, the species Magnigondolella alexanderi has been recognized in British Columbia, Nevada, and the Youping Section of South China (Chen et al., 2020; Golding and Orchard, 2018), and may be a suitable index fossil. Meço (1999) and Muttoni et al. (2019) also report N. regalis (=Magnigondolella sp.) from Kçira in Albania; however, it is not possible to determine from the illustrations whether these specimens correspond to M. alexanderi. Placing the OAB at the FO of this species would situate it in magnetozone MT1-2 of Hounslow and Muttoni (2010), and within the carbon isotope spike recorded at Wantou (Chen et al., 2020). Both the FO of N. curva and the FO of M. alexanderi are stratigraphically higher than the first occurrence of C. timorensis.

    A potential problem with using a species of Neogondolella or Magnigondolella as an index species is the lack of knowledge of potential ancestors to these genera. For example, it had previously been inferred that Magnigondolella (Neogondolella ex gr. regalis of previous workers) evolved from Chiosella by gaining a platform in the early Anisian (Kozur, 1989). The discovery of conodonts belonging to Magnigondolella in the early Spathian, before the first appearance of Chiosella, makes this evolutionary relationship appear unlikely (Chen et al., 2016; Goudemand et al., 2012; Orchard, 2007; Orchard and Rieber, 1999). Recent work suggests that the ancestor of Magnigondolella may be Borinella, with fusion of the carina occurring in the early Spathian (Michael J. Orchard, personal communication). Neogondolella may evolve from Borinella or Columbitella in the Spathian; however, the limited knowledge of the multielement apparatuses of these genera hinders determination of evolutionary relationships. Without a firm understanding of the ancestry of N. curva or M. alexanderi, it is possible that stratigraphically older examples of these species could be identified subsequently. It is important to note that the evolutionary relationships and ancestry of C. timorensis and Gladigondolella tethydis are not well constrained either.

    In order to determine the suitability of species of Neogondolella or Magnigondolella as an index for the OAB, further work is required on Neogondolellin faunas from other sections such as Kçira and Wantou. The recognition of several new species of Neogondolella and Magnigondolella in Tethys and the improvement in early Anisian correlation that they facilitate, demonstrates the benefit of additional work on other sections where the late Olenekian or early Anisian is preserved, such as Greece, Svalbard, Oman, Japan and Russia (e.g., Muto et al., 2018; Nakrem et al., 2008; Zakharov et al., 2005; Orchard, 1995; Tozer and Calon, 1990; Dagys, 1988; Bender, 1970; Nogami, 1968), and on conodont species outside of those traditionally assumed to be indicative of the OAB (such as Neogondolella, Magnigondolella, and Nicoraella).

    Unitary association analysis will be an important next step to analyse the suitability of different proxies for correlation of the OAB; this has been undertaken in a preliminary fashion by Goudemand et al. (2012) and Ovtcharova et al. (2015), but future analyses will need to utilize more sections and more species. Consistent conodont taxonomy between sections will be necessary, and the work in this paper on Neogondolella and Magnigondolella will need to be expanded to other sections and replicated for other genera including Gladigondolella. As several workers have stated previously, a multi-proxy approach to identifying the OAB will yield the most accurate and reliable correlations (Chen et al., 2020; Henderson, 2019; Muttoni et al., 2019; Grădinaru et al., 2007), and lead to the recognition of a natural boundary for the GSSP, as discussed by Henderson (2019) for the Induan-Olenekian GSSP.

  • Two new species of conodonts have been recognized from the lower Anisian of Deşli Caira, Romania, and Guandao, South China. In addition, three species previously recognized in North America have now been identified in sections from the Tethys for the first time. This leads to an increase in the conodont diversity during this time period, and allows more refined correlation of the lower Anisian between North America and Tethys. One of these species may be a suitable alternative to Chiosella timorensis as an index species for the OAB; however, more work needs to be done on the taxonomy of conodont faunas at other sections in order to identify the most suitable index and location for the GSSP of this boundary.

