North American Spathian (upper Olenekian, Lower Triassic) neogondolellin conodonts
Abstract
The taxonomy and biostratigraphy of poorly known neogondolellin conodonts from mostly Spathian (upper Olenekian, Lower Triassic) strata are described from widespread localities in North America: high latitude Canadian Arctic, mid-latitude British Columbia (BC), and lower latitudes in the USA. The occurrence of the neogondolellins in key sections and in matrix of dated ammonoid collections is documented. Neogondolellins characteristic of seven ammonoid zones are identified. Fifteen new conodont species are assigned to four genera: Borinella, Columbitella, Magnigondolella and Neogondolella. Borinella, more common in the Smithian, undergoes a radiation in the early Spathian ‘tirolitid n. gen. A’ ammonoid beds of California eventually resulting in five new Neogondolella species (Ng. bucheri, Ng. darwinensis, Ng. praeacuta, Ng. sinuosa, and later Ng. spathiconstricta) and the first new Magnigondolella, Mg. mutata. Several of these plus Bo.? curvata sp. nov. also occur above the tardus Zone in British Columbia (BC). In the next younger ammonoid zone with Tirolites, the first Columbitella are Cb. joanae and Cb. weitschati. Middle Spathian Columbites and Procolumbites ammonoid beds in the USA are dominated by Cb. elongata, whereas the broadly equivalent strata in the north contain Cb. amica, Cb. brevis sp. nov. and Cb. paragondolellaeformis. Late Spathian radiation produces six new species of Magnigondolella: Mg. incurva, Mg.? minuta and Mg. trutchensis in the Prohungarites ammonoid beds, followed by Mg. acuminata, Mg. tozeri and Mg. peribola in the haugi and subrobustus ammonoid zones.
In an earlier paper, I synthesized and summarized the evolution and diversity of conodonts throughout the Late Permian and Early Triassic (Orchard 2007). To assess extinction and radiation events during the c. 5 myr duration of the Early Triassic, all conodont species known to me at the time were featured, including many taxa introduced in open nomenclature. The results showed that a major faunal turnover occurred during the middle Olenekian, around the undefined Smithian–Spathian substage boundary (SSB). This boundary has been of renewed interest recently (Zhang et al. 2019; Widmann et al. 2020), which has highlighted a need to better document the conodont turnover. In this paper, a new taxonomy for North American Spathian neogondolellins is presented and their relationships discussed. This group is an age-diagnostic tool throughout the upper Permian to Middle Triassic interval but has been under-used in the Spathian (e.g. Orchard 1993, 1995). Proposed origins and ranges of neogondolellins are supported by several fossil successions in Canada and the USA, and additional collections extracted from the matrix of dated ammonoid faunas provided by colleagues. The intercalibrated biostratigraphy provides an improved yardstick for Spathian chronostratigraphy.
Many lower Olenekian (Smithian) species originally assigned to Neogondolella Bender & Stoppel, 1965 have more recently been referred to new genera Scythogondolella Kozur, 1990, Borinella Budurov & Sudar, 1994, and Siberigondolella Kiliç & Hirsch, 2019. Most of these species are confined to the Smithian, and only Borinella has been found in this work to cross the SSB. Transition to Spathian neogondolellin genera Magnigondolella Golding & Orchard, 2018, and Neogondolella appears to involve morphogenesis in the axial part (blade–carina) of Borinella species whereby discrete anterior blade denticles become smaller and more fused, and a variety of blade–carina profiles develop as platform shape diversifies. The genus Columbitella Orchard, 2005, appears slightly later as the anterior platform of the platform elements is reduced. The variation exhibited by these early Spathian elements poses a taxonomic conundrum with respect to the genus assignment of some taxa, although species level identity is clear. The taxonomy herein provides distinguishing features of Spathian neogondolellin genera, and outlines the observed radiation and key succession of neogondolellin and other taxa during the Spathian.
Geological setting
Material
North American regions from which upper Olenekian neogondolellins are known are documented below, along with local stratigraphic context of the conodont collections cited. Specific location and curation data are provided in the Appendix. Locations extend from high latitude Spath Creek in the Canadian Arctic, the type section for both the Spathian Stage and the late Spathian subrobustus ammonoid zone, through progressively more southern latitudes in north-eastern BC, northern Nevada, south-eastern Idaho, and east-central California (Fig. 1). Type locations of most North American Spathian ammonoid zones are located in these regions of the USA.
The history of Spathian ammonoid study in western USA was reviewed by Guex et al. (2010), who introduced a modern zonation comprising eight faunal divisions within the broader Columbites, Subcolumbites and haugi ammonoid zones (Fig. 2). Later, Jenks et al. (2013, fig. 2) introduced a further four-fold subdivision of the beds containing Columbites parisianus Hyatt & Smith, 1905. Based on work in Guangxi, South China, a new basal Spathian interval termed the ‘tirolitid n. gen. A’ beds was identified by Galfetti et al. (2007) and in the review of Widmann et al. (2020, suppl. data sheet 6) it was noted that this also occurs in California and Nevada. This ammonoid zonation of the Spathian is far more complete than that in Canada (Orchard & Tozer 1997) where only two Spathian zones are differentiated: a lower zone of Olenekites pilaticus Tozer, 1967, and an upper zone of Keyserlingites subrobustus (Mojsisovics, 1886) (Tozer 1994). Jenks et al. (2015, fig. 13.10) showed the correlation of the USA and Arctic ammonoid faunas.
Canadian Arctic
Spath Creek on Ellesmere Island in the far north is the type locality for the Spathian Stage, and the type locality for the subrobustus Zone based on GSC collections O-47544 and O-47545 taken from locality 171 (Tozer 1965, 1967, 1994) (Fig. 1, localities 1, 2). Conodonts have been recovered from the matrix of the former collection, and from a corresponding interval in the uppermost strata of the Svartfjeld Member of the Blind Fiord Formation (Embry 1986) sampled by the author in 1996 (Fig. 3). This section is on the north flank of Spath Creek (Orchard 2008) where about 6.5 m of strata includes Olenekites sp. and the bivalve Posidonia aranea (Tozer, 1961) at several levels. The bivalve, which has been regarded as a proxy for the subrobustus Zone, also occurs in the type collections along strike where 8 m of strata separate collections O-47544 and (beneath it) O-47545. This implies the position of collection O-47544 corresponds to the highest fossiliferous level of the adjacent section, as shown in Figure 3.
Arctic conondont collections from the Smithian romunduri and tardus zones were previously described by Orchard (2008).
North-eastern British Columbia
This region includes thick sequences of the Toad Formation, which embraces the entire Lower Triassic (Fig. 1, localities 3–5). However, the ammonoid biostratigraphic record for the Spathian is expressed only as the subrobustus Zone (Tozer 1967, 1994). The Toad Formation, named for the Toad River, includes important Olenekian sections near the confluence of Liard and Toad rivers close to the Yukon border, and further south near Chowade River in Halfway River map-area. Additional late Spathian ammonoid matrix samples from the several subrobustus Zone localities in the region contribute to characterizing the latest Spathian conodont faunas.
About 30 m of section on the east bank of the Toad River was examined and sampled in 1983 at the type locality for the upper Smithian tardus ammonoid Zone (McLearn & Kindle 1950; Tozer 1967, p. 74; Tozer 1994, p. 25). About 25 m of calcareous silty shale containing a bivalve coquina of Peribositria mimer (Oeberg, 1877) was sampled as collections 213D and 213E (Fig. 4). These strata were questionably assigned to the romunduri Zone, and this age is confirmed by the composition of its conodont fauna and comparison with collections elsewhere (Orchard & Zonneveld 2009). Stratigraphically above these faunas, Smithian ammonoids occur in two higher beds that are about 1.5 m apart: the lower sample contains Anawasachites tardus McLearn, 1945, and the upper bed contains Xenoceltites subevolutus Spath, 1930 (Tozer 1994, p. 25). By definition, these two horizons constitute the type fauna of the tardus Zone. A carbonate bed 1 m above the higher ammonoid bed lacks macrofauna but yielded a novel conodont fauna that was originally discussed by Orchard & Tozer (1997, p. 680) as characterized by Neogondolella aff. sweeti (Kozur & Mostler, 1976).
To the south, a section of the Toad Formation south of the headwaters of Chowade River in Halfway 1:250.000 map-area was examined and sampled in 1998 (Fig. 5) as part of the GSC Foreland Project (Lane & Macnaughton 2017). The section is composed of 117 m of generally recessive shale, siltstone, and sandstone overlying the Permian Fantasque Formation. Carbonate nodules appear above 22 m, with sandstone and carbonates up to 0.5-m-thick occurring toward the top of the succession (Fig. 5). Macrofossils identified by E.T. Tozer represent the Dienerian Candidus Zone at 27 m, and late Spathian subrobustus Zone (with Posidonia aranea) at c. 108 m. Intervening conodont collections imply that additional Olenekian strata are present. Conodont elements recovered throughout from this basinal succession are diverse, comparatively small, and occasionally fused, with a conodont alteration index (CAI) of 4.5.
Matrix samples from the late Spathian Keyserlingites subrobustus Zone subsampled from archival ammonoid collections collected in the region yielded small conodont collections. One was a talus concretion collected by Tozer (1963, 1994; GSC O-056259) from about 100 m above the Fantasque Formation and close to the Chowade section; it contained Popovites occidentalis Tozer, 1965 and Isculitoides minor Tozer, 1965 (Tozer 1994, p. 321). Other collections in north-east BC were first described by Tozer (1967, pp 73–74): on the west face of a mountain 11 km north of Mt Laurier (Tozer’s Section 1); and in the gorge of Needham Creek, 3 miles above the junction of Graham River (Tozer’s Section 3). In the first section, the subrobustus Zone occurs over about 6 m of strata in three adjacent gullies, with successive samples GSC O-056234, O-056240, O-056243 collected at approximately 125, 130 and 131 m above the top of the Permian Fantasque Formation. In Needham Creek, collection GSC O-056178 came from about 130 m above the Permian, and about 7.5 m above GSC O-056179. A further sample with Posidonia aranea collected north of Peace River also yielded a conodont collection (GSC O-046990). These late Spathian collections were first summarized by Orchard & Tozer (1997), who pointed out the need to revise the taxonomy of the neogondolellins.
To the south, in the Wapiti Lake area in north-central BC, Spathian conodonts were first described by Orchard & Zonneveld (2009) and are cited in the taxonomy below.
South-eastern Idaho
Outcrops of the Thaynes Formation in the Bear Lake area of south-eastern Idaho have been the subject of modern studies on Spathian ammonoids by Guex et al. (2010, figs 3, 4), Jenks et al. (2013) and Brayard et al. (2019), following earlier accounts by Kummel (1954, 1969). These include the localities of Paris Canyon – Hammond Creek west of Bear Lake, and Hot Springs to the east of the lake (Fig. 1, locality 6). There are important Smithian locations further north near Georgetown, where tardus Zone ammonoids occur. Lower Triassic conodonts were recovered from the matrix of ammonoid samples from the Tirolites and Columbites beds collected prior to the most recent studies, by E.T. Tozer in the 1960s and by W. Weitschat in 1993. More recently, Guex et al. (2010) differentiated four distinct biochronological horizons within the Columbites parisianus beds, although a similar number named by Jenks et al. (2013) do not exactly correspond. The stratigraphic context of these collections, other than their zonal assignment, is informed by the stratigraphic sections of Guex et al. (2010) and locality details in Jenks et al. (2013).
Brayard et al. (2019, fig. 2) provided a composite section for Paris Canyon and Hot Springs which showed successive ammonoid faunas assigned to the Tirolites and the overlying Columbites beds. These two zones were sampled in Paris Canyon by E.T. Tozer as, respectively, GSC O-064672 and O-064673, and later by W. Weitschat as W12 from the Tirolites beds, and from two successive Columbites beds: sample W11 from the lowest horizon and W7 from the highest horizon (Fig. 2). According to J. Jenks (pers. comm. September 2020), these samples almost certainly represent the massive limestone of the classic ‘Tirolites beds’ (GSC O-064672, W12), and the overlying Columbites concretions characterized by C. parisianus (GSC O-064673, W11; corresponding to horizon H4 of Guex et al. 2010; Jenks et al. 2013). Overlying concretions carry C. isabellae Guex et al., 2010 (sample W7; corresponding to horizon H6 of Guex et al. 2010; Jenks et al. 2013)).
