Introduction
The taxonomy of Triassic conodonts from North America is currently undergoing extensive revision, with many new species recognized in both the Middle and Upper Triassic (Orchard, Reference Orchard2014; Golding and Orchard, Reference Golding and Orchard2016). This revision arises from both the great diversity of conodonts in North America during the Triassic, and the relatively conservative taxonomic approach that has been taken by workers previously. For the Anisian (lower Middle Triassic), the majority of conodont specimens recovered in North American strata have previously been referred to one of only seven species, including broad taxonomic interpretations of Neogondolella mombergensis (Tatge), N. regalis Mosher, N. bulgarica (Budurov and Stefanov), N. constricta (Mosher and Clark), N. transita Kozur and Mostler, N. shoshonensis Nicora, and Paragondolella excelsa Mosher (Mosher and Clark, Reference Mosher and Clark1965; Mosher, Reference Mosher1973; Nicora, Reference Nicora1976, Reference Nicora1977; Nicora and Kovács, Reference Nicora and Kovács1984; Ritter, Reference Ritter1989; Orchard, Reference Orchard1994). These names have been applied to a wide range of morphologies, which has obscured morphological variation, extended the stratigraphic ranges of species, and in consequence led to a very coarse resolution for conodont biostratigraphic schemes covering this interval (Orchard and Tozer, Reference Orchard and Tozer1997). Ritter (Reference Ritter1989) went so far as to consider all of the upper Anisian conodonts from the Fossil Hill section in Nevada as belonging to a single species, N. mombergensis; this species was defined in the German Basin, and to date has not been found in North America.
Other taxa from the Anisian of North America have been identified by Nicora et al. (Reference Nicora, Kozur and Mietto1980), Kozur et al. (Reference Kozur, Krainer and Mostler1994), Orchard and Tozer (Reference Orchard and Tozer1997), Orchard (Reference Orchard2010), and Golding and Orchard (Reference Golding and Orchard2016), and some of these species have shown promise for biostratigraphic correlation (Orchard and Tozer, Reference Orchard and Tozer1997; Golding and Orchard, Reference Golding and Orchard2016). A full appreciation of the conodont diversity of the Anisian of North America is necessary in order to understand the biodiversity, systematic relationships, and evolution of conodonts during this time period. Recent studies of these topics have underrepresented the global diversity of conodonts during the Anisian (Chen et al., Reference Chen, Krystyn, Orchard, Lai and Richoz2016; Kiliç et al., Reference Kiliç, Plasencia, Ishida, Guex and Hirsch2016). Taxonomic revision of these conodonts will also improve the resolution of the conodont biostratigraphic zonation during this time interval, which is currently far less refined than that of the ammonoids (compare Orchard and Tozer, Reference Orchard and Tozer1997, fig. 4 with Monnet and Bucher, Reference Monnet and Bucher2005a, fig. 6). This in turn will improve local and regional correlations.
The present paper is concerned with the problematic group of conodonts with high, fused carinas previously referred to Neogondolella ex gr. regalis, and introduces the new genus Magnigondolella, as well as eight new species that encompass these forms. Numerous Anisian conodont samples from British Columbia (B.C.) and Nevada were examined for this study, many of them co-occurring with ammonoids and therefore directly correlated with the regional ammonoid timescales of Tozer (Reference Tozer1994) and Monnet and Bucher (Reference Monnet and Bucher2005a).
Geologic setting
The Anisian rocks that crop out in northeastern B.C. belong to the Toad Formation, which consists primarily of siltstone, shale, fine-grained sandstone and carbonate (Zonneveld, Reference Zonneveld2010). These rocks are interpreted to have formed in relatively deep water, and some of the clastic sediments show evidence for deposition from turbidity currents (Ferri et al., Reference Ferri, Golding, Mortensen, Zonneveld and Orchard2010). The Toad Formation is not recognized in the subsurface of B.C. and Alberta, where Anisian rocks are referred to the upper part of the Montney Formation and the lower part of the Doig Formation, both of which are considered lateral equivalents of the Toad Formation. The Montney Formation consists of shale, siltstone, and very fine-grained sandstone, whereas the Doig Formation is primarily siltstone and sandstone (Zonneveld, Reference Zonneveld2010). The Montney and Doig formations represent deposition in a wide range of environments, from offshore turbidites (e.g., Moslow, Reference Moslow2000) to the shoreface (e.g., Evoy and Moslow, Reference Evoy and Moslow1995). Deposition of all of the Anisian rocks of B.C. took place on the margin of the ancestral North American continent, in the Peace River sub-basin of the Western Canada Sedimentary Basin (Davies, Reference Davies1997).
In Nevada, the Anisian rocks belong to the Fossil Hill Member, shared by both the Prida and Favret formations. This member consists primarily of an alternation of silty shale and micritic limestone, deposited below storm wave base in an oxygen-poor environment (Monnet and Bucher, Reference Monnet and Bucher2005b). These rocks were formed in the Star Peak Basin, an intra-plate extensional basin related to the Early–Middle Triassic Sonoma Orogeny (Nichols and Silberling, Reference Nichols and Silberling1977; Wyld, Reference Wyld2000).
