Use of in situ silica bodies in identification of rope fibers from the Phanom-Surin shipwreck, Samut Sakhon, Thailand

Abstract

The remains of an ancient wooden ship were found in a shrimp farm in Samut Sakhon Province, central Thailand, in 2013. The remains, referred to as the Phanom-Surin shipwreck, are thought to be from the ninth century CE. The objective of this project was to investigate ropes from the shipwreck by comparative scanning electron microscopy in an attempt to identify the sources of the rope fibers. Two types of rope were shown to be made from bundles of fiber cells surrounded by files of stegmatal cells containing silica bodies. Stegmata are found in many species of Arecaceae, as well as in several other monocot families. Fibers from a black rope wrapped around a torpedo-shaped jar had hat-shaped silica bodies with a flat base and spinules on the outer surface, similar to those occurring in the palm tribe Caryoteae, which consists of 3 genera, Caryota, Arenga, and Wallichia, restricted to India eastward to the Pacific Islands. The fibers on a second type of rope had spherical silica bodies with spinules, found in many genera of the subfamilies Calamoideae, Coryphoideae, Ceroxyloideae, and Arecoideae, including the coconut, Cocos nucifera. These results are consistent with reports of many ancient sewn ships using ropes made from fibers of the sugar palm, Arenga pinnata, and coconut. A third type of rope was made from a rattan palm. This study demonstrates the usefulness of SEM analysis of silica bodies and cellular anatomy in determining the taxonomy and biogeographic origins of rope fibers from shipwrecks or other sources.