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101-521: Carnotaurus ( / ˌ k ɑːr n oʊ ˈ t ɔːr ə s / ; lit.   ' meat bull ' ) is a genus of theropod dinosaur that lived in South America during the Late Cretaceous period, probably sometime between 72 and 69 million years ago. The only species is Carnotaurus sastrei . Known from a single well-preserved skeleton, it is one of the best-understood theropods from

202-553: A cornified pad (horny covering). Such a pad also occurred in Majungasaurus but was absent in Abelisaurus and Rugops . A row of large scales did probably surround the eye, as indicated by a hummocky surface with longitudinal grooves on the lacrimal and postorbital bones. The skin was built up of a mosaic of polygonal, non-overlapping scales measuring approximately 5–12 mm (0.20–0.47 in) in diameter. This mosaic

303-407: A genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of

404-425: A high degree of flexibility ( kinesis ) within the skull and especially the lower jaw, somewhat similar to modern snakes . Elasticity of the jaw would have allowed Carnotaurus to swallow small prey items whole. In addition, the front part of the lower jaw was hinged, and thus able to move up and down. When pressed downwards, the teeth would have projected forward, allowing Carnotaurus to spike small prey items; when

505-464: A human, although not nearly as good as those of an ostrich . Scientists calculate that Carnotaurus had a top speed of up to 48–56 km (30–35 mi) per hour. In dinosaurs, the most important locomotor muscle was located in the tail. This muscle, called the caudofemoralis , attaches to the fourth trochanter , a prominent ridge on the thigh bone, and pulls the thigh bone backwards when contracted. Scott Persons and Phil Currie (2011) argued that in

606-651: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as

707-628: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,

808-428: A low dural expansion – a space on top of the forebrain in which the pineal gland is thought to have been located. The olfactory bulbs , which housed the sense of smell, were large, while the optic lobes , which were responsible for sight, were relatively small. This indicates that the sense of smell might have been better developed than the sense of sight, while the opposite is the case in modern birds. The front end of

909-444: A low midline ridge. They were set 8 to 10 cm (3.1 to 3.9 in) apart from each other and became larger towards the animal's top. The bumps probably represent feature scales – clusters of condensed scutes – similar to those seen on the soft frill running along the body midline in hadrosaurid ("duck-billed") dinosaurs. These structures did not contain bone. Stephen Czerkas (1997) suggested that these structures may have protected

1010-542: A markedly strong neck musculature. A similar double row was also present in the tail, formed there by highly modified caudal ribs , in front view protruding upwards in a V-shape, their inner sides creating a smooth, flat, top surface of the front tail vertebrae. The end of each caudal rib was furnished with a forward projecting hook-shaped expansion that connected to the caudal rib of the preceding vertebra. The forelimbs were proportionally shorter than in any other large carnivorous dinosaurs, including tyrannosaurids. The forearm

1111-505: A member of the Brachyrostra, a clade of short-snouted forms restricted to South America. Carnotaurus was a lightly built, bipedal predator, measuring 7.5 to 8 m (24.6 to 26.2 ft) in length and weighing 1.3–2.1 metric tons (1.4–2.3 short tons; 1.3–2.1 long tons). As a theropod, Carnotaurus was highly specialized and distinctive. It had thick horns above the eyes, a feature unseen in all other carnivorous dinosaurs, and

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1212-472: A pair of curved, rod-like ceratobranchials that articulate with a single, trapezoidal element, the basihyal. Carnotaurus is the only known non-avian theropod from which a basihyal is known. The back of the skull had well-developed, air-filled chambers surrounding the braincase, as in other abelisaurids. Two separate chamber systems were present, the paratympanic system, which was connected to the middle ear cavity, as well as chambers resulting from outgrowths of

1313-419: A pair of horns on the frontal bone. The use of these horns is not entirely clear. Several interpretations have revolved around use in fighting conspecifics or in killing prey, though a use in display for courtship or recognition of members of the same species is possible as well. Greg Paul (1988) proposed that the horns were butting weapons and that the small orbita would have minimized the possibility of hurting

