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70-481: Megaraptora is a clade of carnivorous theropod dinosaurs with controversial relationships to other tetanuran theropods. Its derived members, the Megaraptoridae are noted for their large hand claws and powerfully-built forelimbs, which are usually reduced in size in other large theropods. Megaraptorans are incompletely known, and no complete megaraptoran skeleton has been found. However, they still possessed
140-525: A clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group , is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree . In the taxonomical literature, sometimes the Latin form cladus (plural cladi ) is used rather than the English form. Clades are
210-479: A "ladder", with supposedly more "advanced" organisms at the top. Taxonomists have increasingly worked to make the taxonomic system reflect evolution. When it comes to naming , this principle is not always compatible with the traditional rank-based nomenclature (in which only taxa associated with a rank can be named) because not enough ranks exist to name a long series of nested clades. For these and other reasons, phylogenetic nomenclature has been developed; it
280-632: A 2013 review of patagonian theropods, which removed Megaraptora from the Carcharodontosauria and instead placed the group within Coelurosauria. More specifically, megaraptorans were found to be deep within the Tyrannosauroidea , a radiation of basal coelurosaurs including the famed tyrannosaurids . As Novas et al. (2013) removed Megaraptora from Neovenatoridae, they named a new family, Megaraptoridae, which contained all Megaraptorans apart from
350-623: A clade can be described based on two different reference points, crown age and stem age. The crown age of a clade refers to the age of the most recent common ancestor of all of the species in the clade. The stem age of a clade refers to the time that the ancestral lineage of the clade diverged from its sister clade. A clade's stem age is either the same as or older than its crown age. Ages of clades cannot be directly observed. They are inferred, either from stratigraphy of fossils , or from molecular clock estimates. Viruses , and particularly RNA viruses form clades. These are useful in tracking
420-482: A much more slender humerus. The distal part of the humerus (near the elbow) has a well-developed system of condyles and grooves similar to that of coelurosaurs, particularly the dromaeosaurids. The ulna of megaraptorids is characteristic in several regards. The olecranon process is well-developed, though it is thin, blade-like, and extends as a crest longitudinally down the shaft of the ulna. In addition, megaraptorids have acquired another long, crest-like structure on
490-444: A number of unique features. Their forelimbs were large and strongly built, and the ulna bone had a unique shape in members of the family Megaraptoridae, a subset of megaraptorans which excludes Fukuiraptor and Phuwiangvenator . The first two fingers were elongated, with massive curved claws, while the third finger was small. Megaraptoran skull material is very incomplete, but a juvenile Megaraptor described in 2014 preserved
560-458: A pneumatic quadrate , as in a few allosauroids ( Sinraptor , Mapusaurus ) and tyrannosauroids. The dentary , which is only known in Australovenator , is long and graceful, with the first tooth smaller than the rest (as in tyrannosauroids). The mandible as a whole has only a single meckelian foramen, as in carcharodontosaurians, tyrannosaurids, and ornithomimids. However, the rear part of
630-625: A polytomy at the base of Tyrannosauroidea, based on the dataset of Apesteguia et al. (2016). A 2022 study by Naish and Cau , in contrast, classified Eotyrannus as an intermediate gracile tyrannosauroid outside of Megaraptora. Their research supported a tyrannosauroid position for megaraptorans, even though Eotyrannus itself was not a megaraptoran. They recovered Megaraptora as radiation of derived tyrannosauroids close to Tyrannosauridae, similar to that found by Porfiri et al. (2014). Juratyrant [REDACTED] Stokesosaurus [REDACTED] Clade In biological phylogenetics ,
700-643: A portion of the snout, which was long and slender. Leg bones referred to megaraptorans were also quite slender and similar to those of coelurosaurs adapted for running. Although megaraptorans were thick-bodied theropods, their bones were heavily pneumatized , or filled with air pockets. The vertebrae , ribs , and the ilium bone of the hip were pneumatized to an extent which was very rare among theropods, only seen elsewhere in taxa such as Neovenator . Other characteristic features include opisthocoelous neck vertebrae and compsognathid -like teeth. Megaraptorans were originally placed as basal tetanurans as part of