The Anisian of North America is divided into the lower, middle and upper Anisian sub-stages, whereas the Aegean, Bithynian, Pelsonian, and Illyrian sub-stages are recognized in the Tethys region (Ogg et al., Reference Ogg, Huang and Hinnov2014). Tozer recognized five ammonoid zones in the lower and middle Anisian of B.C. (Tozer, Reference Tozer1967, Reference Tozer1994; Silberling and Tozer, Reference Silberling and Tozer1968), and Bucher (Reference Bucher2002) added an additional zone first recognized in Nevada (Fig. 1). In Nevada, a much larger number of ammonoid zones have been recognized through the work of Silberling (Silberling and Tozer, Reference Silberling and Tozer1968; Silberling and Wallace, Reference Silberling and Wallace1969; Silberling and Nichols, Reference Silberling and Nichols1982) and Bucher (Reference Bucher1988, Reference Bucher1989, Reference Bucher1992a, Reference Bucher1992b, Reference Bucher1994; Monnet and Bucher, Reference Monnet and Bucher2005b), who identified a total of eight zones and 14 subzones throughout the lower and middle Anisian (Fig. 1). The correlation between the ammonoid zones in Nevada and B.C. (Fig. 1) follows the work of Monnet and Bucher (Reference Monnet and Bucher2005a). The samples utilized for the present paper are primarily lower and middle Anisian in age, coming from the Lenotropites caurus, Paracrochordiceras americanum, Tetsaoceras hayesi, and Hollandites minor ammonoid zones in B.C., and from the Japonites welteri, Pseudokeyserlingites guexi, Lenotropites caurus, and Acrochordiceras hyatti ammonoid zones in Nevada. Specimens belonging to the upper Anisian have been recovered from the subsurface of B.C., but cannot be related to the ammonoid zonation.
Figure 1 Chart showing the occurrences of the conodont species reported in this paper within lower and middle Anisian ammonoid zones. Squares indicate occurrences within the ammonoid zones of Nevada, and circles indicate occurrences within the ammonoid zones of B.C. Dashed lines between symbols indicate the inferred stratigraphic range of these species. Note that the ranges of M. alexanderi n. sp., M. nebuchadnezzari n. sp., M. julii n. sp., and M. salomae n. sp. continue into the upper Anisian. B.C. ammonoid zones after Tozer (Reference Tozer1994) and Bucher (Reference Bucher2002); Nevada ammonoid zones and correlation after Monnet and Bucher (Reference Monnet and Bucher2005a).
Materials and methods
Material for this study comes from 38 samples that were collected from 21 sections by various workers in northeastern B.C. and Nevada over the course of the past 30 years (Fig. 2; Table 1). Together, these collections yield more than 600 specimens of Magnigondolella n. gen. Samples from northeastern B.C. come from exposures of the Toad Formation at sections on the Liard and Toad rivers (Toad River map area 094 N) and the Alaska Highway (Tuchodi Lakes map area 094 K), and from the Doig Formation recovered in core taken from subsurface hydrocarbon wells drilled in the vicinity of Fort St. John. Samples from Nevada come from outcrop of the Prida and Favret formations exposed at sections in the Humboldt, New Pass, and Augusta mountain ranges of Pershing and Churchill counties.
Figure 2 Maps showing the geographic locations of samples collected from Nevada and B.C.
Table 1 Table of samples from the Anisian of British Columbia and Nevada that contain species of Magnigondolella. Other species recorded from these samples have previously been described in Golding and Orchard (Reference Golding and Orchard2016). Samples from Nevada were collected by H. Bucher (field nos. HB), and those from B.C. were collected by M. Golding and J.-P Zonneveld (curation nos. V-) or by M.J. Orchard and E.T. Tozer (curation nos. C-, O-). Ages are given to the level of ammonoid zone or subzone (see Fig. 1) where possible, or inferred on the basis of the complete conodont fauna. Conodonts: M.=Magnigondolella, N.=Neogondolella. Ammonoids: Ac.=Acrochordiceras, Az.=Azarianites, G.=Grambergia, I.=Intornites, J.=Japonites, L.=Lenotropites, Pa.=Paracrochordiceras, Ps.=Pseudokeyserlingites, T.=Tetsaoceras, U.=Unionvillites.
Collections were primarily obtained from samples of limestone or calcareous siltstone, often taken from the same horizon as ammonoid samples. All of the conodont samples were previously processed at the Geological Survey of Canada in Vancouver, using standard techniques as outlined in Stone (Reference Stone1987) and Jeppsson et al. (Reference Jeppsson, Anehus and Fredholm1999).
Repository and institutional abbreviation
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.
Systematic paleontology
Class Conodonta Pander, Reference Pander1856
Order Ozarkodinida Dzik, Reference Dzik1976
Family Gondolellidae Lindström, Reference Lindström1970
Subfamily Neogondolellinae Hirsch, Reference Hirsch1994
Genus Magnigondolella new genus
Figure 3 Apparatus of Magnigondolella n. gen. (P 1 ) GSC Type No. 131574; (P 2 ) GSC Type No. 131575; (M) GSC Type No. 131576; (S 1 ) GSC Type No. 131577; (S 2 ) GSC Type No. 131578; (S 3 ) GSC Type No. 131579; (S 4 ) GSC Type No. 131580; (S 0 ) GSC Type No. 131581; all from the Prida Formation (Lenotropites caurus Zone, lower Anisian), GSC Cur. No. C-159809, Bloody Canyon, northern Humboldt Range, Nevada.
