Noasauridae

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Noasaurids
Temporal range:
Late Jurassic - Late Cretaceous,
164–66  Ma
Masiakasaurus.JPG
Reconstructed skeleton of Masiakasaurus knopfleri , Royal Ontario Museum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Abelisauria
Family: Noasauridae
Bonaparte & Powell, 1980
Subgroups
Synonyms
  • Velocisauridae Bonaparte, 1991

Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other theropods. Their heads, on the other hand, had unusual adaptations depending on the subfamily. 'Traditional' noasaurids, sometimes grouped in the subfamily Noasaurinae, had sharp teeth which splayed outwards from a downturned lower jaw.

Contents

The most complete and well-known example of these kinds of noasaurids was Masiakasaurus knopfleri from Madagascar. [4] Another group, Elaphrosaurinae, has also been placed within Noasauridae by some studies. [3] Elaphrosaurines developed toothless jaws and herbivorous diets, at least as adults. [5]

The most complete and well known elaphrosaurine was Limusaurus inextricabilis . At least some noasaurids had pneumatised cervical vertebrae. [6] Some are considered to have had cursorial habits. [7] Noasauridae is defined as all theropods closer to Noasaurus than to Abelisaurus. [8]

Description

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.

A skull diagram of Masiakasaurus, the most complete and well-known noasaurine Masiakasaurus knopfleri skull reconstruction.jpg
A skull diagram of Masiakasaurus , the most complete and well-known noasaurine

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 advanced 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 (metatarsal III). Noasaurids varied in size, from the small Velocisaurus which was 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. [3]

A collection of features which characterize noasaurids in particular has been compiled by Rauhut & Carrano (2016), who included controversial taxa such as Deltadromeus and the elaphrosaurines within Noasauridae. If these groups did not belong to Noasauridae as the study claims, then these similarities are examples of convergent evolution. Among the most prominent traits relate to the shoulder region. In this family, the long, upward-stretching scapula (shoulder blade) merges with the smaller and more compact coracoid (shoulder girdle), forming a fused shoulder bone known as a scapulocoracoid. While the presence of a scapulocoracoid is by no means unique to this family, noasaurids do have particularly large and wide scapulocoracoids, with a tall and semicircular coracoid region. The hooked rear edge of the coracoid region is also offset from the glenoid (shoulder socket) by a large U-shaped notch. The humerus (upper arm bone) was thin and straight, with a low and somewhat rounded humeral head (the portion which attached to the shoulder). In contrast, abelisaurids had a large and bulbous humeral head (although similarly rounded) while that of other theropods was flattened from front to back. [3]

A skeletal diagram of Limusaurus, the most complete and well-known elaphrosaurine Limusaurus inextricabilis skeleton.jpg
A skeletal diagram of Limusaurus , the most complete and well-known elaphrosaurine

The leg is also somewhat characteristic in members of this family. The tibia (large innermost bone of the lower leg) was flattened from the front near the foot, although it was rounded further up the leg. As in other theropods, the femur (thigh bone) of a noasaurid had a ridge along the inner rear surface, known as a fourth trochanter. However, in noasaurines and elaphrosaurines (but not necessarily other genera such as Deltadromeus), this fourth trochanter was much smaller and lower than the enlarged crest-like structure present in the majority of basal theropods; [3] only a few other groups of theropods (coelophysoids, coelurosaurs, and a few species of abelisaurids) also have reduced fourth trochanters. [8] In addition, the two subfamilies have a metatarsal II (the foot bone connected to the innermost major toe) which was flattened from the side. Further reductions to this metatarsal were present in noasaurines (particularly Velocisaurus). [7] In these genera as well as Deltadromeus, metatarsal IV (which connected to the outermost major toe) also became reduced in some respects. [8]