770-422: A revised taxonomy based on a concept strongly resembling clades, although the term clade itself would not be coined until 1957 by his grandson, Julian Huxley . German biologist Emil Hans Willi Hennig (1913–1976) is considered to be the founder of cladistics . He proposed a classification system that represented repeated branchings of the family tree, as opposed to the previous systems, which put organisms on
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#1732855910112840-562: A sharp ridge on their lower edge in megaraptorids (non- Fukuiraptor megaraptorans). The carpus (wrist) of megaraptorans incorporated a semilunate (crescent-shaped) carpal similar to that of maniraptorans . Examinations of the forelimbs of megaraptorans by Rolando, Novas, and Porfiri et al., that were published in January 2023 show that the megaraptorans' forelimb bones are remarkably well-developed; powered by strong pectoral and front limb muscle that were functionally significant and important to
910-429: A suffix added should be e.g. "dracohortian". A clade is by definition monophyletic , meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. The ancestor can be known or unknown; any and all members of a clade can be extant or extinct. The science that tries to reconstruct phylogenetic trees and thus discover clades is called phylogenetics or cladistics ,
980-569: A vestigial fourth metacarpal , the hand bone that would have connected to the fourth finger in early dinosaurs. This was a primitive feature lost by most other tetanurans. The first two fingers had absurdly large unguals (claws); in Megaraptor the first claw was larger than the entire ulna. Unlike the large unguals of many other theropods (megalosauroids, for example), megaraptoran claws were thin and oval-shaped in cross-section. These claws also had asymmetrically-positioned grooves on their flat faces and
1050-522: A widespread distribution. Phuwiangvenator and Fukuiraptor , the most basal and second most basal known members of the group, lived in Thailand and Japan , respectively. Megaraptoran material is also common in Australia, and the largest known predatory dinosaur from the continent, Australovenator , was a megaraptoran. Megaraptorans were medium to large-sized theropods, ranging from Fukuiraptor , which
1120-499: Is also used with a similar meaning in other fields besides biology, such as historical linguistics ; see Cladistics § In disciplines other than biology . The term "clade" was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis , the evolutionary splitting of a parent species into two distinct species, a concept Huxley borrowed from Bernhard Rensch . Many commonly named groups – rodents and insects , for example – are clades because, in each case,
1190-594: Is asymmetrical when seen from the front due to the lateral condyle projecting further distally than the medial condyle. The tibia was also similar to that of coelurosaurs. It was a long and thin bone. The front of the lateral condyle of the tibia hooks downwards, similar to the condition in Neovenator, Tanycolagreus , and some tyrannosauroids. The medial and lateral malleoli are expanded and project away from each other, as in advanced tyrannosauroids (both) and carcharodontosaurians (medial malleolus only). The front surface of
1260-471: Is in turn included in the mammal, vertebrate and animal clades. The idea of a clade did not exist in pre- Darwinian Linnaean taxonomy , which was based by necessity only on internal or external morphological similarities between organisms. Many of the better known animal groups in Linnaeus's original Systema Naturae (mostly vertebrate groups) do represent clades. The phenomenon of convergent evolution
1330-487: Is not unusual compared to other theropods. Megaraptorans also had very characteristic hands. The first two fingers were large and slender, but the third one was small. These relative differences in finger length are somewhat similar to the case in tyrannosauroids and various other basal coelurosaurs, but the megaraptoran trend of forearm and finger enlargement is opposite to the trend towards forearm diminishment which characterizes advanced tyrannosauroids. Megaraptor retained
1400-410: Is present in embryos, and in adult forms of some species; in most species including dinosaurs, centra are more ossified with the notochordal opening closed, improving resistance against compressional forces. Heterocoelous vertebrae allow flexibility while preventing rotation. Procoelous and opisthocoelous centra form concavo-convex ( ball and socket ) joints, where the convex end, the condyle , fits into
