The most ancient branch of the tree is Rhineuridae. The remaining five families form a group to the exclusion of rhineurids. Bipedidae, Blanidae and Cadeidae represent the most ancient divergences within this grouping, with Trogonophidae and Amphisbaenidae diverging more recently. South American amphisbaenids apparently are derived from African amphisbaenids that rafted across the Atlantic in the Eocene, about 40 million years ago. Cuban cadeids may be similarly derived from blanids that rafted across from northwestern Africa or southwestern Europe in a similar time frame.