Abelisauridae

    Abelisauridae is a clade of theropods that was first described in the mid 1980s, from Abelisaurus and Carnotaurus, two new LK species from Argentina.  So far, they are known mostly from the late Cretaceous of the Southern Hemisphere.  Many of them appear to have been fairly large.  They were the Gondwanan equivalent of the tyrannosaurids, being the top predators (after the spinosaurids and carcharodontosaurids were out of the way in the early Late Cretaceous).  However, they probably went about their business in different ways than tyrannosaurids, given their less cursorial builds (abelisaurids seem to have been longer and lower than tyrannosaurids, from what we currently know), less robust skulls and teeth, and different prey items (Gondwanan continents being overrun with titanosaurians and with not much in the way of hadrosaurids, ankylosaurians, or ceratopsians).
    The traditional definition of Abelisauridae has Abelisaurus off in a corner and a group of carnotaurines, which is a bit unfair since Abelisaurus is only known from a partial skull.  "Carnotaurines" are traditionally known for very short arms practically lacking the forearm segment, and for elaborate horns and knobs on the skull.  Abelisaurid skulls are known for having deep upper jaws with tall snouts, and slim lower jaws.  They also have "cheeks" expanded side to side, like those of tyrannosaurids, perhaps conferring an additional degree of binocular vision over predators with more narrow skulls. 
    Besides its two founding members, Abelisaurus and Carnotaurus, Abelisauridae has become a home for a number of poorly-known theropods whose affinities had previously been unknown.  With the recent flood of good material from South America and Madagascar, it is very likely that this group will continue to increase in size.

<--Abelisauridae
      |--Kryptops
      `--+--Rugops 
           `--+--Ekrixinatosaurus
                `--+--+--Carnotaurus
                     |    `--Ilokelesia
                     `--+--Indosaurus
                          |--Majungasaurus
                          `--Rajasaurus
                                          
Abelisauridae: This is a sort of theropod "rogue's gallery," where the members are outlandish in appearance.  Horns above the eyes (Carnotaurus means "meat-eating bull"), extraordinarily deep skulls matched with slender dentaries, tiny, seemingly useless arms and hands, and strange thickening of the skull roof are things seen in some or all of these creatures.  It is most probable that the cranial ornamentation was used for display.  "Carnotaurines" also have L-shaped "wings" (sticking out and up on the long end of the L, with the short end pointing forward) for transverse processes on the caudal verts.
    There are a number of poorly-known abelisaurids described from India (Huene and Matley had a great big monograph back in 1933) that have suffered greatly, first from initial misinterpretations (and the fact that they weren't complete enough to draw good comparisons), and later from specimen loss; a great deal of the convoluted taxonomy could probably be cleaned up if the original specimens could be located.  For example, it is entirely within the realm of possibility that Indosaurus, Indosuchus, and Compsosuchus are the same thing, and Lametasaurus and Rajasaurus the same thing.  It appears that there were at least two large theropods, possibly three, in the Lameta, one represented by Indosuchus, one represented by Carnotaurus-like Rajasaurus, and a possible non-abelisaurid abelisauroid (suggested by some skull elements with non-abelisaurid features).
    An abelisaurid tooth, previously referred to Majungasaurus, is known from the Maastrichtian (LK) of Egypt.
    "Carnotaurines", particularly the distinctive namesake, have become the go-to theropods when someone wants to depict a theropod that is not either Tyrannosaurus, Velociraptor (or another "raptor"), or Allosaurus. 

Abelisauridae i.s.: