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111-407: Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most theropod dinosaurs , including megalosauroids , allosauroids , and coelurosaurs (which includes tyrannosauroids , ornithomimosaurs , compsognathids and maniraptorans , the latter including living birds ). Tetanurans are defined as all theropods more closely related to modern birds than to Ceratosaurus and contain
222-695: A Compsognathus longipes fossil was found with a lizard in its stomach, and a Velociraptor mongoliensis specimen was found locked in combat with a Protoceratops andrewsi (a type of ornithischian dinosaur). The first confirmed non-carnivorous fossil theropods found were the therizinosaurs , originally known as "segnosaurs". First thought to be prosauropods , these enigmatic dinosaurs were later proven to be highly specialized, herbivorous theropods. Therizinosaurs possessed large abdomens for processing plant food, and small heads with beaks and leaf-shaped teeth. Further study of maniraptoran theropods and their relationships showed that therizinosaurs were not
333-461: A 1999 paper by Paul Sereno suggests that theropods are characterized by traits such as an ectopterygoid fossa (a depression around the ectopterygoid bone), an intramandibular joint located within the lower jaw, and extreme internal cavitation within the bones. However, since taxa like Herrerasaurus may not be theropods, these traits may have been more widely distributed among early saurischians rather than being unique to theropods. Instead, taxa with
444-810: A basal allosauroid displaying a mosaic of primitive and derived features seen within Tetanurae. Their phylogenetic analysis found traditional Megalosauroidea to represent a basal grade of carnosaurs, paraphyletic with respect to Allosauroidea. Chuandongocoelurus Coelurosauria [REDACTED] Monolophosaurus [REDACTED] Spinosauridae [REDACTED] Megalosauridae [REDACTED] Xuanhanosaurus Piatnitzkysauridae [REDACTED] Asfaltovenator Metriacanthosauridae [REDACTED] Allosaurus [REDACTED] Carcharodontosauria [REDACTED] The biogeographical history of non-avian Tetanurae spans over 110 million years and all continents. The presence of major lineages prior to
555-537: A computed tomography scan and 3D reconstruction software. These finds are of evolutionary significance because they help document the emergence of the neurology of modern birds from that of earlier reptiles. An increase in the proportion of the brain occupied by the cerebrum seems to have occurred with the advent of the Coelurosauria and "continued throughout the evolution of maniraptorans and early birds." Studies show that theropods had very sensitive snouts. It
666-557: A dinosaur. Both of these measures can only be calculated through fossilized bone and tissue , so regression analysis and extant animal growth rates as proxies are used to make predictions. Fossilized bones exhibit growth rings that appear as a result of growth or seasonal changes, which can be used to approximate age at the time of death. However, the amount of rings in a skeleton can vary from bone to bone, and old rings can also be lost at advanced age, so scientists need to properly control these two possibly confounding variables. Body mass
777-416: A group including the relatively derived theropod subgroups Ceratosauria and Tetanurae , and excluding coelophysoids . However, most later researchers have used it to denote a broader group. Neotheropoda was first defined as a clade by Paul Sereno in 1998 as Coelophysis plus modern birds , which includes almost all theropods except the most primitive species. Dilophosauridae was formerly considered
888-457: A higher probability of being within the Theropoda may share more specific traits, such as a prominent promaxillary fenestra, cervical vertebrae with pleurocoels in the anterior part of the centrum leading to a more pneumatic neck, five or more sacral vertebrae, enlargement of the carpal bone, and a distally concave portion of the tibia, among a few other traits found throughout the skeleton. Like
999-465: A pattern of size-cycles, with the extinction of incumbent giant forms allowing for replacement with a new, more bird-like theropod group that then also evolved giant body size. It is, however, possible that more than one giant tetanuran existed at a time in the same paleoenvironment, perhaps with feeding habit variations. Within most dinosaur clades, body size tended to increase over time along a lineage according to Cope's rule . Coelurosaurian theropods are
1110-476: A period of 50 million years, from an average of 163 kilograms (359 lb) down to 0.8 kilograms (1.8 lb), eventually evolving into over 11,000 species of modern birds . This was based on evidence that theropods were the only dinosaurs to get continuously smaller, and that their skeletons changed four times as fast as those of other dinosaur species. In order to estimate the growth rates of theropods, scientists need to calculate both age and body mass of
1221-466: A reconstituted Carnosauria. Debate persists about whether the allosaurids form a clade with spinosauroids/megalosauroids, and whether Allosauroidea belongs in Avetheropoda with Coelurosauria or forms a sister taxa to Megalosauroidea, and whether Megalosauroidea forms a valid clade. Although many phylogenetic analyses found basal tetanurans that were outside both Megalosauroidea and Avetheropoda,
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#17327933820561332-400: A reference to Saltrio with Latin , venator , "hunter", a common suffix in the names of theropods. The authors pointed out that a venator is also a type of Roman gladiator . The specific name honours Zanella. Because the article was published in an electronic publication , Life Science Identifiers were necessary to make the name valid. These are 8C9F3B56-F622-4C39-8E8B-C2E890811E74 for
1443-416: A relationships between tooth size and skull length and also a comparison of the degree of wear of the teeth of non-avian theropods and modern lepidosaurs , it is concluded that theropods had lips that protected their teeth from the outside. Visually, the snouts of such theropods as Daspletosaurus had more similarities with lizards than crocodilians, which lack lips. Tyrannosaurus was for many decades
