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Journal of Paleontology 91(3):512–547
vertical, flexuous enameloid ripples and a somewhat sinuous outline. Root is thick with a medial groove that forms two short, asymmetric root lobes; there is a foramen nested within the medial groove that is oriented toward the labial side; the basal margin is flat, but slopes toward the labial face. The folds on the labial edge and the enameloid ripples on the lingual uvula are a diagnostic feature for the genus Mustelus (Herman, 1982; Cappetta, 1987; Leder, 2013). Two specimens of Mustelus sp. were imaged: UF 281384 in Figure 3.7–3.9 has a CH = 0.23 mm, CW = 1.17mm, and CL = 0.64mm; and UF 281386 in Figure 3.10–3.13 has a CH = 0.27mm, CW = 1.37mm, and a CL = 0.64mm.
Materials.—Sixteen isolated teeth; indeterminate position: UF 281384–88.
Remarks.—Mustelus sp. from the Chucunaque Formation bears similarities to those described by Carrillo-Briceño et al. (2015a), with weak folding on the lingual uvula; however the images provided by Carrillo-Briceño et al. (2015a) do not show the labial face or the root. Mustelus sp. from the Pungo River Formation of the Lee Creek Mine have a CW = 1–1.3mmand a CL roughly half the length of the CW (Purdy et al., 2001). Among the 28 extant species of Mustelus, all have a demersal habit, with most preferring subtropical to tropical conditions; however, Mustelus antarcticus, M. asterias, and M. mustelus prefer temperate waters (Compagno et al., 2005). Some species occur in up to 800mdepth (Kiraly et al., 2003), but most species generally occur at depths <200m (Compagno, 1984).
Family Hemigaleidae Campagno, 1984 Genus Hemipristis Agassiz, 1843
Type.—Hemipristis serra Agassiz, 1843 (Cappetta, 2012).
Hemipristis serra Agassiz, 1843 Figure 5.1–5.16
Holotype.—Originally described by Agassiz (1843, pl. 27, figs. 18–30) from the Miocene of southern Germany. Cappetta (2012, fig. 279G–I) illustrated two syntypes: an upper lateral, UM LEE 4, and a lower anterior, UM LEE 5.
Occurrence.—STRI 290109, STRI 290116, STRI 290125, STRI 290139, STRI 290145, STRI 300029, STRI 300032, and STRI 430011.
Description.—Upper teeth are broad and distally inclined with serrated cutting edges that terminate prior to the apex. The mesial edge is convex with relatively uniform, moderate-sized serrations. The distal edge is concave with serrations that increase in size apically. The root is compressed, bearing a strong lingual protuberence with a deep nutrient groove that forms a Z-shaped basal margin. There is obvious monognathic and dignathic heterodonty, with increasing asymmetry antero- laterally. Lower teeth are narrow, elongate, and unserrated with incomplete cutting edges and small lateral cusplets. The lingual face is convex, whereas the labial face is convex basally and flattens apically. The root is bilobate with a high lingual
protuberance and deep nutrient groove. Hemipristis serra ranges from CH = 10.4–32mm and CW = 4.4–32mm in the Chucunaque Formation.
Materials.—Sixty-one isolated teeth; upper anterior: UF 281404; upper symphyseal: UF 281396; upper: UF 275032, UF 275047, UF 275054, UF 275065, UF 275078, UF 275093, UF 275115, UF 275122, UF 275144, UF 275152, UF 281174; lower: UF 275100, UF 281389–95, and UF 281405.
Remarks.—Hemipristis serra has a cutting-grasping type dentition (Kent, 1994) and the largest teeth among the carcharhiniform sharks from the Chucunaque Formation. Upper teeth of H. serra differ from the genus Carcharhinus in having a smooth apex and coarser serrations on the distal edge; lower teeth differ from the genus Carcharias in having incomplete cutting edges that only comprise roughly the upper third of the crown (Kent, 1994). Purdy et al. (2001) observed H. serra teeth from the lower Miocene Pungo River Formation and from the early Pliocene Yorktown Formation and postulated thatH. serra increased in size throughout its evolutionary history. Teeth from the Chucunaque Formation are larger than that of the younger Pungo River Formation (CH = 14.1–29.1mm and CW = 12.3–35.5mm) and smaller than the older Yorktown Formation (CH = 16.4–41.0mm and CW = 14.0–43.5mm) and, as such, follow the trend proposed by Purdy et al. (2001). Pimiento et al. (2013a) observed size ranges of CH = 5.4–21.6mm and CW = 5.2–29.0mm from the Gatun Formation, which contradicts the trend observed by Purdy et al. (2001). However, the Gatun Formation was described as a shark paleonursery (Pimiento et al., 2010; Pimiento et al., 2013a), in which smaller teethmight be anticipated. Compagno (1988) noted an increase in distal serrations on upper lateral teeth of the extant Hemipristis elongatus during ontogeny; so observation of serration abundance on upper lateral teeth of H. serra from the Gatun Formation may be used to distinguish between juvenile and adult individuals. Hemipristis serra occurs in Atlantic and Pacific deposits from themiddle Eocene to at least the Pleistocene; andwas particularly abundant in neritic, warm-water environments during the Miocene and Pliocene (Cappetta, 1987). Carrillo- Briceño et al. (2015a) observed H. serra in neritic Rio Indio facies and bathyal Piña Sandstone facies of the Chagres Formation. The much smaller, extant species, Hemipristis elongatus, is a coastal species that occurs inshore and offshore on continental and insular shelves, generally at depths of 1–132m (Compagno, 1984; Last and Stephens, 1994; Compagno et al., 2005).
Family Carcharhinidae Jordan and Evermann, 1896 Genus Galeocerdo Müller and Henle, 1837
Type.—Squalus cuvier Peron and Lesueur, 1822 (Cappetta, 2012).
Galeocerdo aduncus (Agassiz, 1835) Figure 5.17–5.20
Holotype.—Originally described as Galeocerdo aduncus by Agassiz (1835, pl. 26, figs. 24–28) from the Schwabia region of southwestern Germany, according to Purdy et al. (2001). These specimens were deposited in Staatliches Museum für
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