Well, I was searching through livebearers on Wikipedia and found this out. Freshwater Stingrays are considered in this group, sort of kind of. well they do give live births like other livebears. Well, that isn't definately my area of expertice
I read about that, too. However, they are totally different, probably diverging at the "family" or even the "order". Then, there are also such oddities as the Anableps anableps