    SYSTEMATIC PALEONTOLOGY

    The following systematic treatment deals with the Neogondolellin conodonts recovered from samples at Deşli Caira and Guandao. For the synonymies, the Richter standard of notation is adopted (Matthews, 1973). Illustrated specimens are housed at the National Type Collection of Invertebrate and Plant Fossils at the Geological Survey of Canada (GSC) in Ottawa, Ontario, Canada.

    Order Ozarkodinida Dzik 1976

    Family Gondolellidae Lindström 1970

    Subfamily Neogondolellinae Hirsch 1994

    Genus Magnigondolella Golding and Orchard 2018

    Type Species: Magnigondolella salomae Golding and Orchard 2018

    Remarks: This genus was established to encompass the group of Middle Triassic conodonts with high, fused carinas, previously referred to Neogondolella ex gr. regalis. This genus is widespread, with examples occurring in Canada, the USA, and throughout Europe and Asia and may be useful stratigraphically (Chen et al., 2020; Golding and Orchard, 2018).

    Magnigondolella aff. dilacerata (Golding and Orchard, 2016)

    Pl. 2, Figs. 1–3

    v 2014 Neogondolella ex gr. regalis morphotype ζ; Golding, p. 128, figs. 2.35, 1–9.

    v 2014    Neogondolella ex gr. regalis morphotype E; Golding et al., figs. 3, 25–27.

    v* 2016   Neogondolella dilacerata sp. nov.; Golding and Orchard, p. 1204, figs. 8.1–8.9.

    2018   Neogondolella dilacerata: Henderson et al., p. 19.

    Description: P1 element is segminiplanate, with a biconvex platform that has a weakly asymmetrical posterior platform margin. There is no posterior platform brim. A posterior denticle is always present, and it is large and strongly inclined to the posterior.

    Material: 1 specimen.

    Occurrence: Sample OU-9, Guandao.

    Comparisons: The posterior carina of Magnigondolella aff. dilacerata resembles that of Neogondolella prava and N. n. sp. A; however the carina is much higher in M. aff. dilacerata. Some species of N. ex gr. transita have asymmetrical platforms, but they also possess a posterior secondary keel, which is absent in M. aff. dilacerata.

    Remarks: This specimen is referred to Magnigondolella aff. dilacerata due to the weak asymmetry of the posterior end of the element. This differs from the strongly asymmetrical margin of the holotype (Golding and Orchard, 2016, figs. 8.7–8.9) but is close to the range of variability displayed by the species (compare the specimen figured by Golding and Orchard, 2016, figs. 8.4–8.6).

    Magnigondolella n. sp. D

    Pl. 2, Figs. 18–29

    v 2007b    Neogondolella sp., Orchard et al., fig. 6, 4–6.

    v 2010    Neogondolella ex gr. regalis, Orchard, fig. 7, parts 6–8.

    Description: The platform of the P1 element is widest at the midpoint of the element, and tapers evenly to the anterior end. In juveniles, the platform also tapers towards the posterior end, with a slight narrowing of the platform close to the end of the element. With growth, this narrowing of the platform becomes more extensive, and in larger growth stages, the entire posterior half of the element may have a narrowed platform. The posterior end of the element is more pointed in smaller growth stages, becoming more rounded in larger specimens; similarly, a platform brim is absent in smaller specimens but appears with growth. In side view, the element is arched and the platform margins are thin and relatively flat. The carina is high and uniformly fused. In profile the carina is uniform in height, apart from the posterior end where it curves downward with the arch of the element. The cusp is broad and posteriorly inclined, but is not much higher than the adjacent denticles. A posterior denticle is always present, and shares a similar orientation to the cusp, although it is much smaller. The keel is narrow and terminates in a rounded basal loop that surrounds the terminal basal pit.

    Material: 5 specimens.

    Occurrence: Samples UGD-21, GDL-50, OU-8, Guandao.