Type Species
Magnigondolella salomae n. gen. n. sp.
Other species
Neogondolella regalis Mosher; Neogondolella dilacerata Golding and Orchard; Neogondolella sp. sensu Orchard et al. (Reference Orchard, Grădinaru and Nicora2007a); Neogondolella sp. sensu Orchard et al. (Reference Orchard, Lehrmann, Wei, Wang and Taylor2007b); Magnigondolella alexanderi n. gen. n. sp.; Magnigondolella cyri n. gen. n. sp.; Magnigondolella julii n. gen. n. sp.; Magnigondolella nebuchadnezzari n. gen. n. sp.; Magnigondolella salomae n. gen. n. sp.; Magnigondolella n. gen. n. sp. A; Magnigondolella n. gen. n. sp. B; and Magnigondolella n. gen. n. sp. C.
Diagnosis
Genus with a 15-element apparatus including a P1 element that is segminiplanate, with a high, fused carina of uniform height; and an S0 element that is alate, with lateral processes that diverge from the cusp.
Description
The diagnostic P1 element is segminiplanate, with a biconvex platform that is widest at, or posterior to the midpoint of the element. A posterior platform brim may be present. Micro-reticulation is present on the margins of the platform. In side view, the element is arched, and the platform margins are upturned. The carina is high and uniformly well fused along its length. The upper margin of the carina is straight for most of its length, but may be deflected downward at the posterior end due to the curvature of the element. The denticles of the carina are laterally compressed and vary from upright to slightly inclined. The sub-terminal cusp is similar in size to, or slightly larger than the adjacent denticles, and a posterior denticle is present at all growth stages. On the lower surface, a relatively low keel of variable width is present, which terminates in a round to sub-quadrate loop around the sub-terminal basal pit.
Comparisons
The uniformly high, fused carina of the P1 element distinguishes Magnigondolella n. gen. from Neogondolella, which has a P1 element with a much lower carina that rises to the anterior and posterior of the element. P1 elements of Paragondolella have a high and fused carina like that of Magnigondolella n. gen., but it forms a convex crest that is highest in the midpoint of the element, descending to both the anterior and posterior. The upper profile of the carina places Anisian species such as Paragondolella bulgarica Budurov and Stefanov and Gondolella szaboi Kovács within Paragondolella rather than Magnigondolella n. gen.
Etymology
From the Latin magnus, meaning “great”, in reference to the high carina that is typical of the genus.
Occurrence
Spathian (Keyserlingites subrobustus Zone) to upper Anisian of B.C. (Mosher, Reference Mosher1970; Orchard, Reference Orchard1987; Orchard and Bucher, Reference Orchard and Bucher1992; Golding Reference Golding2014; Golding et al., Reference Golding, Orchard, Zonneveld, Henderson and Dunn2014a, Reference Golding, Orchard and Zonneveldb, 2015; Golding and Orchard, Reference Golding and Orchard2016; this study); Spathian (Keyserlingites subrobustus Zone) of the Canadian Arctic (Orchard, Reference Orchard2008); middle Anisian of the Yukon (Orchard, Reference Orchard2006); Spathian (Neopopanoceras haugi Zone) to middle Anisian (Balatonites shoshonensis Zone) of Nevada (Mosher, Reference Mosher1968; Nicora, Reference Nicora1977; Clark et al., Reference Clark, Paull, Solien and Morgan1979; Goudemand et al., Reference Goudemand, Orchard, Bucher and Jenks2012; this study); Anisian of Alaska (Wardlaw and Jones, Reference Wardlaw and Jones1980); lower Anisian of China (Orchard et al., Reference Orchard, Lehrmann, Wei, Wang and Taylor2007b); lower Anisian of Tibet (Wang and Wang, Reference Wang and Wang1976; Tian, Reference Tian1982); lower Anisian of the Indian Himalayas (Chhabra and Kumar, Reference Chhabra and Kumar1992); Spathian (Keyserlingites subrobustus Zone) to middle Anisian (Anagymnotoceras varium Zone) of Svalbard (Nakrem et al., Reference Nakrem, Orchard, Weitschat, Hounslow, Beatty and Mørk2008); lower Anisian of Turkey (Nicora, Reference Nicora1977); lower Anisian of Poland (Narkiewicz, Reference Narkiewicz1999); and lower Anisian of Romania (Orchard et al., Reference Orchard, Grădinaru and Nicora2007a).
