Perez et al.—Miocene sharks and rays from Lago Bayano, Panama Occurrence.—STRI 300032 and STRI 430011.
Description.—Upper teeth have a moderately broad crown; the mesial edge is straight with relatively uniform, moderately sized serrations and the distal edge is concave with finer serrations apically. There is no notch on either cutting edge, the lingual face is convex, and the labial face is flat. The root is thick with a transverse groove and obtusely angled basal margin. Carcharhinus plumbeus from the Chucunaque Formation ranges from CH = 5.8–11.9mm and CW = 8.1–14.5mm.
Materials.—Eight isolated teeth; upper: UF 281141–43.
Remarks.—Carcharhinus plumbeus can be distinguished from other species of Carcharhinus by its straight mesial edge with fairly uniform serrations and moderate width; C. obscurus is broader and C. perezi is narrower (Purdy et al., 2001). Carcharhinus plumbeus is relatively uncommon in the Chucu- naque Formation (N = 8), the Gatun Formation (N = 5; Pimiento et al., 2013a), and the Pungo River Formation (N = 6; Purdy et al., 2001). Carcharhinus plumbeus is intermediary in size between specimens from the Gatun Formation (CH = 6.8– 10.6mm andCW = 10.3–16.1mm; Pimiento et al., 2013a) and the Pungo River Formation (CH = 14.0–19.0mm; Purdy et al., 2001), but more closely aligned with the individuals from the Gatun Formation. The teeth from the Pungo River Formation correspond to TL = 2m (Purdy et al., 2001), indicating smaller individuals in both the Chucunaque and Gatun Formations. In the bathyal Piña Sandstone facies C. plumbeus represents ~3% of the chondrichthyan fauna, but is not observed in the neritic Rio Indio facies of the Chagres Formation (Carrillo- Briceño et al., 2015a). Carcharhinus plumbeus have also been recognized in the Miocene deposits of Venezuela and Cuba (Iturralde-Vinent et al., 1996; Aguilera and Rodrigues de Aguilera, 2001; MacPhee et al., 2003). Extant individuals are benthopelagic, commonly found inshore and offshore on continental and insular shelves and adjacent deep water (Compagno, 1984). Carcharhinus plumbeus occurs at depths less than 280 m, but are most commonly found in the range of 20–55m (Compagno, 1984; Compagno et al., 2005).
Carcharhinus spp. Figures 3.20, 3.21, 6.25–6.49
Occurrence.—STRI 290109, STRI 290113, STRI 290116, STRI 290145, STRI 300029, STRI 300032, STRI 430011, STRI 430012, and YPA105.
Description.—Teeth range from small to moderate size. Upper teeth are broad and triangular with serrated edges, have a flat labial face and convex lingual face. Teeth become increasingly asymmetric in lateroposterior positions. The root has a trans- verse nutrient groove or a nutrient pore, convex crown-root margin on the lingual face, and an arciform basal margin. Lower teeth are symmetrical with a tall, narrow crown and complete cutting edges. The root is thick with two prominent lobes and a transverse groove; the basal margin may be near horizontal or arcuate.
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Materials.—Four hundred twenty-seven isolated teeth; upper anterior: UF 281165, UF 281328, UF 281331–32, UF 281335, UF 281344, UF 281346, UF 281348; upper: UF 275038, UF 275140, UF 281167, UF 281327, UF 281334, UF 281339, UF 281343, UF 281345; upper pathologic: UF 281168, UF 281338, UF 281347, UF 281402; lower: UF 275035, UF 275042, UF 275063, UF 275074, UF 275076, UF 275081, UF 275089, UF 275141, UF 275143, UF 275154, UF 281163, UF 281164, UF 281326, UF 281330, UF 281333, UF 281337, UF 281340, UF 281342, UF 281403; posterior: UF 281182–83, UF 281361–63, UF 281269; indeterminate position: UF 275034, UF 275036, UF 275067, UF 275077, UF 275079, UF 275088, UF 275101, UF 275119, UF 275149, UF 281329, UF 281336, and UF 281341.
Remarks.—The genus Carcharhinus is themost abundant among the chondrichthyans from the Chucunaque Formation. There is much debate regarding the assignment of teeth fromthis genus to the species level (Naylor and Marcus, 1994; Purdy et al., 2001; Pimiento et al., 2013a), especially in the case of lower teeth (Kent, 1994). Lower teeth are very similar to Negaprion brevirostris,but can be distinguished by having a shorter crown. This confusion can be attributed to the convergent dignathic heterodonty expressed by this genus, in which the lower jaw has a grasping function and the upper jaw has a cutting function. Naylor and Marcus (1994) determined that upper lateral teeth are the most diagnostic teeth within the dentition and can accurately be identified to the species level. Pimiento et al. (2013a) reported tooth sizes ranging from CH = 1.9–12.9mm and CW = 4.1– 17.6mm, which ismuch smaller than the maximumCHof 20mm observed by Cappetta (1987). Four upper teeth from the Chucu- naque Formation exhibit distinct pathologies (Figs. 3.20, 3.21, 6.47–6.49), represented by twomorphotypes. The first pathologic morphotype is a lack of serrations on one cutting edge near the crown apex (Figs. 3.20, 3.21, 6.48) and the secondmorphotype is a disruption of the cutting edge indicated by a wrinkled pattern (Fig. 6.47, 6.49). The cause of these pathologies is unclear, however, most tooth deformities are often attributed to feeding damage related to bones or tail spines getting lodged into the jaw (Gudger, 1937). Carcharhinus spp. are the most abundant sharks in shallow, nearshore environments, with at least 30 known living species (Kent, 1994; Naylor andMarcus, 1994). This genus has a widespread distribution, occurring in all temperate and tropical seas (Cappetta, 1987), and can most commonly be found in coastal waters (Compagno, 1984).
Genus Negaprion Whitley, 1940
Type.—Aprionodon acutidens subsp. queenslandicus Whitley, 1939 (Cappetta, 2012).
Negaprion brevirostris (Poey, 1868) Figure 7.1–7.4
Holotype.—Originally described as Hypoprion brevirostris by Poey (1868, p. 451, pl. 4, figs. 5, 6, 20). The holotype is unknown; however, the type locality is Cuba (Compagno, 1984).
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