1414-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for

1515-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;

1616-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and

1717-425: A typical death pose with the neck bent back over the torso. Unusually, it is preserved with extensive skin impressions. In view of the significance of these impressions, a second expedition was started to reinvestigate the original excavation site, leading to the recovery of several additional skin patches. The skull was deformed during fossilization, with the snout bones of the left side displaced forwards relative to

1818-435: A valid clade consisting of Carnotaurus , Aucasaurus , Niebla and Koleken . Below is a cladogram published by Canale and colleagues in 2009. Majungasaurus [REDACTED] Aucasaurus [REDACTED] Carnotaurus [REDACTED] Ilokelesia [REDACTED] Skorpiovenator [REDACTED] Ekrixinatosaurus [REDACTED] Carnotaurus is the only known carnivorous bipedal animal with

1919-437: A very deep skull sitting on a muscular neck. Carnotaurus was further characterized by small, vestigial forelimbs and long, slender hind limbs. The skeleton is preserved with extensive skin impressions, showing a mosaic of small, non-overlapping scales approximately 5 mm in diameter. The mosaic was interrupted by large bumps that lined the sides of the animal, and there are no hints of feathers. The distinctive horns and

2020-612: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms

2121-569: Is one of the best-understood genera of the Abelisauridae , a family of large theropods restricted to the ancient southern supercontinent Gondwana . Abelisaurids were the dominant predators in the Late Cretaceous of Gondwana, replacing the carcharodontosaurids and occupying the ecological niche filled by the tyrannosaurids in the northern continents. Several notable traits that evolved within this family, including shortening of

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2222-410: 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

2323-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,

2424-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with

2525-482: Is the result of deformation acting from the sides, which affected the upper jaws but not the lower jaws, possibly due to the greater flexibility of the joints within the latter. The skeleton was collected on a farm named "Pocho Sastre" near Bajada Moreno in the Telsen Department of Chubut Province , Argentina. Because it was embedded in a large hematite concretion , a very hard kind of rock, preparation

2626-429: The promaxillary fenestra , which led into an air-filled cavity within the maxilla. The eye was situated in the upper part of the keyhole-shaped orbit. This upper part was proportionally small and subcircular, and separated from the lower part of the orbit by the forward-projecting postorbital bone . It was slightly rotated forward, probably permitting some degree of binocular vision . The keyhole-like shape of

2727-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to

2828-824: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;

2929-677: The Southern Hemisphere . The skeleton, found in 1984, was uncovered in the Chubut Province of Argentina from rocks of the La Colonia Formation . Carnotaurus is a derived member of the Abelisauridae , a group of large theropods that occupied the large predatorial niche in the southern landmasses of Gondwana during the late Cretaceous . Within the Abelisauridae, the genus is often considered

3030-416: The air sacs of the neck. A number of autapomorphies (distinguishing features) can be found in the skull, including the pair of horns and the very short and deep skull. The maxilla had excavations above the promaxillary fenestra, which would have been excavated by the antorbital air sinus (air passages in the snout). The nasolacrimal duct, which transported eye fluid, exited on the medial (inner) surface of

3131-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,

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3232-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,

3333-403: The surface texture of several skull bones allows for inferences on their probable covering. A hummocky surface with grooves, pits, and small openings is found on the sides and front of the snout and indicates a scaly covering, possibly with flat scales as in today's crocodilians. The top of the snout was sculptured with numerous small holes and spikes – this texture can probably be correlated with

3434-493: The S-curve seen in other theropods, and also unusually wide, especially towards its base. The top of the neck's spinal column featured a double row of enlarged, upwardly directed bony processes called epipophyses , creating a smooth trough on the top of the neck vertebrae. These processes were the highest points of the spine, towering above the unusually low spinous processes . The epipophyses probably provided attachment areas for

