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 spinosauroids 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,
So far, there are carnotaurine abelisaurids and a few non-carnotaurines. Carnotaurines are 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.
|Taxon or Taxa:||Time\Place:||Comments:|
|Rugops primus Sereno, Wilson, and Conrad, 2004||Cenomanian (LK) of Niger||Rugops is a new hornless (no bony horns, at least) basal abelisaurid, known from a partial skull lacking the palate and most of the bones along the side of the face behind the eyes. This skull is distinguished by a row of depressions along the upper surfaces of the nasals, and by a small hole between the lacrimal, prefrontal, frontal, and postorbital (which is a little sketchy on absolute dimensions given that the postorbitals are AWOL). It has been suggested that these holes held blood vessels to supply a nonbony keratinous or fleshy ridge or crest system. I like the name; it is short and direct, like a good predator ought to be.|
|Abelisaurus comahuensis Bonaparte and Novas, 1985||Santonian-early Campanian (LK) of Argentina||Known only from a nearly complete skull, Abelisaurus is usually regarded as closely related to Carnotaurus, although that may seem hard to believe based on the superficial aspects of the skulls (and some researchers have recently suggested that it may be a late-surviving carcharodontosaurid). It is one of my favorite big theropods; I like the no-nonsense look of the skull.|
Abelisauridae i.s.: 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
An abelisaurid tooth, previously referred to Majungasaurus, is known from the Maastrichtian (LK) of Egypt.
|Taxon or Taxa:||Time\Place:||Comments:|
|Compsosuchus solus (N.D.) Huene and Matley, 1933 (?Indosuchus or ?Rajasaurus)||Maastrichtian (LK) of India||Interestingly, the axis cervical that forms the type of this species (and is AWOL), while on the whole corresponding well with carnotaurine axial verts, has some similar characteristics to that of the carnosaurian tetanuran Allosaurus. Thus, this theropod shows some convergence with Allosauridae. It used to be considered a "coelurid" or compsognathid.|
|Dryptosauroides grandis (N.D.) Huene and Matley, 1933||Maastrichtian (LK) of India||This theropod is based upon six incomplete caudals that have no features that would allow it to be distinguished from the multitude of other dubious theropods from the Lameta Formation, or from Majungasaurus. It would have been large, though, on the order of Carnotaurus in size.|
|Indosaurus matleyi Huene and Matley, 1933 (?Indosuchus)||Maastrichtian (LK) of India||I am sad to report that Indosaurus does not appear to have had horns after all, and could potentially be the same as Indosuchus (unfortunately the type material is lost). It was once identified as an allosaurid or "megalosaurid".|
|Indosuchus raptorius Huene, 1932 (?Compsosuchus, ?Indosaurus)||Maastrichtian (LK) of India||This theropod is based on currently absent skull material. It was a contemporary of
Rajasaurus and (possibly synonymous) Indosaurus,
but appears to be closest to Abelisaurus and Majungasaurus.
It was originally identified as a tyrannosaurid.
Much new material has been assigned to it, making up most of a skeleton. This material includes a relatively long arm, especially when compared to Carnotaurus. Unfortunately, the fact that several other large theropods (possibly synonymous) are known from the same time and place means that this identification is not secure.
|Ornithomimoides: (N.D.) Huene and Matley, 1933||O. mobilis (N.D.) (type) Huene and Matley, 1933||Maastrichtian (LK) of India||The caudals assigned to these two species are inadequate for classification beyond Abelisauridae, and are essentially identical to those of Majungasaurus. O mobilis was based on five caudals (thought to be dorsals), and O. barasimlensis was based on four smaller caudals (again, thought to be dorsals).|
|O. barasimlensis (N.D.) Huene and Matley, 1933|
Carnotaurinae: This is a sort of theropodian "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
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.
|Taxon or Taxa:||Time\Place:||Comments:|
|Ekrixinatosaurus novasi Calvo, Rubilar-Rogers, and Moreno, 2004||Cenomanian-early Turonian (LK) of Argentina||Ekrixinatosaurus (name means
"explosion-born lizard," referring to being discovered during a
blasting operation) is based on a fair amount of a skeleton belonging to a
single individual, about 6 m long from its skeletal restoration.