    Comparisons: Magnigondolella n. sp. D resembles a late Spathian (Subrobustus Zone) species from British Columbia which will be described in an upcoming publication (Michael J. Orchard, personal communication). The specimens from Guandao appear to be conspecific with those from British Columbia, and likely represent the continuation of this species into the Anisian.

    Genus Neogondolella Bender and Stoppel 1965

    Type Species: Gondolella mombergensis Tatge, 1956

    Neogondolella cf. bifurcata (Budurov and Stefanov, 1972)

    Pl. 3, Figs. 4–6

    * 1972    Paragondolella bifurcata sp. nov.; Budurov and Stefanov, p. 843, pl. 1, figs. 1–25; pl. 2, figs. 1–9.

    1975    Gondolella bifurcata, Trammer, pl. 25, fig. 6.

    1975    Gondolella bifurcata, Zawidzka, pl. 43, fig. 1.

    1976   Neogondolella bifurcata; Nicora, pl. 84, figs. 10, 12.

    1980    Gondolella bifurcata; Kovács and Kozur, pl. 2, figs. 5–7.

    1980 Gondolella prava; Szabó et al., pl. 59, figs. 12, 13.

    1980    Neogondolella bifurcata; Pisa et al., pl. 60, figs. 5–7.

    1982    Gondolella bifurcata; Sudar, pl. 2, figs. 2–6; pl. 3, figs. 1–2.

    1983    Neogondolella bifurcata; Kolar-Jurkovšek, p. 336, pl. 7, figs. 1, 2; pl. 8, figs. 1, 2.

    1984    "Gondolella" bifurcata; Farabegoli et al., fig. 5, part e.

    p 1986    Gondolella bifurcata; Kovács and Papšová, pl. II, figs. 1, 2, only.

    1997    Gondolella bifurcata bifurcata; Pevný and Salaj, pl. IX, figs. 3, 4, 7, 13.

    2003    Gondolella bifurcata; Kovács, pl. C-V, parts 1–6; pl. C-VI, parts 1–5; pl. C-VII, part 1.

    p 2005 Gondolella bifurcata; Kovács and Rálisch- Felgenhauer, pl. XII, fig. 2; pl. XIV, fig. 2 only.

    2006    Paragondolella bifurcata; Sun et al., pl. 1, figs. 11–15.

    v 2015    Neogondolella bifurcata; Golding et al., p. 156.

    v 2018    Neogondolella bifurcata; Henderson et al., p. 14.

    Description: P1 element is segminiplanate, with a wedge shaped platform and blunted posterior platform margin with a very narrow brim behind the cusp. The platform is flat and tapers to the anterior. The carina is high at the anterior end of the element and becomes lower at the posterior end, where it is bifurcated with at least one denticle offset on one or both sides of the carina.

    Material: 1 specimen.

    Occurrence: Sample OU-31, Guandao.

    Comparisons: Neogondolelaa hanbulogi (Sudar and Budurov) has a similar platform shape to N. cf. bifurcata, but its platform margins are more strongly upturned. Specimens of N. bulgarica (Budurov and Stefanov) have a higher carina and a terminal cusp with no posterior platform brim. Neither of these species exhibit posterior bifurcation of the carina.

    Remarks: This species resembles Neogondolella bifurcata; however, as there is only one fragmentary specimen, this assignment cannot be made with confidence.

    Neogondolella curva Golding and Orchard 2016

    Pl. 1, Figs. 1–12; Pl. 2, Figs. 9, 10; Pl. 3, Figs. 24, 25

    v 2014    Neogondolella n. sp. H; Golding, p. 156, fig. 2.49, 1–12

    v* 2016    Neogondolella curva sp. nov.; Golding and Orchard, p. 1203, fig. 7, 1–9

    2018    Neogondolella curva; Henderson et al., p. 19

    Description: P1 element is segminiplanate, with a convex outer platform margin and an indented inner platform margin. The platform is widest at the midpoint, and the posterior margin varies from rounded to sub-quadrate in outline. The carina is deflected laterally in the posterior part of the element, and is relatively high. The denticles are free in smaller specimens, and become more fused with growth. The cusp may be terminal or a posterior denticle may be present.

