Journal of Paleontology, 92(2), 2018, p. 207–220 Copyright © 2017, The Paleontological Society 0022-3360/18/0088-0906 doi: 10.1017/jpa.2017.123
Magnigondolella, a new conodont genus from the Triassic of North America
Martyn L. Golding and Michael J. Orchard Geological Survey of Canada, 1500-605 Robson Street, Vancouver, British Columbia, Canada, V6B 5J3 ⟨
martyn.golding@
canada.ca⟩, ⟨
mike.orchard@canada.ca⟩
Abstract.—The new conodont genus Magnigondolella is recognized based on specimens recovered from the Anisian (Middle Triassic) of British Columbia in Canada, and Nevada in the USA. This new genus encompasses problematic specimens with high carinas, which have recently been collectively referred to as Neogondolella ex gr. regalis Mosher. Ten species from North America are herein assigned to Magnigondolella n. gen., including the eight new species M. alexanderi, M. cyri, M. julii, M. nebuchadnezzari, M. salomae, M. n. sp. A, M. n. sp. B, and M. n. sp. C, as well as the two existing species M. regalis (Mosher) and M. dilacerata (Golding and Orchard). Other species from the Tethys region are also tentatively assigned to Magnigondolella n. gen. Based on published records, the genus appears to range from the Spathian to the upper Anisian in North America. The recognition of eight new species from the Anisian significantly increases the conodont biodiversity of this period, which has previously been regarded as a time of low diversity. Although some of the species included within Magnigondolella n. sp. have relatively long stratigraphic ranges, many have been identified in both British Columbia and Nevada, and therefore show potential for biostratigraphic correlation on a regional scale.
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, 2014; Golding and Orchard, 2016). 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, 1965; Mosher, 1973; Nicora, 1976, 1977; Nicora and Kovács, 1984; Ritter, 1989; Orchard, 1994). 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, 1997). Ritter (1989) 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. (1980), Kozur et al. (1994), Orchard and Tozer (1997), Orchard (2010), and Golding and Orchard
(2016), and some of these species have shown promise for biostratigraphic correlation (Orchard and Tozer, 1997; Golding and Orchard, 2016). 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., 2016; Kiliç et al., 2016). 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, 1997, fig. 4 with Monnet and Bucher, 2005a, 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 (1994) and Monnet and Bucher (2005a).
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, 2010). These
rocks are interpreted to have formed in relatively deep water, and some of the clastic sediments show evidence for deposition
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