Journal of Earth Science, Vol. 26, No. 2, p. 219–223, April 2015 ISSN 1674-487X Printed in China DOI: 10.1007/s12583-015-0534-y

The Case of the Carnian (Triassic) Conodont Genus Metapolygnathus Hayashi

Ali Murat Kiliç*1, Pablo Plasencia2, Keisuke Ishida3, Francis Hirsch4 1. Department of Geological Engineering, Balıkesir University 10145, Balıkesir, Turkey 2. Department of Geology and ICBIBE, University of Valencia, Dr. Moliner 50. 46100, Burjassot, Spain 3. Laboratory of Geology, Faculty of Sciences, Tokushima University, Tokushima 770-8502, Japan 4. Laboratory of Geology, Faculty of Sciences, Naruto University, Naruto 772-8502, Japan

ABSTRACT: Successive evolutionary trends control the genera Paragondolella Mosher and Meta- polygnathus Hayashi over the about 20 Ma long Aegean–Tuvalian timespan. In consideration of their evolutionary criteria, these genera have been retained together with Carnepigondolella Kozur and the two new genera proposed herein, Mazzaella (type species M. carnica) and Hayashiella (type species H. nodosa). Mazzaella n. gen. represents a Late Julian side branch of Metapolygnathus, harbouring a plat- form ornamentation similar to the several million years younger Tuvalian lineage of Carnepigondolella, issued from Hayashiella n. gen. that is intermediary between Metapolygnathus and Carnepigondolella, based on appearance and platform ornamentation. KEY WORDS: Carnian, conodont, phylogeny, evolutionary trend.

0 INTRODUCTION polygnathiformis (Budurov and Stefanov), M. acuminatus Or- The beginning of the Carnian (Upper Triassic) is marked chard, M. intermedius Orchard, M. zonneveldi Orchard, and M. by the extinction of many conodont forms that characterized lobatus Orchard. For the Tuvalian, Orchard (2007b) listed M. the Middle Triassic; one of the survivors, the genus Paragon- carpathicus (Mock), M. nodosus Hayashi, M. noah Hayashi, M. dolella, diversified during the Carnian in one of the last sig- aff. communisti, M. echinatus (Hayashi), M. parvus Kozur, M. nificant events of radiation that conodonts experimented. The stephanae Orchard, M. polygnathiformis (Budurov and Ste- nature and evolutionary relationships of the many lineages fanov), M. communisti Hayashi, M. reversus (Mosher), M. descendant from Paragondolella have been a subject that in- pseudoechinatus Kozur, M. samueli Orchard, M. pseudodiebeli cited vivid debate during the last decades. (Kozur), M. zoae Orchard, M. lindae Orchard, and M. primitius It was Hayashi (1968) who established the genus Meta- (Mosher). Orchard (2007b) redefined the variations within the polygnathus, encompassing the species M. communisti (type), genus in terms of lineages, based on following morphological M. linguiformis and M. noah. Hayashi (1987) put the species criteria: (1) platform margin profile; (2) pit position; (3) blade that he attributed to the genus Gladigondolella, on the base of length; (4) posterior carina development; (5) node distribution, their centrally located basal pit, to Metapolygnathus echinatus and (6) platform shape. However, Orchard (2013) restricted the (Hayashi), M. nodosus Hayashi, M. abneptis permicus (Hayashi) genus Metapolygnathus to only two groups: communisti and and M. spatulatus (Hayashi). parvus, introducing new genera to accommodate each of his Notwithstanding that Mosher (1973) admitted the priority other six lineages, judging Paragondolella and of Metapolygnathus Hayashi 1968 over Paragondolella Metapolygnathus as inappropriate. Mosher 1968, both genera have been used indistinctly for dec- Significant was the numerical cladistic analysis that led ades. Later, Budurov (1977), Budurov and Sudar (1990) and Mazza et al. (2012a) to recognise three different lineages: Buryi (1996) limited the definition of Metapolygnathus to bifid Paragondolella-Norigondolella, Paragondolella-Metapolygnathus morphs derived from evolved Paragondolella, using the taxon and Paragondolella-Carnepigondolella-Epigondolella, in which Ancyrogondolella Budurov (1972: type A. triangularis) for the genus Metapolygnathus consists of M. praecommunisti Mazza, extreme bifid forms. Rigo and Nicora, M. mersinensis Kozur and Moix, M. cf. primitius Orchard (2007a, 1991a, b, 1983) included into Meta- (Mosher), M. linguiformis Hayashi, M. communisti Hayashi, M. polygnathus the Julian species M. tadpole (Hayashi), M. echinatus (Hayashi) and M. parvus Kozur. In considering the resulting phylogeny from Aegean *Corresponding author: [email protected] through Tuvalian forms, based on the development of a free © China University of Geosciences and Springer-Verlag Berlin blade and bifurcation of the basal cavity, it appears justified to Heidelberg 2015 maintain Paragondolella as the ancestor of Metapolygnathus. While the former genus conforms with smooth (naked) “all Manuscript received October 13, 2014. platform” units without significant free blade, the latter is Manuscript accepted November 24, 2014. characterized by oscillating between “fair platform” units with

