The researchers also made what they say are the first sequences of nuclear dna from the extinct american mastodon .
据研究者说，他们还首次完成了已灭绝的美洲乳齿象细胞核dna序列的测定。
The mastodon became extinct about 10000 years ago - around the same time that mammoths disappeared from most of their range .
美洲乳齿象在约1万年以前灭绝－几乎在同一时间猛犸象也从大多数它们分布的地方消失了。
The researchers compared sequences of dna from the nuclei of african and asian elephants , and from woolly mammoths and the american mastodon .
研究人员对比了非洲象和亚洲象，以及来自猛犸象和美洲乳齿象的细胞核dna序列。
Although mastodon mitochondrial dna has been sequenced before , the researchers say they were the first to do the analysis on dna from the cell nucleus - in this case , using material from a tooth .