Remarks
The multielement apparatus of Magnigondolella n. gen. (figured by Golding, in press) is based on specimens from the upper Anisian of B.C.; this reconstruction is confirmed by specimens from the lower Anisian of Nevada, illustrated in Figure 3. It has previously been postulated that Magnigondolella n. gen. (Neogondolella regalis or N. ex gr. regalis of earlier authors) originated from Chiosella in the early Anisian (Bender, Reference Bender1970; Kozur, Reference Kozur1989). The occurrence of specimens of Magnigondolella n. gen. in the Spathian (Mosher, Reference Mosher1970; Nakrem et al., Reference Nakrem, Orchard, Weitschat, Hounslow, Beatty and Mørk2008; Orchard, Reference Orchard2008; Goudemand et al., Reference Goudemand, Orchard, Bucher and Jenks2012), before the first known occurrence of Chiosella, instead suggests that Magnigondolella n. gen. originated from a Spathian, or older, gondolellid (Orchard, Reference Orchard1994, Reference Orchard2007). Unpublished collections from near the Smithian-Spathian boundary in B.C. support a possible origin from Neogondolella n. sp. D sensu Orchard (Reference Orchard2007).
Magnigondolella alexanderi new genus new species
Figure 4 Magnigondolella alexanderi n. gen. n. sp. (1, 2) GSC Type No. 131582, from the Toad Formation (Lenotropites caurus Zone, lower Anisian), GSC Cur. No. C-201922, Mile Post 375 East, B.C.; (3–5) GSC Type No. 131583, from the Toad Formation (Tetsaoceras hayesi Zone, middle Anisian), GSC Cur. No. C-90852, Liard River, B.C.; (6–8) GSC Type No. 131584, from the Toad Formation (T. hayesi Zone, middle Anisian), GSC Cur. No. O-99588, East Toad River, B.C.; (9–11) GSC Type No. 131585, from the Favret Formation (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176314, Favret Canyon, Augusta Mountains, Nevada; (12–14) GSC Type No. 131586 (holotype), from the Toad Formation (Paracrochordiceras americanum Zone, lower Anisian), GSC Cur. No. C-302187, Mile Post 375 East, B.C.
1987 Neogondolella ex gr. regale Mosher; Reference OrchardOrchard, p. 105.
1992 Neogondolella ex gr. regale; Reference Orchard and BucherOrchard and Bucher, p. 138.
2006 Neogondolella ex gr. regalis; Reference OrchardOrchard, pl. 5, figs. 33, 34.
2014 Neogondolella ex gr. regalis morphotype alpha; Reference GoldingGolding, p. 121, fig. 2.30, parts 1–11.
2014a Neogondolella ex gr. regalis; Golding et alReference Golding, Orchard, Zonneveld, Henderson and Dunn., p. 171, pl. 1, figs. 16–18.
2015 Neogondolella ex gr. regalis morphotype alpha; Golding et alReference Golding, Orchard, Zonneveld and Wilson., p. 166, fig. 11.15–11.17.
Holotype
GSC Type No. 131586 (Fig. 4.12–4.14), from the Paracrochordiceras americanum Zone (lower Anisian) of the Toad Formation, GSC Cur. No. C-302187, Mile Post 375 East, northeastern B.C.
Diagnosis
A species of Magnigondolella n. gen. in which the P1 element has a biconvex platform that is widest at the midpoint of the element and tapers evenly to both the anterior and posterior, leaving a relatively narrow and pointed posterior platform at all growth stages. The carina is deflected downwards at the posterior end of the element.
Occurrence
Lower Anisian (Lenotropites caurus Zone) to upper Anisian of B.C. (Orchard, Reference Orchard1987; Orchard and Bucher, Reference Orchard and Bucher1992; Golding, Reference Golding2014; Golding et al., Reference Golding, Orchard, Zonneveld, Henderson and Dunn2014a, Reference Golding, Orchard, Zonneveld and Wilson2015; this study); lower Anisian (Japonites welteri Zone) to middle Anisian (Unionvillites hadleyi Subzone, Acrochordiceras hyatti Zone) of Nevada (this study); and middle Anisian of the Yukon (Orchard, Reference Orchard2006).
Etymology
Named for Alexander the Great, King of Macedon.
Materials
83 specimens from B.C.; 265 specimens from Nevada.
Comparisons
The biconvex, symmetrically tapering platform and pointed posterior margin of Magnigondolella alexanderi n. gen. n. sp. serves to differentiate it from most other species of the genus. P1 elements of M. regalis and M. salomae n. sp. have a similar platform shape to that of M. alexanderi n. sp., but they can be differentiated from the latter by the straight upper margin of their carinas.
Magnigondolella cyri new genus new species
Figure 5 Magnigondolella cyri n. gen. n. sp. (1–3) GSC Type No. 131587, from the Prida Formation (Lenotropites caurus Zone, lower Anisian), GSC Cur. No. C-159809, northern Humboldt Range, Nevada; (4–6) GSC Type No. 131492, from the Doig Formation (middle Anisian), GSC Cur. No. V-002999, Petro-Canada Kobes c-074-G/094-b-09 well, B.C.; (7–9) GSC Type No. 131588 (holotype), from the Favret Formation (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176314, Favret Canyon, Augusta Mountains, Nevada; (10–12) GSC Type No. 131589, from the Doig Formation (lower Anisian), GSC Cur.No. V-002992, Petro-Canada Kobes d-048-A/094-b-09 well, B.C.
