Verification for the homogeneity of fossil assemblages within the same environment.

虽然在同一环境中的自生化石组合以前被认为是由于时间平均过程而均质的，但很少有人证实这一点。根据日本东南部太平洋一侧高知县东部上新世阿纳奈组内陆架相含化石粉砂岩中25种979个标本，对3个化石地点(地点1、2、3)的物种组成进行了定量比较。三地在180m距离内排列在同一水平线上。(1)各地的优势种均为维氏角虫，其次为海南水蚤，第三种为小叶蛾，第四种为大叶海棠。(2)地1、2中，第5优势种为日本斜纹夜蛾，第3地为第5优势种。(3)第1、2地优势种为第6种，第3地为巴非鱼。因此，第1、2地优势种组成接近均一，而第3地为巴非鱼而残留地3的次要物种组成则有所不同。

Although an autochtonous fossil assemblage within the same environment has been previously considered to be homogenized due to a time-average process, few has verified it. The species compositions among the three fossil localities (localities 1,2, and 3) are quantitatively compared based on the 979 specimens of twenty-five species in fossilferous silty sands of the inner-shelf facies of the Pliocene Ananai Formation, eastern part of Kochi Prefecture, Pacific-side of southeastern Japan. The three localities are arranged in the same horizon within the 180m distance(1) The most dominant species is Angulus vestarioides in all the localities, the second Nassarius caeratus, the third Fulvia mutica, and the fourth Acila divaricata.(2) In the localities 1 and 2, the fifth dominant species is Oblimopa japonica, whereas Gari anomala is the fifth dominant species in the locality 3.(3) Ammusiopenten praesignis is the sixth dominant species in the localities 1 and 2, but in loclity 3, Paphia sp.is.As a result, the species compositions of the localities 1 and 2 are considered to be nearly homogenized, whereas the remnant locality 3 is considered to be different in the minor species composition.