1554-410: A shift in the use of the forearm, with greater flexibility at the shoulder allowing the arm to be raised towards the horizontal plane, and to even greater degrees in flying birds. However, in coelurosaurs, such as ornithomimosaurs and especially dromaeosaurids, the hand itself had lost most flexibility, with highly inflexible fingers. Dromaeosaurids and other maniraptorans also showed increased mobility at
1665-478: A side-branch of more advanced theropods, they may have been ancestral to all other theropods (which would make them a paraphyletic group). Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs , and is the only group of theropods that survived the Triassic–Jurassic extinction event . Neotheropoda was named by R.T. Bakker in 1986 as
1776-425: A single unit with little flexibility. In theropods and prosauropods, the only way for the palm to face the ground would have been by lateral splaying of the entire forelimb, as in a bird raising its wing. In carnosaurs like Acrocanthosaurus , the hand itself retained a relatively high degree of flexibility, with mobile fingers. This was also true of more basal theropods, such as herrerasaurs . Coelurosaurs showed
1887-518: A sister taxa that diverged during the late Triassic. After their initial appearance, Tetanurae radiated into two main clades, Spinosauroidea or Megalosauroidea and Avetheropoda or Neotetanurae. Spinosauroidea are believed to represent basal Tetanurans. At the Neotetanurae/Avetheropoda node, allosaurids split from the Coelurosauria. Tyrannosauridae has been placed within Coelurosauria. The allosaurids and their closest relatives form
1998-406: A slope between a shallow carbonate platform and a deeper basin. Various scratches, grooves, and striations indicate that the carcass was subject to scavenging by marine invertebrates. The specimen represents a subadult individual, nearing its maximum size, of which the age has been estimated at twenty-four years. Because of the fragmentary nature of the remains, it was impossible to directly measure
2109-538: A small clade within Neotheropoda, but was later considered to be paraphyletic . By the Early Jurassic , all non-averostran neotheropods had gone extinct. Averostra (or "bird snouts") is a clade within Neotheropoda that includes most theropod dinosaurs , namely Ceratosauria and Tetanurae . It represents the only group of post-Early Jurassic theropods. One important diagnostic feature of Averostra
2220-399: A sophisticated air-sac-ventilated lung system similar to birds, and an advanced circulatory system. In megalosaurids and allosaurids, the orientation of the femoral head is anteromedial such as in ceratosaurs, but in avetheropods this orientation is fully medial. Tetanuran locomotor morphology is relatively generalized, with few variations between taxa. The hands of tetanurans, unlike those of
2331-494: A taxon comprising birds and theropods closer to birds than to Carnosauria, and listed within Carnosauria several large-bodied theropod taxa but did not formally define the group. Many of these original carnosaurs have since been reclassified as coelurosaurs or primitive tetanurans, and Carnosauria has now been defined as Allosaurus and all Avetheropods closer to Allosaurus than to birds. Initial cladistics studies supported
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#17327933820562442-406: A wide variety of tasks (see below). In modern birds, the body is typically held in a somewhat upright position, with the upper leg (femur) held parallel to the spine and with the forward force of locomotion generated at the knee. Scientists are not certain how far back in the theropod family tree this type of posture and locomotion extends. Non-avian theropods were first recognized as bipedal during
2553-468: Is also believed to have also been different among different families. The spinosaurids could have used their powerful forelimbs to hold fish. Some small maniraptorans such as scansoriopterygids are believed to have used their forelimbs to climb in trees . The wings of modern birds are used primarily for flight, though they are adapted for other purposes in certain groups. For example, aquatic birds such as penguins use their wings as flippers. Contrary to
2664-487: Is an extant dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous , although a number of theropod groups evolved to become herbivores and omnivores . Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago ( Ma ) and included
2775-600: Is as shown: Ornithischia Sauropodomorpha Herrerasauridae Eodromaeus Buriolestes Dracoraptor Coelophysoidea (incl. Liliensternus and Zupaysaurus ) Sarcosaurus Cryolophosaurus Dilophosaurus Sinosaurus Berberosaurus Saltriovenator Genyodectes Ceratosaurus Eoabelisaurus Elaphrosaurus Austrocheirus MNN TIG6 Limusaurus Masiakasaurus Noasaurus Abelisauroidea Szechuanosaurus Xuanhanosaurus Megalosauroidea Allosauroidea Coelurosauria Saltriovenator
2886-525: Is harder to determine as bone mass only represents a small proportion of the total body mass of animals. One method is to measure the circumference of the femur, which in non-avian theropod dinosaurs has been shown to be a relatively proportional to quadrupedal mammals, and use this measurement as a function of body weight, as the proportions of long bones like the femur grow proportionately with body mass. The method of using extant animal bone proportion to body mass ratios to make predictions about extinct animals
2997-483: Is however agreed that Megalosauroids, Allosauroids and Coelurosaurians are all members of the Orionides, a subset within Tetanurae that contains dinosaurs more derived than animals such as Chuandongcoelurus and Kayentavenator. Tetanuran evolution was characterized by parallel diversification of multiple lineages, repeatedly attaining large body size and similar locomotor morphology. Cryolophosaurus has been claimed as
3108-470: Is known as the extant-scaling (ES) approach. A second method, known as the volumetric-density (VD) approach, uses full-scale models of skeletons to make inferences about potential mass. The ES approach is better for wide-range studies including many specimens and doesn't require as much of a complete skeleton as the VD approach, but the VD approach allows scientists to better answer more physiological questions about