2014 Neogondolella ex gr. regalis morphotype beta; Reference GoldingGolding, p. 122, fig. 2.31, parts 1–6.
2014 Neogondolella ex gr. regalis morphotype delta; Reference GoldingGolding, p. 126, fig. 2.33, parts 1–6.
2015 Neogondolella ex gr. regalis morphotype beta; Golding et alReference Golding, Orchard, Zonneveld and Wilson., p. 166, fig. 11.18–11.20.
2015 Neogondolella ex gr. regalis morphotype delta; Golding et alReference Golding, Orchard, Zonneveld and Wilson., p. 166, fig. 12.1–12.3.
Holotype
GSC Type No. 131588 (Fig. 5.7–5.9), from the Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone (middle Anisian) of the Favret Formation, GSC Cur. No. C-176314, Favret Canyon, Nevada.
Diagnosis
A species of Magnigondolella n. gen. in which the P1 element has a platform that is widest in the posterior half of the element. Specimens tend to have a sub-quadrate to quadrate posterior margin, and generally lack a posterior platform brim. The carina is deflected downwards at the posterior end of the element.
Occurrence
Lower Anisian (Lenotropites caurus Zone) to middle Anisian (Hollandites minor Zone) of B.C. (Golding Reference Golding2014; Golding et al., Reference Golding, Orchard, Zonneveld and Wilson2015; this study); and lower Anisian (Pseudokeyserlingites guexi Zone) to middle Anisian (Unionvillites hadleyi Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Etymology
Named for Cyrus the Great, King of the Persians.
Materials
44 specimens from B.C.; 134 specimens from Nevada.
Comparisons
The position of the widest part of the platform in Magnigondolella cyri n. gen. n. sp., behind the midpoint of the element, together with the sub-quadrate to quadrate posterior margin, serve to distinguish it from most other species of the genus. The platform of M. nebuchadnezzari n. sp. is also wide in the posterior half of the element, however the widest part of its platform is at the midpoint, and it possesses a narrow posterior brim.
Magnigondolella julii new genus new species
Figure 6 Magnigondolella julii n. gen. n. sp. (1–3) GSC Type No. 131590, from the Favret Formation (Unionvillites hadleyi Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176526, Muller Canyon, Augusta Mountains, Nevada; (4–6) GSC Type No. 131591, from the Prida Formation (Lenotropites caurus Zone, lower Anisian), GSC Cur. No. C-159809, northern Humboldt Range, Nevada; (7–9) GSC Type No. 131592; (10–12) GSC Type No. 131593 (holotype), from the Toad Formation (Tetsaoceras hayesi Zone, middle Anisian), GSC Cur. No. O-68294, Mile Post 375 West, B.C.; (13–15) GSC Type No. 131493, from the Doig Formation (middle Anisian), GSC Cur. No. V-002955, Murphy Swan d-054-B/094-P-09 well, B.C.
1970 Neogondolella regalis Reference MosherMosher, p. 110, fig. 5 (only).
1992 Neogondolella ex gr. regale; Orchard and Bucher, pl. 1, fig. 18 (only).
2014 Neogondolella ex gr. regalis morphotype gamma; Reference GoldingGolding, p. 124, fig. 2.32, parts 1–9.
2015 Neogondolella ex gr. regalis morphotype gamma; Golding et alReference Golding, Orchard, Zonneveld and Wilson., p. 166, fig. 11.21–11.23.
Holotype
GSC Type No. 131593 (Fig. 6.10–6.12), from the Tetsaoceras hayesi Zone (middle Anisian) of the Toad Formation, GSC Cur. No. O-68294, Mile Post 375 West, northeastern B.C.
Diagnosis
A species of Magnigondolella n. gen. in which the P1 element has a narrow, biconvex platform with a posterior constriction, which causes an expansion of the posterior end of the platform around the cusp. The carina is deflected downwards at the posterior end of the element.
Occurrence
Middle Anisian (Tetsaoceras hayesi Zone) to upper Anisian of B.C. (Mosher, Reference Mosher1970; Orchard and Bucher, Reference Orchard and Bucher1992; Golding, Reference Golding2014; Golding et al., Reference Golding, Orchard, Zonneveld and Wilson2015; this study); and lower Anisian (Lenotropites caurus Zone) to middle Anisian (Unionvillites hadleyi Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Etymology
Named for Gaius Julius Caesar, Dictator of the Roman Republic.
Materials
15 specimens from B.C.; 41 specimens from Nevada.
Comparisons
The constricted posterior platform of Magnigondolella julii n. gen. n. sp. serves to distinguish it from most other species of the genus. The posterior platform of M. n. sp. A narrows markedly, but it is not constricted. Some specimens of M. salomae n. sp. possess a small posterior platform constricton, but the carina has a straight upper margin. Paragondolella szaboi also possesses a posterior platform constriction, but its convex carina that is highest near the midpoint of the element differs from that of M. julii n. sp. The high, fused carina of M. julii n. sp. differentiates it from species of Neogondolella that have posterior platform constrictions, including the N. constricta group and the N. transita group.