At Hot Springs, Columbites beds crop out at several places along the c. 10-km-long Bear Lake Hot Springs ridge (Jenks et al. 2013, fig. 3). W. Weitschat differentiated three samples from the Columbites beds: W13 from the lower main level of the zone; sample W5 from the highest level of the zone, and sample W10 from an intermediate stratigraphic level lacking ammonoids. These are probably sourced from, respectively, the C. parisianus and C. isabellae beds (as in Paris Canyon), and the intermediate Arctomeekoceras popovi Guex et al., 2010 bed of Jenks et al. (2013) (collection W10; corresponding to horizon H5 of Guex et al. 2010), a thin limestone bed with rare concretions in which ammonoids are very rare.
In the Hammond Creek area, Guex et al. (2010, figs 9, 10) documented several sections with multiple ammonoid levels. From these, E.T. Tozer collected Spathian ammonoids assigned to the Procolumbites (GSC O-064670–1) and Prohungarites (GSC O-064675) faunas that yielded matrix conodonts, and these were supplemented by a bulk sample (W9) collected by W. Weitschat from the Prohungarites beds.
Weitschat also collected two samples from the late Smithian tardus Zone in Georgetown: W8 from the Anasibirites beds, and W3 from the overlying randomly occurring concretions that contain Xenoceltites.
North-central Utah
Conodonts from a section of the Thaynes Formation in Cephalapod Gulch on the University of Utah campus in Salt Lake City, Utah were described by Solien (1979) (Fig. 1, locality 7). This account is supplemented by a tardus Zone collection made by W. Weitschat (sample W14) (see Orchard & Zonneveld 2009, fig. 11).
Northern and central Nevada
The classic Crittenden Springs site in Long Canyon, Elko County (Fig. 1, locality 8) contains many overturned, stratigraphically discontinuous fossiliferous limestone blocks within the lower part of the Thaynes Group. Most recently Jenks & Brayard (2018) described the Smithian ammonoids, and Maekawa & Jenks (2021) described the conodonts. W. Weitschat collected a sample from the tardus Zone (sample W2) that probably corresponds to 5–7 cm-thick bed full of ammonoids (block JJ5-76 of Jenks et al. 2013). Orchard & Zonneveld (2009) noted the conodont fauna from this bed.
The Spathian–Anisian ammonoid record in the northern Humboldt Range (Fig. 1, locality 8) was previously documented by Silberling & Wallace (1969), Silberling & Nicols (1982), Bucher (1990) and Monnet & Bucher (2005). Further revision is underway (H. Bucher pers. comm. 2020). Late Spathian collections come from the Carbonate Unit of the Lower Member of the Prida Formation, and Anisian collections come from the succeeding Fossil Hill Member. Upper Spathian ammonoid matrix samples from beds with Tardicolumbites (sample HB538), Prohungarites gutstadti Kummel, 1969 (HB501, 540, 586), Prohungarites mckelvei Kummel, 1969 (HB536), Neopopanoceras haugi (Hyatt & Smith, 1905) (HB106, 110, 143, 236, 588), and the Anisian Japonites welteri Bucher, 1989 (HB92, HB184 = type locality) were collected by Bucher (1990, fig. 6), who also guided the author in John Brown Canyon in 1992, when 12 conodont samples were collected in two short sections. Sample COY-1 was sampled from a haugi Zone horizon (HB250), and the next nine samples were collected in stratigraphically higher beds up through the ‘Brown Calcareous Sandstone Unit’ (Silberling & Wallace 1969), which lies beneath Anisian ammonoid faunas. In an adjacent gulley, three additional samples (COY-A10–12) were collected from the upper part Sandstone Unit and the overlying 6.5 m of probably basal Anisian strata (Fig. 6). To the south-east in the southern Tobin Range (Fig. 1, locality 10), an additional Spathian sample (GSC O-064700) was collected by E.T. Tozer.
East-central California
Triassic outcrops of the Union Wash Formation in the Inyo Mountains and Darwin Hills of California (Fig. 1, locality 11) were described by Stone et al. (1991), who reviewed the history of study. Olenekian ammonoids described from Union Wash (Smith 1932) include a lower Meekoceras bed and a much higher Neopopanoceras haugi bed. The latter is the type locality of the haugi Zone, later established as late Spathian in age (Silberling & Tozer 1968; Silberling & Wallace 1969). The strata overlying the haugi Zone in Union Wash contain indicators of the Canadian subrobustus Zone (Stone et al. 1991, p. 18), as shown in Figure 2.
In Darwin Canyon (Stone et al. 1991, fig. 8), about 40 m of section in the lowest part of the middle member of the Union Wash Formation was first sampled in detail by the author and H. Bucher in 1992 (Fig. 7), and briefly summarized by Goudemand et al. (2006). The section consists of carbonate beds and nodules interbedded with shales and siltstones in which early Spathian ammonoids occur at multiple levels. The section was re-sampled by Goudemand and is currently under study. The work of Lewes et al. (1983) formed the basis for initial conodont work documented by Stone et al. (1991, pp 18, 19), which identified both Smithian and Spathian faunas. Sampling by the author of the late Spathian type haugi Zone were unproductive, but the Darwin site produced a diverse lower–middle Spathian conodont succession.
Results: biostratigraphic synthesis
The temporal framework provided by fossiliferous sections and ammonoid matrix samples from the described North American regions permits a preliminary biozonation of neogondolellins in the late Olenekian (Spathian), and provides insights into their phylogeny during an important radiation. No formal zones are proposed, but the succession of conodonts, both neogondolellins and others are shown in Figure 8. Lower Olenekian, upper Smithian, tardus Zone ammonoid matrix collections from Toad River, Salt Lake City, Georgetown, and Crittenden Springs are dominated by segminiplanate elements of Scythogondolella accompanied by novispathodids and ellisonids. The Neogondolellinae are represented by fewer Borinella species, which are regarded as ancestral to many younger representatives of the subfamily.
The youngest conodont fauna from Toad River, overlying the Smithian tardus Zone beds, broadly correlate with those from the lower Spathian tirolitid beds in Darwin Canyon, and include holdover Borinella species plus ‘conservative’ Neogondolella species and the first Magnigondolella. Younger tirolitid-bearing strata in Idaho show the emergence of Columbitella, which then becomes dominant in the middle Spathian Columbites beds. Collections from the Chowade section in BC well illustrate the turnover from Columbitella to late Spathian faunas dominated by Magnigondolella. The late Spathian of Nevada and the Canadian Arctic record parallel development of Neogondolella and Magnigondolella.
Orchard & Zonneveld (2009, p. 775) described Smithian conodonts from the Wapiti Lake area in BC and introduced the Scythogondolella phryna Orchard & Zonneveld, 2009 and Sc. milleri (Müller, 1956) subzones of the Sc. mosheri (Kozur & Mostler, 1976) Zone, both displayed on Toad River, the type section for the tardus Zone (Fig. 4; samples 213E and 213C–213B respectively). In the present work, the fauna of the uppermost Smithian milleri Subzone, recognized in both Anasibirites- and Xenoceltites-bearing horizons, is modified to include the new (herein) α and β morphotypes of Borinella buurensis (Dagis, 1984), and Sc. dolosa Bonderenko & Popov, 2020 (= Sc. n. sp. E sensu Orchard 2007). Novispathodus waageni (Sweet, 1970) occurs in both ammonoid beds and Nv. pingdingshanensis (Zhao & Orchard in Zhao et al., 2007) questionably in the upper one.
Collections from Anasibirites beds at both Georgetown and Salt Lake City, and from younger Xenoceltites beds at Crittenden Springs, also contain Sc. milleri (Fig. 2), but the Xenoceltites beds in Georgetown contain only segminate elements, including Nv. pingdingshanensis. The sample from the top of the Toad River section (213A) is dominated by neogondolellins originally assigned collectively to Neogondolella aff. sweeti by Orchard & Tozer (1997). This fauna is newly identified as Bo.? curvata sp. nov., Bo. sweeti, Mg. mutata sp. nov., Ng. darwinensis sp. nov., Ng. sinuosa sp. nov., and includes rare Nv. pingdingshanensis.
Conodonts from the Union Wash Formation in Darwin Canyon (Goudemand et al. 2006) span the Smithian–Spathian boundary but the conodont faunas are relatively sparse prior to the occurrence of the first ammonoid faunas. Novispathodus pingdingshanensis is notable in these beds, and is followed by variants of Nv. abruptus (Orchard, 1995) and Nv. brevissimus (Orchard, 1995), which will be documented elsewhere. The first ammonoids are characterized as the ‘tirolitid n. gen. A’ fauna or zone (TAZ), which includes the earliest species of Bajarunia and is indicative of the basal Spathian in California as well as in Nevada and South China (Widmann et al. 2020, suppl. data sheet 6). The evolutionary radiation seen in tirolitid ammonoids in TAZ occurs also within neogondolellin conodonts.
The first neogondolellins in Darwin occur at c. 16.5 m above datum (Fig. 7, DC-13) and are small elements of Bo. sweeti and probable Ng. darwinensis. Amongst the associated conodonts are early Icriospathodus species. Immediately above (c. 17 m, DC-12), large specimens of Ng. darwinensis plus Ng. aff. bucheri appear, and at 20 m (DC-10), the first Mg. mutata and Ng. sinuosa appear. The following 3 m of strata at Darwin contain a richer neogondolellin fauna in which several of the previously mentioned taxa are joined by Ng. praeacuta (DC-8A, 8). The presence of four of these species at the top of the Toad River succession and in Darwin Canyon suggest broad contemporaneity.
Particularly useful appearances of conodont taxa that help constrain the relative age of the neogondolellins are the successive appearance of Platyvillosus asperatus Clark et al., 1964 (sample DC-8A), Icriospathodus collinsoni (Solien, 1979) (DC-7) and Aduncodina sp. (DC-4, 5). The first two species characterize, respectively, the upper part of Range Zone 10 and Zone 11 of Solien (1979) based on the Olenekian succession in Salt Lake City, Utah, where Platyvillosus appears 80 m above the Smithian Sc. milleri Zone, and I. collinsoni appears about 10 m higher. In Paris Canyon, Idaho, the latter species occurs first in the Tirolites beds alongside a new neogondolellin species, Cb. weitschati (Fig. 2). The latter taxon may be represented by the single poorly preserved specimen from Darwin (Fig. 7, DC-6), although that element also resembles Cb. joanae, which is the first Columbitella in the Chowade section (Fig. 5), where it also occurs with I. collinsoni.
In West Pakistan (Sweet 1970), Utah (Solien 1979) and elsewhere, a generalized zone based on Neogondolella jubata Sweet, 1970 (= Cb. jubata), was recognized in the Spathian, but this neogondolellin has been confused with Columbitella elongata (Sweet, 1970), both species having been recorded throughout the lower Spathian in West Pakistan. In Utah, Cb. elongata rather than Cb. jubata co-occurs with Icriospathodus collinsoni (cf. Solien 1979), as it does throughout most of the Columbites beds and into the Procolumbites beds in Idaho (Fig. 2). Columbitella jubata, the holotype of which is re-illustrated herein, is not known to occur in North America.
In the Chowade section in BC, Cb. joanae (Orchard & Zonneveld, 2009) (Fig. 5, sample CHOW-5) is amongst the first Columbitella species, and is followed by neogondolellin species chiefly described previously from high latitude successions in Siberia (Dagis 1984; Klets 1998) and Svalbard (Nakrem et al. 2008): Cb. paragondolellaeformis (Dagis, 1984), Cb. amica (Klets, 1998) (Fig. 5, CHOW-7) and Cb. brevis (Fig. 5, CHOW-8–12). The first of these species was originally described from the Olenekites spiniplicatus (Mojsisovics, 1886) Zone on the Mengilyakh River, central Siberia (Dagis 1984), and Cb. amica was described from the comparable Spathian of north-eastern Russia (Klets 1998), where the two species co-occur. The contrasting biogeographical distribution of Cb. elongata and these northern taxa may reflect different palaeolatitude preferences.