3219-771: Is recovered in many papers; however, recent findings suggest a monophyletic Carnosauria model with allosauroids and megalosauroids as each other's closest relatives instead of Allosauroids and Coelurosaurs. The cladogram presented below follows a phylogenetic analysis published by Zanno and Makovicky in 2013. † Cryolophosaurus [REDACTED] † Sinosaurus [REDACTED] † Chuandongocoelurus † Monolophosaurus [REDACTED] † Piatnitzkysauridae † Spinosauridae [REDACTED] † Megalosauridae [REDACTED] Coelurosauria [REDACTED] † Metriacanthosauridae † Allosauridae [REDACTED] † Neovenatoridae † Carcharodontosauridae [REDACTED] In 2019, Rauhut and Pol described Asfaltovenator vialidadi ,
3330-512: Is suggested they might have been used for temperature detection, feeding behavior, and wave detection. Shortened forelimbs in relation to hind legs was a common trait among theropods, most notably in the abelisaurids (such as Carnotaurus ) and the tyrannosaurids (such as Tyrannosaurus ). This trait was, however, not universal: spinosaurids had well developed forelimbs, as did many coelurosaurs. The relatively robust forelimbs of one genus, Xuanhanosaurus , led D. Zhiming to suggest that
3441-507: Is the common ostrich , up to 2.74 m (9 ft) tall and weighing between 90 and 130 kg (200 - 290 lb). The smallest non-avialan theropod known from adult specimens is the troodontid Anchiornis huxleyi , at 110 grams in weight and 34 centimeters (1 ft) in length. When modern birds are included, the bee hummingbird ( Mellisuga helenae ) is smallest at 1.9 g and 5.5 cm (2.2 in) long. Recent theories propose that theropod body size shrank continuously over
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3552-584: Is the absence of the fifth metacarpal. Other saurischians retained this bone, albeit in a significantly reduced form. The somewhat more advanced ceratosaurs (including Ceratosaurus and Carnotaurus ) appeared during the Early Jurassic and continued through to the Late Jurassic in Laurasia . They competed alongside their more anatomically advanced tetanuran relatives and—in the form of
3663-434: Is used to signify groups with no living members. The following family tree illustrates a synthesis of the relationships of the major theropod groups based on various studies conducted in the 2010s. † Herrerasauridae [REDACTED] † Eoraptor † Eodromaeus † Daemonosaurus Saltriovenator Saltriovenator (meaning " Saltrio hunter") is a genus of ceratosaurian dinosaur that lived during
3774-481: The Aalenian stage, 25% longer than Ceratosaurus from the late Jurassic. Comparing with Ceratosaurus itself, resulted in a body length of 730 centimetres, a hip height of 220 centimetres and a skull length of eighty centimetres. The thighbone length would then have been about eighty to eighty-seven centimetres, which indicates a body weight of 1160 to 1524 kilogrammes. Another method consisted in extrapolating from
3885-605: The Allosauroidea (the diverse carcharodontosaurs ) and the Coelurosauria (a very large and diverse dinosaur group including the birds). Thus, during the late Jurassic, there were no fewer than four distinct lineages of theropods—ceratosaurs, megalosaurs, allosaurs, and coelurosaurs—preying on the abundance of small and large herbivorous dinosaurs. All four groups survived into the Cretaceous, and three of those—the ceratosaurs, coelurosaurs, and allosaurs—survived to end of
3996-671: The Coelophysoidea . The coelophysoids were a group of widely distributed, lightly built and potentially gregarious animals. They included small hunters like Coelophysis and Camposaurus . These successful animals continued from the Late Carnian (early Late Triassic) through to the Toarcian (late Early Jurassic ). Although in the early cladistic classifications they were included under the Ceratosauria and considered
4107-667: The Moltrasio Formation . The plants have been recovered between the locations of Cellina and Arolo (eastern side of Lake Maggiore), from rocks that have been found to be coeval in age to the Saltrio Formation . The Flora includes genera such as Bennettitales ( Ptilophyllum ), terrestrial Araucariaceae ( Pagiophyllum ), and Cheirolepidiaceae ( Brachyphyllum ), that developed on inland areas with dry-warm conditions. Saltriovenator probably come from this nearby landmass, as other emerged zones, such as
4218-748: The Salnova marble quarry in Saltrio , northern Italy. Zanella had already been working for the Museo Civico di Storia Naturale di Milano and this institution after being informed sent out a team to investigate the find. Cristiano Dal Sasso and the volunteers of the Paleontological Group of Besano, under the direction of Giorgio Teruzzi managed to salvage a number of chalk blocks visibly containing bones. The skeleton had shortly before its discovery been blown to pieces by explosives used in
4329-565: The Sinemurian stage of the Early Jurassic in what is now Italy . The type and only species is Saltriovenator zanellai ; in the past, the species had been known under the informal name "saltriosaur". Although a full skeleton has not yet been discovered, Saltriovenator is thought to have been a large, bipedal carnivore similar to Ceratosaurus . On 4 August 1996, the first remains of Saltriovenator were discovered by amateur paleontologist Angelo Zanella, searching for ammonites in
4440-589: The abelisaur lineage—lasted to the end of the Cretaceous in Gondwana . The Tetanurae are more specialised again than the ceratosaurs. They are subdivided into the basal Megalosauroidea (alternately Spinosauroidea ) and the more derived Avetheropoda . Megalosauridae were primarily Middle Jurassic to Early Cretaceous predators, and their spinosaurid relatives' remains are mostly from Early and Middle Cretaceous rocks. Avetheropoda, as their name indicates, were more closely related to birds and are again divided into
4551-481: The clade Tetanurae for one branch of a basic theropod split with another group, the Ceratosauria. As more information about the link between dinosaurs and birds came to light, the more bird-like theropods were grouped in the clade Maniraptora (also named by Gauthier in 1986 ). These new developments also came with a recognition among most scientists that birds arose directly from maniraptoran theropods and, on
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4662-742: The coelurosaurs , feathers may have been confined to the young, smaller species, or limited parts of the animal. Many larger theropods had skin covered in small, bumpy scales. In some species, these were interspersed with larger scales with bony cores, or osteoderms . This type of skin is best known in the ceratosaur Carnotaurus , which has been preserved with extensive skin impressions. The coelurosaur lineages most distant from birds had feathers that were relatively short and composed of simple, possibly branching filaments. Simple filaments are also seen in therizinosaurs, which also possessed large, stiffened "quill"-like feathers. More fully feathered theropods, such as dromaeosaurids , usually retain scales only on