1470-515: Is responsible for many cases of misleading similarities in the morphology of groups that evolved from different lineages. With the increasing realization in the first half of the 19th century that species had changed and split through the ages, classification increasingly came to be seen as branches on the evolutionary tree of life . The publication of Darwin's theory of evolution in 1859 gave this view increasing weight. In 1876 Thomas Henry Huxley , an early advocate of evolutionary theory, proposed
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#17328559101121540-489: Is still controversial. As an example, see the full current classification of Anas platyrhynchos (the mallard duck) with 40 clades from Eukaryota down by following this Wikispecies link and clicking on "Expand". The name of a clade is conventionally a plural, where the singular refers to each member individually. A unique exception is the reptile clade Dracohors , which was made by haplology from Latin "draco" and "cohors", i.e. "the dragon cohort "; its form with
1610-408: The centra , and a pair of large lateral pits known as pleurocoels . In fact, one or more pleurocoels were present in most megaraptoran vertebrae, and they connected to a complex system of numerous small air pockets within the vertebrae. This web-like internal structure of megaraptoran vertebrae (and that of a few other theropods) has been described as " camellate ". The proximal caudals (vertebrae at
1680-401: The ilia and ribs), which likely housed sinuses connected to the lungs, similar to modern birds. The slender leg bones and long metatarsals of several species indicate that members of this group likely had cursorial habits. Most megaraptorans are part of the family Megaraptoridae, which was named by Fernando Novas and his colleagues in 2013. This family is united by several adaptations of
1750-453: The "lightning ridge megaraptoran" by Bell et al. supported the idea that megaraptorans were tyrannosauroids based on the fact that Porfiri et al. (2014) incorporated skull data from Megaraptor and a wider variety of coelurosaurians compared to Benson, Carrano, & Brusatte (2010). Motta et al . (2016) agreed, and proposed that a new fragmentary patagonian theropod, Aoniraptor , was a non-megaraptorid megaraptoran. Their study also noted
1820-459: The 1990s due to the large hand claws being misidentified as foot claws. However, these mistakes were rectified after closer inspection of the holotype (in the case of Fukuiraptor ) or the discovery of new specimens (in the case of Megaraptor ). By the mid-to-late 2000s, they were considered to be basal tetanurans, usually members of Allosauroidea. Smith et al. (2008) reported Megaraptor -like ulnae from Australia, and found evidence that Megaraptor
1890-505: The K-Pg extinction. The authors also noted that while their phylogenetic analysis didn't support it, Australian megaraptorids likely formed a paraphyletic grade leading to South American forms. The genera which make up Megaraptora had been placed in a number of different theropod groups before the formation of the clade in 2010. Megaraptor and Fukuiraptor were independently considered to be giant dromaeosaurids when they were first discovered in
1960-406: The added effect of making the portion of the femur near the hip socket rectangular, when seen from above. In non-coelurosaur theropods, the greater trochanter is small, making the femur teardrop-shaped when seen from above. The femoral head is slightly upturned as in carcharodontosaurians (particularly carcharodontosaurids) and some coelurosaurs. In megaraptorans, the portion of the femur near the knee
2030-468: The basal ("primitive") taxon Fukuiraptor . They found little evidence that Chilantaisaurus , Neovenator , or Siats were megaraptorans, but they did place the tyrannosauroid Eotyrannus within Megaraptora. Despite the hypothesized close relation between megaraptorans and tyrannosaurids, Novas et al. noted that the megaraptoran lineage had a functional morphology which diverged in a direction opposite to
2100-541: The base of the tail) had a longitudinal ridge running along their lower surface, similar to the case in Neovenator but unlike tyrannosauroids. They also had a pair of lateral ridges which stretched downwards from the transverse processes to the centra. These ridges, known as centrodiapophyseal laminae , defined a large depression (infradiapophyseal fossa) under the transverse processes. Although these ridges were also present in dorsal (back) vertebrae and have been found in other theropods, megaraptorans were practically unique in
