Starting in the late 19th century, most paleontologists thought that turtles belonged in the clade we now call parareptilia, because they shared the same basic skull structure with other parareptiles.

从 19 世纪后期开始， 大多数古生物学家认为海龟属于我们现在称为副爬行动物的进化枝，因为它们与其他副爬行动物具有相同的基本头骨结构。

Taking a step back, the reason there are so many different steroids is because the term refers to substances with a shared molecular structure, rather than shared effects on the body.

退一步说，之所以有这么多不同的类固醇，是因为该术语指的是具有共同分子结构的物质，而不是对身体的共同作用。