Icriospathodus zaksi ( Buryi, 1979 )

Leu, Marc, Bucher, Hugo, Vennemann, Torsten, Bagherpour, Borhan, Ji, Cheng, Brosse, Morgane & Goudemand, Nicolas, 2022, A Unitary Association-based conodont biozonation of the Smithian-Spathian boundary (Early Triassic) and associated biotic crisis from South China, Swiss Journal of Palaeontology (19) 141 (1), pp. 1-61 : 44

Icriospathodus zaksi ( Buryi, 1979)

Fig. 25A–F

*1979 Neospathodus zaksi Buryi , p. 60 pl. 18 figs. 3a, b.

2007 Icriospathodus? zaksi (Buryi) ; Orchard, fig. 2.

2013 Neospathodus novaelhollandiae McTavish ; Yan et al., p. 516, fig. 6BB–DD.

2014 Icriospathodus? zaksi (Buryi) ; Maekawa & Igo in Shigeta et al., fig. 192, nr. 14–29.

2015 Novispathodus pingdingshanensis (Zhao & Orchard) ; Chen et al., p.111, figs. 7.1–7.2.

2016 Neospathodus planus sp. nov. Chen & Kolar-Jurkovšek; Chen et al., p.92, fig. 7.9a–c, 8.10.

2016 Neospathodus robustus Koike ; Chen & Kolar-Jurkovšek in Chen et al., p.92, figs. 8.7–8.9.

2016 Icriospathodus? zaksi (Buryi) ; Komatsu et al., p. 69, fig. 5, nr. 2–3.

2018 Icriospathodus zaksi (Buryi) ; Henderson et al., p.18 pl. 1, figs. 18–19.

2018 Icriospathodus zaksi (Buryi) ; Maekawa in Maekawa et al., p. 51, figs. 29.20–29.26.

2018 Icriospathodus ? sp. 1; Maekawa in Maekawa et al., p. 54, figs. 30.1–30.2.

2019 Triassospathodus symmetricus (Orchard) ; Chen et al., fig. 5, nr. 8 (only).

2019 Neospathodus ex. gr. planus Chen & Kolar-Jurkovšek ; Chen et al., fig. 6, nr. 2.

2019 Icriospathodus zaksi (Buryi) ; Chen et al., fig. 6, nr. 4, fig. 7, nr. 9, 10.

2019 Novispathodus pingdingshanensis (Zhao & Orchard) ; Liu et al., p. 13, pl. 3, fig. 4 (only).

Number of specimens:>30

Revised diagnosis. Low, robust segminate P 1 elements usually with 8–9 wide denticles. 2–3 small denticles may be located behind the variably conspicuous cusp. Denticles are node-like in form. Te lower margin is straight. Deep, wide basal cavity. One or two variably shaped, lateral processes are occasionally present.

Description. Robust segminate P 1 element with 7–12 short, robust, erect to uniformly recurved, mostly fused, triangular-shaped denticles. Rectangular to subrectangular outline of the element. In most elements, the cusp is distinct. Unit lowest at the posteriormost end. Big sub-rounded, bulbous, slightly concave basal cavity. Te basal cavity occupies the entire posterior half of the element. Te posterior margin coincides with the edge of the cavity.

Remarks. Te holotype ( Buryi, 1979) has postero-lateral processes, which, in the original diagnosis were considered “complex in form” and characteristic of this species. Because the holotype is broken and the original diagnosis was based only on that specimen, we revise here the diagnosis on the basis of more than 30 specimens that show broader morphological variation in the platform: as illustrated by others (e.g. Chen et al., 2019), a lateral process may or may not be present. Koike (1992) reported a similar morphological variation within Ic. crassatus and Ic. collinsoni , suggesting it is a generic property of Icriospathodus . Te P 1 element of Ic. zaksi resembles that of Ic. crassatus but it is smaller, has a shorter carina and a much larger basal cavity relatively to its length.

Occurrence. Worldwide occurrence. India: Unit H3, Khunamuh formation, Guryul Ravine; North-eastern Vietnam: Novispathodus pingdingshanensis Zone , Xenoceltites variocostatus beds, Bac Tuy Formation (Maekawa & Igo in Shigeta et al., 2014); Russia: upper part of Anasibirites nevolini Zone to lower part of Tirolites cassianus Zone , South Primorye ( Buryi, 1979); South China: Bed 51, Luolou Formation, Bianyang Section, Guizhou province ( Yan et al., 2013); Canada: British Columbia, Montney Formation; late Smithian– early Spathian ( Henderson et al., 2018). Oman; Wadi Bani Khalid section, UAZ 4, Nv. pingdingshanensis range Zone ( Chen et al., 2019); Japan: Taho Formation, Novispathodus brevissimus Zone ( Maekawa et al., 2018) .

Figures

Fig. 25 Novispathodinae from Laren, Shanggang and Lilong. Magnification is ×80.The scale bar is 400 μm. All elements are considered to be P1 elements if not specifically identified otherwise. A–F, Icriospathodus zaksi (Buryi); A LAR205, PIMUZ 39170; B LIL508, PIMUZ 39171; C LIL508,PIMUZ 39172; D LAR204,PIMUZ 39173; E LIL510, PIMUZ 39174; F LAR203, PIMUZ 39175.G–L Icriospathodus aff. crassatus (Orchard); G LIL510, PIMUZ 39159; H LIL508,PIMUZ 39160; I LAR203, PIMUZ 39161; J LIL509, PIMUZ 39162; K LAR202,PIMUZ 39163; L LAR210, PIMUZ 39164.M, O, P Icriospathodus collinsoni (Solien); M SHA313,PIMUZ 39165; O SHA320,PIMUZ 39166; P LIL515A,PIMUZ 39167. N Triassospathodus symmetricus (Orchard); SHA320, PIMUZ 39319