4773-524: The cranium and forelimb, with injuries occurring in about equal frequency at each site. Most pathologies preserved in theropod fossils are the remains of injuries like fractures, pits, and punctures, often likely originating with bites. Some theropod paleopathologies seem to be evidence of infections , which tended to be confined only to small regions of the animal's body. Evidence for congenital malformities have also been found in theropod remains. Such discoveries can provide information useful for understanding
4884-630: The furcula (wishbone), pneumatized bones, brooding of the eggs , and (in coelurosaurs, at least) feathers . O. C. Marsh coined the name Theropoda (meaning "beast feet") in 1881. Marsh initially named Theropoda as a suborder to include the family Allosauridae , but later expanded its scope, re-ranking it as an order to include a wide array of "carnivorous" dinosaur families, including Megalosauridae , Compsognathidae , Ornithomimidae , Plateosauridae and Anchisauridae (now known to be herbivorous sauropodomorphs ) and Hallopodidae (subsequently revealed as relatives of crocodilians). Due to
4995-455: The spinosaurids ) appear to have specialized in catching fish. Diet is largely deduced by the tooth morphology , tooth marks on bones of the prey, and gut contents. Some theropods, such as Baryonyx , Lourinhanosaurus , ornithomimosaurs, and birds, are known to use gastroliths , or gizzard-stones. The majority of theropod teeth are blade-like, with serration on the edges, called ziphodont. Others are pachydont or folidont depending on
5106-480: The 19th century, before their relationship to birds was widely accepted. During this period, theropods such as carnosaurs and tyrannosaurids were thought to have walked with vertical femurs and spines in an upright, nearly erect posture, using their long, muscular tails as additional support in a kangaroo-like tripodal stance. Beginning in the 1970s, biomechanical studies of extinct giant theropods cast doubt on this interpretation. Studies of limb bone articulation and
5217-469: The Early Cretaceous. A few palaeontologists, such as Gregory S. Paul , have suggested that some or all of these advanced theropods were actually descended from flying dinosaurs or proto-birds like Archaeopteryx that lost the ability to fly and returned to a terrestrial habitat. The evolution of birds from other theropod dinosaurs has also been reported, with some of the linking features being
5328-569: The Late Jurassic and Early Cretaceous, large spinosaurids and allosaurids flourished, but the latter possibly died out before the end of the Cretaceous due to the Cenomanian-Turonian boundary event , while spinosaurids are known from the Santonian. Soon afterwards the niche of terrestrial apex predator was filled by ceratosaurs and tyrannosaurids, which dominated terminal Cretaceous terrestrial ecosystems. Coelurosaurs persisted through
5439-681: The Order Saurischia into two suborders, Theropoda and Sauropoda. This basic division has survived into modern palaeontology, with the exception of, again, the Prosauropoda, which Romer included as an infraorder of theropods. Romer also maintained a division between Coelurosauria and Carnosauria (which he also ranked as infraorders). This dichotomy was upset by the discovery of Deinonychus and Deinocheirus in 1969, neither of which could be classified easily as "carnosaurs" or "coelurosaurs". In light of these and other discoveries, by
5550-468: The Saltrio formation, on Switzerland ). This was an emerged structural high close to the Saltrio Formation , that caused a division between two near subsiding basins located at Mt. Nudo (East) and Mt. Generoso (West). It settled over a carbonate platform linked with other wider areas that appear along the west to the southeast, developing a large shallow water gulf to the north, where the strata deposited
5661-409: The Tetanurae and Ceratosauria. While some used to consider coelophysoids and ceratosaurs to be within the same group due to features such as a fused hip, later studies showed that it is more likely that these were features ancestral to neotheropods and were lost in basal tetanurans. Averostrans and their close relatives are united via the complete loss of any digit V remnants, fewer teeth in the maxilla,
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#17327933820565772-515: The abandonment of ranks in cladistic classification, with the re-evaluation of birds as a subset of theropod dinosaurs that survived the Mesozoic extinctions and lived into the present. The following is a simplified classification of theropod groups based on their evolutionary relationships, and organized based on the list of Mesozoic dinosaur species provided by Holtz. A more detailed version can be found at dinosaur classification . The dagger (†)
5883-551: The absence of the fourth digit of the hand, placement of the maxillary teeth anterior to the orbit, a strap-like scapula, maxillary fenestrae, and stiffened tails. During the Late Jurassic and Early Cretaceous, large spinosaurids and allosaurs flourished but possibly died out in the northern hemisphere before the end of the Cretaceous, and were replaced as apex predators by tyrannosauroid coelurosaurs. At least in South America, carcharodontosaurid allosaurs may have persisted until
5994-546: The animal might have been quadrupedal. However, this is no longer thought to be likely. The hands are also very different among the different groups. The most common form among non-avian theropods is an appendage consisting of three fingers; the digits I, II and III (or possibly II, III and IV ), with sharp claws. Some basal theropods, like most Ceratosaurians , had four digits, and also a reduced metacarpal V (e.g. Dilophosaurus ). The majority of tetanurans had three, but some had even fewer. The forelimbs' scope of use