2170-460: The concave end, the cotyle (also: cotyla ). This configuration allows for greater stability without restricting mobility. In long necks and tails, this stabilization works best when the convex part is pointing away from the body. In sauropods, vertebrae in front of the sacrum are therefore typically opisthocoelous, while those of the tail are procoelous. As a vertebral column can contain different types of central morphologies, transitional centra with
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2240-413: The distal tip of the tibia (near the ankle) had the form of a flattened facet for the reception of the astragalus bone of the ankle, similar to the case in coelurosaurs. The inner edge of this facet was defined by a ridge, a feature unique to megaraptorids. The upper edge of the facet lacked a well-defined supra-astragalar buttress, unlike allosauroids. The ascending process of the astragalus, which lays on
2310-428: The facet, is expanded into a large trapezoidal plate of bone, similar to coelurosaurs but unlike the small, triangular ascending process of allosauroids. Fukuiraptor , Australovenator , and Aerosteon have a distinct forward-pointing prong on the outer edge of the astragalus, and Fukuiraptor and Australovenator have an additional prong that projects backwards. The fibula is also long and strongly tapers away from
2380-472: The fact that their centrodiapophyseal laminae were well-developed at the base of the tail, sometimes even more so than the dorsal vertebrae. Only spinosaurids share this feature. The strong development of these ridges may indicate that the tail was deep and muscular. The dorsal ribs were thick and curved yet hollow and pierced by a hole near their connection to the vertebrae. The gastralia (belly ribs) were wide and strongly built paddle-shaped structures, with
2450-476: The fact that they were strongly opisthocoelous . This means that they were convex from the front and concave from behind. Opisthocelous vertebrae are also characteristic of Allosaurus and sauropods , and they may facilitate high flexibility without sacrificing defense against shear forces . Otherwise, the cervicals were similar to those of carcharodontosaurians, with short neural spines , transverse processes (projecting rib facets) located around mid-length on
2520-462: The family Neovenatoridae within the allosauroid clade Carcharodontosauria . By the early 2020s, many studies had come to find that megaraptorans instead represented members of Coelurosauria , with their exact position within this group being uncertain. However, some studies still support an allosauroid classification. Megaraptorans were most diverse in the early Late Cretaceous period of South America, particularly Patagonia . However, they had
2590-493: The family Neovenatoridae. The cladogram follows Coria & Currie (2016), who added Murusraptor to the study and utilized the family Megaraptoridae, which was originally named by Novas et al. (2013). Allosauridae [REDACTED] Fukuiraptor Megaraptor Aerosteon Orkoraptor [REDACTED] However, an alternative hypothesis was forming, first published as an Ameghiniana abstract by Fernando Novas et al. (2012). Novas and his colleagues argued that
2660-407: The features used to link Neovenator to Megaraptora were more widespread than the 2010 paper implied, and that the proposed coelurosaurian convergences may have signified a legitimate connection between Megaraptora and Coelurosauria. In addition, they noted that Benson, Carrano, & Brusatte only sampled three coelurosaurs in their analysis. Novas et al .'s arguments were formulated and published in
2730-451: The fundamental unit of cladistics , a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population , or a species ( extinct or extant ). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over
2800-546: The group consists of a common ancestor with all its descendant branches. Rodents, for example, are a branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant , each of which consists of even smaller clades. The clade "rodent"
2870-423: The highly derived hands, as well as enhanced humeral protraction; attributes that likely aided in prey capture. The femur (thigh bone) of megaraptorans is only known in Australovenator and Fukuiraptor , but it is similar to that of coelurosaurs in several respects. For example, the greater trochanter is well-developed and offset from the femoral shaft by a deep concavity. The size of the greater trochanter has