In all noasaurids, the mid caudals (vertebrae in the middle of the tail) had very low neural spines. The cervical (neck) vertebrae, on the other hand, were quite varied within this family. In noasaurines and a few other genera (such as Laevisuchus ), the neural spines of vertebrae at the front of the neck were positioned towards the front part of their respective vertebrae. This is quite unusual compared to other theropods, which have neural spines roughly midway down their vertebrae. These genera also have long and spine-like epipophyses on the cervicals of most of the neck, although they diminish near the neck. [6] Epipophyses are bony projections located above the postzygapophyses (joints on the rear edge of a vertebra connecting to the front edge of the following vertebra). Elaphrosaurines, on the other hand, have cervical epipophyses which are much more diminished or even absent in the case of Elaphrosaurus. [3] Many noasaurids are only known from vertebrae, including both valid (Laevisuchus, Spinostropheus ) and dubious ( Composuchus, Jubbulpuria, Ornithomimoides, Coeluroides ) genera. [8]

Noasaurinae

Velocisaurus, a small and swift noasaurine Velocisaurus.jpg
Velocisaurus, a small and swift noasaurine

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). In 2020 indeterminate remains were described from the Barremian-Aptian and Cenomanian of Australia. [9] Members of this subfamily are definitively part of Noasauridae, although this group may not necessarily be elevated to subfamily status whenever elaphrosaurines are found to be outside of Noasauridae. Many members of this subfamily are quite fragmentary, and as a result the appearance and biology of the average noasaurine must be inferred from the most complete member of the group, Masiakasaurus. Rauhut & Carrano (2016) define Noasaurinae as "all noasaurids more closely related to Noasaurus than to Elaphrosaurus, Abelisaurus , Ceratosaurus, or Allosaurus". [3]

Masiakasaurus (and presumably other noasaurines) had a downturned lower jaw with long teeth splaying forwards. These teeth were spoon-shaped with sharply pointed tips and serrations along their outer edge. The rest of the teeth in the mouth were similar to the teeth of more conventional theropods. The rest of the body was also more similar to that of conventional theropods, with a neck, arms, and legs of moderate length. At least one noasaurine, the eponymous Noasaurus, had a large and deeply curved "sickle-shaped" claw of the hand. The diet of noasaurines is difficult to determine, with hypotheses ranging from fish to insects or other small animals.

Rauhut & Carrano (2016) found only a single unambiguous trait used to diagnose noasaurines to the exception of other noasaurids. That trait is the fact that their metatarsal II has a diminished proximal (near) end. [3] One noasaurine, Velocisaurus, took this trait even further, with both its metatarsal II and IV reduced to very thin rod-like bones along their entire length. [7]

Elaphrosaurinae

Elaphrosaurus, an elaphrosaurine and also one of the largest putative noasaurids Elaphrosaurus (flipped).jpg
Elaphrosaurus , an elaphrosaurine and also one of the largest putative noasaurids

It is not entirely certain if elaphrosaurines are legitimate examples of noasaurids. Both Limusaurus and Elaphrosaurus have been considered basal ceratosaurians by many studies, with most of these studies considering them even more primitive than Ceratosaurus. [8] [10] The most well-known elaphrosaurines lived during the Jurassic period, much older than the Late Cretaceous period noasaurines. Nevertheless, the existence of Eoabelisaurus shows that even abelisaurids had evolved by the Middle Jurassic, and Cretaceous elaphrosaurines such as Huinculsaurus have been discovered. It would make sense for Noasauridae (the sister taxa to Abelisauridae) to have evolved during the Jurassic, meaning that the early appearance of elaphrosaurines would not preclude a within Noasauridae. In 2016, a redescription of Elaphrosaurus by Oliver Rauhut and Matthew Carrano argued against earlier hypotheses that elaphrosaurines were basal ceratosaurs, instead placing them alongside noasaurines within a monophyletic Noasauridae. This study formally defined Elaphrosaurinae as "all noasaurids more closely related to Elaphrosaurus than to Noasaurus, Abelisaurus, Ceratosaurus, or Allosaurus". [3]

Generally speaking, 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. However, juvenile Limusaurus specimens retained teeth and lacked these signs of herbivory, meaning that young elaphrosaurines may have been more capable of a carnivorous or omnivorous diet. [5] The largest known noasaurid, Elaphrosaurus, is the namesake of Elaphrosaurinae. Members of this genus could grow up to 20 feet (6.1 meters) long, although they were significantly lighter than similarly sized carnivorous contemporaries such as Ceratosaurus.