Although Icriospathodus is common throughout all but the highest strata of the Columbites parisianus beds in Idaho, the genus is rare in BC, which may also be a result of biogeographical control. Both Nv. abruptus and Nv. brevissimus occur with (Orchard 1995) and, in Idaho, above Icriospathodus spp., and are joined by Spathicuspus and Aduncodina. Icriospathodus has not been recovered from the Procolumbites beds, which contain the upper range of Cb. elongata and a unique, incomplete specimen of Mg. cf. incurva in Hammond Creek (Fig. 2, sample GSC O-46471). The latter element is close to the species from Chowade River, where the abundance of Mg. incurva increases with that of Mg. trutchensis (Fig. 5, CHOW-11, 12).
A marker taxon, Neostrachanognathus sp. (‘Oncodella’ n. sp. A sensu Orchard 1995; Fig. 5) occurs alongside Cb. brevis, Spathicuspus spp. and Triassospathodus symmetricus Orchard, 1995 at Chowade River (Fig. 5, samples CHOW-8–11). The marker also occurs with Mg. trutchensis and Mg.? minuta in collections assigned to the Tardicolumbites beds in Coyote Canyon, Nevada (HB538), and in collections lacking one or both Magnigondolella species from the Prohungarites beds in Hammond Creek, Idaho (Fig. 2, GSC O-64675, W9); from the northern Humboldt Range (HB106, 501, 540, 586); and from the Tobin Range (GSC O-64700) in Nevada. Only single specimens of Mg.? minuta occur in collections from Idaho (GSC O-64675) and from the Tobin Range, Nevada (GSC O-64700) where Novispathodus? triangularis (Bender, 1970) is associated; collections from the Humboldt Range lack neogondolellins. In the Chowade section, Neostrachanognathus disappears as Magnigondolella becomes dominant (Fig. 5, CHOW-12) and then more elongate, as in Mg. acuminata (Fig. 5, CHOW-13 et seq.)
Conodont data from the late Spathian haugi Zone in the USA and the broadly contemporaneous subrobustus Zone in Canada comes largely from Nevada, BC and Nunavut Territory. Few conodonts are known from the type haugi Zone in Union Wash in California, where the presence of Keyserlingites subrobustus above Neopopanoceras haugi establishes broad contemporaneity between the two biozones. Much more data is available from the northern Humboldt Range in Nevada where both short sections and spot samples reveal the character of the conodont faunas. Neogondolella bucheri characterizes several samples from the Humboldt Range (Fig. 6), although it is common for ammonoid matrix samples from the haugi Zone (e.g. HB110, 143, 588) to yield monospecific faunas that contain only the multielement apparatus of Triassospathodus ex gr. homeri (Bender, 1970), commonly Tr. symmetricus (Orchard, 1995) (see below). A single Ng. bucheri occurs in collection HB236 but that species is more common in additional samples from John Brown Canyon (Fig. 6). The haugi Zone matrix sample reported by Goudemand et al. (2012a) is an exception in containing Chiosella timorensis (Nogami, 1968), a species that was formerly found only in samples lacking ammonoids (e.g. Fig. 6, samples COY4, A11, A12), or in direct association with early Anisian welteri Zone ammonoids (Fig. 2, samples HB92, 184).
The uppermost c. 12 m of the Chowade section (CHOW-13+) is characterized by Mg. acuminata with the long-ranging Ng. spathiconstricta and rare Mg. aff. tozeri. These are later joined by Mg. peribola as well as a single element with Borinella-like denticulation. The highest strata in the Chowade section, which includes subrobustus Zone ammonoids, correlates with the nearby collection from the matrix of an archival subrobustus Zone talus concretion (Fig. 5, GSC O-56259) that yielded Mg. tozeri as well as Mg. acuminata. Additional collections from matrix samples from BC include neogondolellins assigned to one or more of Mg. acuminata, Mg. tozeri and Mg. peribola. The collection from near Mt Laurier also yielded Ng. bucheri and Triassospathodus sp. Two of these neogondolellin taxa are common to Nevada, and in common with that area, monospecific Triassospathodus faunas occur in Needham Creek (Fig. 2, GSC O-56178). This partitioning, observed in both Nevada and BC, presumably arises from a palaeoecological preference for cooler, perhaps deeper water habitats preferred by neogondolellins over the other taxa (Chen et al. 2020; Sun et al. 2020).
The conodonts from the subrobustus Zone of Nunavut Territory, including its type locality in Spath Creek (GSC O-47544), were described by Orchard (2008), with revisions herein (Fig. 3). Both Mg. acuminata and Ng. bucheri are common to collections from that zone in BC and to the haugi Zone faunas from Nevada. In addition, Ng. panlaurentia Golding & Orchard, 2016 (Ng. sp. C sensu Orchard 2008) occurs at the top of the Spath Creek section and in the early Anisian Japonites welteri beds in Nevada.
Conclusion
Neogondolellin conodonts from Spathian (upper Olenekian) strata in North America are described and differentiated into four genera: Borinella, Columbitella, Magnigondolella, and Neogondolella. Several species are redefined and these 15 are new: Bo.? curvata, Cb. brevis, Cb. weitschati, Mg. acuminata, Mg. incurva, Mg. mutata, Mg. peribola, Mg. tozeri, Mg. trutchensis, Mg.? minuta, Ng. bucheri, Ng. darwinensis, Ng. praeacuta, Ng. sinuosa and Ng. spathiconstricta.
Conodonts from ammonoid-bearing strata in Toad River (BC), Darwin Canyon (California), Bear Lake area (Idaho), Chowade River (BC), Humboldt Range (Nevada) and Spath Creek (Nunavut Territory) collectively provide a profile of the neogondolellin succession through the upper Olenekian (Fig. 8). These zones emphasize the representative species for each ammonoid zone but conodont zones are not formally defined pending improved knowledge of their stratigraphic range and common associates. Conodont based division of the Spathian has generally been based on segminate elements such as Novispathodus and Triassospathodus, but there are many undescribed species of these and other genera that should contribute to a more holistic zonation like those introduced by Chen et al. (2015a) and Widmann et al. (2020). Meanwhile, the notable species associated with the neogondolellin taxa provide a parallel succession derived from North American occurrences (Fig. 8).
In the late Smithian, many North American faunas contained both Scythogondolella and Borinella in addition to Nv. waageni, and Nv. pingdingshanensis. Close to the SSB, Scythogondolella disappeared while Borinella radiated into diverse forms. The distinctive discrete blade–carina denticulation of Borinella became diminished, increasingly fused, and relatively elevated in new species Bo.? curvata, Mg. mutata and the asymmetrical Ng. sinuosa. Each of these species display relatively discrete anterior denticulation like that of Borinella, but blade–carina configuration varied, and platform shapes diversified, ranging from broad-plated Ng. darwinensis to pointed Ng. praeacuta. Several of these species are common to both California and BC and are regarded as indicators of the earliest Spathian. In addition, segminate conodont taxa appearing low in the stage include representatives of Nv. ex gr. abruptus and Nv. ex gr. brevissimus, followed by species of Icriospathodus and Spathicuspus.
The youngest neogondolellin in Darwin is a Columbitella species that resembles both Cb. weitschati from the Tirolites beds in Idaho, and broadly contemporaneous Cb. joanae from Chowade River in BC. Both of these species resemble the subjacent Ng. praeacuta but differ in their reduced anterior and posterior platforms, which suggests they may be derivatives. Further platform reduction occurs later in the Columbites beds and overlying Procolumbites beds in Idaho where abundant Cb. elongata occur, and in Chowade River where Cb. paragondolellaeformis, Cb. amica and Cb. brevis may be the higher latitude equivalents. A further index, Mg. incurva, is rare in the Procolumbites beds in Hammond Creek, Idaho but common in Chowade River. Species of Novispathodus, Spathicuspus and Triassospathodus, some of them new, occur throughout the Columbites and Procolumbites intervals.
The Prohungarites beds in Hammond Creek, Idaho, in the Tobin Range, Nevada, and the Tardicolumbites beds in the Humboldt Range, Nevada, all contain rare Mg.? minuta and common Tr. symmetricus; Nv.? triangularis also occurs in the Tobin Range collection. Magnigondolella trutchensis, a species that occurs in Chowade River, is also rare in the Tardicolumbites beds.
The late Spathian haugi Zone in Nevada and the subrobustus Zone in Canada are characterized by several Neogondolella species of which Ng. bucheri and the long ranging Ng. spathiconstricta are widespread. Magnigondolella species, particularly Mg. acuminata, are common in Canada but much less so in the USA. A feature of haugi and subrobustus Zone conodont faunas is their variable genus composition, presumably arising from differing biofacies. Some, especially in the USA, are composed only of Triassospathodus (see Fig. 2), some are exclusively neogondolellins (Fig. 6), some contain both, and one reported by Goudemand et al. (2012a) consists of Chiosella with Triassospathodus. Abundant specimens of Ch. timorensis appear with neogondolellins in the early Anisian welteri Zone (Orchard 1994). An uncommon species around the Spathian–Anisian boundary in both Nevada and Nunavut Territory is Ng. panlaurentia.
Systematic palaeontology
By Michael J. Orchard with contributions from Nicolas Goudemand and Martyn Golding.
Repository abbreviations
Most 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. Two re-illustrated holotypes bear OSU numbers at School of Earth Sciences, Ohio State University. Sample numbers prefixed by ‘HB’ were collected by H. Bucher, ‘W’ by W. Weitschat, and ‘O’ by E.T. Tozer; all others were collected by the author. In all cases, GSC curation numbers (prefixed ‘C’ or ‘O’) are also provided for these samples in the Appendix.
Class CONODONTA Eichenberg, 1930
Order OZARKODINIDAE Dzik, 1976
Family GONDOLELLIDAE Lindström, 1970
Subfamily NEOGONDOLELLINAE Hirsch, 1994
Remarks
Segminiplanate P1 elements of the Olenekian have been assigned to the genera Borinella, Columbitella, Magnigondolella, Neogondolella, Scythogondolella and Siberigondolella. Multielement apparatuses have been reconstructed for four of these (Orchard 2005; Golding 2018). The apparatuses of Magnigondolella and Neogondolella are demonstrably the same, whereas Columbitella has a different S1 element (S2 in Orchard 2005); the largely Smithian Scythogondolella has very different S1, S3 and S4 elements that led to its inclusion in a separate subfamily, the Scythogondolellinae Orchard 2007. Sun et al. (2021) recently described a natural assemblage of Sc. milleri that largely corresponded to the reconstruction of Sc. mosheri described by Orchard (2005), but differed in its P elements. Subfamily characteristics are manifest in the other elements of the apparatus, whereas differences in P elements define separate species. The apparatuses of Borinella and Siberigondolella have not been described, but they are thought to belong to the present subfamily (Orchard 2007, p. 100). The following account is based on P1 elements.
Genus BORINELLA Budurov & Sudar, 1994
Type species
Neogondolella buurensis Dagis, 1984 (pp 12–13).
Remarks
Borinella is characterized by long and discrete anterior blade denticles. The Smithian succession of Borinella species demonstrate an increasing but variable platform development concurrent with a lowering and greater fusion of blade denticles. Herein, anterior denticle fusion of <50% of their height is regarded as characteristic for the genus. Dagis (1984) introduced several species with such denticulation, namely Neogondolella buurensis, Ng. composita, Ng. jakutensis, and Ng. siberica. The first of these species later became the type species for Borinella, whereas the second was recently designated as the type species for Siberigondolella. However, discrimination of these two genera in the Smithian, and their relationship with possibly extant Neogondolella species, remains problematic.
The first representative of Borinella may be the Induan Bo. megacuspa Orchard, 2007 but the genus becomes common around the Induan–Olenekian boundary with the appearance of Bo. nepalensis (Kozur & Mostler, 1976). Platform development increases as the anterior denticles become lower, and platform shape allows the differentiation of several younger species. Around the SSB, changes in the configuration of the blade–carina in Borinella leads to new neogondolellins questionably assigned to the genus as well as other included in both Magnigondolella and Neogondolella.
Borinella buurensis (Dagis, 1984)
Figure 9I–N, S–V
| p 1984 | Neogondolella buurensis Dagis, pp 12–13, pl. 2 figs 6–9, ?10, 12; pl. 3 fig. 1; pl. 11 figs 1–4; pl. 12 figs 1, 2; pl. 16 figs 1–3 (only). |
Diagnosis
The platform of the segminiplanate P1 element extends from close to the anterior end as a narrow flange that broadens to the posterior and attains maximum breadth at midlength: this transition may be progressive and form an arcuate antero-lateral margin, or uneven with an inflection point. Length : breadth ratio of the platform is 3.5–4:1. The posterior carinal axis is curved and inturned at the rounded platform termination where a small accessory node commonly lies behind the cusp and in front of a very narrow posterior platform brim. The high anterior blade denticles are about 2–3 times high as wide, and pass progressively into smaller and lower, subequal denticles of the carina. The cusp is the largest denticle in later growth stages. The total number of blade–carinal denticles and nodes in adult elements is 15–16.