Magnigondolella nebuchadnezzari new genus new species
Figure 7 Magnigondolella nebuchadnezzari n. gen. n. sp. (1–3) GSC Type No. 131594, from the Doig Formation (lower Anisian), GSC Cur. No. V-002992, Petro-Canada Kobes d-048-A/094-b-09 well, B.C.; (4–6) GSC Type No. 131595, from the Prida Formation (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176324, Congress Canyon, northern Humboldt Range, Nevada; (7–9) GSC Type No. 131596, from the Toad Formation (Tetsaoceras hayesi Zone, middle Anisian), GSC Cur. No. O-68294, Mile Post 375 West, B.C.; (10–12) GSC Type No. 131506 (holotype), from the Toad Formation (Tetsaoceras hayesi Zone, middle Anisian), GSC Cur. No. C-101077, Mile Post 375 East, B.C.
2014 Neogondolella ex gr. regalis morphotype theta; Reference GoldingGolding, p. 131, fig. 2.37, parts 1–6 (only).
2014b Neogondolella ex gr. regalis morphotype C; Golding et alReference Golding, Orchard and Zonneveld., fig. 3.13–3.15.
Holotype
GSC Type No. 131506 (Fig. 7.10–7.12), from the Tetsaoceras hayesi Zone (middle Anisian) of the Toad Formation, GSC Cur. No. C-101077, Mile Post 375 East, northeastern B.C.
Diagnosis
Species of Magnigondolella n. gen. in which the P1 element has a biconvex platform that is widest at the midpoint of the element and remains broad to the posterior end. The posterior platform margin is rounded and a narrow posterior platform brim is present. The anterior platform margins may develop a weak crenulation. The carina is deflected downwards at the posterior end of the element.
Occurrence
Middle Anisian (Tetsaoceras hayesi Zone) to upper Anisian of B.C. (Golding, Reference Golding2014; Golding et al., Reference Golding, Orchard and Zonneveld2014b; this study); and lower Anisian (Pseudokeyserlingites guexi Zone) to middle Anisian (Unionvillites hadleyi Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Etymology
Named for Nebuchadnezzar II, King of Babylon.
Materials
14 specimens from B.C.; 23 specimens from Nevada.
Comparisons
The wide posterior platform and presence of a posterior platform brim serve to distinguish Magnigondolella nebuchadnezzari n. gen. n. sp. from most other species of the genus. Specimens of M. cyri n. sp. have wide posterior platforms, and some may possess a posterior platform brim; however, the platform of M. cyri n. sp. is longer and narrower than that of M. nebuchadnezzari n. sp., and the carina of M. cyri n. sp. has more numerous denticles.
Remarks
The holotype of this species was figured previously in Golding et al. (Reference Golding, Orchard and Zonneveld2014b), where it was erroneously labeled as coming from the Mile Post 375 West section.
Magnigondolella regalis (Mosher, Reference Mosher1970)
Figure 8 Magnigondolella regalis (Mosher). (1–3) GSC Type No. 25048 (holotype), from the Toad Formation (Tetsaoceras hayesi Zone, middle Anisian), GSC Cur. No. O-68294, Mile Post 375 West, B.C.
1968 Gondolella mombergensis Tatge; Reference MosherMosher, pl. 116, fig. 15 (only).
1970 Neogondolella regale Reference MosherMosher, p. 741, pl. 110, figs. 1, 4 (only).
1976 Neogondolella regale; Reference Wang and WangWang and Wang, pl. 4, fig. 7 (only).
1977 Neogondolella regale; Reference NicoraNicora, pl. 5, fig. 3b (only).
Holotype
GSC Type No. 25048 (Fig. 8.1–8.3), from the Tetsaoceras hayesi Zone (middle Anisian) of the Toad Formation, GSC Cur. No. O-68294, Mile Post 375 West, northeastern B.C.
Emended diagnosis
Species of Magnigondolella n. gen. in which the P1 element has a platform that is widest at the midpoint of the element, and maintains its width nearly to the anterior end. The platform margins are strongly upturned, producing deep adcarinal grooves. The upper profile of the carina is uniformly straight along its length, with no curvature. The keel is very wide and deeply excavated.
Occurrence
Middle Anisian (Testsaoceras hayesi Zone) of B.C. (Mosher, Reference Mosher1970; this study); middle Anisian of Nevada (Mosher, Reference Mosher1968; Nicora, Reference Nicora1977); and middle Ansian of Tibet (Wang and Wang, Reference Wang and Wang1976).
Materials
One specimen from B.C.
Comparisons
The upper margin of the carina of Magnigondolella regalis is similar to that of M. salomae n. sp., which differs from M. regalis by possessing a flatter, more anteriorly tapered platform, and a shallower keel.
Remarks
The revised, more restricted diagnosis of this species includes only forms similar to the holotype, which was described from the Tetsaoceras hayesi Zone in B.C. (Mosher, Reference Mosher1970), and is re-illustrated in Figure 8. This is the only specimen of this species to be recovered in B.C. thus far. After examination of the original specimen, Mosher’s (Reference Mosher1970) figured paratype from B.C. is excluded from the present definition of the species, and is instead considered to belong to Magnigondolella julii n. gen. n. sp.