Both maxillae and dentaries, part of the braincase, a couple of cervicals,
many dorsals, the sacrum, anterior-middle caudals, most of the pelvis
(except for the distal ischia), ribs, most of one hindlimb, and the knee
of the other hindlimb were preserved. It has standard
"carnotaur" caudal process wings and pelvic form.
It has a relatively bigger head than Carnotaurus (extrapolated skull-femur ratio 1.00 compared to 0.58), but is not particularly unique compared to other abelisaurids (some different proportions and holes and depressions on the verts, and so on).
|Majungasaurus crenatissimus Lavocat, 1955 (originally Megalosaurus crenatissimus Depéret, 1896; including Majungatholus atopus Sues and Taquet, 1979)||mid Maastrichtian (LK) of Madagascar||This theropod has been through a mess.
For a long time, there was Megalosaurus crenatissimus, or Dryptosaurus
crenatissimus, or Majungasaurus crenatissimus, a large
theropod. Then, there was Majungatholus, thought to be a large,
strange pachycephalosaurid. Then,
skull set the record straight partially by showing that Majungatholus
was really a theropod. Because the crenatissimus material
wasn't the greatest, it was left out of the party until there were enough
remains to show that indeed it was the same as Majungatholus and by
priority should be the name used.
In one of those things that happen, "Megalosaurus" crenatissimus and Majungasaurus actually are based on different material. Depéret based his species on a collection of teeth, verts, and a phalanx, with no actual holotype, whereas Lavocat designated a Carnotaurus-like dentary from an immature individual as the neotype for Majungasaurus, while explicitly recognizing "M." crenatissimus and Majungasaurus to be the same thing.
Among the many interesting skull features are the thickened nasals, a horn on the frontal, a parietal prominence, and pneumatic chambers. Remains from several individuals and size classes are known. Tooth markings on some remains suggest cannibalism.
|Rajasaurus narmadensis Wilson, Sereno, Srivastava, Bhatt, Khosla, and Sahni, 2003||Maastrichtian (LK) of India||Based on material including a skull with a low horn, hip material, caudals, and hindlimb material, this new large abelisaurid puts interesting questions to those who delight in taxonomy, given the tangled state of theropod taxonomy of the Lameta Formation of India. It may put to rest some of the controversy surrounding Lametasaurus, as its ilia are very similar to the ilia included in the material of the latter.|
|Aucasaurus garridoi Coria, Chiappe, and Dingus, 2002||Santonian (LK) of Argentina||This carnotaurine is based
on an almost complete skeleton back to the 13th caudal, including soft tissue impressions about
the hips. The animal is considered to be about 70% of Carnotaurus'
size, with a longer, lower skull with bumps instead of horns, but very
similar to the other animal. The
arms were also somewhat longer.
It had been buried in a shallow lake; damage to the skull suggests it had been involved in a fight shortly before death.
|Carnotaurus sastrei Bonaparte, 1985||Maastrichtian (LK) of Argentina||This theropod is known from some of the best material of any dinosaur. Its type is a virtually complete skeleton and skull with extensive skin impressions, showing this animal to have had widely-spaced rows of small scutes, in addition to the bony horns which give this theropod its name. Its hands and arms were so small as to be virtually useless; for example, the lower arm bones (ulna and radius) were functionally part of the hand. Once dated to the "middle" Cretaceous, it is now known to be much younger.|
|?Quilmesaurus curriei Coria, 2001||mid Campanian (LK) of Argentina||Based on a small to medium sized femur and tibia, Quilmesaurus initially defied classification, but it now appears as though this animal probably was a carnotaurine.|
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