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Abelisauroidea
Temporal range: Middle Jurassic - Late Cretaceous, 179–66 Ma
Majungasaurus crenatissimus skeleton, Stony Brook University
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Ceratosauria
Clade: Neoceratosauria
Superfamily: Abelisauroidea
Bonaparte & Novas, 1985
Families

Abelisauroidea is typically regarded as a Cretaceous group, though the earliest abelisauridae remains are known from the Middle Jurassic of Argentina (classified as the species Eoabelisaurus mefi) and possibly Madagascar (fragmentary remains of an unnamed species) possible abelisauridae remains (an isolated left tibia, right femur, and right tibia) were also discovered in Late Jurassic Tendaguru Beds in Tanzania.

Shared characteristics

Complete skeletons have been described only for the most advanced abelisauridae (such as Carnotaurus and Aucasaurus), making the establishment of defining features of the skeleton for the family as a whole more difficult. However, most are known from at least some skull bones, so known shared features come mainly from the skull. Many abelisaurid skull features are shared with carcharodontosaurids. These shared features, along with the fact that abelisauridae seem to have replaced carcharodontosauridae in South America, have led to suggestions that the two groups were related.

Classification

Abelisauroid were separated into two types which are Noasauridae and abelisauridae. And Noasauridae can seperate Elaphrosaurinae and Noasaurinae. For abelisauridae were separate are Majungasaurinae and Brachyrostra. Noasauridae was a very diverse group, with the two most complete members, Masiakasaurus and Limusaurus, showing unusual features very different from each other. Masiakasaurus had an unusually downturned jaw, with long and sharply pointed spoon-shaped teeth. Some of these teeth were nearly horizontal in orientation. Limusaurus, on the other hand, was completely toothless as an adult and likely possessed a horny beak. This large disparity means that it is difficult to find any skull features shared by members of Noasauridae as a whole. Abelisauridae remains are mainly known in the southern continents, which once made up the supercontinent of Gondwana.

 Abelisauroidea 

Discovery

Most Abelisauroid were found in Madagascar, Asia, or sometimes in Africa. Abelisauridae thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar. In Madagascar, we are known as “Majungasaurus”, were discovered by Charles Depéret (French paleontologist). Majungasaurus was the most common abelisauroid which we know. Studies of the abelisauridae Majungasaurus indicate that it was a much slower-growing dinosaur than other theropods, taking nearly 20 years to reach adult size. Not only Majungasaurus was found in Madagascar but also Masiakasaurus which was the most complete fossil noasauridae found. Similar studies on other abelisaurid genera indicate that this slow maturation may have been a common trait to the whole of the Abelisauridae. Noasaurines are Late Cretaceous noasaurids known exclusively from southern continents and islands such as South America, Madagascar, and India which was an island near Madagascar during the Cretaceous. Elaphrosaurines were lightly built theropods, with small skulls and long necks and legs. If Limusaurus is any indication, adult elaphrosaurines were completely toothless, and their mouths were probably edged with a horny beak. It is likely that Limusaurus and other elaphrosaurines were primarily herbivorous as adults, due to mature Limusaurus specimens preserving gastroliths and chemical signatures resembling those of herbivorous dinosaurs. In South America, many of abelisauroids were discovered such as Skorpiovenator, Tarasscosaurus, Erikasaurus, Quilmesaurus, Aucasarus, Ilokelesia, Pycnonemosaurus etc. In Africa, we can find many abelisauroid which were Rugops, Kryptops, etc. Many abelisauroid can grow in South America, because they can evolve in a fruitful place. Kurupi itaata represents the first formally named vertebrate of the Marília Formation (Bauru Group, Bauru Basin) and one of the few theropod records for the Maastrichtian of the Bauru Basin. Its abelisauridae affinities are well-established based on the anatomy of the pelvis and anterior caudal vertebrae; however, closer relationships with other abelisauridae are still unclear.

Paleobiology

Using three methods, namely a cladistic analysis performed on a dentition-based data matrix, and a discriminant and cluster analyses conducted on a large dataset of theropod teeth measurements, we identify three dental morphotypes which are confidently referred to abelisaurid theropods. Whether the morphotypes represent different abelisaurid subclades or different positional entities within the jaw of the same abelisaurid species, is unknown. Such an identification, nevertheless, provides additional evidence of abelisaurids feeding on sauropod carcasses.

References