6105-459: The animal, such as locomotion and center of gravity. The current consensus is that non-avian theropods didn't exhibit a group wide growth rate, but instead had varied rates depending on their size. However, all non-avian theropods had faster growth rates than extant reptiles, even when modern reptiles are scaled up to the large size of some non-avian theropods. As body mass increases, the relative growth rate also increases. This trend may be due to
6216-483: The arrangement of primitive megalosaurs as serial outgroups to a clade of allosaurids, followed by the Coelurosauria. Subsequent studies have discovered that many of these basal tetanurans formed a true clade, termed Megalosauroidea or alternatively Spinosauroidea. Current phylogeny agrees on a monophyletic Tetanurae that includes a series of generally large-bodied basal taxa outside a monophyletic Coelurosauria. Coelophysoids are basal to Tetanurae, with Ceratosauria forming
6327-484: The avian theropods (birds). However, discoveries in the late 20th and early 21st centuries showed that a variety of diets existed even in more basal lineages. All early finds of theropod fossils showed them to be primarily carnivorous . Fossilized specimens of early theropods known to scientists in the 19th and early 20th centuries all possessed sharp teeth with serrated edges for cutting flesh, and some specimens even showed direct evidence of predatory behavior. For example,
6438-521: The beginning of the Jurassic, from Hettangian to earliest Sinemurian on the western Lombardy Basin there was a notorious continental area that was found to be wider than previously thought, where a warm humid paleoclimate developed. The Dinosaur Fossils found on the Saltrio formation could have been translated from this area, or alternatively, the Arbostora swell (that was located at the north of
6549-406: The breakup of Pangaea implies wide dispersal of these clades, with later absences indicating regional extinctions or dispersal failure. The density of sampling is currently insufficient to provide a detailed analysis of biogeographical evolution for the Tetanurae. Tetanurae and Ceratosauria likely diverged during the late Triassic, more than 200 mya. By the Early Jurassic, Tetanurae fossils appear in
6660-432: The clades by roughly 20-30 million years. Benson considered it a member of Coelophysoidea in his review of Magnosaurus . The presence of a wishbone may support its placement as a tetanuran, although wishbones have been reported from coelophysoids. The 2018 description paper ran a large phylogenetic analysis, and found it to be a basal ceratosaur , the sister-taxon of Berberosaurus . The phylogenetic analysis
6771-556: The closely related ceratosaurs, lack a fourth finger. Early tetanurans still possessed metacarpal IV, but it was vestigial and not part of a finger anymore. The tridactyl manus was preserved in birds. Evidence from the basal ceratosaur Saltriovenator indicates the tetanuran digits are I, II and III instead of II, III and IV. Basal tetanurans were the first theropods to achieve truly giant body sizes, with both megalosauroid and allosauroid taxa weighing over 1 ton. Sequential temporal appearances of large body size in subsequent clades suggest
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#17327933820566882-472: The core dichotomy was named only in 2012. Carrano, Benson and Sampson (2012) named that clade Orionides , and defined it as the node comprising Megalosauroidea , Avetheropoda, their most recent common ancestor, and all its descendants. In 2015, Hendrickx, Hartman and Mateus clarified this definition, specifying it as the least inclusive clade including Allosaurus fragilis , Megalosaurus bucklandii , and Passer domesticus . The clade name "Orionides"
6993-499: The different parts of theropod anatomy. The most common sites of preserved injury and disease in theropod dinosaurs are the ribs and tail vertebrae . Despite being abundant in ribs and vertebrae, injuries seem to be "absent... or very rare" on the bodies' primary weight supporting bones like the sacrum , femur , and tibia . The lack of preserved injuries in these bones suggests that they were selected by evolution for resistance to breakage. The least common sites of preserved injury are
7104-492: The dinosaur, now thought to be a species new to science, the Italian name Saltriosauro . Although this has been occasionally Latinised to "Saltriosaurus", even in the scientific literature, in both the Italian and Latin form it remained an invalid nomen nudum . In December 2018, Dal Sasso, Simone Maganuco and Andrea Cau named and described the specimen as the type species Saltriovenator zanellai . The generic name combines
7215-421: The early sauropodomorphs, the second digit in a theropod's hand is enlarged. Theropods also have a very well developed ball and socket joint near their neck and head. Most theropods belong to the clade Neotheropoda, characterized by the reduction of several foot bones, thus leaving three toed footprints on the ground when they walk (tridactyl feet). Digit V was reduced to a remnant early in theropod evolution and
7326-475: The end of the Mesozoic Era, and died out at the same time as the non-avian coelurosaurs. Tetanurans have two basic skull morphologies. The first skull type, typical in large theropods such as Allosaurus , is common within ceratosaurs and may be primitive for tetanurans. In this type, the skull is about three times longer than tall, with a blunter snout and frequent elaborations such as horns or spikes along
7437-476: The end of the Mesozoic Era. Modern birds are the only living representatives of the Tetanurae. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Theropoda This is an accepted version of this page Theropoda ( / θ ɪəˈr ɒ p ə d ə / ; from ancient Greek θηρίο- ποδός [ θηρίον , ( therion ) "wild beast"; πούς , ποδός ( pous, podos ) "foot"]) whose members are known as theropods ,
7548-619: The evolutionary history of the processes of biological development. Unusual fusions in cranial elements or asymmetries in the same are probably evidence that one is examining the fossils of an extremely old individual rather than a diseased one. The trackway of a swimming theropod, the first in China of the ichnogenus named Characichnos , was discovered at the Feitianshan Formation in Sichuan. These new swim tracks support
7659-413: The feet. Some species may have mixed feathers elsewhere on the body as well. Scansoriopteryx preserved scales near the underside of the tail, and Juravenator may have been predominantly scaly with some simple filaments interspersed. On the other hand, some theropods were completely covered with feathers, such as the troodontid Anchiornis , which even had feathers on the feet and toes. Based on
