[B-PT07] 地球生命史

[BPT07-P04] 同一堆積物上におけるコウノトリ足跡の計測～足跡に印跡動物の情報はどの程度残るのか～

*田中 郁子^1,2、江崎 保男^3,4、船越 稔⁴、山崎 和仁¹、兵頭 政幸^5,1 (1.神戸大学大学院理学研究科、2.日本学術振興会特別研究員、3.兵庫県立大学大学院地域資源マネジメント研究科、4.兵庫県立コウノトリの郷公園、5.神戸大学内海域環境教育センター)

キーワード：足形態、コウノトリ、分類、足跡化石、足の解剖学

An ichnological experiment using Ciconia boyciana was carried out to reveal morphological variability of tracks left on a potter sediment by 2 individual birds. We obtained a total of 56 tracks, for each of which the area, length, width, depth, and volume were measured. The average value of the track area was almost equal to its median value. Ciconia boyciana generally left morphologically uniform tracks, suggesting that it controls digit-substrate interaction to keep body balance. A unique anatomical feature is that Ciconia boyciana does not leave metatarsal impression, unlike other wading birds. This feature will be useful to identify Ciconia boyciana from other trackmakers being similar in body weights and habitats. Track width has a wide range of variability up to 40 %, which can be caused by the linkage of muscles between leg and foot being characteristic to birds. The co-efficient analysis of track geometry reveals that the width and depth of a track have a trade-off relationship to keep a same volume. Application of the theoretical morphology analysis to the track data reveals that the outer digits take a lot of the body weight in Ciconia boyciana while walking.