Golding and Orchard—A new conodont genus from the Triassic of North America
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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.
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
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 differ- entiate Magnigondolella sp. C from other species of the genus.
Remarks.—Thus far, only 22 specimens of Magnigondolella sp. Chave been recovered fromtwo samples inNevada, so despite its distinctivemorphology, 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, 2016) 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 (2014) and Golding et al. (2014b), and a final version incor- porating newly described species will be presented after
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
taxonomic work on the conodont fauna from B.C. and Nevada is completed. Magnigondolella alexanderi n. gen. n. sp. is a relatively
from across North America, including examples of M. julii n. sp. from the Quesnel terrane of B.C. (Orchard and Bucher, 1992); M. alexanderi n. sp. from the Yukon and the Stikine terrane of B.C. (Orchard, 1987, 2006; Orchard and Bucher, 1992); and Magnigondolella sp. from Alaska and the Canadian Arctic (Wardlaw and Jones, 1980; Orchard and Bucher, 1992; Orchard, 2008). The widespread occurrence of this genus demonstrates the potential for its use in correlation at a continental scale.
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