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2940-452: The hip) has a much more pronounced scythe-like expansion at its tip, which is over 60% as long as the main shaft of the bone. This adaptation, known as a pubic boot, is also known in carcharodontosaurians and tyrannosaurids. The pubis is also expanded near its contact with the ilium. The left and right pubic bones are not entirely fused to each other, they are separated along their midline by an oval-shaped hole. A palaeobiogeographic assessment
3010-521: The ilium has a large depression known as a brevis fossa, which is visible from the outer face of the ilium. However, coelurosaurs and megaraptorans have a much smaller brevis fossa which occupies only a portion of the rear edge of the ilium, and it is mostly hidden from outside observers. The ischium (rear lower plate of the hip) is only known in Murusraptor . It is slightly expanded, similar to that of carcharodontosaurids. The pubis (front lower plate of
3080-441: The knee, as in coelurosaurs. It connects to a small facet on the outer edge of the astragalus (as in coelurosaurs) rather than a large facet on the upper edge (as in allosauroids). Near the knee and facing the tibia, the fibula has a wide groove or depression known as a proximomedial fossa. Metatarsal III, the foot bone which connected to the middle toe, was very long and slender in all megaraptorans, as in coelurosaurs. The joint for
3150-590: The last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic . Some of the relationships between organisms that the molecular biology arm of cladistics has revealed include that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria , and multicellular organisms may have evolved from archaea. The term "clade"
3220-518: The latter term coined by Ernst Mayr (1965), derived from "clade". The results of phylogenetic/cladistic analyses are tree-shaped diagrams called cladograms ; they, and all their branches, are phylogenetic hypotheses. Three methods of defining clades are featured in phylogenetic nomenclature : node-, stem-, and apomorphy-based (see Phylogenetic nomenclature§Phylogenetic definitions of clade names for detailed definitions). The relationship between clades can be described in several ways: The age of
3290-429: The left and right sides fused at the midline of the chest. These features signified that megaraptorans were wide-bodied theropods, akin to the condition in tyrannosaurids. Megaraptorans have a sigmoid (S-shaped) humerus (upper arm bone), similar to that of both basal allosauroids and basal coelurosaurs. Most megaraptorans had large, robust humeri akin to those of Allosaurus , but the basal-most member Fukuiraptor has
3360-574: The mandible (as seen in Murusraptor ) was significantly more lightly built than that of tyrannosauroids. Preserved braincase material has similarities to both carcharodontosaurians and tyrannosauroids. The premaxillary teeth of Megaraptor were variably similar to those of tyrannosauroids, being small, incisiform (chisel-like) and D-shaped in cross section. However, Murusraptor 's premaxillary teeth were fang-like, as in non-tyrannosauroid theropods. Megaraptoran maxillary teeth show much variety between genera , although they were generally small compared to
3430-455: The megaraptorid radiation of Late Cretaceous Gondwana. The specimen also allowed for alternative phylogenetic testing as to the placement of megaraptorans as either tyrannosauroids or carcharodontosaurids. This was expanded upon by Lamanna et al. (2020) who hypothesized that the megaraptorid dispersal from Australia to South America (probably via Antarctica) came with an increase in body size, and that megaraptorids kept their large body size until
3500-455: The middle toe is tall and pulley-shaped, with a deep and crescent-shaped depression visible from below. The ilium (upper plate of the hip) was a heavily pneumatized bone, filled with air pockets and perforated by pits. The only other large theropod known to possess a pneumatic ilium is Neovenator . In some megaraptorans, the preacetabular blade has a notch along its front edge, as in tyrannosauroids but also in Neovenator . A stronger concavity
3570-524: The newly discovered theropod Siats in 2013, which they placed within Megaraptora. Fukuiraptor and Australovenator were consistently found to be close relatives of each other; this was also the case for Aerosteon and Megaraptor ; Orkoraptor was a "wildcard" taxon difficult to place with certainty. The cladogram below illustrates the most recent revision of the Benson, Carrano, & Brusatte (2010) hypothesis that megaraptorans were allosauroids within