    Material: 8 specimens.

    Occurrence: Sample 204/5, Deşli Caira; samples OU-11, OU-21, Guandao.

    Comparisons: Some younger species belonging to the genus Budurovignathus, such as B. hungaricus, show a similar platform shape to Neogondolella curva; however, the basal pit in Budurovignathus is commonly located in a more anterior position than that of N. curva.

    Remarks: Small specimens of Neogondolella curva from North America appear to show a greater degree of posterior platform constriction than those from Romania and South China (e.g., Golding and Orchard, 2016, fig. 7, 1–3).

    Neogondolella hastata Golding and Orchard 2016

    Pl. 3, Figs. 7–18

    vp 1973    Neogondolella mombergensis (Tatge); Mosher, pl. 19, figs. 4, 6 only

    v 1997    Neogondolella n. sp. N; Orchard and Tozer, p. 682

    v 2014    Neogondolella n. sp. A; Golding, p. 142, fig. 2.42, 1–13

    v 2014    Neogondolella n. sp. N sensu Orchard and Tozer; Golding et al., fig. 3, 16–18

    v* 2016    Neogondolella hastata sp. nov.; Golding and Orchard, p. 1205, fig. 9, 1–13

    Description: P1 element is segminiplanate, with a narrow, biconvex platform that tapers to a point at both the anterior and posterior ends. The cusp is large, inclined and terminal, with no posterior platform brim present. The carina is low with discrete denticles, becoming more fused with growth.

    Material: 14 specimens.

    Occurrence: Samples 9045, 612, 9048, 615b, Deşli Caira; sample OU-30, Guandao.

    Comparisons: The early Anisian Neogondolella n. sp. E and younger species belonging to N. ex gr. constricta also have slender biconvex platforms, but N. hastata can be differentiated from these by its lack of a posterior platform constriction and the terminal nature of the cusp. The cusp of N. gradinarui is also large, however the posterior platform is much wider than in N. hastata, and the carina of N. gradinarui is commonly higher and more fused.

    Remarks: The occurrences of Neogondolella hastata in Romania and South China represent the oldest records of this species, which appears to range all the way into the Ladinian in North America (Poseidon Zone; Mosher, 1973).

    Neogondolella cf. prava (Kozur 1968a)

    Pl. 2, Figs. 15–17

    * 1968a    Gondolella (Gondolella) mombergensis prava subsp. nov., Kozur, p. 933, pl. II, figs. 2a, 2b.

    1968b    Gondolella (Gondolella) mombergensis prava, Kozur, p. 941, pl. 2, fig. 2.

    1971    Gondolella (Gondolella) mombergensis prava, Trammer, pl. 2, fig. 8.

    ? 1972    Gondolella prava, Kozur, p. 27, pl. 5, fig. 5.

    ? 1973    Gondolella prava, Głazek et al., fig. 1.

    1975    Gondolella prava, Zawidzka, p. 253, pl. 41, fig. 5.

    1977    Neogondolella prava, Rafek, pl. 4, figs. 28, 29; pl. 5, fig. 30.

    1999    Neogondolella prava, Narkiewicz, pl. II, figs. 6, 7.

    2019    Neogondolella prava, Chen et al., p. 12, fig. 6, M–O.

    Description: The P1 element is segminiplanate, with an elongate, oval-shaped platform that is widest just posterior of the middle part of the element. The carina is low in the middle, becoming higher at both the anterior and posterior ends of the element, and the denticles are well fused. The inclined cusp is located at the posterior end of the platform, and a small accessory denticle is always present to the posterior of the cusp, offset laterally.

    Material: 1 specimen.

    Occurrence: Sample OU-19, Guandao.