Rauhut & Carrano (2016) listed several features which could be used to diagnose Elaphrosaurinae. Elaphrosaurine cervical vertebrae are amphicoelous, meaning that both their front and rear faces are concave, particularly the front face which is quite strongly concave. While strongly concave front faces are common among many archosaurs, they are quite rare in all but the most basal theropods. Carnosaurs, megalosauroids, coelurosaurs, and most other ceratosaurians (including noasaurines) all have vertebrae which have front faces ranging from very weakly concave to flat (platycoelous) or convex (opisthocoelous). Another notable feature of elaphrosaurine cervical vertebrae is that their cervical ribs are completely fused to the centrum (main body) of their corresponding vertebrae. [3]

Elaphrosaurines also have several diagnostic hip features. The hip is quite small compared to their long legs. The femur (thigh bone) is more than 1.3 times the length of the ilium (upper plate-like bone of the hip) in members of this subfamily, while most other ceratosaurians have shorter legs and a femur approximately the same length of the ilium. The connection between the ilium and the pubis (forward-projecting rod-like lower bone of the hip) is also more simple than in other ceratosaurians. While other ceratosaurians have a peg-and-socket connection between the two bones, elaphrosaurines simply have a flat contact between the two. [3]

In 2020 a middle cervical vertebra from the lower Albian Eumeralla Formation of Cape Otway, Victoria, Australia was referred to Elaphrosaurinae. This is the first evidence of Elaphrosaurinae from Australia. [11] [12]

Classification

The following cladogram is based on the phylogenetic analysis conducted by Rauhut and Carrano in 2016, showing the relationships among the Noasauridae: [3]

Abelisauroidea

Even in recent studies, the composition of Noasauridae has been difficult to resolve. An analysis conducted by Tortosa et al. (2013) [10] recovered Dahalokely as a basal noasaurid. [10] However, another analysis later that year found it to be a basal carnotaurine instead. [3] Similarly, the genus Genusaurus has been found to be a noasaurid by some older studies, but other studies have classified it as an abelisaurid. [13] [3] Deltadromeus is a particularly controversial genus, as it shares many features with noasaurids but is also very similar to Gualicho , which has been classified as a close relative of the enigmatic (but generally considered non-ceratosaurian) megaraptorans. [14] A 2017 study describing ontogenetic changes in Limusaurus and the effect of juvenile taxa on phylogenetic analyses provided various phylogenetic trees which varied based on which Limusaurus specimens were used. The structure of Noasauridae changed greatly depending on the age of the Limusaurus specimens, although Genusaurus and Deltadromeus were resolved as noasaurids in each diagnosis. [5]

See also

Related Research Articles

<i>Ceratosaurus</i> Genus of theropod dinosaur from the Late Jurassic period

Ceratosaurus was a carnivorous theropod dinosaur that lived in the Late Jurassic period. The genus was first described in 1884 by American paleontologist Othniel Charles Marsh based on a nearly complete skeleton discovered in Garden Park, Colorado, in rocks belonging to the Morrison Formation. The type species is Ceratosaurus nasicornis.

<span class="mw-page-title-main">Ceratosauria</span> Extinct clade of dinosaurs

Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with Ceratosaurus than with birds. The oldest known ceratosaur, Saltriovenator, dates to the earliest part of the Jurassic, around 199 million years ago. Ceratosauria includes three major clades: Ceratosauridae, Noasauridae, and Abelisauridae, found primarily in the Southern Hemisphere. Originally, Ceratosauria included the above dinosaurs plus the Late Triassic to Early Jurassic Coelophysoidea and Dilophosauridae, implying a much earlier divergence of ceratosaurs from other theropods. However, most recent studies have shown that coelophysoids and dilophosaurids do not form a natural group with other ceratosaurs, and are excluded from this group.