Kiliç, A. M., Plasencia, P., Ishida, K., et al., 2015. The Case of the Carnian (Triassic) Conodont Genus Metapolygnathus Hayashi. Journal of Earth Science, 26(2): 219–223. doi:10.1007/s12583-015-0534-y 220 Ali Murat Kiliç, Pablo Plasencia, Keisuke Ishida and Francis Hirsch short free blades and “residual” platforms with an “almost all” The genus Carnepigondolella Kozur (Type species: free blade. Moreover, forms classified as Metapolygnathus that Metapolygnathus zoae Orchard), according to the original di- developed platform ornamentation in the form of increasing agnosis, adopted by Mazza et al. (2010), a long to moderately numbers of marginal nodes and denticles are classified into the long platform, bears nodes or short node-like denticles on the genus Carnepigondolella. anterior part of the platform and often on its entire length. The In the present paper we analyse some of the difficulties free blade, when present, is short to moderately long. The basal generated by the wide morphological discrepancies between the cavity is sub-terminal with respect to the keel end and to the ornamented Carnian taxa, as already sensed by our predeces- platform, or it may be slightly forward shifted, but it always sors. lies distinctly behind the middle of the platform. The keel ter- mination is broadly rounded, blunt or little bifurcated, but never 1 CASE pointed. We summarise the respective original diagnoses. Orchard (2007b) observed that platform shapes and orna- The genus Paragondolella Mosher (Type species: P. ex- ment vary in all Carnepigondolella Kozur species, but that the celsa Mosher) is defined in Mazza et al. (2010) by a character- progressive platform morphogenesis, blade ratio and anterior istic lower side with a subterminal to backward shifted pit, with migration of the pit are distinctive. respect both to keel and platform (Kozur, 1989; Mosher, 1968). Summing up, the array of species referred to the genus has The platform is rounded or blunt at the posterior end, while it varied over the years and according to the authors. For Orchard may extend completely to the anterior end or leave a short free (2007b), Carnepigondolella Kozur includes C. zoae (=Orchard, blade. Platform margins never bear any nodes. The keel is nar- 1991a, sp. F), C. samueli (=Orchard, 1991a, sp. G), C. “pseu- row or broad and its termination may be pointed, squared or doechinata” Kozur as well as Epigondolella orchardi Kozur, rounded, but never bifurcated. This long living taxon evolved Metapolygnathus nodosus Hayashi, Gondolella carpathica during the Early Anisian, persisted until the Carnian, when its Mock, Metapolygnathus lindae (=Orchard, 1991a, sp. E), M. advanced form-characteristics eventually evolved into pseudodiebeli (Kozur) and Epigondolella carnica Krystyn. At Metapolygnathus. Pizzo Mondello, Mazza et al. (2012b) listed Carnepigondolella The genus Metapolygnathus Hayashi (Type species: M. baloghi (Kovacs), C. nodosa (Hayashi), C. orchardi (Kozur), C. communisti) is characterized for Mazza et al. (2010) by a lack carpathica (Mock), C. tuvalica Mazza and Rigo, C. pseu- of denticles on the platform margins and the forward-shifted dodiebeli, C. zoae (Orchard), C. angulata Mazza, Cau and Rigo, position of the pit in respect to keel end. The lower side has a C. samueli (Orchard), C. pseudoechinata (Kozur), and C. gul- very