In 1911, a looped string-like object was discovered in a 1.6 billion year old graphite schist in Finland. It was named Corycium because it was thought to be a fossil of algae. However, it was made of carbon particles and was suspected to be a false fossil created by metamorphism. Later, the Carnegie Institution for Science in the United States confirmed that the fossil was of biological origin by examining the ratio of the stable isotopes of sulfur (molecular weight 34 and 32) and the ratio of the carbon isotopes (molecular weight 12 and 13), but doubts remain to this day. When Corycium was discovered, it was noted as the oldest valuable fossil, but today, the record of fossil life goes back 3.8 billion years, the record of blue-green algae fossils goes back about 3 billion years, and fossils of green algae and brown algae from 2 billion years ago have also been discovered. [Masae Omori] [References] | | | |Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend |
1911年にフィンランドの約16億年前の石墨片岩から発見された、輪になっている紐(ひも)状のもので、藻類の化石と考えられてCoryciumと命名された。しかし、炭素粒子でできていて、変成作用に伴って生じた偽化石の疑いももたれた。その後、アメリカのカーネギー研究所は、この化石に含まれている硫黄(いおう)の安定同位体である分子量34と32の比や、炭素同位体の分子量12と13の比を調べて、生物起源の化石であることが確認されたとしているが、現在でもなお疑問が残されている。コリシウムが発見された当時は、貴重な最古の化石として注目されたが、現在では生命の化石の記録は38億年前までさかのぼり、藍(らん)藻の化石の記録も約30億年前にまでさかのぼり、20億年前の緑藻、褐藻などの化石も発見されている。 [大森昌衛] [参照項目] | | | |出典 小学館 日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について 情報 | 凡例 |
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