3535-543: The anatomy of Carnotaurus . The holotype skeleton is displayed in the Argentine Museum of Natural Sciences , Bernardino Rivadavia ; replicas can be seen in this and other museums around the world. Sculptors Stephen and Sylvia Czerkas manufactured a life-sized sculpture of Carnotaurus that was previously on display at the Natural History Museum of Los Angeles County . This sculpture, ordered by

3636-434: The animal's sides while fighting members of the same species ( conspecifics ) and other theropods, arguing that similar structures can be found on the neck of the modern iguana where they provide limited protection in combat. More recent studies of the skin of Carnotaurus published in 2021 suggest that previous depictions of the scales on the body are inaccurate, and the larger feature scales were randomly distributed along

3737-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of

3838-532: The bite force in Carnotaurus was around 3,392 newtons at the anterior portion of the jaws; slightly higher than the previous estimate. The posterior bite force at the back of the jaws meanwhile, was estimated at 7,172 newtons. This interpretation was questioned by François Therrien and colleagues (2005), who found that the biting force of Carnotaurus was twice that of the American alligator , which may have

3939-616: The body, not distributed in discrete rows like in older artistic depictions and illustrations. There is also no sign of progressive size variation in feature scales along different areas along the body. The basement scales of Carnotaurus were by comparison highly variable, ranging in size from small and elongated, to large and polygonal, and from circular-to-lenticular in the thoracic, scapular, and tail regions, respectively. This scale differentiation may have been related to regulating body heat and shedding excess heat via thermoregulation due to its large body size and active lifestyle. Carnotaurus

4040-400: The bony cores of much longer keratinous sheaths. Mauricio Cerroni and colleagues, in 2020, agreed that the horns supported keratinous sheaths, but argued that these sheaths would not have been greatly longer than the bony cores. As in other dinosaurs, the skull was perforated by six major skull openings on each side. The frontmost of these openings, the external naris (bony nostril),

4141-471: The brain would only have filled a fraction of this space. The authors used two different brain size estimates, assuming a brain size of 50% and 37% of the endocranial cavity, respectively. This results in a reptile encephalization quotient (a measure of intelligence) larger than that of the related Majungasaurus but smaller than in tyrannosaurids . The pineal gland , which produces hormones , might have been smaller than in other abelisaurids, as indicated by

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4242-460: 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

4343-581: The dentary and the hindmost jaw bones. This articulation, therefore, was very flexible but not necessarily weak. The bottom margin of the dentary was convex, while it was straight in Majungasaurus . The lower jaw was found with ossified hyoid bones , in the position they would be in if the animal was alive. These slender bones, supporting the tongue musculature and several other muscles, are rarely found in dinosaurs because they are often cartilaginous and not connected to other bones and therefore get lost easily. In Carnotaurus , three hyoid bones are preserved:

4444-527: The deposits of an environment of estuaries , tidal flats or coastal plains . The climate would have been seasonal with both dry and humid periods. The most common vertebrates collected include ceratodontid lungfish , turtles, plesiosaurs , crocodiles, dinosaurs, lizards, snakes and mammals. Other dinosaurs include Koleken inakayali , which is closely related to Carnotaurus ; the saltasauroid titanosaur Titanomachya gimenezi ; an unnamed ankylosaur ; and an unnamed hadrosauroid , among others. Some of

4545-405: The eyes while fighting. Gerardo Mazzetta and colleagues (1998) suggested that Carnotaurus used its horns in a way similar to rams. They calculated that the neck musculature was strong enough to absorb the force of two individuals colliding with their heads frontally at a speed of 5.7 m/s each. Fernando Novas (2009) interpreted several skeletal features as adaptations for delivering blows with

4646-410: The fastest large theropods. While the caudofemoralis muscle was enlarged, the epaxial muscles situated above the caudal ribs would have been proportionally smaller. These muscles, called the longissimus and spinalis muscle, were responsible for tail movement and stability. To maintain tail stability in spite of reduction of these muscles, the caudal ribs bear forward projecting processes interlocking