narrow basal cavity, centrally located in juvenile speci- loae Mazza and Rigo. Orchard (2013) added C. pseudodiebeli mens to strongly forward-shifted in advanced forms. The posi- (Kozur), C. samueli (Orchard), C. zoae (Orchard), C. eozoae tion of the pit is advanced with respect to both platform and (Orchard), and C. medioconstricta (Orchard). keel end (Kozur, 2003). The robust platform generally lacks Consequently, as platform ornamentation became a key ornamentation. In some species a few nodes may be present, criterion in classification of species within the genus Meta- but they are always confined to the anterior platform or in cor- polygnathus, discrepancies could not be preserved under “one respondence to the geniculation point. A distinct free blade is roof”. This has resulted in the redefinition of existing genera, present, with a high carina with highly fused denticles. The keel such as Paragondolella, but also in the introduction of addi- end is often, but not necessarily, bifurcated. tional genera, such as Carnepigondolella. Orchard (2013) has In the case of M. samueli Orchard, which corresponds to introduced five new genera for mostly endemic Orchard’s (1991a) sp. G, Mazza et al. (2010) wrote that the North-American taxa. basal cavity is sub-terminal with respect to keel end and plat- At a more accurate glance, it clearly appears that all crite- form, or slightly forward shifted, but always distinctly behind ria, such as relations between platform and free blade, platform the middle of the platform. The platform is long to moderately shape, position and shape of the basal cavity or the distribution long and it bears nodes or short node-like denticles on the ante- of platform nodes, respond to evolutionary trends within the 20 rior part of the platform and often on its entire length. The free Ma long Paragondolella-Metapolygnathus phylogenetic line- blade, when present, is short to moderately long. The keel ter- ages. mination is broadly rounded, blunt or little bifurcated, but never pointed (Kozur, 2003). 2 EVOLUTIONARY TRENDS Mazza et al. (2012a) added M. praecommunisti Mazza, The main evolutionary trends during the Ladinian-Carnian Rigo and Nicora and considered further M. communisti Hayashi, interval is the emergence of Metapolygnathus from Paragon- M. echinatus Orchard, M. linguiformis Hayashi, M. mersinensis dolella by (a) the reduction of the platform and development of Kozur and Moix, and M. parvus Kozur, as part of the genus, all a free blade (M. tadpole Hayashi) and (b) the trend of splitting other species being redistributed in the re-defined genera the basal groove (Budurov, 1977). Further development of free Paragondolella and Carnepigondolella. blades and widening of the posterior end by bifurcation of the Carter and Orchard (2013) only figured Metapolygnathus basal cavity, characterize post-Ladinian Metapolygnathus, but ex gr. communisti Hayashi and M. ex gr. parvus Kozur, while increased platform ornamentation is by far the most important in the same year Orchard (2013) introduced new genera to ac- criterion (Fig. 1). Starting from (i) smooth to very low orna- commodate most other species, judging Paragondolella and mentation (e.g., polygnathiformis-communisti-parvus) to (ii) Metapolygnathus as inappropriate. slightly nodose (carpathicus-nodosus), (iii) strongly nodose