    Comparisons: Specimens of Neogondolella mombergensis have a similar carina to that of N. cf. prava, however the platform of N. cf. prava is broader and the accessory denticle is absent in N. mombergensis. The posterior denticulation of N. cf. prava is reminiscent of that of N. bifurcata, which differs in its more upright cusp and more quadrate posterior platform margin.

    Remarks: This specimen is morphologically very close to Neogondolella prava; however, this species typically occurs in much younger strata (Pelsonian), and although it is common in the Germanic Basin and western Tethys, this would be the first description of the species from South China. As such, it is considered most appropriate to refer to this specimen as N. cf. prava, at least until additional specimens are recovered.

    Neogondolella gradinarui sp. nov. Golding and Orchard

    Pl. 1, Figs. 16–32

    v 2007a    Neogondolella sp., Orchard et al., fig. 5, 35–37

    Holotype: Specimen GSC Type No. 101578, Pl. 1, Figs. 24–26.

    Type locality: Sample 9043, Deşli Caira Section, Romania.

    Etymology: Named for Eugen Grădinaru of the University of Bucharest, in recognition of his research on the stratigraphy of the Olenekian and Anisian, particularly of the Deşli Caira Section.

    Diagnosis: P1 element is segminiplanate, with a biconvex platform that is widest in the posterior half of the element. The carina is relatively high and fused, and the cusp is large, terminal and inclined to the posterior.

    Description: The biconvex platform of the P1 element is widest in the posterior half of the element, and it terminates in a broadly rounded to sub-quadrate posterior margin. To the anterior, the platform tapers evenly to the end of the element where it leaves no free blade. In side view, the element is arched, and the platform margins are thin and slightly upturned, becoming thicker with growth. The carina is moderately high and weakly fused, with denticles becoming more discrete to the anterior. The profile of the carina is curved. The cusp is large, posteriorly inclined, and commonly terminal, although in some of the largest specimens a posterior platform brim may be present. The keel is narrow and terminates in a basal loop that varies from sub-rounded to sub-quadrate with growth, and surrounds the terminal basal pit.

    Material: 25 specimens.

    Occurrence: Samples 9043, 9044, 612, 9049 Deşli Caira; samples OU-23, OU-29, OU-30, OU-31, Guandao.

    Comparisons: See above for comparisons between this species and Neogondolella hastata. The large cusp of N. gradinarui is reminiscent of that of the younger N. cornuta, which differs in possessing a much less fused carina.

    Neogondolella n. sp. A

    Pl. 1, Figs. 13–15

    Description: The biconvex platform of the P1 element is widest at the midpoint or just to the posterior of it. The platform remains broad to the posterior of the element, and the posterior margin is sub-rounded to pointed. To the anterior, the platform decreases in width in the final third of the element, continuing to the anterior end as a narrow platform. The platform may also be laterally deflected in the anterior third. In side view, the element is relatively straight, and the platform margins are upturned. The carina is low but well fused, and of uniform height. The carina transitions into a fixed blade at the anterior end of the element. The carina is small, only slightly large than the adjacent denticles, and upright. A posterior denticle is commonly present, and there is no platform brim. The keel is low and narrow, terminating in a small, rounded basal loop that surrounds the sub-terminal basal pit.

    Material: 3 specimens.

    Occurrence: Sample OU-21, Guandao.

    Comparisons: Neogondolella n. sp. A differs from N. gradinarui in lacking the large posterior cusp of the latter species, and by having the widest part of the platform occurring at mid-length. Unpublished specimens from the early Anisian of British Columbia resemble N. n. sp. A, which may indicate the occurrence of this species in Panthalassa as well as in Tethys; however, the North American material is too sparse to be confidant of this assignment. Therefore, the species is kept in open nomenclature until additional material can be identified.