Remarks
Besides the distinctive anterior denticles, the original diagnosis emphasized the broad tapered platform and the incurved posterior platform and carina. However, Dagis (1984) included in the species a variety of platform shapes and carinal configurations, and previous workers have interpreted the species broadly. The present diagnosis excludes forms with a straight axis and more symmetrical posterior configuration, which are here assigned to Bo. sweeti. The Siberian type material of Bo. buurensis exhibits variability in blade–carina configuration, notably in the fusion of the posterior carinal denticles and the shape of the anterior denticles (e.g. Dagis 1984, pl. 2, figs 6, 10), but those variants have not been reported elsewhere. Specimens with a narrower platform and a more prominent posterior carina were assigned to Ng. jakutensis by Dagis (1984). The North American material includes two variants assigned to Bo. buurensis, here differentiated as morphotypes α and β.
α morphotype
Figure 9I, J, N
| 1973 | Neogondolella jubata Sweet; Mosher, p. 167, pl. 19 fig. 27. | |
| 1998 | Gondolella sweeti (Kozur & Mostler); Garzanti et al., fig. 7.8. | |
| 2008 | Borinella buurensis (Dagis); Orchard, p. 400, fig. 5.9–11 (only). | |
| 2008 | Borinella aff. buurensis (Dagis); Nakrem et al., fig. 4.17–18. | |
| 2008 | Borinella buurensis (Dagis); Nakrem et al., fig. 4.19. | |
| ? | 2015b | Neogondolella sp. Chen et al., fig. 9.11. |
Remarks
The platform of this P1 element gradually narrows towards the anterior blade tip in evenly arcuate margins showing no inflection. The holotype of Bo. buurensis appears to be an example.
Material & occurrence
6 specimens from tardus Zone, sample 213C, Toad River, BC. In addition to the Siberian types, it is known elsewhere from the Vikinghøgda and Tvillingodden formations, Svalbard (Nakrem et al. 2008); Tamba Kurkur Formation, Selong, south Tibet (Garzanti et al. 1998); ?Jiarong section in South China, Tulong, Tibet (Chen et al. 2015b).
β morphotype
Figure 9K–M, S, T–V
Remarks
The platform of the P1 element narrows more abruptly in the anterior 1/3 of the element. This produces an inflection point and a narrower anterior flange flanking a more differentiated blade. A broad, rectangular platform characterizes the posterior 2/3 of the element.
Material & occurrence
This morphotype is less common in the tardus Zone of Toad River (sample 213C), BC; tardus Zone (sample SMC3), near Smith Creek, Ellesmere Island, Nunavut Territory (Orchard 2008).
Borinella? curvata Orchard sp. nov.
Figure 9O–R
| 1997 | Neogondolella aff. sweeti Kozur & Mostler; Orchard & Tozer, p. 680. |
LSID
urn:lsid:zoobank.org:act:1E65E576-1409-4F22-9FDD-10864BD0A14E
Derivation of name
Latin, curvus, bent, as in the posterior platform.
Holotype
GSC 141789 (Fig. 9P–R)
Type stratum & locality
Toad Formation (sample 213A), Toad River, BC.
Diagnosis
The segminiplanate P1 element has a long, narrow platform of relatively uniform width that terminates in a rounded, often incurved posterior margin. Length : breadth ratio of the platform is 4:1. Long anterior blade denticles are fused for half their length, and pass posteriorly into a moderately high and fused medial carina, and finally several discrete nodes that extend to, or near to, the posterior margin, which may carry an extended carina. The carina commonly terminates in a large terminal denticle. The total number of blade–carinal denticles and nodes in adult elements is c. 17.
Comparisons
This species lies closest to, and is thought to have developed from, the α-morphotype of Bo. buurensis but differs in its longer platform, and the higher, more developed medial carina that is continuous to the terminal denticle; there is no offset accessory posterior node as seen in its precursor. Unlike most Borinella species, the new species has a fully developed anterior platform. Early growth stages of Bo. buurensis (Fig. 9N) most closely resemble this new species, but later growth stages have divergent morphology.
Remarks
This is the most common element from the type locality, which also includes the first Magnigondolella species and others assigned to Neogondolella. The transitionary nature of the newly recognized taxa makes assignment of genus questionable. The anterior blade denticles are like those of Borinella, but the fused medial carina is like that in some Neogondolella, whereas its elevation is similar to that of Magnigondolella.
Material & occurrence
100+ specimens, many fragmentary specimens in the Toad formation (sample 213A), Toad River, BC.
Borinella chowadensis Orchard, 2007
Figure 9W–Y
| 2007 | Borinella chowadensis Orchard, p. 113, pl. 1 figs 12–14, 26. |
Diagnosis
The segminiplanate P1 element has a broad symmetrical platform that tapers progressively from its broad and rounded posterior end to the anterior end of the blade where it is a narrow flange. Length : breadth ratio of the platform is 3.5:1. A large reclined cusp lies at the posterior end of the carina and may be accompanied by an accessory node. There is no platform brim. The discrete blade denticles are relatively broad with a triangular outline in profile. The total number of blade–carinal denticles and nodes in adult elements is c. 11.
Remarks
In upper view, this species has a subtriangular platform outline, unlike the subparallel margins of Bo. sweeti, or the plano-convex outline and curved axes of Bo. buurensis and Bo.? curvata. See also Orchard (2007).
Material & occurrence
About 40 specimens from sample CHOW-4, Toad Formation, near Chowade River, BC.
Borinella sweeti (Kozur & Mostler, 1976)
Figure 9A–H
| p 1970 | Neogondolella elongata Sweet, pp 239–240, pl. 3 figs 23, 25 (only). |
| 1976 | Gondolella sweeti Kozur & Mostler, p. 10. |
| p 1984 | Neogondolella buurensis Dagis, pp 12, 13, pl. 2 figs 11?, 13, 15 (only). |
| 1994 | Gondolella sweeti Kozur & Mostler; Garzanti et al., pl. 2 fig. 1a–c. |
| 2007 | Borinella sweeti (Kozur & Mostler); Orchard, pl. 1 figs 4–6. |
| p 2008 | Borinella buurensis (Dagis); Orchard, p. 400, fig. 5.12–13 (only). |
| 2009 | Neogondolella n. sp. D; Orchard & Zonneveld, fig. 15.29–31. |
| 2010 | Borinella sweeti (Kozur & Mostler); Orchard, pl. 1 figs 4–6. |
| 2018 | Borinella buurensis (Dagis); Henderson et al., pl. 1 figs 20–22. |
| 2018 | Neogondolella n. sp. D; Moslow et al., fig. 19.15–17. |
Diagnosis
The arched platform of this Borinella P1 element has a straight axis with subparallel margins in its posterior 2/3, anterior of which it gradually decreases in breadth. Length : breadth ratio of the platform is 3.5–4:1. A moderately large cusp is often terminal, although a very narrow posterior platform brim may be developed. The total number of blade–carinal denticles and nodes in adult elements is c. 16.
Comparisons
The lateral margins of the platform are subparallel rather than curved as in Bo. buurensis and Bo.? curvata. An accessory posterior node may be developed in later growth stages, but this is not offset, as in the former species.
Remarks
The present diagnosis is revised as a clear definition of this species has been lacking. Kozur & Mostler (1976) established this species based on a single paratype of Neogondolella (= Cb.) elongata illustrated by Sweet (1970) from the upper Gandaderian (Dienerian) of Nammal in West Pakistan; they did not figure or cite additional records. It was compared with Spathian Cb. elongata sensu stricto, which differs in its more compact denticulation and free blade. Later, Smithian Bo. buurensis was introduced by Dagis (1984), but no comparison with the present species was provided. As presently conceived, this species is long ranging.
Material & occurrence
Post-tardus-Zone, Toad River (sample 213A), and Chowade River (sample CHOW-14); tardus Zone (sample SMC3) of Smith Creek, Nunavut Territory; Montney Formation (subsurface) Petro-Canada Kobes (Henderson et al. 2018) and Progress Graham (Moslow et al. 2018) wells, BC; Vega member of Sulphur Mountain Fm., Mt Becker, BC (Orchard & Zonneveld 2009); tardus Zone, Crittenden Springs, Nevada; Darwin Canyon (DC-13, 10), California; Thini Chu Group, Manang, central Nepal (Garzanti et al. 1994). The holotype comes from the Mittiwali Member of the Mianwali Formation at Nammal, West Pakistan, where it occurs with Neospathodus pakistanensis Sweet, 1970, and was dated as Dienerian. A second specimen figured by Sweet (1970, pl. 3 fig. 18) from the same sample resembles Bo. nepalensis (Kozur & Mostler), which supports an age around the Induan–Olenekian boundary. Most specimens from Nunavut Territory, BC, and California are from the upper Smithian or lower Spathian; a single Chowade specimen is late Spathian in age.
‘Borinella’ laii (Chen in Chen et al., 2020)
Figure 9Z, AA
Remarks
This species from Oman is included here because it was included in the summary of Orchard (2007). The discrete blade denticles resemble those of Borinella and the subfamily Gladigondolellinae, which led to the suggestion of a relationship (Orchard 2007). However, the neogondolellin multielement apparatus does not occur in Oman, but nor does that of Gladigondolella tethydis (see Orchard 2005). The species was illustrated by Chen et al. (2015b, 2019), and very recently named, but the assignment of genus remains uncertain.
Material & occurrence
Very common from Jabal Safra, Oman (sample 104a; Orchard 1995); Unitary Association 12, Oman and Jiarong, South China.
Genus COLUMBITELLA Orchard, 2005
| 2005 | Columbitella Orchard, p. 87, fig. 13. |
Type species
Neogondolella elongata Sweet, 1970
Remarks
Orchard (2005) introduced this genus based on a multielement reconstruction of Cb. elongata from the middle Spathian Columbites beds of Paris Canyon, Idaho. This interpretation was based on an S1 (formerly S2) element that differed from that of Neogondolella (Orchard 2005, fig. 13), although the reconstruction has not been confirmed in the Pakistan type material of Cb. elongata. Nevertheless, these morphological characteristics of the segminiplanate P1 element serve to differentiate the genus from other neogondolellin P1 elements: a relatively short platform with upturned edges; geniculation points marking anterior platform narrowing; a well-differentiated anterior (fixed) blade; and a generally prominent terminal cusp.
Columbitella amica (Klets, 1998)
Figure 10AM–AO
| 1998 | Neogondolella amica Klets, p. 115, pl. 1 figs 1–5. |
Diagnosis
These segminiplanate P1 elements are relatively short and broad with an expanded anterior part immediately behind strong geniculation points and precipitous anterior platform edges, which may bear weak nodes. The posterior platform gradually and then rapidly tapers to the roundly pointed posterior tip. Length : breadth ratio of the platform is 2:1. The anterior fixed blade is high and has c. 6 largely fused, denticles, flowed by an equal number of shorter carina nodes that maintain a straight upper profile. A large upright cusp lies at the posterior end of the platform. The total number of blade–carinal denticles and nodes in adult elements is c. 13.
Remarks
This species is close to Cb. paragondolellaeformis and juvenile specimens may be indistinguishable. The platform of Cb. amica is shorter, broader, less tapered posteriorly, and has steeper anterior edges. Rare specimens from the Columbites beds in Idaho assigned to Cb. aff. elongata (e.g. Fig. 10AI, AJ) have a short platform like that of Cb. amica, but they have fewer, larger and less fused blade denticles, as in the associated specimens of Cb. elongata.
Material & occurrence
A single specimen from Toad Formation (sample CHOW-7), Chowade River, BC.
Columbitella brevis Orchard sp. nov.
Figure 10V–Z
LSID
urn:lsid:zoobank.org:act:D5B285D9-EA02-40A2-BB59-B8C3989ED6BA
Derivation of name
Latin, brevis, short: both the blade and entire element is shorter than other species of the genus.
Holotype
GSC 141801 (Fig. 10V–X)
Type stratum & locality
Toad Formation (sample CHOW-8), Chowade River, BC, Canada.
