Carcharodontosaurids and Abelisaurs

["T. Mike Keesey" <tkeese1@gl.umbc.edu>]

I was browsing through the new Encyclopedia of Dinosaurs at a bookstore
today (being a college student, buying it is unfortunately not an option),
and I noticed something odd in the section on South American dinosaurs.
The cladogram placed _Giganotosaurus_ closer to abelisaurs than to
tetanurines! Furthermore, I think in the section on abelisaurs there was
some mention of carcharodontosaurids possibly being related to abelisaurs.
What's going on here? Carcharodontosaurids are carnosaurs, right? Is
someone proposing that tridactyly evolved twice among theropods?

Confused--

--T. Mike Keesey
tkeese1@gl.umbc.edu
http://umbc.edu/~tkeese1 -- Dinosaur Web Pages