    Neogondolella n. sp. B

    Pl. 2, Figs. 4–8

    Description: The biconvex platform of the P1 element is widest at the midpoint or in the posterior half of the element, and it remains wide until the posterior end, where it terminates in a broad, rounded to sub-rounded posterior margin, where a narrow platform brim may be present. From the widest point, the platform tapers evenly to anterior end of the element, leaving no free blade. In side view, the element is arched, and the platform margins are slightly upturned. The carina is relatively high and fused, with the denticles becoming more discrete towards the anterior and posterior ends. In upper view, the carina is deflected laterally in the anterior half of the element. The cusp is slightly larger than the neighbouring denticles, and is clearly separated and inclined. A posterior denticle is present in one of the specimens, and a posterior platform brim is present in one specimen. The keel is low and narrow, terminating in a small rounded basal loop that surrounds the terminal basal pit.

    Material: 2 specimens.

    Occurrence: Sample 9048, Deşli Caira; sample OU-10, Guandao.

    Comparisons: The deflected carina differentiates Neogondolella n. sp. B from all other species of Neogondolella in the early Anisian. Some specimens of Magnigondolella salomae show a similar kinked carina, but the carina of M. salomae is much higher and uniform in height than that of Neogondolella n. sp. B. The species is kept in open nomenclature due to the small number of specimens identified thus far.

    Neogondolella ex gr. constricta

    Pl. 3, Figs. 29–35

    * 1965    Gondolella constricta sp. nov., Mosher and Clark, p. 560, pl. 79, figs. 6–8.

    1968    Gondolella constricta, Mosher, p. 937, pl. 116, figs. 65, figs. 11, 14, 15, 18, 19, 21, 22, 24, 25.

    1975    Gondolella constricta, Zawidzka, pl. 42, figs. 1, 3.

    1975    Gondolella constricta; Trammer, pl. 24, figs. 2, 3, 7.

    1976    Neogondolella constricta; Wang and Wang, p. 407, figs. 3, 4, 7, 11.

    p 1977    Neogondolella constricta; Rafek, p. 35, pl. IV, figs. 23–25, 30 only.

    1980    Gondolella constricta; Kovács and Kozur, pl. 3, fig. 4.

    1983    Neogondolella constricta; Kolar-Jurkovšek, p. 339, pl. 9, figs. 1, 2.

    1984    Gondolella constricta, Nicora and Kovács, p. 144, pl. 7, figs. 1, 4, 8, 9, 10, 11, 12, 14; pl. 8, fig. 3

    p 1997    Gondolella constricta; Pevný and Salaj, pl. X, figs. 1–2 only

    2000    Neogondolella constricta; Marquez-Aliaga et al., pl. 4, figs. 8–13.

    2006    Neogondolella constricta; Sun et al., p. 625, pl. I, 21–24.

    v 2014    Neogondolella ex gr. constricta; Golding, p. 99, figs. 2.22–2.27.

    v 2018    Neogondolella ex gr. constricta; Henderson et al., pl. 1, parts 1–3.

    Description: P1 element is segminiplanate, with a very narrow, biconvex platform that is constricted at the posterior end. The carina is relatively low and the denticles are discrete. The carina is large and posteriorly inclined, and a posterior denticle of similar size and orientation is always present. There is no platform brim.

    Material: 16 specimens.

    Occurrence: Samples 9044, 9045, 9046, 9048, Deşli Caira; samples OU-23, OU-31, Guandao.

    Comparisons: Neogondolella ex gr. constricta differs from N. hastata by the presence of a posterior platform constriction, and an accessory denticle posterior to the prominent cusp.

    Remarks: The Neogondolella constricta group encompasses a wide range of conodonts with a variety of morphologies. This group is currently undergoing taxonomic revision based on material from North America (Golding, 2014) and Europe. The examples from Deşli Caira show similarity with specimens previously referred to N. aldae, N. posterolonga, and N. constricta sensu stricto; for now it is considered most appropriate to refer these specimens to N. ex gr. constricta pending the completion of the taxonomic revision. The oldest reported species of N. ex gr. constricta are from the Pelsonian of Hungary, Slovakia, Slovenia and Bosnia (Pevný and Salaj, 1997; Sudar, 1986; Kolar-Jurkovšek, 1983; Kovács and Kozur, 1980); the specimens from Deşli Caira occur above the level of the ammonite Aegeiceras ugra and are therefore likely to be Bithynian. However, similar species have been recognised in the Spathian of British Columbia and Nevada (Subrobustus Zone and Haugi Zone; Michael J. Orchard, personal communication), which suggests that these Bithynian specimens from Deşli Caira and Guandao may not be related to true N. constricta.