Diagnosis
The segminiplanate P1 element has an arched, ovoid platform about twice as long as broad. The anterior margins taper rapidly and slope downward anterior of inconspicuous geniculation points to meet the short downturned blade. The blade–carina denticles are of a constant height and become increasingly fused with growth. The rounded posterior margins are also downturned and border a large, prominent, reclined cusp. The total number of blade–carinal denticles and nodes in adult elements is c. 10.
Comparisons
These P1 elements have a shorter, more rounded platform than those of Cb. elongata, which differs noticeably in its long free blade and steep anterior platform edges. The platform of Cb. paragondolellaeformis has a longer, more tapered posterior platform.
Material & occurrence
100+ specimens from Toad Formation (CHOW-8–11, ?12), Chowade River, BC.
Columbitella elongata (Sweet, 1970)
Figure 10A–G, J–O, ?AI–AJ
Diagnosis
A species of Columbitella characterized by arched segminiplanate P1 elements with a platform typically developed in the posterior 2/3, initially with a biconvex outline and with later growth characterized by subparallel, upturned lateral margins. Length : breadth ratio of the platform is 2–2.5:1. The anterior free blade is composed of relatively large denticles that pass posteriorly into smaller, more fused carina nodes and finally into a large, strongly reclined, circular cusp that projects beyond the platform and imparts a pointed appearance to the element. The total number of blade–carinal denticles and nodes in adult elements varies from 12 to 15, although the smaller holotype has 9. In profile, the blade–carina maintains a constant height due to the down arching of both the anterior blade and posterior platform. The anterior platform ends abruptly close to the pronounced geniculation point to produce a free anterior blade, sometimes with narrow flanking flanges.
Remarks
Columbitella elongata was originally recorded from both Smithian and Spathian strata in West Pakistan, but the holotype (refigured here) is from Spathian strata and older records should be assigned to Borinella (see Bo. sweeti). The revised diagnosis applies to the species that is very common in USA in strata with the ammonoid Columbites. Two morphotypes that differ in the configuration of the posterior carina are differentiated within the very large populations of this species, although they appear to have the same stratigraphic range. Rare elements assigned to Cb. aff. elongata (Sweet) have short platforms that mimic Cb. amica (q.v.), but the blade and cusp correspond to those of Cb. elongata.
Material & occurrence
100+ specimens from the Thaynes Formation, throughout the Columbites beds in Paris Canyon (GSC O-064673, W7, W11) and Hot Springs (W5, W10, W13); and the Procolumbites beds in Hammond Creek (GSC O-064670–1), Idaho. The holotype comes from the Narmia Member of Mianwali Formation at Nammal in the Salt Range of Pakistan, where it was assigned to Zone 8 of Sweet (1970).
α morphotype
Figure 10A–G, ?AI–AJ
| 2007 | Columbitella elongata (Sweet); Lucas & Orchard, fig. 7.19–22. |
Remarks
This morphotype has a large terminal cusp that rises well above the adjacent carinal nodes, which are relatively low and fused. This is the more common morphotype, and includes the type species. The Siberian Columbitella taimyrensis (Dagis, 1984) has a similar cusp, but the single holotype and additional specimens illustrated by Klets (1998) provide an incomplete picture of the taxon: the platform of Cb. taimyrensis appears smaller and lacks geniculation points. See also Cb. amica.
β morphotype
Figure 10J–O
Remarks
This posterior carina of the P1 element in this morphotype has a pair of large denticles, one of which is the cusp, but these are not distinctly higher than the adjacent carina denticles. The carina is sometimes higher in this morphotype.
Columbitella joanae (Orchard & Zonneveld, 2009)
Figure 10AE–AH
Diagnosis
The relatively long platform of the segminiplanate P1 element has parallel margins for much of its length, and a rapidly tapered posterior most part that terminates in a pointed extension of the carina. Incipient nodes may occur about the well-developed geniculation points, anterior of which the platform is much reduced in breadth and steps down, as seen in profile. Length : breadth ratio of the platform is 2.5:1. The high anterior blade occupies about 1/3 of the element length, and passes posteriorly into a moderately high carina that tends to be fused on the anterior half of the platform, and composed of discrete nodes on the downturned posterior part. The terminal denticle of the carina is reclined and larger than nodes to the anterior. The total number of blade–carinal denticles and nodes in adult elements is c. 18.
Remarks
This is an older Columbitella species and has the most developed platform compared with younger species. Overall, the pointed platform is similar to that of Ng. praeacuta, from which the genus may have arisen through both anterior and posterior platform reduction.
Material & occurrence
About 70 specimens from the Toad Formation (sample CHOW-5), Chowade River, and Sulphur Mountain Formation (sample WAP-A11), Ganoid Ridge, Wapiti Lake, BC; Tvillingodden Formation, Milne Edwardsfjellet section, Svalbard.
Columbitella jubata (Sweet, 1970)
Figure 11V–X
| p 1970 | Neogondolella jubata Sweet, pp 243–244, pl. 2, figs 1,·3, 14–16 (only). |
| non 1984 | Neogondolella jubata Sweet; Dagis, pp 15–16, pl. 4, figs 4–11, 13. |
| p 1994 | Gondolella aff. jubata (Sweet); Garzanti et al., pl. 3, figs 6, 7, 9 (only). |
| p 1998 | Gondolella aff. jubata (Sweet); Garzanti et al., fig. 7.9, 7.11 (only). |
| 2000 | Neogondolella jubata Sweet; Balini et al., pl. 3 fig. 16a–c , pl. 4 figs 2a–c. |
Diagnosis
The segminiplanate P1 element has a high, even-crested carina, and a platform that extends almost the entire length of the unit, but strongly reduced in the anterior 1/3 to a narrow flange along the fixed blade. The anterior narrowing begins at variably differentiated geniculation points, whereas to the posterior the platform expands to reach its maximum breadth in its posterior 1/3. The length : breadth ratio is 3:1. At the posterior end, a narrowing of the platform may impart a weak constriction opposite the cusp. The fixed blade adjacent to the reduced platform is composed of pointed denticles fused except for their tips. These pass posteriorly into a mostly fused carina and then 2–3 more discrete posterior denticles; a total of 17 denticles include the indistinct cusp. A narrow platform brim surrounds the posterior carina. In lateral view, the upper margin is arched and the crest of the carina is visible above the platform margins.
Remarks
Anterior geniculation points marking the reduced anterior platform are not conspicuous in the holotype (re-illustrated here), but are well shown in topotype specimens illustrated by Balini et al. (2000), and by specimens from Tibet (Garzanti et al. 1998). The blade–carina is higher and more fused than is typical of Columbitella, and approaches that of Magnigondolella. The relatively high fixed blade and anterior geniculation points are regarded as typical for the present genus. Sweet (1970) illustrated elements in which the blade increased in height to the anterior, as is common in the genus, and others in which the blade maintains a lower, uniform height. The former, including the holotype, have a broader platform than those elements with a lower blade, which are excluded from the present species, as are all of the specimens figured by Dagis (1984), and a specimen figured by Garzanti et al. (1998, fig. 7.10).
Occurrence
Sweet (1970) noted that the species occurs also in the Columbites beds of the Thaynes Formation in south-eastern Idaho, although only Cb. elongata was recovered from those strata during this study. The species occurs widely in Asia, in: the Narmia Member of Mianwali Formation at Landa, Narmia and Zaluch in west Pakistan (Sweet 1970); the Tamba Kurkur Formation, Selong, south Tibet (Garzanti et al. 1998); and the Manang area, central Nepal (Garzanti et al. 1994).
Columbitella paragondolellaeformis (Dagis, 1984)
Figure 10AK–AL
| p 1984 | Neogondolella paragondolellaeformis Dagis, pp 16–17, pl. 4 fig. 12, pl. 5 fig. 2 (only). |
| p 1994 | Gondolella aff. jubata Sweet; Garzanti et al., pl. 2 figs 6–8 (only). |
| p 1998 | Neogondolella jubata Sweet; Klets, pl. 2 fig. 3 (only). |
| p 2008 | Columbitella? paragondolellaeformis (Dagis); Nakrem et al., fig. 4.26–28 (only). |
Diagnosis
The segminiplanate P1 element has three parts: 1/3 anterior blade flanked by narrow platform flanges; 1/3 subparallel anterior platform margins; and 1/3 posterior margins that taper to a point. The arched, marginally upturned platform narrows and slopes downward at geniculation points that often bear small nodes. The short blade is composed of high compressed denticles that are fused except for their triangular tips, and which pass into lower, increasingly fused nodes of the posterior carina. There are 13 denticles in total, of which the sub terminal inclined cusp is moderately large.
Comparisons
The species is close to Cb. elongata but differs in its longer, more tapered posterior platform, less abrupt geniculation points, and less differentiated free blade with more fused denticles. Columbitella amica differs in its broader platform and its steep anterior platform edges.
Remarks
All the types illustrated by Dagis (1984) were shown in only one view so it is difficult to evaluate the character of this species. Some of the BC specimens have nodose anterior platform margins, in common with a paratype of Dagis (1984, pl. 5 fig. 2), and additional specimens illustrated by Nakrem et al. (2008) from Svalbard, and by Garzanti et al. (1994) from central Nepal.
Material & occurrence
16 specimens from the Toad Formation (CHOW-7), Chowade River, BC; plus Vendomdalen Member of the Tvillingodden Formation in the Milne Edwardsfjellet section (Nakrem et al. 2008); Thini Chu Group, Manang, central Nepal (Garzanti et al. 1994); and the types from the Olenekites spiniplicatus Zone on the Mengilyakh River, central Siberia (Dagis 1984).
Columbitella weitschati Orchard sp. nov.
Figure 10AA?, AB–AD
LSID
urn:lsid:zoobank.org:act:DDE85D73-5C60-45A8-AC6B-3435BEFF5FCF
Derivation of name
Named for W. Weitschat, who provided the sample that yielded the holotype.
Holotype
GSC 141804 (Fig. 10AB–AD)
Type stratum & locality
Thaynes Formation, Tirolites beds (sample W12), Paris Canyon, Idaho.
Diagnosis
The segminiplanate P1 element has a relatively narrow, marginally upturned platform that occupies the posterior 2/3 of the total element, is broadest in its anterior, and tapered to the often constricted and pointed posterior tip. Anterior of the platform geniculation points, the platform narrows abruptly, extending as a narrow flange to the end of the blade, which is relatively low. Length : breadth ratio of the platform is 3.5:1. The holotype has 4 large, triangular anterior denticles, followed by 6 smaller, partly fused carinal denticles, and posteriorly a moderately large reclined, terminal cusp.
Comparisons
Compared with the P1 element of Cb. elongata and Cb. joanae, this species has a tapered, partly constricted posterior platform rather than subparallel margins; less abrupt anterior platform edges; a smaller cusp than the Cb. elongata α morphotype; and lower and larger blade denticles. The new species is narrower and more strongly tapered than Cb. paragondolellaeformis, and has a lower blade.
Remarks
A single poorly preserved specimen from Darwin Canyon is assigned to Cb. cf. weitschat as it is insufficiently preserved to identify for certain.
Material & occurrence
12 specimens from the Tirolites beds (W12, ?GSC O-64672), Thaynes Formation, Paris Canyon, Idaho; ?Union Wash Formation (DC-6), Darwin Canyon, California.
MAGNIGONDOLELLA Golding & Orchard, 2018
Type species
Magnigondolella salomae Golding & Orchard, 2018
Remarks
The segminiplanate P1 element typically has a high, strongly fused blade–carina of relatively uniform height extending throughout its length. This carina is often wall-like with only the tips of the laterally compressed denticles visible. The platform is downturned at its posterior end above which the cusp is relatively discrete. The multielement apparatus was described by Golding (2018), who showed it is the same as that of contemporaneous Neogondolella species.
Magnigondolella acuminata Orchard sp. nov.
Figure 12S–Y
LSID
urn:lsid:zoobank.org:act:38203DDA-B677-44FA-8070-0DE00DBE9F6E
Derivation of name
Latin, acuminata, referring to the sharply terminated, tapered platform.
Holotype
GSC 141828 (Fig. 12X–Y)
Type stratum & locality
Toad Formation (GSC O-056259), Chowade River, BC, Canada.
