Figure 1.
Location of New Caledonia and Lifou.
Map showing location of Lifou within the Loyalty Islands, New Caledonia. The entrance of the Ani e Wee cenote on Lifou (marked with an X) is approximately 200 m from the coast.
Figure 2.
Vertical section of the Ani e Wee cenote.
Schematic vertical section of the cenote (NNW-SSE) as determined by a dive in 2010. The entrance of the cenote is approximately 30 m in diameter. The Nautilus shells occur between 35 and 45 m. Because of the cenote geometry, a shell thrown into the opening by humans could not have come to rest in its present position.
Figure 3.
Specimens of Nautilus macromphalus.
A. Live specimen of Nautilus macromphalus from New Caledonia. B, C. Specimens of N. macromphalus from the Ani e Wee cenote with faded red-brown color stripes. D, E. Still frames from a video clip showing specimens of N. macromphalus in situ on the rocky cenote floor. F, G. Scanning electron micrographs of the cross-section and surface, respectively, of the shell wall of a specimen of N. macromphalus from the Ani e Wee cenote.
Figure 4.
Radiocarbon and 210Pb/226Ra data for N. macromphalus from the Ani e Wee cenote.
A. Radiocarbon dates range from 6380±30 to 7095±30 y BP. B. Activity ratio of 210Pb/226Ra. Two of the specimens show an activity ratio of approximately 1.0 suggesting an age of >100 years, which is consistent with the old radiocarbon ages. The other specimens show an excess of 210Pb. Correcting the 226Ra activities for decay (∼7000 years) produces values much greater than those observed in living Nautilus. Shells were likely exposed to high activities of 222Rn and 226Ra in the groundwater of the cenote such that 210Pb and 226Ra were adsorbed on the shell surfaces elevating their activities.
Table 1.
Radiocarbon data for specimens of Nautilus macromphalus from the Ani e Wee cenote on Lifou, Loyalty Islands, New Caledonia.
Table 2.
Activities of 210Pb and 226Ra in specimens of Nautilus macromphalus from the Ani e Wee cenote on Lifou, Loyalty Islands, New Caledonia.