4747-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this

4848-430: The former of which was considered the first record of a South American docodont , and the possible gondwanatherians or multituberculates Argentodites coloniensis and Ferugliotherium windhauseni . Remains of an enantiornithine and, possibly, of a neornithine bird have been discovered. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Genus The composition of

4949-443: The fourth, splint-like metacarpal as the longest bone in the hand. A 2009 study suggests that the arms were vestigial in abelisaurids, because nerve fibers responsible for stimulus transmission were reduced to an extent seen in today's emus and kiwis , which also have vestigial forelimbs. Carnotaurus was the first theropod dinosaur discovered with a significant number of fossil skin impressions. These impressions, found beneath

5050-737: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,

5151-463: The head. He suggested that the shortness of the skull might have made head movements quicker by reducing the moment of inertia , while the muscular neck would have allowed strong head blows. He also noted an enhanced rigidity and strength of the spinal column that may have evolved to withstand shocks conducted by the head and neck. Other studies suggest that rivaling Carnotaurus did not deliver rapid head blows, but pushed slowly against each other with

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5252-490: The jaw, and can be studied using CT imaging. The replacement teeth had low, flattened crowns , were closely spaced, and inclined forwards at approximately 45°. In his 1990 description, Bonaparte noted that the lower jaw was shallow and weakly constructed, with the dentary (the foremost jaw bone) connected to the hindmost jaw bones by only two contact points; this contrasts to the robust-looking skull. Cerroni and colleagues instead found multiple but loose connections between

5353-424: The lacrimal through a canal of uncertain function. Other proposed autapomorphies include a deep and long, air-filled excavation in the quadrate and an elongated depression on the pterygoid of the palate . The vertebral column consisted of ten cervical (neck), twelve dorsal , six fused sacral and an unknown number of caudal (tail) vertebrae. The neck was nearly straight, rather than having

5454-633: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,

5555-435: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Glossary of dinosaur anatomy#premaxillae 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

5656-434: The modern marine iguana , or in blows to the opponent's neck and flanks, as seen in the modern giraffe . The latter possibility had been previously proposed for the related Majungasaurus in a 2011 conference paper. Gerardo Mazzetta and colleagues (1998) propose that the horns might also have been used to injure or kill small prey. Though horn cores are blunt, they may have had a similar form to modern bovid horns if there

5757-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus

5858-624: The muscular neck may have been used in fighting conspecifics . According to separate studies, rivaling individuals may have combated each other with quick head blows, by slow pushes with the upper sides of their skulls, or by ramming each other head-on, using their horns as shock absorbers. The feeding habits of Carnotaurus remain unclear: some studies suggested the animal was able to hunt down very large prey such as sauropods , while other studies found it preyed mainly on relatively small animals. Its brain cavity suggests an acute sense of smell, while hearing and sight were less well developed. Carnotaurus

5959-501: The museum during the mid-1980s, is probably the first life restoration of a theropod showing accurate skin. Carnotaurus was a large but lightly built predator. The only known individual was about 7.5–8 m (24.6–26.2 ft) in length, making Carnotaurus one of the largest abelisaurids. Ekrixinatosaurus and possibly Abelisaurus , which are highly incomplete, might have been similar or larger in size. A 2016 study found that only Pycnonemosaurus , at 8.9 m (29.2 ft),

6060-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this

6161-490: The olfactory tracts and bulbs were curved downwards, a feature only shared by Indosaurus ; in other abelisaurids, these structures were oriented horizontally. As hypothesized by Cerroni and Paulina-Carabajal, this downward-curvature, together with the large size of the bulbs, might indicate that Carnotaurus relied more on the sense of smell than other abelisaurids. The flocculus , a brain lobe thought to be correlated with gaze stabilization (coordination between eyes and body),

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6262-408: The orbit was possibly related to the marked skull shortening, and is also found in related short-snouted abelisaurids. As in all abelisaurids, the frontal bone (on the skull roof between the eyes) was excluded from the orbit. Behind the orbit were two openings, the infratemporal fenestra on the side and the supratemporal fenestra on the top of the skull. The infratemporal fenestra

