And they found that the first  chitin-use genes appeared deep in picocyanobacteria evolution, about 500 million years ago, when their ancestors were making that  initial transition to the open oceans.

他们发现，大约 5 亿年前，第一个使用几丁质的基因出现在微微蓝藻进化的深处，当时它们的祖先正在向开放海洋进行最初的过渡。