Abelisauridae
Cretaceous carnivorous bipeds with short skulls and vestigial forelimbs.
Wikipedia / Wikimedia Commons
Abelisauridae, whose name translates to "Abel's lizards," is a group of ceratosaurian theropod dinosaurs. The suffix -idae denotes the family rank in zoological nomenclature. These carnivores were most common during the Cretaceous period, living primarily on the ancient southern landmass of Gondwana. Their fossils have since been uncovered across modern-day Africa, South America, western Europe, India, and Madagascar. The earliest possible member, *Eoabelisaurus* from Patagonia, suggests they may have first appeared in the Middle Jurassic (Toarcian to Bajocian, ~179–170 million years ago), and some species survived until the very end of the Mesozoic, roughly 66 million years ago.
Like most theropods, abelisaurids walked on two legs and ate meat. They had sturdy hind limbs and heavily ornamented skulls marked by grooves and pits. Many species, such as *Carnotaurus*, had very short, almost useless forelimbs, a shortened skull, and bony crests above the eyes. Most known abelisaurids measured between 5 and 9 meters (17 to 30 feet) from snout to tail tip, though an unnamed specimen from northwestern Turkana, Kenya, may have reached 11 to 12 meters (36 to 39 feet). Before they were well understood, fragmentary remains were sometimes mistaken for South American tyrannosaurids.
The hind limbs of abelisaurids were typical of ceratosaurs: the astragalus and calcaneum (upper ankle bones) were fused to each other and to the tibia, forming a tibiotarsus. The tibia was shorter than the femur, giving the leg a stocky build. The foot had three functional toes (the second, third, and fourth), while the first toe, or hallux, did not touch the ground.
Abelisaurid skulls varied in shape but were generally very tall and short in length. In *Carnotaurus*, the skull was nearly as tall as it was long. The premaxilla was very tall, making the front of the snout blunt rather than tapered. Two skull bones—the lacrimal and postorbital—projected into the eye socket from the front and back, nearly splitting it in two. The eye sat in the upper compartment, which in *Carnotaurus* tilted slightly outward, possibly allowing some binocular vision. These same bones met above the eye socket, forming a ridge or brow. Many skull bones had sculpturing in the form of grooves, pits, and protrusions. As in other ceratosaurs, the frontal bones of the skull roof were fused. Carnotaurines often had b
- time_period
- Cretaceous (possibly Middle Jurassic to end of Mesozoic, ~66 million years ago)
Lore & Background
Abelisaurids were characterized by stocky hind limbs and extensive ornamentation of the skull bones, with grooves and pits. In many abelisaurids, such as Carnotaurus, the forelimbs are vestigial, the skull is shorter, and bony crests grow above the eyes. Most known abelisaurids would have been between 5 and 9 m in length, with a new and as yet unnamed specimen from northwestern Turkana in Kenya, Africa reaching a possible length of 11–12 m. Before becoming well known, fragmentary abelisaurid remains were occasionally misidentified as possible South American tyrannosaurids.
Reader's Guide
Abelisauridae represents a significant group of theropod dinosaurs that dominated the southern continents during the Cretaceous. Their fossils have helped paleontologists understand the biogeography of Gondwana, as their distribution across South America, Africa, Madagascar, India, and even Europe shows they existed prior to the breakup of that supercontinent. The discovery of Rugops in northern Africa disproved the earlier hypothesis that abelisaurids evolved after Africa separated from Gondwana. Their distinctive skull ornamentation—horns, domes, and rugose brow ridges—suggests they used these features for species recognition or intimidation, similar to modern animals. The evolution of their extremely reduced forelimbs, with no wrist bones and only two tiny immobile fingers in advanced forms, has been linked by paleobiologist Alexander O. Vargas to a genetic defect involving loss of function in HOXA11 and HOXD11 genes. Abelisaurids also show an interesting replacement pattern, seemingly taking over from carcharodontosaurids in South America, though cladistic analysis has not found a direct relationship between the two groups.
Did You Know?
- The genus Abelisaurus was named in honor of Roberto Abel, the director of the museum where the fossil was housed, not its discoverer. The name was given by paleontologists Bonaparte and Novas.
- Abelisaurid forelimbs were so reduced that in Carnotaurus the forearm bones were only 25% the length of the upper arm, and the elbow joint was immobile.
- The skull of Carnotaurus was nearly as tall as it was long, and its eye sockets were nearly divided into two compartments.
More in Extinct Archosaurs 1-24
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record