Noasauridae
Diverse theropod family with unusual skull adaptations.
Noasauridae is an extinct family of theropod dinosaurs within Ceratosauria, defined as all theropods more closely related to *Noasaurus* than to *Abelisaurus*. They were close relatives of the short-armed abelisaurids, but most noasaurids had more typical theropod body plans. Their skulls, however, showed unusual adaptations that varied by subfamily. The “traditional” noasaurids, sometimes grouped as Noasaurinae, had sharp teeth that splayed outward from a downturned lower jaw. The best-known example of this type is *Masiakasaurus knopfleri* from Madagascar. Another group, Elaphrosaurinae, has also been placed within Noasauridae in some studies; these dinosaurs developed toothless jaws and herbivorous diets, at least as adults, with *Limusaurus inextricabilis* being the most complete known member.
Noasauridae was highly diverse, and its two most complete members—*Masiakasaurus* and *Limusaurus*—display very different unusual features. *Masiakasaurus* had a downturned jaw with long, sharply pointed spoon-shaped teeth, some nearly horizontal. *Limusaurus* was completely toothless as an adult and likely had a horny beak. This disparity makes it difficult to find skull features shared across the whole family. Noasaurids had longer arms than their abelisaurid relatives, whose arms were tiny and diminished. While not as large or specialized as those of advanced bird-like theropods, noasaurid arms were functional and possibly used for hunting in large-clawed genera like *Noasaurus*. Some genera, such as *Limusaurus*, had somewhat reduced arms and hands, but not to the extent seen in abelisaurids. Noasaurids were nimble and lightly built, with feet adapted for running, including a long central foot bone (metatarsal III). Their size ranged from the small *Velocisaurus* (under 1.5 meters long) to much larger genera like *Elaphrosaurus* and *Deltadromeus* (over 6.1 meters long).
A set of characteristic features for noasaurids was compiled by Rauhut & Carrano (2016), who included controversial taxa like *Deltadromeus* and elaphrosaurines within the family. If these groups do not belong, the similarities would be convergent. Prominent traits involve the shoulder region: the long, upward-stretching scapula merges with the smaller coracoid to form a fused scapulocoracoid.
Quick Facts
- Taxon
- Noasauridae
Facts from the source article.
Lore & Background
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 nearly horizontal. 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.
Noasaurids had longer arms than their relatives the abelisaurids, whose arms were tiny and diminished. Some genera such as Noasaurus had large claws possibly used for hunting. Noasaurids were nimble and lightly built, with feet showing adaptations for running such as a long central foot bone. A collection of features characterizing noasaurids was compiled by Rauhut & Carrano (2016), including a fused scapulocoracoid with a tall semicircular coracoid region and a U-shaped notch offset from the glenoid. The humerus was thin and straight with a low rounded head.
The leg also had characteristic traits: the tibia was flattened near the foot, and the fourth trochanter of the femur was much smaller and lower than in most basal theropods. In noasaurines and elaphrosaurines, metatarsal II was flattened from the side. The mid-caudal vertebrae had very low neural spines, while cervical vertebrae varied between subfamilies.
Reader's Guide
Noasauridae represents a significant but often fragmentary branch of ceratosaurian theropods, illustrating the morphological diversity within the group. Their most notable feature is the contrast between the two well-known members: Masiakasaurus with its bizarre forward-splaying teeth and downturned jaw, and Limusaurus with its toothless beak and herbivorous diet. This disparity makes it challenging to define the family based on skull traits, but postcranial features—especially the fused scapulocoracoid with a large U-shaped notch and reduced fourth trochanter—help unite them. The family's placement within Ceratosauria as the sister group to Abelisauridae is widely accepted, though the inclusion of elaphrosaurines remains debated. Noasaurids also show adaptations for cursorial habits and varied body sizes, from small forms like Velocisaurus to larger ones like Elaphrosaurus. Their fossils, mostly from southern continents and India, provide insight into theropod evolution during the Jurassic and Cretaceous, though many taxa are known only from vertebrae, leaving much of their biology inferred from the most complete specimens.
Did You Know?
- Masiakasaurus knopfleri had spoon-shaped teeth that splayed outward from a downturned lower jaw, with some teeth nearly horizontal.
- Noasaurids had a fused shoulder bone called a scapulocoracoid with a large U-shaped notch.
- Some noasaurids, like Velocisaurus, were under 5 feet long, while others like Elaphrosaurus exceeded 20 feet.
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