Diagnosis
A Magnigondolella species in which the P1 element has a narrow platform with biconvex lateral margins that taper in both directions from the maximum width at mid-platform. Length : breadth ratio of the platform is 4:1. The high, blade–carinal denticles are fused except for their tips, and the discrete, reclined cusp is terminal at the pointed posterior end. The total number of blade–carinal denticles and nodes in adult elements is c. 15.
Comparisons
The P1 element is very similar to that of Ng. praeacuta in platform shape but differs in the character of the blade–carina-cusp. At all growth stages, the denticles of the present species are strongly fused and their short tips produce a saw-tooth carina profile. The denticles of Ng. praeacuta are more variable, being generally lower, with less fused tips in smaller elements and with strongly fused medial carina in larger ones, and a secondary denticle posterior of the cusp.
Material & occurrence
100+ specimens from the Toad Formation (samples CHOW-12–15, GSC O-056259), Chowade River, and in multiple samples from the subrobustus Zone in north-east BC and the Arctic (Figs 2, 3).
Magnigondolella incurva Orchard sp. nov.
Figure 13S–Y
| 2007 | Neogondolella n. sp. F; Orchard, p. 99, fig. 1. |
LSID
urn:lsid:zoobank.org:act:71D75988-D622-4FC5-8D66-DEC3D114ADE1
Derivation of name
Latin, incurvo, bend: reflecting the irregular platform outline.
Holotype
GSC 141842 (Fig. 13V–W)
Type stratum & locality
Toad Formation (sample CHOW-11), Chowade River, BC, Canada.
Diagnosis
The segminiplanate P1 element has a short, asymmetrical platform that has a convex outer margin and a sinuous inner margin that narrows abruptly in its posterior half. Length : breadth ratio of the platform is 2.5:1. A large, terminal cusp is upright and largely fused with the high, wall-like carina. The total number of blade–carinal denticles and nodes in adult elements is c. 13, although fusion obscures them.
Comparisons
The relative dimensions of the platform is like that of Mg. trutchensis but this species differs in its distinctive asymmetrical platform. Both Ng. sinuosa sp. nov. and Ng. curva Golding & Orchard, 2016, are species with similar platform asymmetry but they lack the high and fused carina.
Remarks
A single specimen from the USA is much larger than the type material and differs in its relatively long anterior platform margins, which also bear subdued nodes. Based on its preserved pit, only the platform tip is missing, so the posterior platform is likely to be comparable to that of the present species. Subdued nodes and the greater length of its anterior platform may be a function of its larger size, so the specimen is included here.
Material & occurrence
100+ specimens from the Toad Formation (samples CHOW-11, 12, ?8, ?10), Chowade River, BC; 1 specimen from Thaynes Formation, Procolumbites beds (GSC O-064671), Hammond Creek, Idaho.
Magnigondolella mutata Orchard & Goudemand sp. nov.
Figure 13Z–AF
LSID
urn:lsid:zoobank.org:act:7ED72EC6-0A2F-4A09-B918-D544704C0E24
Derivation of name
Latin, mutate, change. This species is the first Olenekian neogondolellin with significant elevation of the carina.
Holotype
GSC 141846 (Fig. 13AD–AF)
Type stratum & locality
Union Wash Formation (DC-10), Darwin Canyon, California.
Diagnosis
The arched segminiplanate P1 element has a straight axis and an often thickened, well-developed platform that broadens gradually from its anterior to the maximum breadth near the rounded to quadrate posterior end. Length : breadth ratio of the platform is 3.5:1. The anterior fixed blade is high and its denticles mostly fused except for their discrete tips; this passes into an equally elevated medial carina composed of irregularly fused denticles of variable size and, near the posterior end, a few more discrete denticles that includes the inconspicuous terminal cusp. There are typically 16–18 denticles in total. A very narrow posterior brim may be developed.
Comparisons
The platform outline resembles that of Bo. sweeti and Mg. tozeri and this new species provides a morphological link between them. Compared with Bo. sweeti, the blade–carina of the present species has smaller and more fused anterior denticles and a higher carina. The blade–carina of Mg. tozeri is very similar to the present species but it has more uniform denticulation in terms of both denticle size and their greater fusion, and its cusp is more differentiated.
Remarks
This species is regarded as the first representative of Magnigondolella, and transitional in nature from Borinella as reflected in the intermediate character of its blade–carina. Orchard & Tozer (1997) originally combined it with other species in Bo. aff. sweeti. Chen et al. (2019) illustrated some similar specimens from Oman as Ng. ex gr. jakutensis, but most of those specimens have a broader medial platform, less fused anterior blade denticles, and a more prominent terminal cusp; moreover, the juvenile specimens from Oman are unlike any found in North America.
Material & occurrence
4 specimens from the Toad Formation above the tardus Zone (sample 213A), Toad River, BC; additional material from Union Wash Formation (DC-10, 8a), Darwin Canyon, California.
Magnigondolella peribola Orchard & Golding sp. nov.
Figure 13A–E
| ? 1998 | Gondolella aff. jubata (Sweet); Garzanti et al., fig. 7.10 (only). |
| 2007 | Neogondolella sp. Orchard et al., fig. 6.4–6. |
| ? 2008 | Neogondolella ex gr. regalis Mosher; Orchard, p. 405, fig. 5.22–25. |
| 2009 | Neogondolella ex gr. regalis Mosher; Orchard & Zonneveld, p. 782, fig. 15.32–33. |
| 2010 | Neogondolella ex gr. regalis Mosher; Orchard, fig. 7.6–8. |
| 2021 | Magnigondolella n. sp. D; Golding, p. 582, pl. 2 figs 18–29. |
LSID
urn:lsid:zoobank.org:act:71137DD8-A63B-4058-8961-886FBC52CF92
Derivation of name
Latin, peribolus, wall, as in the wall-like blade–carina.
Holotype
GSC 141834 (Fig. 13A–C)
Type stratum & locality
Toad Formation, subrobustus Zone (GSC O-046990), near Mount Brewster.
Diagnosis
A species of Magnigondolella with a P1 element that is long, narrow, typically broadest at midlength, narrowing gradually to the anterior, and to the posterior becoming narrower with subparallel margins. Length : breadth ratio of the platform is 4:1. The posterior end of the platform is rounded and surrounds a large relatively discrete cusp, and in some cases smaller accessory denticles. In total, the high, fused blade–carina consists of 18–20 denticles.
Comparisons
This species has a distinctive platform shape that is broader anteriorly and narrower in its posterior half. In contrast, the contemporaneous Mg. tozeri has a lachrymiform outline. The shape of Mg. peribola also differs from species reported from the Anisian, most of which also have smaller and more numerous denticles. This appears to be a trend because this new species has more denticles than early Spathian Mg. mutata of comparable size, and fewer than, for example, the Anisian Mg. cyri (with 21–23 denticles).
Remarks
This species was first illustrated by Orchard et al. (2007) from around the Olenekian–Anisian boundary in Guandao, China as a generalized member of Ng. ex gr. regalis, a group later assigned to Magnigondolella. These elements have recently been recognized as a new species by Golding (2021), who has provided a more complete description of the Chinese material, including several growth stages that imply juveniles may have had a pointed platform like that which characterizes Mg. acuminata. Retention of this juvenile morphology in mature Mg. acuminata is possible, as is the occurrence of the second species in Guando. Although broken anteriorly, a specimen from Selong (Garzanti et al. 1998) has a longer platform than Cb. jubata and has a similar high blade to the new species.
Material & occurrence
About 12 specimens from the Toad Formation (CHOW-14, GSC O-056259), Chowade River, BC, and the matrix of several subrobustus Zone collections in north-east BC (GSC O-056179, 46990, 56240). Also from the Sulphur Mountain Formation (MBK8), Mt Becker, BC (Orchard & Zonneveld 2009); Luolou Formation, Guandao, China (Golding 2021); ?Tamba Kurkur Formation, Selong, south Tibet (Garzanti et al. 1998).
Magnigondolella tozeri Orchard sp. nov.
Figure 13F–H
LSID
urn:lsid:zoobank.org:act:CFF53318-D550-4EF9-ADC4-02838ED30E42
Derivation of name
Named for E.T. (Tim) Tozer, who provided the sample that yielded the holotype.
Holotype
GSC 141836 (Fig. 13G–H)
Type stratum & locality
Toad Formation, subrobustus Zone (GSC O-046990), near Mount Brewster, BC.
Diagnosis
A species of Magnigondolella with P1 elements that are broadest in the posterior 1/3, progressively narrower to the anterior, and symmetrically rounded to the posterior. Length : breadth ratio of the platform is 4:1. In total, the high, fused blade–carina consists of 17–18 high, largely fused denticles that terminate in a discrete, relatively large cusp, and in some cases smaller accessory denticles. A narrow platform brim may be developed.
Comparisons
The shape of this species is close to Magnigondolella cyri Golding & Orchard, 2016 from the early Anisian but, unlike the latter, its posterior platform is rounded rather than quadrate, it has a more differentiated cusp, and a platform brim. Anisian Mg. nebuchadnezzari Golding & Orchard, 2016 may have a similar posterior platform but it is typically broadest at midlength. See also Mg. mutata.
Material & occurrence
5 specimens from the matrix of subrobustus Zone collections from the Toad Formation (GSC O-046990, 056259) in BC.
Magnigondolella aff. tozeri Orchard
Figure 12Z–AA
Remarks
These uncommon P1 elements have a biconvex platform that extends along the posterior 2/3 of the element, and a reduced anterior 1/3 without marginal geniculation points. The posterior margin is narrowly rounded and includes a reclined terminal denticle posterior of slightly enlarged cusp. The blade–carina is moderately high and fused and bears a total of c. 16 denticles and nodes in adult elements.
The platform outline is transitional between that of the pointed Mg. acuminata and the more rounded Mg. tozeri, neither of which show the anterior platform reduction. The blade–carina is not as high and wall-like as many Magnigondolella species, but is higher than that of Neogondolella species. Unlike Columbitella, there are no geniculation points in Mg. aff. tozeri.
Material & occurrence
4 specimens from the Toad Formation (CHOW-13, 14), Chowade River, BC.
Magnigondolella trutchensis Orchard sp. nov.
Figure 13I–R
LSID
urn:lsid:zoobank.org:act:98B56ECC-916A-4A7B-AED8-921C2F13FD7C
Derivation of name
Named after the 1:250.000 map-area that was the focus of the project under which the species was recovered.
Holotype
GSC 141838 (Fig. 13K–M)
Type stratum & locality
Toad Formation (CHOW-12), Chowade River, BC.
Diagnosis
The P1 segminiplanate element is short and broad with slightly upturned edges, has an ovoid outline, and a rounded posterior platform margin. From about midlength, the platform narrows to the anterior without geniculation points; its length : breadth ratio is 2–2.5:1. The high blade–carina is composed of 15 fused denticles, and terminates in a relatively large and discrete, reclined cusp. A very narrow posterior platform brim may be developed.
Comparisons
This Magnigondolella P1 element is shorter than both Mg. peribola and Mg. tozeri, but in common with those species it has a wall-like carina and a rounded posterior platform. Columbitella brevis and Ng. dolnapae Balini et al., 2000 have similar platform dimensions to this new species, but they both have blade–carina denticles that are much less fused and, in Cb. brevis, a more prominent cusp and more abrupt anterior platform reduction. Neogondolella dolnapae, from west Kazakhstan, has fewer denticles (9–12) than the new species (13–15) and these are less fused so as that the tips of the denticles produce a clear saw-tooth profile. Comparison of the holotypes of the two species emphasizes this difference.
Remarks
The type material of Gondolella shevyrevi Kozur & Mostler, 1976 also has a high fused carina to the anterior but apparently a low carina to the posterior, and a reduced platform, although not in one paratype. The true nature of Gondolella shevyrevi needs to be determined as it may be a broken Magnigondolella.
Material & occurrence
100+ specimens from the Toad Formation (CHOW-12, ?8), Chowade River, BC. A single specimen from the Tardicolumbites beds (HB538) of the northern Humboldt Range, Nevada.
Magnigondolella? minuta Orchard sp. nov.
Figure 10H–I, P–U
LSID
urn:lsid:zoobank.org:act:D91E1BB8-48F6-4F21-9E0E-5A9AC4A70C01
Derivation of name
Latin, minutus, small: this is the smallest species of the present study.
