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Figure 3. East side of Ferguson Hill, New York
Canyon, Nevada. Coral-bearing Involutum
Zone is visible at the top of the photo where
resistant darker siliceous limestone beds are
overlain by primarily non-resistant light brown
siltstone beds 40 m above the T/J boundary.

base of the Involutum Zone. The first corals are at 4 m in the all belong to the family Stylophyllidae. They are enclosed in
Coroniceras fergusoni horizon. The next corals occur at 10–12 m fine-grained, poorly sorted siliciclastic limestone with abundant
in the Volcanoense Subzone, and lastly at 13–15 m in the coated and micritized molluscan bioclasts. Most coral calices are
Mullerense Subzone (Taylor et al., 2001). The most abundant infilled with peloids, indicating a shallow, well-lit, energetic
coral-bearing outcrops are on top of Ferguson Hill at N marine environment. While a few corals occur in life positions,
38°29.237�; W 118°5.033� and the first ridge southeast of the many appear overturned and reworked (Fig. 5). The early
Involutum Zone Type Section at N 38°29.478�; W 118°5.669�. Sinemurian stylophyllids at New York Canyon are unique in
Co-occurring with the corals is Weyla alata, an endemic being solitary, with gregarious associations. The coral larvae
Hettangian to Pliensbachian bivalve of eastern Panthalassa were likely fixosessile, attaching either to small grains or shell
(Damborenea and González-León, 1997). Corals at New York fragments. They also show distinctive expansions and constric-
Canyon were first recorded by Muller and Ferguson (1936) and tions, expressed both internally and externally on the epithecal
subsequently recognized by current researchers (Guex, personal wall (Fig. 4). This indicates polyp rejuvenation, likely as an
commun., Sept. 2014; Caruthers, personal commun. Aug. 2014; ecological avoidance to smothering by frequent, perhaps cyclic
Ritterbush et al., 2014). Unfortunately, no taxonomic determi- influxes of exogenous sediment. Such cyclic rejuvenescence is
nations have been published pertaining to the corals. well known among solitary rugose (Berkowski, 2012) and
modern corals (Chevalier and Beauvais, 1987). Corals at New
Hundreds of solitary corals were collected. Genera identified York Canyon were capable of surviving smothering by both
are Stylophyllopsis, Protostylophyllum, and Haimeicyclus (Fig. 4);

GSA TODAY | OCTOBER 2015 Figure 4. Cross-sectional views of coral from the Ferguson Hill Member of the Sunrise Formation. Haimeicyclus (left; specimen
no. UMPC14687), Protostylophyllum (middle; specimen no. UMPC14688). A weathered specimen of Stylophyllopsis (right;
specimen no. UMPC14689) displays a series of expansions and constrictions of the corallite indicating high sedimentation rates.

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