Magnigondolella salomae n. gen. new species
Figure 9 Magnigondolella salomae n. gen. n. sp. (1–3) GSC Type No. 131597, from the Toad Formation (Tetsaoceras hayesi Zone, middle Anisian), GSC Cur. No. O-68294, Mile Post 375 West, B.C.; (4–6) GSC Type No. 131476, from the Doig Formation (middle Anisian), GSC Cur.No. V-002978, Talisman Altares 16-17-083-25W6 well, B.C.; (7–9) GSC Type No. 131598, (holotype) from the Toad Formation (Paracrochordiceras americanum Zone, lower Anisian), GSC Cur. No. C-302187, Mile Post 375 East, B.C.
2014 Neogondolella ex gr. regalis morphotype eta; Reference GoldingGolding, p. 130, fig. 2.36, parts 1–6.
2014a Neogondolella ex gr. regalis morphotype A; Golding et alReference Golding, Orchard, Zonneveld, Henderson and Dunn., p. 171, Pl. 2, figs. 4–6.
2014b Neogondolella ex gr. regalis morphotype D; Golding et alReference Golding, Orchard and Zonneveld., fig. 3.22–3.24.
Holotype
GSC Type No. 131598 (Fig. 9.7–9.9), from the Paracrochordiceras americanum Zone (lower Anisian) of the Toad Formation, GSC Cur. No. C-302187, Mile Post 375 East, northeastern B.C.
Diagnosis
A species of Magnigondolella n. gen. in which the relatively narrow platform of the P1 element is widest at, or just posterior to the midpoint of the element, and tapers evenly to both the anterior and posterior ends. The upper profile of the carina is uniformly straight along its length, with little to no curvature.
Occurrence
Lower Anisian (Paracrochordiceras americanum Zone) to upper Anisian of B.C. (Golding, Reference Golding2014; Golding et al., Reference Golding, Orchard, Zonneveld, Henderson and Dunn2014a, Reference Golding, Orchard and Zonneveldb; this study); and middle Anisian (Intornites mctaggarti Subzone to Isculites constrictus Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Etymology
Named for Salome Alexandra, Queen of Judea.
Materials
Five specimens from B.C.; five specimens from Nevada.
Comparisons
See above for comparisons with Magnigondolella regalis and M. julii n. sp.
Magnigondolella new species A
Figure 10 Magnigondolella n. gen. n. sp. A. (1–3) GSC Type No. 131599; (4–6) GSC Type No. 131600; both from the Favret Formation (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176314, Favret Canyon, Augusta Mountains, Nevada.
Occurrence
Middle Anisian (Intornites mctaggarti Subzone to Unionvillites hadleyi Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Description
A species of Magnigondolella n. gen. in which the platform of the P1 element is widest at the midpoint, and narrows rapidly in the posterior third to form a very narrow, flange-like platform that continues to the end of the element.
Comparisons
See above for comparison with Magnigondolella julii n. gen. n. sp.
Remarks
Thus far, only four specimens of Magnigondolella n. sp. A have been recovered from three samples in Nevada, so despite its distinctive morphology, this species is kept in open nomenclature until its geographic and stratigraphic range can be determined.
Magnigondolella new species B
Figure 11 Magnigondolella n. gen. n. sp. B. (1–3) GSC Type No. 131601; (4–6) GSC Type No. 131602; both from the Favret Formation (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176314, Favret Canyon, Augusta Mountains, Nevada.
Occurrence
Middle Anisian (Intornites mctaggarti Subzone to Ginsbergites americanus Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Description
A species of Magnigondolella n. gen. in which the platform of the P1 element is strongly biconvex and lachrymiform, being widest in the posterior half of the element and possessing rounded postero-lateral margins. A large posterior denticle projects beyond the end of the platform in upper view.
Comparisons
The teardrop shaped platform, large posterior denticle, and lack of posterior platform brim serve to distinguish Magnigondolella n. sp. B from other species of this genus.
Remarks
Thus far, only six specimens of Magnigondolella n. sp. B have been recovered from two samples in Nevada, so despite its distinctive morphology, this species is kept in open nomenclature until its geographic and stratigraphic range can be determined.
Magnigondolella new species C
Figure 12 Magnigondolella n. gen. n. sp. C. (1–3) GSC Type No. 131603; (4–6) GSC Type No. 131604; (7–9) GSC Type No. 131605; (10–12) GSC Type No. 131606; all from the Prida Formation (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone, middle Anisian), GSC Cur. No. C-176324, Congress Canyon, northern Humboldt Range, Nevada.
Occurrence
Middle Anisian (Intornites mctaggarti Subzone, Acrochordiceras hyatti Zone) of Nevada (this study).
Description
A species of Magnigondolella n. gen. in which the platform of the P1 element is reduced to form a very narrow flange that runs along the length of the element at all growth stages.
Comparisons
The very narrow platform serves to differentiate Magnigondolella sp. C from other species of the genus.
Remarks
Thus far, only 22 specimens of Magnigondolella sp. C have been recovered from two samples in Nevada, so despite its distinctive morphology, this species is kept in open nomenclature until its geographic and stratigraphic range can be determined.
