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Journal of Paleontology 92(5):804–837
p. 10, 12, pl. 4, fig. 2). Williams (2017, fig. 6f) recently figured a specimen of “Conus sp.” from the Gatun Formation that has a coloration pattern consistent with most specimens of C. spurius from YN020. Apart from variability in coloration pattern, the shells from
YN020 assigned here to C. spurius are otherwise consistent in shell formwith one another and overlap in shell shape with extant C. spurius as circumscribed by Kohn (2014), who provided the following shell shape data for the species: RD 0.56–0.75, mean=0.67; PMD 0.81–0.95, mean=0.89; RSH 0.05–0.26, mean=0.17. The specimens from YN020 are on average smaller than modern specimens (typical SL 58mm, maximum SL 105mm; Kohn, 2014, p. 346). Further, the distinctive carinate shoulder of specimens from YN020 is “subangulate to rounded” (Kohn, 2014, p. 346) inmodernC. spurius,which is also observed inWoodring’s specimen from the Gatun Formation (Fig. 13.1). The specimens found at UF locality YN020 add additional
support to Kohn’s (2014, p. 356) suggestion that Conus spurius may have the longest fossil record of any known extant species of Conidae (also see Hendricks, 2015). Its occurrence in the lower Gatun Formation puts a minimum age for the taxon at 10 Ma, offering a potentially useful calibration date for the clade that includes C. spurius (Puillandre et al., 2014). Landau et al. (2008) listed C. spurius as occurring in the lower Miocene of Cubagua, Venezuela so, pending additional study, the duration of the species may extend even further back in time. Without the aid of UV light to reveal their very different
shell coloration patterns, specimens of C. spurius from the Gatun Formation could be most easily confused with immature specimens of Conus molis as circumscribed here. A key difference is that C. molis has strong spiral threads on its sutural ramps, while such ornamentation is either very fine or absent in C. spurius. Notably, the absence of this spiral ornamentation is what led Pitt and Pitt (1993) to assign their figured specimen Conus cf. molis, rather than to assign it to C. molis outright. For comparisons between C. spurius and other species with which it co-occurs in other deposits, see Hendricks (2009, 2015). Dr. Judy Smith of the Smithsonian Institution recently
recognized (J. Smith, personal communication, October 24, 2016) that Woodring’s (1970) sole specimen (USNM 645738; Fig. 13.1, 13.2) of C. spurius from the Gatun Formation bears great similarity to Conus bramkampi Hanna and Strong, 1949, a species described from the Pliocene (Redman et al., 2007) Imperial Formation of Alverson Canyon, Imperial County, California (holotype UCMP 34199). Conus bramkampi has a coloration pattern that is very similar to that of C. spurius, but has a much more rounded shoulder, which is evident on USNM 645738. Comparison of C. spurius with C. bramkampi requires
Table 2. Numbers of specimens of each species found at UF locality YN020. Species
Conasprella (Ximeniconus) burckhardti (Böse, 1906) Conus?(Dauciconus?) multiliratus Böse, 1906 Conus (Pyruconus II) molis Brown and Pilsbry, 1911 Conus aemulator Brown and Pilsbry, 1911 Conus (Pyruconus I) recognitus Guppy, 1867 Conus (Stephanoconus) woodringi n. sp.
Conus (Spuriconus) spurius Gmelin, 1791
Conasprella imitator (Brown and Pilsbry, 1911) Conus (Dauciconus) taphrus Woodring, 1970 Conus symmetricus? Sowerby I, 1850 Conidae spp. Total
258 156 81 56 18 6 2 2 1 5
No. YN020 Specimens 304
889
additional study, especially because of the potential biogeo- graphic importance of C. bramkampi for understanding the history of the Spuriconus clade in tropical America prior to the closure of the Central American Seaway.
Results
Of the 25 species-group Conidae taxa previously reported from the Gatun Formation of Panama (Table 1), nine (including a questionable record for Conus symmetricus) are recognized as occurring in the lower Gatun Formation at UF locality YN020 and one additional species was newly recognized as Conus (Stephanoconus) woodringi (Table 2). An additional five of the 25 taxa are considered valid, but were not found at YN020; type and previously figured specimens of four of the latter group were examined and photographed as part of this study and are shown in Figure 14 (Conus tortuosostriatus Toula, 1911, Conus musaensis Olsson, 1922, Conus acolus Woodring, 1970, and Conus bravoi Spieker, 1922). Finally, 11 of the 25 species are considered synonymous with other species, or are otherwise dubious. For example, Conus tortuosopunctatus Toula, 1911 (NHMW1933/0018/0223), which is known from a single shell (Fig. 14.1), is almost certainly not from the Gatun Formation. Woodring (1970) noted that sediment preserved in its aperture is not consistent with that of the Gatun Formation. The relatively well-preserved coloration pattern of this shell suggests that it may be a worn specimen of a modern species, possibly Cona- sprella (Ximeniconus) mahogani (Reeve, 1843).
Discussion
The 10 species recognized here from UF locality YN020 are represented by a total of 884 specimens (Table 2). This collec- tion highlights the importance of attaining large sample sizes for documenting species-level and phylogenetic diversity at local
Figure 14. Type and other specimens of taxa previously reported from the Gatun Formation of Panama, but not found at UF locality YN020: (1–6, 8, 10, 11) photographed under regular light; (7, 9) photographed under UV light. (1) NHMW 1933/0018/0223, holotype, Conus tortuosopunctatus Toula, 1911, Gatun, Panama Canal, SL 19.5mm (measured from digital image); (2) NHMW 1933/0018/0224, holotype, Conus tortuosostriatus Toula, 1911, Gatun, Panama Canal, SL 34.3mm (measured from digital image); (3) USNM 645756, specimen of Conus tortuosostriatus Toula, 1911 figured by Woodring (1970, pl. 57, fig. 5), Panama Canal Zone (eastern area), Woodring locality 175, upper Gatun Formation, SL 26.2mm; (4) USNM 645755, specimen of Conus tortuosostriatus Toula, 1911 figured by Woodring (1970, pl. 57, fig. 6), Panama Canal Zone (eastern area), Woodring locality 175, upper Gatun Formation, SL 28.3mm; (5) PRI 20887, lectotype, Conus musaensis Olsson, 1922, Banana River, Costa Rica, SL 17.7mm; (6) USNM 645737, specimen of Conus musaensis Olsson, 1922 figured by Woodring (1970, pl. 57, fig. 2), Panama Canal Zone, Woodring locality 170, middle Gatun Formation, SL 20.6mm; (7) USNM 645741, holotype, Conus acolus Woodring, 1970, Panama Canal Zone, Woodring locality 136a, lower Gatun Formation, SL 35.1mm; (8, 9) USNM 645739, specimen of Conus bravoi Spieker, 1922 figured by Woodring (1970, pl. 56, fig. 10), Panama Canal Zone, Woodring locality 138c, lower Gatun Formation, SL 58.5mm; (10) USNM 645740, specimen of Conus bravoi Spieker, 1922 figured by Woodring (1970, pl. 56, fig. 11), Panama Canal Zone, Woodring locality 137a, lower Gatun Formation, SL 63.9mm; (11) YPM 520, syntype (one of four), Conus molis var. bravoi Spieker, 1922, near mouth of Quebrada Tusillal, Zorritos Formation, Peru, SL 76.8mm (measured from digital image). Scale bar to the left of (1) equals 10mm and pertains to (1–7); scale bar to the left of (8) equals 10mm and pertains to (8–11).
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