If the Hadar jaw really is Homo, says Berger, then perhaps its dating is wrong-a contention Kimbel disputes as vigorously as he supports the validity of his fossil.
伯杰说，如果在哈达尔发现的颌骨真的是人属，那么时间上可能是错的——在这一点上，吉姆·贝尔一直据理力争，就像他不遗余力地认定自己发现的化石具有说服力一样。
It lived around 125 million years ago, based on the dating of radioactive elements in the sediments that encased the fossil.
研究者通过对包裹化石的沉积层进行放射性元素年代测定，推断出中华龙鸟生活在1.25亿年前。
The isotopic dating and fossil geochronometry are the basic methods of ophiolite geochronometry.
同位素测年及化石年代学法是蛇绿岩年代学研究的基本方法。
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