Discussion
The genus Magnigondolella n. gen. appears to range from the Spathian to the upper Anisian, and the stratigraphic ranges of the nine Anisian species discussed in this paper are shown in Figure 1. These ranges can be combined with those of other new species recognized in B.C. and Nevada (Golding and Orchard, Reference Golding and Orchard2016) to generate a more refined conodont biostratigraphic scheme for the Anisian of North America. Preliminary versions of this scheme have previously been published by Golding (Reference Golding2014) and Golding et al. (Reference Golding, Orchard and Zonneveld2014b), and a final version incorporating newly described species will be presented after taxonomic work on the conodont fauna from B.C. and Nevada is completed.
Magnigondolella alexanderi n. gen. n. sp. is a relatively long ranging taxon, occurring first in the Azarianites bufonis Subzone of the Lenotropites caurus Zone and continuing into the upper Anisian in B.C., and ranging from the Japonites welteri Zone to the Unionvillites hadleyi Subzone of the Acrochordiceras hyatti Zone in Nevada. The range of M. nebuchadnezzari n. sp. is markedly different in B.C. than it is in Nevada; in B.C., this species appears first in the Tetsaoceras hayesi Zone, whereas in Nevada representatives are found as low as the Pseudokeyserlingites guexi Zone. Similarly, M. julii n. sp. appears in the T. hayesi Zone of B.C., but ranges down into the L. caurus Zone in Nevada. Specimens of M. cyri n. sp. are present in the P. guexi Zone in Nevada, where they range up to the U. hadleyi Subzone of the A. hyatti Zone; in B.C., this species continues to a slightly higher level, the H. minor Zone. Of all the newly recognized species, M. salomae n. sp. has the most restricted range in Nevada, being confined to the A. hyatti Zone. There it spans from the Isculites constrictus Subzone to the Ginsburgites americanus Subzone, whereas in B.C. it ranges from the P. americanum Zone to the upper Anisian. Magnigondolella regalis and the three species left in open nomenclature are very stratigraphically restricted, although this likely reflects the limited number of specimens identified, rather than short stratigraphic ranges for these species.
Specimens of Magnigondolella n. gen. have been recorded from across North America, including examples of M. julii n. sp. from the Quesnel terrane of B.C. (Orchard and Bucher, Reference Orchard and Bucher1992); M. alexanderi n. sp. from the Yukon and the Stikine terrane of B.C. (Orchard, Reference Orchard1987, Reference Orchard2006; Orchard and Bucher, Reference Orchard and Bucher1992); and Magnigondolella sp. from Alaska and the Canadian Arctic (Wardlaw and Jones, Reference Wardlaw and Jones1980; Orchard and Bucher, Reference Orchard and Bucher1992; Orchard, Reference Orchard2008). The widespread occurrence of this genus demonstrates the potential for its use in correlation at a continental scale.
Additional specimens belonging to the genus can also be identified throughout the Tethys region, including Poland (Narkiewicz, Reference Narkiewicz1999), Romania (Orchard et al., Reference Orchard, Grădinaru and Nicora2007a), Turkey (Nicora, Reference Nicora1977), China (Orchard et al., Reference Orchard, Lehrmann, Wei, Wang and Taylor2007b), India (Chhabra and Kumar, Reference Chhabra and Kumar1992), and Tibet (Wang and Wang, Reference Wang and Wang1976; Tian, Reference Tian1982). It is not clear from the published illustrations whether the Tethyan specimens represent species that can be identified in North America, so detailed correlation between these regions is not possible at this time. However, the occurrence of Magnigondolella n. gen. close to the proposed position of the Olenekian-Anisian boundary in the sections at Desli Caira in Romania (Orchard et al., Reference Orchard, Grădinaru and Nicora2007a) and Guandao in China (Orchard et al., Reference Orchard, Lehrmann, Wei, Wang and Taylor2007b) suggests that the genus is potentially important for the recognition of this boundary. Further study of specimens of Magnigondolella n. gen. from these sections will be necessary as work on defining and correlating the Olenekian-Anisian boundary continues.
The recognition of five new species of Magnigondolella n. gen., and three additional species in open nomenclature, increases the number of conodont species identified from the lower and middle Anisian of North America considerably. The early and middle parts of the Anisian were characterized as a low diversity period globally by Chen et al. (Reference Chen, Krystyn, Orchard, Lai and Richoz2016) and Kiliç et al. (Reference Kiliç, Plasencia, Ishida, Guex and Hirsch2016), with both studies recognizing ~30 species for the Aegean, Bithynian, and Pelsonian (equivalent to the lower and middle Anisian). Such a low value may be due partially to the preliminary nature of the study of North American Anisian taxa, and partially to endemism of North American species. This highlights the need to carry out detailed taxonomic work before accurate judgments of biodiversity can be made.
Table 2 Table showing the number of P1 elements of Magnigondolella n. gen. species identified from localities in B.C. and Nevada.
Acknowledgments
The authors wish to thank Associate Editor H.-D. Sues and an anonymous reviewer for comments that helped to improve this manuscript. The samples from B.C. utilized in this study were collected by the authors as well as by E.T. Tozer and J.-P. Zonneveld. The samples from Nevada were largely derived from the matrix of ammonoid collections made by H. Bucher. Samples were processed and specimens photographed by P. Krauss and H. Taylor. Financial support for this study was provided by the Cordillera Project of the Geological Survey of Canada GEM-2 Program.