    Figure Plate 1.  1–12. Neogondolella curva Golding and Orchard; 1–3. GSC Type No. 139583; 4–6. GSC Type No. 139584, both sample OU-21, Guandao; 7–9. GSC Type No. 139585, sample OU-11, Guandao; 10–12. GSC Type No. 139586, sample 204/5, Deşli Caira. 13–15. Neogondolella n. sp. A, GSC Type No. 139587, sample OU-21, Guandao. 16–32. Neogondolella gradinarui sp. nov; 16–18. GSC Type No. 139588, sample 9049, Deşli Caira; 19–20. GSC Type No. 139589, sample 9044, Deşli Caira; 21–23. GSC Type No. 139590, sample OU-29, Guandao; 24–26. GSC Type No. 101578, sample 9043, Deşli Caira (holotype); 27–29. GSC Type No. 139591 sample OU-30, Guandao; 30–32. GSC Type No. 139592, sample 612, Deşli Caira. Scale bar=200 μm.

    Figure Plate 2.  1–3. Magnigondolella aff. dilacerata (Golding and Orchard), GSC Type No. 139593, sample OU-9, Guandao. 4–8. Neogondolella n. sp. B; 4–6. GSC Type No. 139594, sample OU-10, Guandao; 7–8. GSC Type No. 139595, sample 9048, Deşli Caira. 9–10. Neogondolella curva Golding and Orchard, GSC Type No. 139596, sample OU-24, Guandao. 11–14. Neogondolella spp.; 11, 12. GSC Type No. 139597; 13, 14. GSC Type No. 139598, both sample 9044, Deşli Caira. 15–17. Neogondolella cf. prava (Kozur), GSC Type No. 139599, sample OU-19. 18–29. Magniondolella n. sp. D; 18–20. GSC Type No. 139600, sample OU-9, Guandao; 21–22. GSC Type No. 139601, sample UGD-21, Guandao; 23–25. GSC Type No. 101543; 26, 27. GSC Type No. 139602, both sample GDL-50, Guandao; 28–29. GSC Type No. 139603, sample OU-8, Guandao. Scale bar=200 μm.

    Figure Plate 3.  1–3, 21–23, 26–28. Neogondolella spp.; 1–3. GSC Type No. 139604, sample 609, Deşli Caira; 21–23. GSC Type No. 139605, sample OU-31, Guandao; 26–28. GSC Type No. 139606, sample 9043, Deşli Caira. 4–6. Neogondolella cf. bifurcata (Budurov and Stefanov), GSC Type No. 139607, sample OU-31, Guandao. 7–20. Neogondolella hastata Golding and Orchard; 7–9. GSC Type No. 139608, sample 9048, Deşli Caira; 10–12. GSC Type No. 139609, sample OU-30, Guandao; 13–15. GSC Type No. 139610, sample 612, Deşli Caira; 16–18. GSC Type No. 139611, sample 615b, Deşli Caira; 19–20. GSC Type No. 139612, sample 9045, Deşli Caira. 24–25. Neogondolella curva Golding and Orchard, GSC Type No. 139613, sample OU-27, Guandao. 29–35. Neogondolella ex gr. constricta (Mosher and Clark); 29, 30. GSC Type No. 139614, sample 9045, Deşli Caira; 31, 32. GSC Type No. 139615; 33–35. GSC Type No. 139616, both sample 9048, Deşli Caira. Scale bar=200 μm.

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