The Case of the Carnian (Triassic) Conodont Genus Metapolygnathus Hayashi 221

(baloghi-carnica; zoae-echinata) and finally (iv) denticulated (orchardi-triangularis). We have retained (i) into Metapolyg- nathus, which remains conform with most other authors; for (ii), we introduce Hayashiella n. gen.; (iii) corresponds to two line- ages, a Late Julian Mazzaella n. gen. and Tuvalian Carnepi- gondolella; while (iv) belongs in Ancyrogondolella Budurov. Epigondolella is herein considered mainly a junior synonym of Metapolygnathus, with part of its species reassigned to other genera.

2.1 Systematic Paleontology Class Conodonta Eichenberg, 1930 Order Ozarkodinida Dzik, 1976 Superfamily Gondolelloidea Lindström, 1970 Family Gondolellidae Lindström, 1970

Genus Hayashiella n. gen., Fig. 2 Type species: Metapolygnathus nodosus Hayashi 1968. Derivation of the name: After Shingo Hayashi, Omama City, Gunma Prefecture, Japan. Type level: Tuvalian. Diagnosis: Platform edges are smooth over most of their length, with characteristic nodes in their anterior part. The platform varies from narrow (H. nodosus) to wide and piriform

(H. carpathica) or narrower and constricted (H. lindae). Carina is high with fused (H. carpathica) or well developed denticles Figure 2. Main morphology and structure of Hayashiella n. (H. nodosa). Short free blade (carpathica, lindae) to medium gen.. Figures are drawings from the original holotype of (nodosus, permica). The cusp lies at the end of the carina. Metapolygnathus nodosus (Hayashi, 1968). Keel-end is slightly quadrate, blunt or bifurcated. The basal cavity lies below the small cusp, sub-terminal or slightly There are direct phylogenetic links with its ancestor Meta- forward-shifted with respect to the platform. polygnathus and the Late Tuvalian offspring Carnepigon- Lineage: The lineage of Hayashiella n. gen. derives from dolella. the smooth platform Metapolygnathus Hayashi lineage and is Remark: Orchard (2007a) used the term “group” for what composed of H. carpathica (Mock), H. nodosa (Hayashi), H. he called the most commonly identified elements of Late lindae (Orchard) and H. permica (Hayashi). Carnian age. As such figures the Metapolygnathus carpathicus- Range: Tuvalian. M. nodosus group (Orchard, 2007a: Plate 1, Figs. 9–31; Or- Discussion: Hayashiella differs from Metapolygnathus, chard, 2007b: Figs. 1: 1–3, 10–12, 19–21) that “has tradition- only by having nodes on the anterior edge of the platform. ally been regarded as evolving from the ubiquitous Lower Carnian species Metapolygnathus polygnathiformis (Budurov and Stefanov 1965), which typically lacks platform ornament, through progressive development of anterior platform nodes, first on the anterior margins of the anterior platform, as in M. carpathicus (Mock 1979), and then on the upper margins, as in M. nodosus (Hayashi 1968).” Genus Mazzaella n. gen. Fig. 3 Derivation of the name: after Michele Mazza, Milano University, Milano, Italy. Type species: Epigondolella carnica Krystyn (1975). Type level: Late Julian. Diagnosis: Platform rather wide (half to one third of total length), with strong nodes on the margin. Carina is high with Figure 1. Phylogenetic tree of the ornamented gondolellid fused denticles. Medium free blade, nearly half total length. Julian and Tuvalian lineages: Metapolygnatus-Mazzaella and The cusp lies at the end of the carina. Keel-end is rounded, Metapolygnathus-Hayashiella-Carnepigondolella, showing from blunt or bifurcated. The basal cavity lies below the cusp and left to right the evolution from smooth platform edges to nodose sub-terminal or slightly forward-shifted with respect to the platforms. platform.