Holotype
GSC 141796 (Fig. 10P–R)
Type stratum & locality
Thaynes Formation, Prohungarites beds (GSC O-64675), Hammond Creek, Idaho.
Diagnosis
The P1 element is a small, arched segminiplanate element with a relatively flat, asymmetrical platform extending the full length of the unit with a length : breadth ratio of 2:1. The outer platform margin is semicircular whereas the inner platform is widest near its anterior end and then relatively straight to the posterior; the anterior platform margin curves down in an arc without geniculation points. A high, arched blade–carina is composed of 11–13 mostly fused, subequal denticles with triangular tips; a very prominent terminal cusp is strongly reclined.
Comparisons
The abbreviated platform of this new species is suggestive of a Columbitella species, similar to that of Cb. brevis, but this small species differs in its asymmetric, flat platform, lack of distinct geniculation points, and a high, partly fused carina. The morphology is also reminiscent of Middle Triassic Paragondolella, although there are no similar forms that link the present species with the much younger type species, P. excelsa Mosher, 1968.
Remarks
This species is assigned with question to Magnigondolella because it lacks the wall-like, fused carina, and has a very prominent reclined cusp. The species might belong to an independent group that includes Ng. captica Klets, 1998 (denticles larger and more upright), Gondolella shevyrevi (see Mg. trutchensis), and a specimen illustrated by Balini et al. (2000, pl. 3 fig. 9c) and assigned to Ng. dolnapae (broader anterior platform).
Material & occurrence
Single specimens from two samples from the Prohungarites beds (GSC O-064675, 064700) of the Thaynes Formation in, respectively, Hammond Creek, Idaho, and Tobin Range, Nevada. Five specimens from the Tardicolumbites beds (sample HB538) of the northern Humboldt Range, Nevada.
Genus NEOGONDOLELLA Bender & Stoppel, 1965
| ? 1989 | Pridaella Budurov & Sudar, pp 250, 253. |
Type species
Gondolella mombergensis Tatge, 1956
Remarks
This genus has been regarded as bearing an octomembrate apparatus as described by Orchard & Rieber (1999), Orchard (2005), and modified by Goudemand et al. (2012b). As noted by Orchard (2005), the multielement apparatus of neogondolellins was established in Permian Jinogondolella and Clarkina and remained stable until the anterior bifurcation of the S0 element changed position during the middle Anisian (Orchard & Rieber 1999, pls 1, 4, 5). The apparatus of the type species of Neogondolella has not been described but has been assumed to be as the natural assemblage described by Orchard & Rieber (1999), and reconstructed as Ng. ex gr. constricta (see Orchard 2005). However, Budurov & Sudar (1989) claimed that the apparatus of the type species, Ng. mombergensis, differed from most other species included in the genus, and therefore introduced the new genus Pridaella for those forms. No account of these differences has yet been given other than a reference by Budurov & Petrunova (2000) to the presence of elements of the form-genus Chirodella Hirschmann in Pridaella, and unique but undefined aspects of the ramiform elements of Neogondolella. There are no elements of Chirodella in any neogondolellin known to the author, but should the multielement Ng. mombergensis be determined as different from the Ng. constricta template (Orchard 2005), then Pridaella is available as a name for those ‘conservative’ neogondolellin species of the Triassic.
Based on the segminiplanate P1 element, features of Neogondolella are the differentiation of the blade–carina in mature growth stages into relatively high and discrete anterior and posterior blade–carina denticles, and a lower, more fused medial carina. Neogondolella species do not have the long discrete denticles seen in Borinella; a high wall-like blade–carina as in Magnigondolella; or a high anterior blade and anterior platform geniculation points as in Columbitella.
Neogondolella bucheri Orchard sp. nov.
Figure 11A–N, T–U
| p 2008 | Neogondolella sp. A; Orchard, p. 405, fig. 5.16, 21, 26–28 (only). |
LSID
urn:lsid:zoobank.org:act:98CD7C8F-22C9-4372-AF20-FA0CE10A2C39
Derivation of name
Named for H. Bucher, who provided the sample that yielded the holotype.
Holotype
GSC 141810 (Fig. 11I–K)
Type stratum & locality
Prida Formation (COY-1), John Brown Canyon, northern Humboldt Range, Nevada.
Diagnosis
The arched, segminiplanate P1 elements are characterized by biconvex lateral platform margins extending the length of the element, and a roundly terminated posterior end where a brim surrounds a discrete cusp. Length : breadth ratio of the platform is 3–3.5:1. The carina is of moderate height, typically lower and strongly fused in the medial part, and becoming raised in its posterior part. The distinctive cusp is well differentiated, upright to weakly reclined, and clearly separated from the nodes of the adjacent posterior carina. The total number of blade–carinal denticles and nodes in adult elements is c. 15.
Comparisons
The discrete cusp distinguishes this from most contemporary species but the cusp and posterior outline and brim are similar to that of the younger species Ng. panlaurentia. The latter differs in having parallel rather than biconvex platform margins and an abruptly narrowed anterior platform.
Remarks
Juvenile growth stages have narrow biconvex platforms that are initially pointed and then more rounded posteriorly as that part of the platform grows broader. The carina, initially of uniform height, becomes lower and progressively more fused medially. The maximum platform width shifts to the posterior with growth.
Material & occurrence
100+ specimens from the Blind Fiord Formation (E44-48), Spath Creek, Ellesmere Island; Toad Formation (CHOW-13–15, GSC O-056259), Chowade River, BC; matrix from subrobustus Zone in BC (Fig. 2); haugi Zone, Prida Formation (COY-1, COY-3, HB236), northern Humboldt Range, Nevada.
Neogondolella aff. bucheri Orchard
Figure 11O–S
Remarks
Two relatively large elements have a partly constricted medial platform and a laterally expanded posterior platform, which imparts a weak ‘figure 8’ outline. They also have a posterior carina of more uniform height that lacks the fusion seen in Ng. bucheri. The older specimen (Fig. 11O–P), from the lower Spathian, has relatively discrete blade denticles like those of ancestral Borinella. The platform shape of these elements resembles that of Mg. peribola, which has a much higher blade–carina.
Material & occurrence
Single specimens from the Union Wash Formation (DC-12), and Prida Formation (COY-1), northern Humboldt Range, Nevada.
Neogondolella darwinensis Orchard & Goudemand sp. nov.
Figure 11Y–AE
LSID
urn:lsid:zoobank.org:act:4BEA81CB-613A-4A06-B879-B28169160BD1
Derivation of name
From the type locality, Darwin Canyon, California.
Holotype
GSC 141816 (Fig. 11AD–AE)
Type stratum & locality
Union Wash Formation (DC-8), Darwin Canyon, California.
Diagnosis
The P1 segminiplanate element has a broad, thick platform with biconvex lateral margins and a subrectangular posterior margin. Length : breadth ratio of the platform is 3:1. The anterior fixed blade has 4–5 relatively high denticles fused for more than half their length. Posteriorly, the carina nodes are low, and mostly fused. The cusp is larger than adjacent denticles but is not well differentiated. The total number of blade–carinal denticles and nodes in adult elements is 15–17, although fusion obscures them.
Comparisons
The species differs from Ng. bucheri in lacking a high posterior carina and markedly discrete cusp. Specimens of Ng. praeacuta differ in their pointed platforms, although early growth stages may be indistinguishable. The platform may resemble that of Mg. mutata, but that species has a broader posterior platform, and a dissimilar blade–carina.
Material & occurrence
Union Wash Formation (DC-8, 12), Darwin Canyon, California; Toad Formation (sample 213A), Toad River, BC.
Neogondolella praeacuta Orchard & Goudemand sp. nov.
Figure 12AB–AJ
| 2007 | Neogondolella n. sp. C; Orchard, p. 99, fig. 1. |
LSID
urn:lsid:zoobank.org:act:9A5E703B-AA69-420F-A264-52C5B476A05A
Derivation of name
Latin, praeacutus, pointed: referring to the pointed posterior platform.
Holotype
GSC 141830 (Fig. 12AB–AD)
Type stratum & locality
Union Wash Formation (DC-8), Darwin Canyon, California.
Diagnosis
The arched segminiplanate P1 elements are lenticular in shape with broadly biconvex lateral margins and a pointed posterior platform. Broadest at midlength, the platform extends throughout the length of the element and tapers to both ends; its length : breadth ratio is 3–3.5:1. In adult growth stages, the blade–carina has several relatively high and discrete anterior fixed-blade denticles that pass posteriorly into a more fused carina and then a less fused posterior carina. The triangular cusp has a smaller denticle to its posterior. The total number of blade–carinal denticles and nodes in adult elements is 16–18, although fusion obscures them.
Comparisons
Within the Spathian, P1 elements of this species resemble Mg. acuminata in its pointed platform shape, but the carina of the latter has the high fused blade–carina typical of that genus, and a terminal cusp with no posterior accessory denticle. The new species is similar to Ng. hastata Golding & Orchard, 2016, but that Anisian species has a narrower platform, a lower, less fused carina, and a much more prominent cusp. Neogondolella dilacerata Golding & Orchard, 2016 has a similar carina and a ‘double cusp’, but the latter are well developed unlike in the present species; the posterior platform asymmetry also distinguishes the two species.
Remarks
The early growth stages of this species have a moderately high and fused carina with triangular denticle tips evident throughout, a more conspicuous cusp, and a tiny posterior denticle. With growth, the platform broadens, the medial denticles become relatively lower and fused, and the terminal denticle enlarges.
Material & occurrence
Union Wash Formation (DC-8A, 8), Darwin Canyon, California.
Neogondolella sinuosa Orchard & Goudemand sp. nov.
Figure 12J–M, Q–R
| 2007 | Neogondolella n. sp. E; Orchard, p. 99, fig. 1. |
LSID
urn:lsid:zoobank.org:act:F8B8C234-206F-49CD-82E8-7809C609CBB7
Derivation of name
Latin sinuosa, roundabout; after the irregular outline of the platform.
Holotype
GSC 141821 (Fig. 12J–L)
Type stratum & locality
Union Wash Formation (DC-8a), Darwin Canyon, California.
Diagnosis
The arched segminiplanate P1 element has an asymmetrical platform with its maximum breadth in the anterior part, a narrow posterior platform that tapers to a point, a sinuous inner platform margin, and an inturned posterior platform. Length : breadth ratio of the platform is 3.5:1. In lateral view, the blade–carina has an arcuate profile. Anterior denticles are high and partly fused, and with growth become lower and increasingly fused posterior of the blade. The cusp is inconspicuous and the pit is terminal. The total number of blade–carinal denticles and nodes in adult elements is 15–17, although fusion obscures them.
Comparisons
An asymmetrical platform is also a feature of the Spathian Mg. incurva and the Anisian Ng. curva. The high and fused carina distinguishes the first, whereas the latter has its maximum breadth less anteriorward, its blade denticles are more fused, and it has a large cusp.
Remarks
The lower Spathian holotype has some large and discrete Borinella-like anterior denticles, reflecting its probable origin in that genus. In this respect, the species is similar to the contemporaneous Bo.? curvata, which also has a moderately high and largely fused medial carina but it differs in platform shape. Both early Spathian species are early derivatives of Borinella with novel features. The pointed platform shape of Ng. sinuosa relates it to the symmetrical, biconvex Ng. praeacuta, and it resembles an asymmetrical variation of the latter.
Material & occurrence
3 specimens from the Toad Formation (sample 213A), Toad River, BC; 3 specimens from Union Wash Formation (DC-8a), Darwin Canyon, California.
Neogondolella aff. sinuosa Orchard & Goudemand
Figure 12N–P
Remarks
This uncommon element differs from its associate Ng. sinuosa in having a strong constriction close to the posterior end, which results in an inturned posterior tip. In Ng. sinuosa, the inner platform narrows gradually to the posterior rather than abruptly at a constriction. This element resembles a Ng. praeacuta in its otherwise biconvex platform outline.
Material & occurrence
One specimen from Union Wash Formation (DC-8a).
Neogondolella spathiconstricta Orchard sp. nov.