6363-580: The owner of the ranch where the skeleton was found. A comprehensive description of the whole skeleton followed in 1990. After Abelisaurus , Carnotaurus was the second member of the family Abelisauridae that was discovered. For years, it was by far the best-understood member of its family, and also the best-understood theropod from the Southern Hemisphere . It was not until the 21st century that similar well-preserved abelisaurids were described, including Aucasaurus , Majungasaurus and Skorpiovenator , allowing scientists to re-evaluate certain aspects of

6464-541: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for

6565-453: The right side, the nasal bones pushed upwards, and the premaxillae pushed backwards onto the nasal bones . Deformation also exaggerated the upward curvature of the upper jaw. The snout was more strongly affected by deformation than the rear part of the skull, possibly due to the higher rigidity of the latter. In top or bottom view, the upper jaws were less U-shaped than the lower jaws, resulting in an apparent mismatch. This mismatch

6666-470: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or

6767-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in

6868-414: The skeleton's right side, come from different body parts, including the lower jaw, the front of the neck, the shoulder girdle , and the rib cage . The largest patch of skin corresponds to the anterior part of the tail. Originally, the right side of the skull also was covered with large patches of skin—this was not recognized when the skull was prepared, and these patches were accidentally destroyed. However,

6969-456: The skull and arms as well as peculiarities in the cervical and caudal vertebrae, were more pronounced in Carnotaurus than in any other abelisaurid. Though relationships within the Abelisauridae are debated, Carnotaurus is consistently shown to be one of the most derived members of the family by cladistical analyses. Its nearest relative might have been Aucasaurus or Majungasaurus . A 2008 review, in contrast, suggested that Carnotaurus

7070-449: The snakes that have been found belong to the families Boidae and Madtsoidae, such as Alamitophis argentinus . Turtles are represented by at least five taxa , four from Chelidae ( Pleurodira ) and one from Meiolaniidae ( Cryptodira ). Plesiosaurs include two elasmosaurs ( Kawanectes and Chubutinectes ) and a polycotylid ( Sulcusuchus ). Mammals are represented by Reigitherium bunodontum and Coloniatherium cilinskii ,

7171-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,

7272-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being

7373-506: The strongest bite of any living tetrapod . These researchers also noted analogies with modern Komodo dragons : the flexural strength of the lower jaw decreases towards the tip linearly, indicating that the jaws were not suited for high precision catching of small prey but for delivering slashing wounds to weaken big prey. As a consequence, according to this study, Carnotaurus must have mainly preyed upon large animals, possibly by ambush. Cerroni and colleagues, in 2020, argued that flexibility

7474-402: 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

7575-408: The tail vertebrae of Carnotaurus , the caudal ribs did not protrude horizontally ("T-shaped"), but were angled against the vertical axis of the vertebrae, forming a "V". This would have provided additional space for a caudofemoralis muscle larger than in any other theropod—the muscle mass was calculated at 111 to 137 kilograms (245 to 302 lb) per leg. Therefore, Carnotaurus could have been one of

7676-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for

7777-510: The teeth were curved upwards, the now backward projecting teeth would have hindered the caught prey from escaping. Mazzetta and colleagues also found that the skull was able to withstand forces that appear when tugging on large prey items. Carnotaurus may therefore have fed mainly on relatively small prey, but also was able to hunt large dinosaurs. In 2009, Mazzetta and colleagues estimated a bite force of around 3,341 newtons. A 2022 study estimating bite force for 33 different dinosaurs suggests that

7878-459: The upper jaw was used like a serrated club to inflict wounds; big sauropods would have been weakened by repeated attacks. Mazzetta and colleagues (1998, 1999) presumed that Carnotaurus was a swift runner, arguing that the thigh bone was adapted to withstand high bending moments while running; The ability of an animal's leg to withstand those forces limits its top speed. The running adaptations of Carnotaurus would have been better than those of