<i>Masiakasaurus</i> Noasaurid theropod dinosaur genus from the Late Cretaceous period

Masiakasaurus is a genus of small predatory noasaurid theropod dinosaurs from the Late Cretaceous of Madagascar. In Malagasy, masiaka means "vicious"; thus, the genus name means "vicious lizard". The type species, Masiakasaurus knopfleri, was named after the musician Mark Knopfler, whose music inspired the expedition crew. It was named in 2001 by Scott D. Sampson, Matthew Carrano, and Catherine A. Forster. Unlike most theropods, the front teeth of M. knopfleri projected forward instead of straight down. This unique dentition suggests that they had a specialized diet, perhaps including fish and other small prey. Other bones of the skeleton indicate that Masiakasaurus were bipedal, with much shorter forelimbs than hindlimbs. M. knopfleri was a small theropod, reaching 1.8–2.1 m (5.9–6.9 ft) long and weighing 20 kg (44 lb).

<span class="mw-page-title-main">Abelisauridae</span> Extinct family of dinosaurs

Abelisauridae is a family of ceratosaurian theropod dinosaurs. Abelisaurids 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. Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera Tarascosaurus and Arcovenator have been described in France. Abelisaurids first appear in the fossil record of the early middle Jurassic period, and at least three genera survived until the end of the Mesozoic era 66 million years ago.

<i>Deltadromeus</i> Theropod dinosaur genus from mid-Cretaceous Period

Deltadromeus is a genus of theropod dinosaur from the Aoufous Formation of Morocco.

<span class="mw-page-title-main">Abelisauroidea</span> Extinct clade of dinosaurs

Abelisauroidea is a diverse superfamily of ceratosaurian dinosaurs, typically regarded as a Cretaceous group, though the earliest abelisaurid remains are known from the Middle Jurassic of Argentina and possibly Madagascar. Possible Abelisauridae remains were also discovered in Late Jurassic Tendaguru Beds in Tanzania.

<i>Elaphrosaurus</i> Ceratosaurian theropod dinosaur genus from the Late Jurassic Period

Elaphrosaurus is a genus of ceratosaurian theropod dinosaur that lived approximately 154 to 150 million years ago during the Late Jurassic Period in what is now Tanzania in Africa. Elaphrosaurus was a medium-sized but lightly built member of the group that could grow up to 6.2 m (20 ft) long. Morphologically, this dinosaur is significant in two ways. Firstly, it has a relatively long body but is very shallow-chested for a theropod of its size. Secondly, it has very short hindlimbs in comparison with its body. Phylogenetic analyses indicate that this genus is likely a ceratosaur. Earlier suggestions that it is a late surviving coelophysoid have been examined but generally dismissed. Elaphrosaurus is currently believed to be a very close relative of Limusaurus, an unusual beaked ceratosaurian which may have been either herbivorous or omnivorous.

<i>Compsosuchus</i> Extinct genus of dinosaurs

Compsosuchus is a dubious genus of abelisauroid dinosaur from the Late Cretaceous Lameta Formation of India.

<i>Majungasaurus</i> Abelisaurid theropod dinosaur from the Late Cretaceous period

Majungasaurus is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 66 million years ago, at the end of the Cretaceous Period, making it one of the last-known non-avian dinosaurs that went extinct during the Cretaceous–Paleogene extinction event. The genus contains a single species, Majungasaurus crenatissimus. This dinosaur is also called Majungatholus, a name which is considered a junior synonym of Majungasaurus.

Genusaurus is a genus of abelisauroid dinosaur from the Early Cretaceous. Its fossils were found in France. Genusaurus is believed to have lived during the Albian stage, around 112-100 million years ago.

<i>Noasaurus</i> Extinct genus of dinosaurs

Noasaurus is a genus of ceratosaurian theropod dinosaur genus from the late Campanian-Maastrichtian of Argentina. The type and only species is N. leali.

<i>Laevisuchus</i> Extinct genus of dinosaurs

Laevisuchus is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian "Carnosaur Bed" deposits in the Lameta Formation in Madhya Pradesh, central India, and were named and described by paleontologists Friedrich von Huene and Matley in 1933.

<i>Spinostropheus</i> Extinct genus of dinosaurs

Spinostropheus is a genus of carnivorous neotheropod theropod dinosaur that lived in the Middle Jurassic period and has been found in the Tiouraren Formation, Niger. The type and only species is S. gautieri.