7770-470: The first known dromaeosaurid ( Dromaeosaurus albertensis ) in 1922, W. D. Matthew and Barnum Brown became the first paleontologists to exclude prosauropods from the carnivorous dinosaurs, and attempted to revive the name "Goniopoda" for that group, but other scientists did not accept either of these suggestions. In 1956, "Theropoda" came back into use—as a taxon containing the carnivorous dinosaurs and their descendants—when Alfred Romer re-classified
7881-567: The first true member of the group, but subsequent studies have disagreed on whether it is a dilophosaurid or tetanuran. Arcucci and Coria (2003) classified Zupaysaurus as an early tetanuran, but it was later placed as a sister taxon to the clade containing dilophosaurids, ceratosaurs, and tetanurans. Shared tetanuran features include a ribcage indicating a sophisticated air-sac-ventilated lung system similar to that in modern birds. This character would have been accompanied by an advanced circulatory system. Other tetanuran characterizing features include
7992-620: The fossil record and reached global distribution by the Middle Jurassic. In the Late Jurassic, the fossil record demonstrates widespread presence of multiple clades within both megalosauroids and avetheropods. The Megalosauroidea contained high diversity with two Jurassic clades, Piatnitzkysauridae and Megalosauridae, as well as the Cretaceous Spinosauridae. Tetanuran evolution appears to exhibit waves of diversification, although this may be due to uneven sampling. During
8103-474: The genus and BDD366A7-6A9D-4A32-9841-F7273D8CA00B for the species. Saltriovenator is the third dinosaur named from Italy, the first from the Alps and the second theropod from Italy, after Scipionyx . The holotype , MSNM V3664 , was found in a layer of the Saltrio Formation dating from the earliest early Sinemurian , 199 million years old. It consists of a fragmentary skeleton with a lower jaw. About 10% of
8214-621: The hypothesis that theropods were adapted to swimming and capable of traversing moderately deep water. Dinosaur swim tracks are considered to be rare trace fossils, and are among a class of vertebrate swim tracks that also include those of pterosaurs and crocodylomorphs . The study described and analyzed four complete natural molds of theropod foot prints that are now stored at the Huaxia Dinosaur Tracks Research and Development Center (HDT). These dinosaur footprints were in fact claw marks, which suggest that this theropod
8325-432: The infraorder Coelurosauria and larger taxa into the infraorder Pachypodosauria. Later, he transferred large, carnivorous taxa to the new infraorder Carnosauria, which came to include all known large-bodied carnivores other than Ceratosaurus . The size-based arrangement persisted until Gauthier, who redefined Carnosauria and Coelurosauria based on new cladistic analyses but retained the terms. Gauthier defined Coelurosauria as
8436-422: The knee was normally strongly flexed in all theropods while walking, even giants like the tyrannosaurids. It is likely that a wide range of body postures, stances, and gaits existed in the many extinct theropod groups. Although rare, complete casts of theropod endocrania are known from fossils. Theropod endocrania can also be reconstructed from preserved brain cases without damaging valuable specimens by using
8547-584: The known length of the forelimb. Applying the usual limb ratio indicated a hindlimb length of 198 centimetres. The thighbone would then have been 822 to 887 millimetres long, indicating a weight of 1269 to 1622 kilogrammes. The precise systematic position of Saltriovenator has been traditionally uncertain, but it is known to be a theropod . Dal Sasso originally referred it to the Tetanurae He later considered that it may represent an allosauroid , although in either case it would predate other members of
8658-604: The lacrimals, nasals, and frontals. In the second skull type, the skull is lower and longer, with a less elaborated skull roof and a more elongated snout. Shared tetanuran features include the maxillary fenestra (an opening in the antorbital fossa), a pneumatic excavation in the jugal, and the position of the maxillary teeth anterior to the orbit. The posterior skull is little modified in tetanurans, except within Spinosauridae. The presence of an antorbital tooth row in tetanurans may be associated with macropredatory habits. In
8769-414: The largest known theropod and best known to the general public. Since its discovery, however, a number of other giant carnivorous dinosaurs have been described, including Spinosaurus , Carcharodontosaurus , and Giganotosaurus . The original Spinosaurus specimens (as well as newer fossils described in 2006) support the idea that Spinosaurus is longer than Tyrannosaurus , showing that Spinosaurus
8880-469: The largest living land animal today, the African elephant , which is characterized by a rapid period of growth until maturity, subsequently followed by slowing growth in adulthood. As a hugely diverse group of animals, the posture adopted by theropods likely varied considerably between various lineages through time. All known theropods are bipedal , with the forelimbs reduced in length and specialized for
8991-457: The late 1970s Rinchen Barsbold had created a new series of theropod infraorders: Coelurosauria, Deinonychosauria , Oviraptorosauria , Carnosauria, Ornithomimosauria, and Deinocheirosauria . With the advent of cladistics and phylogenetic nomenclature in the 1980s, and their development in the 1990s and 2000s, a clearer picture of theropod relationships began to emerge. Jacques Gauthier named several major theropod groups in 1986, including
9102-514: The majority of large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous , about 66 Ma. In the Jurassic , birds evolved from small specialized coelurosaurian theropods, and are today represented by about 11,000 living species. Various synapomorphies for Theropoda have been proposed based on which taxa are included in the group. For example,
9213-549: The majority of predatory dinosaur diversity. Tetanurae likely diverged from its sister group, Ceratosauria , during the late Triassic. Tetanurae first appeared in the fossil record by the Early Jurassic about 190 mya and by the Middle Jurassic had become globally distributed. The group was named by Jacques Gauthier in 1986 and originally had two main subgroups: Carnosauria and Coelurosauria, the clade containing birds and related dinosaurs such as compsognathids, tyrannosaurids, ornithomimosaurs, and maniraptorans. The original Carnosauria