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#17328559101123640-699: The other neovenatorids on the basis of several features spread out throughout the skeleton, particularly the large amount of pneumatization present. The pneumatic ilium of Aerosteon was particularly notable, as Neovenator was the only other taxon known to have that trait at the time. Neovenatorids were envisioned as the latest-surviving allosauroids, which were able to persist well into the Late Cretaceous due to their low profile and coelurosaur-like adaptations. Later studies supported this hypothesis, such as Carrano, Benson & Sampson large study of tetanuran relationships in 2012, and Zanno & Makovicky description of
3710-491: The paleobiology of this group of theropods. Their data also suggests these muscle attachments became increasingly pronounced through megaraptoran evolutionary history, being substantially better developed in derived taxa such as Australovenator and especially Megaraptor itself than in earlier genera such as Fukuiraptor . Their results further suggest that the highly specialized forelimbs were capable of highly complex movements, such as great extension and flexion, particularly in
3780-420: The question of their classification. They found that megaraptorans lacked most of the key features in the hands of derived coelurosaurs including Guanlong and Deinonychus . Instead, their hands retain a number of primitive characteristics seen in basal tetanurans such as Allosaurus . Nevertheless, there are still a number of traits that support megaraptorans as members of the Coelurosauria. A 2016 study of
3850-553: The similaritires between Aoniraptor , the enigmatic theropod Deltadromeus , and Bahariasaurus , a giant African theropod with remains destroyed by World War II bombings. Therefore, they suggested that Bahariasaurus and Deltadromeus were also basal megaraptorans, and that Aoniraptor , Bahariasaurus , and Deltadromeus could have formed a distinct family, the Bahariasauridae. A 2019 redescription of Murusraptor by Rolando, Novas, & Agnolín continued to find Megaraptora in
3920-579: The snout as well as parietal fragments. Teeth have been found in many genera. Collectively, megaraptorans can be reconstructed as having a long, lightly built skull with many relatively small teeth. Based on Megaraptor , the premaxillary bone at the tip of the snout is small, with a long and rod-like branch of bone which extends above the external nares (nostril holes). The nares themselves were very large and elongated, akin to some early tyrannosauroids ( Dilong , Proceratosaurus , etc.). The snout also had some similarities to carcharodontosaurids, namely
3990-570: The snout with minimal enamel ornamentation. Some megaraptorans, such as Orkoraptor, Australovenator, and Megaraptor , had teeth which were 8-shaped in cross section and completely unserrated from the front (similar to dromaeosaurids and compsognathids ), while Murusraptor had anterior serrations only at the tip of its teeth. Fukuiraptor had very laterally compressed and blade-like teeth (similar to carcharodontosaurs ) with both anterior and posterior serrations. The cervical (neck) vertebrae of megaraptorans were nearly unique among theropods in
4060-620: The spread of viral infections . HIV , for example, has clades called subtypes, which vary in geographical prevalence. HIV subtype (clade) B, for example is predominant in Europe, the Americas and Japan, whereas subtype A is more common in east Africa. Glossary of dinosaur anatomy#parietal This Glossary explains technical terms commonly employed in the description of dinosaur body fossils . Besides dinosaur -specific terms, it covers terms with wider usage, when these are of central importance in
4130-421: The straight upper edge of the maxilla and rectangular nasal bones. The parietal bones at the top of the skull, behind the eyes, had a strongly developed sagittal crest , as in tyrannosauroids. Otherwise, the rear part of the skull is rather simple, without any pronounced crests or bosses, although the lacrimal and postorbital bones did have rugose patches in some genera. Aerosteon and Murusraptor possessed
4200-402: The study of dinosaurs or when their discussion in the context of dinosaurs is beneficial. The glossary does not cover ichnological and bone histological terms, nor does it cover measurements. Amphicoely is the primitive condition tetrapods. In fishes, the ends of the centra are deeply excavated and connected via a small opening, the passage for the notochord . In reptiles, this type of centrum