<i>Berberosaurus</i> Extinct genus of dinosaurs

Berberosaurus is a genus of neotheropod dinosaur, possibly a ceratosaur, from the Toarcian-age "Toundoute Continental Series" found in the Central High Atlas of Toundoute, Ouarzazate, Morocco. The type species of the genus Berberosaurus is B. liassicus, in reference to the Lias epoch. Berberosaurus might be the oldest known ceratosaur, and is based on partial postcranial remains. This genus represents the oldest formally identified theropod from the North of Africa, as well one of the few from the region in the Early Jurassic.

<span class="mw-page-title-main">Bahariasauridae</span> Probable family of averostran theropods

Bahariasauridae is a potential family of averostran theropods that might include a handful of African and South American genera, such as Aoniraptor, Bahariasaurus, Deltadromeus, and Gualicho. The placement of these theropods is controversial, with some studies placing them as basal ceratosaurs possibly related to Noasauridae, others classifying them as megaraptorans, basal neovenatorids, or basal coelurosaurs. There is also a possibility the group might not be monophyletic, as a monograph on the vertebrate diversity in the Kem Kem Beds published in 2020 found Bahariasaurus to be nomen dubium. In the same paper Deltadromeus is classified as an noasaurid, a result also recovered by some previous studies. A 2024 analysis found Aoniraptor, Bahariasaurus, Deltadromeus, Elaphrosaurus and Gualicho to form a monophyletic clade at the base of Ceratosauria.

<i>Limusaurus</i> Genus of theropod dinosaur

Limusaurus is a genus of theropod dinosaur that lived in what is now China during the Late Jurassic, around 161 to 157 million years ago. The type and only species Limusaurus inextricabilis was described in 2009 from specimens found in the Upper Shishugou Formation in the Junggar Basin of China. The genus name consists of the Latin words for "mud" and "lizard", and the species name means "impossible to extricate", both referring to these specimens possibly dying after being mired. Limusaurus was a small, slender animal, about 1.7 m in length and 15 kg (33 lb) in weight, which had a long neck and legs but very small forelimbs. It underwent a drastic morphological transformation as it aged: while juveniles were toothed, these teeth were completely lost and replaced by a beak with age. Several of these features were convergently similar to the later ornithomimid theropods as well as the earlier non-dinosaurian shuvosaurids.

<i>Arcovenator</i> Extinct genus of dinosaurs

Arcovenator is an extinct genus of abelisaurid theropod dinosaurs hailing from the Late Cretaceous of France. The type and only described species is Arcovenator escotae.

<span class="mw-page-title-main">Timeline of ceratosaur research</span>

This timeline of ceratosaur research is a chronological listing of events in the history of paleontology focused on the ceratosaurs, a group of relatively primitive, often horned, predatory theropod dinosaurs that became the apex predators of the southern hemisphere during the Late Cretaceous. The nature and taxonomic composition of the Ceratosauria has been controversial since the group was first distinguished in the late 19th century. In 1884 Othniel Charles Marsh described the new genus and species Ceratosaurus nasicornis from the Late Jurassic Morrison Formation of the western United States. He felt that it belonged in a new family that he called the Ceratosauridae. He created the new taxon Ceratosauria to include both the Ceratosauridae and the ostrich-like ornithomimids. The idea of the Ceratosauria was soon contested, however. Later that same decade both Lydekker and Marsh's hated rival Edward Drinker Cope argued that the taxon was invalid.

<i>Afromimus</i> Extinct genus of dinosaurs

Afromimus is a genus of theropod dinosaur from the Early Cretaceous Elrhaz Formation of Niger. It contains a single species, A. tenerensis, named in 2017 by Paul Sereno from parts of the right leg, vertebrae, and ribs found in the Ténéré Desert. It was originally classified as an ornithomimosaurian, but subsequently it was argued to be an abelisauroid.

<i>Kiyacursor</i> Genus of theropod dinosaurs

Kiyacursor is an extinct genus of noasaurid theropod dinosaur from the Early Cretaceous Ilek Formation of Russia. The genus contains a single species, K. longipes, known from a partial skeleton. Kiyacursor represents the first Early Cretaceous ceratosaur discovered in Asia, as well as the second non-avian theropod named from Russia, after Kileskus in 2010.

References

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