Abelisauroidea
Abelisauroids | |
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Majungasaurus crenatissimus skeleton, Stony Brook University
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | †Ceratosauria |
Clade: | † Neoceratosauria
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Superfamily: | †Abelisauroidea Bonaparte & Novas , 1985
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Families | |
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Abelisauroidea is a diverse superfamily of
Abelisauroids flourished in the
Diversity
In an assessment of the phylogenetic position of Eoabelisaurus, the analysis found it as the most basal member of the Abelisauridae. Abelisaurid synapomorphies include the laterally covered lacrimal antorbital fossa, broad cervical prespinal fossae, anteroposteriorly short anterior caudal neural spines, absence of a ventral groove in the anterior caudals, presence of rudimentary centrodiapophyseal laminae in the anterior mid-caudals, reduced distal ginglymus in the manual phalanges, and the presence of a flexor depression in the pedal unguals. Alternative phylogenetic placements of Eoabelisaurus are significantly suboptimal, except for a slightly more basal position.[3] Noasaurids had longer arms than their relatives the abelisaurids, whose arms were tiny and diminished. Although by no means as large or specialized as the arms of advfanced bird-like theropods, noasaurid arms were nevertheless capable of movement and use, possibly even for hunting in large-clawed genera such as Noasaurus. Some genera such as Limusaurus did have somewhat reduced arms and hands, but far from the extent that abelisaurids acquired. Noasaurids were also nimble and lightly built, with feet showing adaptations for running such as a long central foot bone. Noasaurids varied in size, from the small Velocisaurus under 5 feet (1.5 meters) long, to much larger genera such as Elaphrosaurus and Deltadromeus, which were more than 20 feet (6.1 meters) in length.[4]
Classification
Abelisauroidea is a superfamily which contains the family Noasauridae and Abelisauridae. 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. It has had several definitions in phylogenetic taxonomy. It was originally defined as a node-based taxon including Abelisaurus, Carnotaurus, and all of its descendants. Later, it was redefined as a stem-based taxon, including all animals more closely related to Abelisaurus (or the more complete Carnotaurus) than to Noasaurus.
Abelisauroidea | |
Complete skeletons have been described only for the most advanced abelisaurids (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.[5] These shared features, along with the fact that Abelisauridae seem to have replaced Carcharodontosauridae in South America, has led to suggestions that the two groups were related. Noasaurids were considered to be distinctive abelisauroids with a peculiar "sickle claw" on the second toe of the foot, convergently developed with that of deinonychosaurians. Among noasaurids, the Argentinean genera Noasaurus (Later Cretaceous) and Ligabueino (Early Cretaceous) are known from incomplete specimens, including disarticulated non-ungual phalanges and in Noasaurus, a claw. A detailed overview of these elements indicates that the supposed raptorial claw of the second pedal digit actually belongs to the first or second finger of the manus, and the putative pedal non-ungual phalanges or both genera also pertain to the manus.[6]
Discovery
Most abelisauroids were found in
Paleobiology
Behavior
Using three methods, namely a cladistic analysis performed on a dentition-based data matrix, and discriminant and cluster analyses conducted on a large dataset of theropod teeth measurements, three dental morphotypes which are confidently referred to abelisaurid theropods are identifiable. 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.[9]
See also
References
- ISBN 978-0-520-24209-8.
- ^ Martín D. Ezcurra, M.D. and Agnolín, F.L. (2012). "An abelisauroid dinosaur from the Middle Jurassic of Laurasia and its implications on theropod palaeobiogeography and evolution." Proceedings of the Geologists' Association, (advance online publication).
- ^ T Carrano, Matthew. "The appendicular skeleton of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar". ResearchGate.
- PMID 22628475.
- ^ T Carrano, Matthew. "The appendicular skeleton of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar". June 2007.
- ^ Agnolin, Federico; Chiarelli, Pablo. "The position of the claws in Noasauridae (Dinosauria: Abelisauroidea) and its implications for abelisauroid manus evolution". ResearchGate.
- PMID 23637961.
- ^ Méndez, Ariel; E Novas, Fernando; Vidoi Iori, Fabiano. "New records of abelisauroid theropods from the Bauru Basin (Upper Cretaceous), Sao Paulo State, Brazil". ResearchGate.
- ^ G. Meso, Jorge; Hendrickx, Christophe; A. Baiano, Mattia; I. Canale, Juan; Salgado, Leonardo; Diaz Martinez, Ignacio. "Isolated theropod teeth associated with a sauropod skeleton from the Late Cretaceous Allen Formation of Río Negro, Patagonia, Argentina". Acta Paleontologica Polonica. Retrieved 2021-06-30.
This article incorporates text from this source, which is by Jorge G. Meso, Christophe Hendrickx, Mattia A. Baiano, Juan I. Canale, Leonardo Salgado, and Ignacio Diaz Martinez available under the CC BY 4.0 license.