9324-404: The movement of the tooth row further down the maxilla and a lacrimal fenestra. Averostrans also share features in their hips and teeth. Theropods exhibit a wide range of diets, from insectivores to herbivores and carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of diets was historically considered a characteristic exclusive to
9435-660: The need to reach the size required for reproductive maturity . For example, one of the smallest known theropods was Microraptor zhaoianus , which had a body mass of 200 grams, grew at a rate of approximately 0.33 grams per day. A comparable reptile of the same size grows at half of this rate. The growth rates of medium-sized non-avian theropods (100–1000 kg) approximated those of precocial birds, which are much slower than altricial birds. Large theropods (1500–3500 kg) grew even faster, similar to rates displayed by eutherian mammals. The largest non-avian theropods, like Tyrannosaurus rex had similar growth dynamics to
9546-421: The notable exception to the pattern of body size increases. Tetanurae was recognized and named by Gauthier in 1986. The earliest-discovered non-avian tetanuran is Megalosaurus . For a century after the description of Megalosaurus , most large carnivorous dinosaurs were serially arrayed into the family Megalosauridae within the order Theropoda. In 1914, Friedrich von Huene separated small, lightly built forms into
9657-495: The oldest known bird, Archaeopteryx ), the bird-like troodontids and oviraptorosaurs, the ornithomimosaurs (or "ostrich Dinosaurs"), the strange giant-clawed herbivorous therizinosaurs, and the avialans, which include modern birds and is the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event . While the roots of these various groups are found in the Middle Jurassic, they only became abundant during
9768-407: The only early members of this group to abandon carnivory. Several other lineages of early maniraptorans show adaptations for an omnivorous diet, including seed-eating (some troodontids ) and insect-eating (many avialans and alvarezsaurs ). Oviraptorosaurs , ornithomimosaurs and advanced troodontids were likely omnivorous as well, and some early theropods (such as Masiakasaurus knopfleri and
9879-418: The palms faced the ground or backwards towards the legs. In humans, pronation is achieved by motion of the radius relative to the ulna (the two bones of the forearm). In saurischian dinosaurs, however, the end of the radius near the elbow was actually locked into a groove of the ulna, preventing any movement. Movement at the wrist was also limited in many species, forcing the entire forearm and hand to move as
9990-400: The past considered the herrerasaurians to be members of Theropoda, while other theorized the group to be basal saurischians, and may even have evolved prior to the saurischian-ornithischian split. Cladistic analysis following the discovery of Tawa , another Triassic dinosaur, suggests the herrerasaurs likely were early theropods. The earliest and most primitive unambiguous theropods are
10101-541: The period, where they were geographically separate, the ceratosaurs and allosaurs in Gondwana, and the coelurosaurs in Laurasia. Of all the theropod groups, the coelurosaurs were by far the most diverse. Some coelurosaur groups that flourished during the Cretaceous were the tyrannosaurids (including Tyrannosaurus ), the dromaeosaurids (including Velociraptor and Deinonychus , which are remarkably similar in form to
10212-403: The postcranial skeleton, tetanurans transition between the most primitive theropod morphologies in basal tetanurans towards more derived, bird-like states in coelurosaurs. Most tetanurans possess specialized wrist bones, the absence or reduction of the fourth digit of the hand, a strap-like scapula, stiffened tails, and a laminar astragalar ascending process. Advanced tetanurans would have possessed
10323-414: The quarry to break the marble layers. Blocks that had been secured were inserted into a bath of formic acid for 1,800 hours to free the bones. Initially, 119 bone fragments were reported to have been collected in total; this was later increased to 132. However, most cannot be exactly identified. In 2000, the museum opened a special exhibition of the bones. On this occasion, Dal Sasso provisionally gave
10434-439: The relative absence of trackway evidence for tail dragging suggested that, when walking, the giant, long-tailed theropods would have adopted a more horizontal posture with the tail held parallel to the ground. However, the orientation of the legs in these species while walking remains controversial. Some studies support a traditional vertically oriented femur, at least in the largest long-tailed theropods, while others suggest that
10545-468: The scope of Marsh's Order Theropoda, it came to replace a previous taxonomic group that Marsh's rival E. D. Cope had created in 1866 for the carnivorous dinosaurs: Goniopoda ("angled feet"). By the early 20th century, some palaeontologists, such as Friedrich von Huene , no longer considered carnivorous dinosaurs to have formed a natural group. Huene abandoned the name "Theropoda", instead using Harry Seeley 's Order Saurischia , which Huene divided into
10656-787: The shape of the tooth or denticles . The morphology of the teeth is distinct enough to tell the major families apart, which indicate different diet strategies. An investigation in July 2015 discovered that what appeared to be "cracks" in their teeth were actually folds that helped to prevent tooth breakage by strengthening individual serrations as they attacked their prey. The folds helped the teeth stay in place longer, especially as theropods evolved into larger sizes and had more force in their bite. Mesozoic theropods were also very diverse in terms of skin texture and covering. Feathers or feather-like structures (filaments) are attested in most lineages of theropods (see feathered dinosaur ). However, outside
10767-487: The shores of an ancient beach before being washed out to sea. After death, the skeletal remains suffered from prolonged transport, during which many bones were lost and the remaining ones highly fragmented. Although Saltriovenator was not aquatic, the environment in which the carcass was deposited was likely pelagic , judging by the associated ammonites . The locality is also rich in crinoids , gastropods , bivalves , brachiopods and bryozoans . Deposition occurred on
