SUMMARY OF RESEARCH RESULTS

Aalysis of atlases and periotic bones, found in the excavation grids within Stratum �]�T of District �T of the Mawaki site, helped to identify individual dolphins. Periotic bones were chosen over cranium bones because, being very tough, they are often found undamaged.

In the living body, periotic bones are joined with tympanic bullae at the posterior process and are loosely articulated to craniums by two ligaments, and so easily separate from the craniums upon tissue decay. A total of 60 periotic bones (28 left, 32 right) and 55 tympanic bullae (25 left, 30 right) were found. Before left-right pair-matching, the MNI (Minimum Number of Individuals) of periotic bones was 33: 21 Lagenorhyncus obliquidens (63.6%), 11 Delphinus delphis (33.3%) and 1 Tursiops truncatus (3.0%). 22 pieces (36.7%) of the 60 periotic bones were joined with the tympanic bullae. After sorting by SLp (Standard Length of periotic) and OWp (Oblique Width of periotic) and by non-metrical characters with high confidence, 22 pairs (36.7%, 8 pairs of L. obliquidens and 3 pairs of D. delphis) of the 60 periotic bones were ascertained as belonging to 22 individual dolphins.

The association of the atlases and the periotic bones with individual dolphins was achieved mainly by comparing SLp with BC (Breadth of the facies terminalis caudalis of atlas) and by their horizontal distribution in the grids. About 30% or more periotic bones belonged to different individuals from those of the atlases. Assuming that the remains of a catch were discarded together in one place, a catch was 11 individuals at the most and usually about 6 or 7 more than previously assumed.

Two craniums of L. obliquidens, CC-73 and CC-74, were found lying parallel in the H24 grid. Though their bases were facing upwards on the earth, their timpano-periotic bones were not found in this grid or adjacently. It may therefore be assumed that they were moved from another place after decay of the soft tissue.

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