Perez et al.—Miocene sharks and rays from Lago Bayano, Panama
Table 2. Strontium isotope data and age estimates from the Chucunaque Formation of Lago Bayano. Locality (STRI) Height (m) Analytical sample Taxon
300032 300032 300032 290138 290138 290138
n/a n/a n/a n/a n/a n/a
LB-32A LB-32B LB-32C LB-38A LB-38B LB-38C
Lindapecten sp. 0.708901 Lindapecten sp. 0.70889 Lindapecten sp. 0.7088864 Lindapecten sp. 0.7089003 Lindapecten sp. 0.7089039 Lindapecten sp. 0.708899
515
87Sr/86Sr Age (Ma) Age range (Ma) 9.35–9.77
9.57 9.90
10.00 9.60 9.50 9.65
9.70–10.07 9.82–10.20 9.40–9.80 9.25–9.67 9.42–9.82
made assuming 86Sr/88Sr ratio of 0.1194. Errors in measured 87Sr/86Sr are better than ±0.00002 (2 σ), based on long-term reproducibility of NBS 987 (87Sr/86Sr = 0.71024). Due to the poor preservation of shell material in the Lago Bayano succes- sion, 87Sr/86Sr isotope analyses were only conducted on samples from two localities (STRI 290138 and 300032) where calcitic shells of Lindapecten were present; at many localities even calcitic taxa are represented as external molds. Information regarding biology, anatomy, distribution, habitat
oxidized tungsten single filaments and run in triple collector dynamic mode. Data were acquired at a beam intensity of ~1.5 V for 88Sr, with corrections for instrumental discrimination
Figure 2. Sampling effort for surface-collected and screenwashed material via two randomized species accumulation curves. (1) Accumulation curves reported as number of specimens versus number of species (i.e., richness) for surface- collected (light gray) and screenwashed material (dark gray), respectively; shaded polygons represent confidence intervals. (2) Accumulation curve reported as number of localities (i.e., collecting sites versus richness) for surface-collected (light gray) and screenwashed material (dark gray), respectively; shaded polygons indicates the confidence interval.
(Fig. 2) using the vegan package (Oksanen et al., 2010) in the program R (R Development Core Team, 2012). Age estimates derived from 87Sr/86Sr isotopic ratios of
marine calcareous shells and marine calcareous sediment may be compared to global ratios of 87Sr/86Sr through geologic time to estimate a geological age (Burke et al., 1982; Koepnik et al., 1985; Hodell and Woodruff, 1994; McArthur, 1994). Samples were obtained from the Lago Bayano assemblage itself, and from presumably coeval strata outcropping nearby (Table 2). Age estimates were determined using the Miocene and Pliocene portions of Look-Up Table Version 4:08/03 (Howarth and McArthur, 1997; McArthur et al., 2001) associated with the strontium isotopic age. Strontium isotope analyses of Lago Bayano samples used well-preserved calcitic shells and followed the sampling and analytical protocols of Kirby et al. (2007, 2008). These were performed on a Micromass Sector 54 Thermal Ionization Mass Spectrometer (TIMS) in the Depart- ment of Geological Sciences at UF. Strontium was loaded onto
preferences, and feeding mechanisms were gathered from the literature cited below. Much of this information can be found in a coherent format in The IUCN Red list of Threatened Species (
www.iucnredlist.org) or Fishbase (
www.fishbase.org). Measurements of macro teeth were taken using calipers, whereas measurements of micro teeth were taken directly from SEM images. Crown height (CH = the distance between the crown tip and crown-root margin) and crown width (CW = maximum distance between the mesial and distal edge at the crown-root margin) were measured for labio-lingually flatten teeth (i.e., most taxa belonging to the subdivision Selachii). Crown length (CL = tooth thickness, defined herein as the maximum distance between the labial and lingual edge in occlusal view) was additionally measured in teeth with a broad occlusal surface (i.e., those belonging to the superorder Batomorphii and the genus Mustelus). In order to measure CH, a line was drawn from the crown apex
perpendicular to the crown-root contact (e.g., Pimiento et al., 2010, fig. S2). It is important to note that many other authors will report the tooth height, which is generally a measurement of the entire tooth (crown and root) and is not directly comparable to the CH measurements reported herein. Taxonomic composition is reported as a histogram depicting
the relative abundance of chondrichthyan genera. Functional diversity is interpreted via two proxies (dentition types and ecomorphotypes).Dentition types, as definedbyKent(1994),were assigned to each taxon based on tooth morphology of fossil and modern representatives. For example, in the case of Carcharhinus plumbeus, fossil occurrences were limited to upper teeth that have a cutting-type morphology; however, based on the dentition of the living representatives, we can infer a cutting-grasping type dentition. Ecomorphotypes, as defined by Compagno (1990), were assigned to each taxon based onmorphology, habitat, and behavior ofmodern analogs. Both proxies were then plotted as pie charts that illustrate the relative abundance of dentition types and ecomorphotypes, respectively. A weighted analysis of paleodepth frequency was performed using R. This analysis incorporated the abundance (in the fossil assemblage) and depth preference (as reported in the literature) from taxa with modern analogs. Taxa that
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216