10878-474: The size of the animal. The describing authors therefore compared the fossils with those of two theropods of a roughly similar volume. Comparing with the skeletal elements of MOR 693, an Allosaurus fragilis specimen, they conservatively concluded that the Saltriovenator holotype individual was at least seven to eight metres long. This would make Saltriovenator the largest known theropod living before
10989-415: The skeleton has been discovered, including a tooth, a right splenial, a right prearticular, a neck rib, fragments of the dorsal ribs and scapulae , a well preserved but incomplete furcula , humeri , metacarpal II, phalanx II-1, phalanx III-1, phalanx III-2, manual ungual III, a distal tarsal III, a distal tarsal IV and the proximal second to fifth metatarsals. The holotype individual likely died on
11100-496: The suborders Coelurosauria and Pachypodosauria . Huene placed most of the small theropod groups into Coelurosauria, and the large theropods and prosauropods into Pachypodosauria, which he considered ancestral to the Sauropoda (prosauropods were still thought of as carnivorous at that time, owing to the incorrect association of rauisuchian skulls and teeth with prosauropod bodies, in animals such as Teratosaurus ). Describing
11211-476: The theropod dinosaurs were the carnivorous Eodromaeus and, possibly, the herrerasaurids of Argentina . The herrerasaurs existed during the early late Triassic (Late Carnian to Early Norian ). They were found in North America and South America and possibly also India and Southern Africa. The herrerasaurs were characterised by a mosaic of primitive and advanced features. Some paleontologists have in
11322-408: The way theropods have often been reconstructed in art and the popular media, the range of motion of theropod forelimbs was severely limited, especially compared with the forelimb dexterity of humans and other primates . Most notably, theropods and other bipedal saurischian dinosaurs (including the bipedal prosauropods ) could not pronate their hands—that is, they could not rotate the forearm so that
11433-603: The wrist not seen in other theropods, thanks to the presence of a specialized half-moon shaped wrist bone (the semi-lunate carpal) that allowed the whole hand to fold backward towards the forearm in the manner of modern birds. In 2001, Ralph E. Molnar published a survey of pathologies in theropod dinosaur bone. He found pathological features in 21 genera from 10 families. Pathologies were found in theropods of all body size although they were less common in fossils of small theropods, although this may be an artifact of preservation. They are very widely represented throughout
11544-535: Was a polyphyletic group including any large carnivorous theropod. Many of Gauthier's carnosaurs, such as tyrannosaurids, have since been re-classified as coelurosaurs or primitive tetanurans. Carnosauria has been reclassified as a group containing allosaurids that split from the Coelurosauria at the Neotetanurae/Avetheropoda node. Members of Megalosauroidea are believed to represent basal tetanurans, but recent discoveries have shown that they might be members of Carnosauria expanding Carnosauria back to its original meaning. It
11655-492: Was controlled by a horst and tectonic gaben. Several outcrops of the so-called "terra rossa" paleosoils were also found, including at Castello Cabiaglio-Orino , a dozen of kilometers West of Saltrio. These outcrops show that the emerged areas that on the Hettangian-Sinemurian, the current location of the modern Maggiore Lake was covered with forests, what was proven by the presence of large plant fragments on
11766-421: Was first defined as a clade by Currie and Padian in 1997, to include Allosaurus , modern birds , and other animals descended from their most recent ancestor. In 1999, Paul Sereno named another group, Neotetanurae , for the clade containing Allosauroidea and Coelurosauria , and excluding other tetanurans such as megalosauroids , but this definition was published slightly later. A monophyletic Avetheropoda
11877-430: Was first established by Matthew T. Carrano, Roger B. J. Benson and Scott D. Sampson in 2012 . It is derived from Orion , the giant hunter of Greek mythology in references to the large size and carnivorism of basal orionidans. The name also refers to the alternative name for the constellation of Orion , Alektropodion, meaning "rooster foot". The smaller clade, Avetheropoda was named by Gregory S. Paul in 1988, and
11988-426: Was found on an open marine environment, where it was probably washed from the nearest mainland, being scavenged by invertebrates as proven by the presence of Sedilichnus sp. on the bones. This depositional environment, part of the Saltrio Formation is considered as part of a proximal slope or ramp that was probably an open subtidal zone reached by the effects of storm waves and with constant bottom currents. Since
12099-408: Was gone by the late Triassic. Digit I is reduced and generally do not touch the ground, and greatly reduced in some lineages. They also lack a digit V on their hands and have developed a furcula which is otherwise known as a wishbone. Early neotheropods like the coelophysoids have a noticeable kink in the upper jaw known as a subnarial gap. Averostrans are some of the most derived theropods and contain
12210-403: Was possibly 3 meters longer than Tyrannosaurus , though Tyrannosaurus could still be more massive than Spinosaurus . Specimens such as Sue and Scotty are both estimated to be the heaviest theropods known to science. There is still no clear explanation for why these animals grew so heavy and bulky compared to the land predators that came before and after them. The largest extant theropod
12321-423: Was swimming near the surface of a river and just the tips of its toes and claws could touch the bottom. The tracks indicate a coordinated, left-right, left-right progression, which supports the proposition that theropods were well-coordinated swimmers. During the late Triassic , a number of primitive proto-theropod and theropod dinosaurs existed and evolved alongside each other. The earliest and most primitive of
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