222 Ali Murat Kiliç, Pablo Plasencia, Keisuke Ishida and Francis Hirsch

After these recent discussions, we propose a revision of the main genera that evolved during the Carnian. From Para- gondolella evolved Metapolygnathus, which diversified in four branches or lineages, distinguishable by the degree of devel- opment of the marginal platform nodes. Two of these lineages correspond to the preexistent genera Metapolygnathus and Ancyrogondolella. To formalize the significance of the other two lineages we propose two new genera, Hayashiella and Mazzaella that can help to understand the evolutionary tendencies of the group during the Carnian. Both genera evolved from smooth repre- sentatives of Metapolygnathus. Mazzaella n. gen. evolved in the Late Julian by developing strongly nodose forms, extinct by the Early Tuvalian with no descendants or phylogenetic link to the Tuvalian Carnepigon- dolella lineage. Hayashiella n. gen. evolved in the Early Tuvalian by de- veloping species with moderate anterior marginal nodes that represent the link between Metapolygnathus and Carnepigon- dolella. Carnian conodonts, instead of being represented only by the genus Metapolygnathus Hayashi on grounds of priority, are at present based on evolutionary criteria. These consist in a number of trends, progressive platform reduction or develop- ment of a free blade, broadening of the posterior platform end with development of a bifid basal cavity, and increasing orna- mentation of the platform borders. Figure 3. Main morphology and structure of Mazzaella n. gen. Figures are drawings from the original holotype of REFERENCES CITED Epigondolella carnica (Krystyn, 1975). Budurov, K., Stefanov, S. 1965. Gattung Gondolella aus der Trias Bulgariens. Trav. sur Géol. Bulg., sér. Paéeont., (7): Lineage: the Mazzaella lineage derives from Metapolyg- 115–127 nathus auriformis (Kovacs) that has still a smooth platform Budurov, K. J., 1972. Ancyrogondolella Triangularis gen. et sp. with a possible constriction and large free blade. Mazzaella n. (Conodonta). Mitteilungen der Gesellschaft der baloghi (Kovacs) is characterized by a platform with strong Geologie-und Bergbaustudenten, 21: 853–860 nodes and a large free blade, while M. carnica Budurov, K. J., 1977. Revision of the Late Triassic Platform (Krystyn) has a shorter free blade and a slightly narrower plat- Conodonts. Geologica Balcanica, 7: 31–48 form. Budurov, K. J., Sudar, M. N., 1990. Late Triassic Conodont Array: M. carnica, M. baloghi. Stratigraphy. In: Ziegler, W., ed., 1st International Senck- Range: Late Julian. enberg Conference and 5th European Conodont Sympo- Discussion: Mazzaella n. gen. differs from Carnepigon- sium (ECOS V) Contributions IV. Papers on Conodonts dolella Kozur (2003) by having a longer free blade and a rela- and Ordovician to Triassic Conodont Stratigraphy. Cou- tively broader platform without constriction. There is no ap- rier Forschungsinstitut Senckenberg, 118: 203–240 parent or direct phylogenetic link between the Late Julian Buryi, G. I., 1996. Evolution of Late Triassic Conodont Plat- Mazzaella branch, derivable from M. auriformis (Kovacs), and form Elements. Acta Micropaleontol. Sinica, 13(2): the Late Tuvalian Carnepigondolella lineage that begins with C. 135–142 zoae (Orchard), the ancestry of which may be derived from Carter, E., Orchard, M. J., 2013. Intercalibration of Conodont Hayashiella lindae (Orchard). and Radiolarian Faunas from the Carnian-Norian Boundary Interval in Haida Gwaii, British Columbia, 3 CONCLUSIONS Canada. In: Tanner, L. H., Spielmann, J. A., Lucas, S. G., The diversification of Paragondolella during the Carnian eds., The Triassic System. New Mexico Museum of Natu- is one of the last significant evolutionary events of the history ral History and Science, 61: 67–92 of conodonts; complex in its nature, the extent and complexity Hayashi, S., 1968. The Permian Conodonts in Chert of the of which has been subject of an important debate by specialists. Adoyama Formation, Ashio Mountains, Central Japan. This situation has caused discrepancies in the criteria used by Earth Science (Chikyu Kagaku), 22: 63–77 the different authors to discriminate between the implied taxa, Hayashi, S., 1987. Conodont Arekore. Geoscience Magazine, subtle in some cases but contradictory in others. Chigaku Kenkyu, 37: 1–16 (in Japanese) Kozur, H. W., 1989. The Taxonomy of the Gondolellids

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