common ancestry的用法和样例：
例句
- Mr. Smith and the queen have a common ancestor in king Charles II.
查理二世国王是史密斯先生和女王的共同祖先。 - For instance, all birds and reptiles are believed to have descended from a single common ancestor, so this taxonomic grouping is called monophyletic.
例如，所有的鸟类和爬行动物被认为是从一个单一的共同祖先传下来的，因此这个分类学的分组被称为单系类群。
