Romano et al.—Early Triassic Fishes of Elko County (Nevada)
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Figure 7. Actinopterygii indet. (NMMNH P-77357) from the early late Spathian of Crittenden Springs, Elko County, Nevada, USA. (1) The fossil (enhanced using ammonium chloride); (2) interpretive drawing of 7.1; anterior is left. Scale bar = 50mm (total).
Triassic age is PIMUZ A/I 4301 from Spitsbergen, a few fragments of which were illustrated by Scheyer et al. (2014). This specimen had an estimated total length of >2m (skull without shoulder girdle length is ~35 cm). SpecimensNMMNH P-66225 and NMMNH P-77117 from Nevada are both large individuals. With an estimated total length of 1.72–1.85 m, P-66225 had a size comparable to the birgeriids from the Smithian of Spitsbergen (Stensiö, 1921, 1932; Scheyer et al., 2014), the Middle Triassic of Monte San Giorgio and Besano (Swiss-Italian borderland; Schwarz 1970; Romano and Brinkmann, 2009), the Middle–Late Triassic of China (Liu et al., 2006; Jiang et al., 2016; Sun et al., 2016), and possibly the Middle?–Late Triassic of Europe (B.? costata; Münster, 1839;
Boni, 1937; Bürgin and Furrer, 1993). Others were distinctly smaller (~1m or less), for example individuals from the Early Triassic of Greenland (Stensiö, 1932; Nielsen, 1949) and Madagascar (Lehman, 1952; Guffroy, 1956; Beltan, 1980), the Middle–Late Triassic of China (Jin, 2001; Liu et al., 2006; Sun et al., 2016), and the Late Triassic of Slovenia (Jurkovšek and Kolar-Jurkovšek, 1986), Italy (e.g., Boni, 1937), and Switzerland (Bürgin and Furrer, 1992). A clear evolutionary trend in body size is not apparent, except that very large birgeriids (>120 cm) are as yet unknown from strata older than Smithian. As a member of the ‘Palaeopterygii,’ Birgeria mostly retained the plesiomorphic ‘paleoniscoid’ bauplan, being
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