Figure 12A–I
| ? 1984 | Neogondolella sp. 2; Dagis, pl. 5 fig. 6. |
| 2007 | Neogondolella n. sp. H; Orchard, p. 99, fig. 1. |
| p 2008 | Neogondolella sp. A; Orchard, p. 405, fig. 5.14, 15, 32, 33. |
| ? 2008 | Neogondolella sp. B; Orchard, p. 405, fig. 5.29–31. |
| p 2012a | Neogondolella ex gr. regalis Mosher; Goudemand et al., pl. 3.12, ?14 (only). |
LSID
urn:lsid:zoobank.org:act:90C67DD0-ADFB-40C3-8ABE-12E7A8B0DC8F
Derivation of name
Latin, constrictus: refers to the constricted posterior platform, and its Spathian age.
Holotype
GSC 141817 (Fig. 12A–C)
Type stratum & locality
Prida Formation (COY-4), northern Humboldt Range, Nevada.
Diagnosis
The segminiplanate P1 elements have a long and narrow platform with a length : breadth ratio of 5:1. The platform has a convex outer margin and a more irregular inner margin, commonly with a constriction on the inner posterior margin. The posterior platform is narrowly rounded adjacent to, and sometimes merged with the terminal denticle of the carina, which lies posterior of the smaller cusp. The blade–carina is moderately high in the anterior and progressively lower to the posterior, forming an arcuate profile like that of the arched basal profile; its denticles are fused except for their triangular tips. The total number of blade–carinal denticles and nodes in adult elements is 17–20.
Comparisons
These elements are similar to Middle Triassic Ng. ex gr. constricta (Mosher & Clark, 1965), a large and diverse clade currently under revision. It is closest to Ng. constricta postcornuta Kovács, 1994, from which it differs in its higher carina that is continuous to the posterior end. Dagis (1984) and Klets & Yadrenkin (2001) described similar elongate species from the Smithian (e.g. Ng. composita, Ng. altera) but the blade–carina-cusp features differ.
Remarks
Long and narrow, lanceolate P1 elements like this occur sporadically through the Spathian. Their origin may lie in some of the older lanceolate species of Neogondolella described by Dagis (1984), Klets & Yadrenkin (2001) and Orchard (2007). These species were brought together as a new genus, Siberigondolella, by Kiliç & Hirsch (2019), although most of the Siberian species have discrete denticulation like that of Borinella, to which they may belong.
Other lanceolate specimens of this group include the Arctic species Neogondolella sp. B of Orchard (2008, fig. 5.29–31), which has a longer, more strongly reclined cusp than any of the present specimens, and some assigned to Neogondolella sp. A of Orchard (2008), which has more regular platform margins and no posterior constriction. The specimen of Dagis (1984) is similar in platform morphology but has a much lower carina.
Material & occurrence
About 30 specimens from the Blind Fiord Formation (samples E45, 47, 48), Spath Creek, Ellesmere Island; Toad Formation (CHOW-5, ?11, 13–15), Chowade River, BC; Needham Creek (GSC O-056719), BC; Prida Formation (COY-1, 3, 4, 6-8, A11), northern Humboldt Range, Nevada.
Acknowledgements
This paper evolved over time during which the author obtained carbonate matrix from dated ammonoid collections provided by E.T. Tozer, H. Bucher and W. Weitschat. These samples supplemented the biostratigraphical framework provided by guided collecting trips with E.T. Tozer on Toad River of BC; H. Bucher in the Humboldt Range of Nevada; and P. Stone and C.H. Stevens in the Inyo Mountains of California. J. Jenks guided Weitschat and kindly provided detailed data on the Idaho localities. S. Irwin assisted in the fieldwork in the Canadian Arctic, and J. Dixon and M. Johns helped collect the Chowade section. P. Krauss and H. Taylor provided essential technical support. N. Goudemand, M. Golding, M. Leu, Z. Lyu and C. Han are thanked for discussions on Olenekian conodonts and sharing data on neogondolellin conodonts in their collections. C. Henderson, S. Thomas and an anonymous reviewer helped improve the manuscript.
Appendix 1: Localities
Numbers prefixed with ‘O’ or ‘C’ are curation numbers and may be cited without an original sample number. Abbreviation: NTS, National Topgraphic Series.
Nunavut, Canada
NTS Bukken Fiord 560A: 80°54′36″N 89°15′45″W. The N side of Spath Creek, 3.2 km NE of Cape St. Andrew, Svartfjeld Peninsula, Ellesmere Island is the type locality for the Spathian Stage, and for the subrobustus Zone, as represented by GSC collections O-047544 and O-047545 from locality 171 of Tozer (1965, 1967, 1994). Matrix from the former, lying 8 m higher, supplements collections from a short corresponding section in the uppermost strata of the Svartfjeld Member, Blind Fiord Formation (Fig. 3: samples E40–48, which are curated as GSC C-303113–303122).
North-eastern British Columbia
Toad River
NTS Toad River, 94N/7: 59°21′20″N 124°48′56″W. The N bank of Toad River, 3.2 km above Liard River (McLearn & Kindle 1950; Tozer 1967, p. 74; 1994, p. 25) is the type locality for the upper Smithian tardus ammonoid Zone (Fig. 4). Smithian ammonoids occur in two beds about 1.5 m apart. Matrix from the lower sample (= GSC O-042364 of Tozer 1967) and its recollection 213C (= GSC O-099584) contains a large fauna including Anawasachites tardus and others (see Tozer 1994, p. 310). The upper bed (= GSC O-042363 of Tozer 1967) contains only Xenoceltites subevolutus and was recollected as sample 213B (= GSC O-099583). The highest sample, 213A, is curated as GSC O-099582. See also Orchard & Zonneveld (2009).
Chowade River
NTS Emerslund Lakes, 94B/6: UTM coordinates 471900 E, 6282600 N. This section is exposed on the N flank of the WSW trending spur off an unnamed mountain near the headwaters of Chowade River. Figure 5 shows position of samples CHOW3–15, curated as GSC C-303937–303962. Nearby, ammonoid matrix collection GSC O-056259 came from a talus concretion about 100 m above the Fantasque Formation: it contained Popovites occidentalis and Isculitoides minor (Tozer 1994, p. 321).
North Peace Region
NTS Emerslund Lakes, 94B/6: 56°08′33.6″N 123°13′09.3″W. Matrix from GSC O-046990, a subrobustus Zone sample collected by E.J.W. Irish in 1961 from outcrop bearing 314° to Mount Burden, 170° to high peak of Mount Brewster. Reported in GSC Paleontology Report 62/1 by Tozer as containing Posidonia cf. aranea and Prosphingites? sp.
NTS Christina Falls, 94B/11: 56°31′3″N, 123°5′38″W. From the gorge on the N side of Needham Creek, 3 miles above the junction of Graham River (Tozer 1967, pp 73–74, Section 3). Matrix from two subrobustus Zone collections: GSC O-056178 lies about 130 m above the top of the Fantasque Formation, and 7.5 m above GSC O-056179. The former contains Popovites occidentalis and Procarnites modestus Tozer, 1965, assigned to the subrobustus Zone (Tozer 1994, p. 319).
NTS Mount Robb, 94B/13: 56°52′20″N, 123°31′30″W (Tozer 1967, pp 73–74, Section 1). Matrix collections from the W face of a ridge 11 km north of Mt Laurier. The subrobustus Zone occurs over about 6 m of strata in three adjacent gullies, with successive collections made at approximately 125, 130 and 131 m above top of Fantasque Formation (respectively, GSC O-056234, 056240, 056243). Tozer (1994, p. 321) lists ammonoids from each.
South-eastern Idaho
Georgetown area
The Anasibirites beds and an overlying concretion horizon with Xenoceltites are exposed for about 300 m along the E facing bluff on the W side of the Bear River, just N of the road from Georgetown to Nounan. Sample W8 (= GSC C-301221) probably came from the highest of three beds with an Anasibirites fauna (Jenks et al. 2013, JJ3-75); and sample W3 (= GSC C-301216) came from a c. 3-m-thick horizon with randomly occurring concretions containing rare xenoceltitid ammonoids, at 42°28′45.6″N, 111°24′44.6″W.
Hammond Creek
Collection GSC O-064670 came from Procolumbites beds on the N side of Hammond Creek, 2.5 miles W of Highway 89; GSC O-064671 was collected in an irrigation ditch, directly on strike and a short distance north: 42°14′29.6″N, 111°25′30.9″W. Sample W9 (= GSC C-301222) was collected from the Prohungarites mckelvei bed (Jenks et al. 2013, JJ1-76) at 42°15′25.5″N, 111°25′51.1″W. Matrix collection GSC O-064675 is from the Prohungarites beds on S side of road running up Hammond (= Little Valley) Creek.
Paris Canyon
A massive Tirolites limestone bed and Columbites beds are exposed intermittently for about 1.5 km along the N side of Paris Canyon (Jenks et al. 2013, fig. 6). Sample W12 (= GSC C-301225) and matrix from GSC O-064672 represent the massive Tirolites limestone bed, at 42°13′33.1″N, 111°25′52.7″W. Samples W11 (= GSC C-301224) and GSC O-064673 from the Columbites parisianus concretion horizon; and W7 (= GSC C-301220) from the C. isabellae concretion horizon between 42°13′34.0″N, 111°25′36.5″W and 42°13′23.5″N, 111°26′20.3″W.
Bear Lake Hot Springs
Columbites beds crop out intermittently along the 10-km-long ridge, between 42°06′40.1″N, 111°14′50.6″W, and 42°09′59.3″N, 111°14′11.8″W (Jenks et al. 2013, fig. 3A–B). Sample W13 (= GSC C-301226) from the C. parisianus concretion horizon; W10 (= GSC C-301223) from the Arctomeekoceras popovi concretion horizon; W5 (= GSC C-301218) from the C. isabellae concretion horizon.
North-central Utah
Sample W14 (= GSC C-301227) from the Anasibirites beds of the Thaynes Formation in Cephalopod Gulch, Salt Lake City, at 40°46′35.2″N, 111°49′52.0″W (Jenks et al. 2013, JJ14-12). See also Solien (1979).
Northern and central Nevada
Crittenden Springs
The classic Crittenden Springs site in Elko County contains many overturned, discontinuous blocks including a 5–7-cm-thick uppermost bed full of tardus Zone ammonoids. Sample W2 (= GSC C-301215) probably corresponds to block JJ5-76 (Jenks et al. 2013) at 41°33′06.1″N, 114°08′45.6″W.
Humboldt range
40°30–35′N, 118°16′30″W. Samples come from several adjacent canyons and were precisely plotted by Bucher (1990, fig. 7), who made collections from the Prida Formation prior to the author (see Fig. 6). Upper Spathian collections come from the Carbonate Unit of the Lower Member of the formation, and Anisian collections come from the succeeding Fossil Hill Member. Sample HB538 (= GSC C-209958) assigned to the Tardicolumbites beds comes from Coyote Canyon; samples HB540 (= GSC C-300268) and HB586 (= GSC C-209953) come from the Prohungarites gutstadti beds in the same area, and sample HB501 (= GSC C-201571) represents the same fauna from E of Saurian Hill in the southern Humboldt Range (40°16′52″N 118°05′07″W). Sample HB536 (= GSC C-209957) comes from the Prohungarites mckelvei beds in Coyote Canyon (JGX-NHR-2360A in Guex et al. 2010).
Younger samples come from several adjacent canyons: haugi Zone matrix from HB106 (= GSC C-176332), HB110 (= GSC C-201552), HB588 (= GSC C-209956) and welteri Zone matrix HB92 (= GSC C-176327) come from the N side of Coyote Canyon; haugi Zone matrix HB236 (= GSC C-159815) comes from the S side of Bloody Canyon; welteri Zone (the type locality) matrix HB184 (= GSC C-176347; = M2364 of Silberling & Wallace 1969) comes from the S side of Star Creek Canyon. The sections depicted in Figure 6 come from the S side of John Brown Canyon, as does haugi Zone matrix HB143 (= GSC C-176336). Samples COY 1–8, A10–12 (Fig. 6) are curated as GSC C-303254–303265.
Tobin range
Matrix sample GSC O-064700 from the Prohungarites beds in the Tobin Formation at the southern tip of the range in Pershing County. This corresponds broadly with USGS locality M2562 of Silberling & Wallace (1969), described as Cain Mountain 1:62 500 quad., centre NW ¼ sec. 9, T. 26N, R. 39E, 5500 ft. S, 27.5 ft. W of elevation point 5088′ on range crest.
Open Research
Data archiving statement
This published work and the nomenclatural acts it contains, have been registered in ZooBank: http://zoobank.org/References/2F95B90D-3218-4BF3-BA73-0AD343522C23
