Perez et al.—Miocene sharks and rays from Lago Bayano, Panama
et al. (2001) only measured a single tooth with CH = 14.2mm and CW = 15.0mm that was estimated to have originated from an ~3m shark. The teeth from the Chucunaque Formation are more closely aligned with the size range observed from the Gatun Formation. In past descriptions of this species, a gap in the serrations on the mesial edge around the midpoint of the crown has been used as a definitive feature (Purdy et al., 2001; Pimiento et al., 2013a). However, this feature is not observed in extant individuals of Carcharhinus falciformis (Purdy et al., 2001) and, as such, should not be considered definitive. This interpretation of a gap in serrations can likely be attributed to the transition from coarse to fine serrations at the mesial notch. Extant C. falciformis has a circumtropical distribution and are commonly found at depths ranging from 18 to 500m near the edge of continental and insular shelves, but also occur in open sea and occasionally inshore (Compagno, 1984; Compagno et al., 2005; Bonfil et al., 2009).
Carcharhinus brevipinna (Müller and Henle, 1839) Figure 6.5–6.7
Holotype.—Originally described as Carcharias (Aprion) brevipinna by Müller and Henle (1839, p. 31–32, pl. 9). The holotype is a 785mm mounted skin, RMNH D2525, from Java, Indonesia that resides in Naturalis - National Natuurhistorisch Museum, Leiden, Netherlands (Compagno, 1984).
Occurrence.—STRI 290109, STRI 290113, STRI 290116, STRI 300029, STRI 300032, STRI 430011, STRI 430012, and YPA105.
Description.—Small, triangular teeth; slender, finely serrated crown that is often inclined lingually, with straight mesial and distal cutting edges. The lingual face is convex and the labial face is flat apically and convex basally, forming a ridge along the crown-root margin. The root is short with a nutrient groove and horizontal basal margin. Differentiating between upper and lower teeth is difficult, however in extant individuals upper teeth are often slightly broader (personal observation, V.J. Perez, 2015). Carcharhinus brevipinna from the Chucunaque Forma- tion range from CH = 2.7–8.6mm and CW = 5.4–13.2mm.
Materials.—One hundred forty-seven isolated teeth; lower: UF 281159; indeterminate position: UF 275041, UF 275070, UF 281153–58, and UF 281322.
527
Remarks.—Carcharhinus brevipinna is a relatively common species; however, its range and abundance are difficult to surmise given the constant confusion with the closely related species, Carcharhinus limbatus (Burgess, 2009). The two differ in that C. brevipinna has a shorter, slightly more asymmetric crown than C. limbatus. Also, upper teeth of C. limbatus typi- cally have coarser serrations on the shoulders, particularly on the distal heel. Naylor (1990) conducted a principal component analysis to determine if upper teeth of these two species could be distinguished when monognathic variation was removed (i.e., could isolated upper teeth of these two species be distinguished from one another). The statistical analysis found that the two do in fact form distinct clusters, suggesting that isolated upper teeth can be identified to the species level. However, teeth belonging to C. brevipinna formed two sub-clusters that separated juveniles from adults, implying that ontogenetic variability could still pose a problem in identifying C. brevipinna. Neither C. brevipinna nor C. limbatus have been identified from the fossil record of Panama. Aguilera et al. (2011) did not recognize C. brevipinna from any Neogene locality from the Caribbean Neotropics, and only recognized C. limbatus from Venezuela. Carillo-Briceño et al. (2015b) identified two upper lateral teeth of C. limbatus from the middle-late Miocene Urumaco Forma- tion in Venezuela. Carcharhinus brevipinna typically occurs on continental and insular shelves at depths of 0–100m in warm temperate to tropical waters in the Atlantic, Mediterranean, and Indo-West Pacific (Compagno, 1984; Reiner, 1996; Burgess, 2009).
Carcharhinus aff. C. macloti (Müller and Henle, 1839) Figure 6.8–6.13
Holotype.—Originally described as Carcharias (Hypoprion) macloti by Müller and Henle (1839, p. 34, pl. 10). The holotype is an adult male from New Guinea deposited in Rijksmuseum van Natuurlijke Historie, Leiden (Compagno, 1984).
Occurrence.—STRI 290109, STRI 290113, STRI 290145, STRI 300032, and YPA105.
Description.—The crown is small with complete cutting edges that lack serrations; however the heels are equipped with distinct lateral cusplets. On the labial face, the enamel extends well onto the root. The robust root is bilaterally symmetrical with a nutrient groove that penetrates the horizontal basal margin. Images of Carcharhinus macloti from Purdy et al. (2001)
Figure 6. Carcharhiniformes II: Carcharhinus from the Chucunaque Formation. (1–4) Carcharhinus falciformis (Bibron, 1841 in Muller and Henle, 1839–1841), UF 281162, upper tooth in lingual, labial, distal lateral, and mesial lateral view, respectively (scale bar = 1cm); (5–7) Carcharhinus brevipinna (Blainville, 1816), UF 281159, upper tooth in lingual, labial, and distal lateral view, respectively (scale bar = 1cm); (8–13) Carcharinus aff. C. macloti (Müller and Henle, 1839): (8, 9) UF 281323, upper anterior tooth in lingual and labial view, respectively (scale bar = 0.5 cm); (10) UF 281325, upper lateral in lingual view (scale bar = 0.5 cm); (11–13) UF 275061, upper lateral tooth in lingual, labial, and mesial lateral view, respectively (scale bar = 1cm); (14–20) Carcharhinus obscurus (Lesueur, 1818): (14–16) UF 281147, upper tooth in lingual, labial, and distal lateral view, respectively (scale bar = 1cm); (17–20) UF 281152, lower tooth in lingual, labial, mesial lateral, and distal lateral view, respectively (scale bar = 1cm); (21–24) Carcharhinus plumbeus (Nardo, 1827), UF 281143, upper tooth in lingual, labial, mesial lateral, and distal lateral view, respectively (scale bar = 1cm); (25–49) Carcharhinus sp.: (25–28) UF 281165, upper anterior tooth in lingual, labial, distal lateral, and mesial lateral view, respectively (scale bar = 1cm); (29–32) UF 281348, upper anterior tooth in lingual, labial, distal lateral, and mesial lateral view, respectively (scale bar = 1cm); (33–36) UF 275141, lower anterior tooth in lingual, labial, distal lateral, and mesial lateral view, respectively (scale bar = 1cm); (37–39) UF 275141, lower lateral tooth in lingual, labial, distal lateral, and mesial lateral view, respectively (scale bar = 1cm); (40–42)UF281164, lower posterior tooth in lingual, labial, distal lateral view, respectively (scale bar = 1cm); (43–46) UF 281182, lower posterior tooth in lingual, labial, mesial lateral, and distal lateral view, respectively (scale bar = 1cm); (47) UF 281402, upper pathologic tooth in lingual view; (48) UF 281167, upper pathologic tooth in lingual view (scale bar = 1cm); (49) UF 281168, upper pathologic tooth in apical view (scale bar = 1 cm). Photo credit: R. Leder.
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