4270-456: The tyrannosaurids. While tyrannosaurids had small arms and large, powerful heads, megaraptorans had large arms, giant claws, and relatively weak jaws. The skull of a newly discovered juvenile specimen of Megaraptor , published in 2014, supported this hypothesis due to its similarities to the skull of basal tyrannosauroids such as Dilong . Nevertheless, megaraptorans still retained many similarities to carcharodontosaurians such as Neovenator , so
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#17328559101124340-429: The ulna and claws which are not present in the basal megaraptoran Fukuiraptor . No megaraptoran fossil is known to preserve a complete skull, although skull material is known for several taxa. Aerosteon , Megaraptor , Orkoraptor , and Murusraptor preserve several bones of the rear part of the skull, lower jaws are known from Australovenator , and a juvenile specimen of Megaraptor described in 2014 preserved much of
4410-411: The ulna called the lateral tuberosity, which is perpendicular to the blade of the olecranon. As a result, the ulna of megaraptorids is T-shaped in cross section, with three prongs formed by the forward-projection anterior process, the outwards-projecting lateral tuberosity, and the backwards-projecting olecranon process. These adaptations are absent in the most basal megaraptoran, Fukuiraptor . The radius
4480-453: The uncertainty behind their classification was not fully resolved. The cladogram below illustrates the results of a study which supports the Novas et al. (2013) hypothesis that megaraptorans are derived tyrannosauroids. This study was Porfiri et al. (2014), which described the juvenile Megaraptor specimen. Gualicho , Murusraptor , and Tratayenia were not yet described when this study
4550-623: Was a spinosauroid . The same year, Orkoraptor was described as an unusual giant coelurosaurian with some similarities with the much smaller compsognathids. Aerosteon was considered a relative of Allosaurus in its description less than a year later, while Australovenator was considered to be the sister taxon to Carcharodontosauridae. This influx of new data in the late 2000s led to several major reanalyses of basal tetanuran phylogenetics, with interesting implications for these taxa. A study by Roger Benson, Matt Carrano & Steve Brusatte in 2010 found that Allosauroidea (or Carnosauria , as it
4620-472: Was about 4.2 meters (13.8 feet) in length, to the 9 meter (30 feet) long Aerosteon , the 9 to 10 meter (30 to 33 feet) long Maip and the 12.8 meter (42 foot) long Bahariasaurus , if it is a member. Most megaraptorans are known from very fragmentary remains, although certain characteristics can be identified in multiple members of the clade. At least some megaraptorans, such as Murusraptor and Aerosteon , had extensively pneumatic bones (most noticeably
4690-524: Was conducted by Phil Bell, Steve Salisbury et al., which accompanied the description of an unnamed megaraptorid (referred to by the public media as "Lightning Claw," and possibly synonymous with Rapator ) from opal fields southwest of Lightning Ridge, Australia. This supports an Asian origin of Megaraptora in the latest Jurassic (150–135 Ma), an Early Cretaceous (130–121 Ma) divergence of the Gondwanan lineage leading to Megaraptoridae, and an Australian root for
4760-422: Was present a bit lower, between the preacetabular blade and pubic peduncle. This concavity, known as the cuppedicus (or preacetabular) fossa, was rimmed by a prominent shelf on the inner face of the ilium. This trait is also known in various coelurosaurs, Chilantaisaurus , and probably Neovenator . The postacetabular blade, on the other hand, lacks a large concavity. In non-coelurosaurian tetanurans, this portion of
4830-495: Was sometimes called) included a major subdivision known as Carcharodontosauria, which was split into the Carcharodontosauridae and a newly named family: Neovenatoridae . Neovenatorids, as formulated by these authors, contained Neovenator , Chilantaisaurus , and a newly named clade: Megaraptora. Megaraptora contained Megaraptor , Fukuiraptor , Orkoraptor , Aerosteon , and Australovenator . These genera were allied with
4900-445: Was undertaken. Sinraptor Allosaurus [REDACTED] Compsognathidae [REDACTED] Maniraptoriformes [REDACTED] Dilong Santanaraptor Xiongguanlong Tyrannosauridae [REDACTED] Fukuiraptor Eotyrannus Orkoraptor [REDACTED] Aerosteon Megaraptor In 2016, Novas and his colleagues published a study of megaraptoran hand anatomy, in an attempt to help settle
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