7979-577: The upper part of the Gorro Frigio Formation , which was considered to be approximately 100 million years old ( Albian or Cenomanian stage). Later, they were realized to pertain to the much younger La Colonia Formation , dating to the Campanian and Maastrichtian stages (83.6 to 66 million years ago). Novas, in a 2009 book, gave a narrower time span of 72 to 69.9 million years ago (lower Maastrichtian stage). Carnotaurus therefore

8080-477: The upper sides of their skulls. Mazzetta and colleagues, in 2009, argued that the horns may have been a device for the distribution of compression forces without damage to the brain. This is supported by the flattened upper sides of the horns, the strongly fused bones of the top of the skull, and the inability of the skull to survive rapid head blows. Rafael Delcourt, in 2018, suggested that the horns could have been used either in slow headbutting and shoving, as seen in

8181-576: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up

8282-414: The vertebrae with each other and with the pelvis, stiffening the tail. As a consequence, the ability to make tight turns would have been diminished, because the hip and tail had to be turned simultaneously, unlike in other theropods. Cerroni and Paulina-Carabajal, in 2019, used a CT scan to study the endocranial cavity that contained the brain. The volume of the endocranial cavity was 168.8 cm, although

8383-452: The very short teeth seen in other abelisaurids. However, Cerroni and colleagues, in their 2020 description of the skull, stated that all erupted teeth have been severely damaged during excavation and were later reconstructed with plaster (Bonaparte, in 1990, only noted that some lower jaw teeth had been fragmented). Reliable information on the shape of the teeth is therefore limited to replacement teeth and tooth roots that are still enclosed by

8484-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in

8585-458: Was a keratinous covering. However, this would be the only reported example of horns being used as hunting weapons in animals. Analyses of the jaw structure of Carnotaurus by Mazzetta and colleagues, in 1998, 2004, and 2009, suggest that the animal was capable of quick bites, but not strong ones. Quick bites are more important than strong bites when capturing small prey , as shown by studies of modern-day crocodiles . These researchers also noted

8686-513: Was a highly specialized theropod , as seen especially in characteristics of the skull , the vertebrae and the forelimbs. The pelvis and hind limbs, on the other hand, remained relatively conservative, resembling those of the more basal Ceratosaurus . Both the pelvis and hind limb were long and slender. The left femur (thigh bone) of the individual measures 103 cm in length, but shows an average diameter of only 11 cm. The skull, measuring 59.6 cm (23.5 in) in length,

8787-479: Was complicated and progressed slowly. In 1985, Bonaparte published a note presenting Carnotaurus sastrei as a new genus and species and briefly describing the skull and lower jaw. The generic name Carnotaurus is derived from the Latin carno [carnis] ("flesh") and taurus ("bull") and can be translated with "meat-eating bull", an allusion to the animal's bull-like horns. The specific name sastrei honors Angel Sastre,

8888-464: Was defined to include all derived abelisaurids with the exclusion of Abelisaurus , which is considered a basal member in most studies. However, a 2008 review suggested that Abelisaurus was a derived abelisaurid instead. Carnotaurini was proposed to name the clade formed by Carnotaurus and Aucasaurus ; only those paleontologists who consider Aucasaurus as the nearest relative of Carnotaurus use this group. A 2024 study recovered Carnotaurini as

8989-452: Was divided by thin, parallel grooves. Scalation was similar across different body parts with the exception of the head, which apparently showed a different, irregular pattern of scales. There is no evidence of feathers. Larger bump-like structures were distributed over the sides of the neck, back and tail in irregular rows. These bumps were 4 to 5 cm (1.6 to 2.0 in) in diameter and up to 5 cm (2.0 in) in height and often showed

9090-423: Was large in Carnotaurus and other South American abelisaurids. This could indicate that these forms frequently used quick movements of the head and body. Hearing might have been poorly developed in Carnotaurus and other abelisaurids, as indicated by the short lagena of the inner ear . The hearing range was estimated to be below 3 kHz. Originally, the rocks in which Carnotaurus was found were assigned to

9191-447: Was longer than Carnotaurus ; it was estimated at 7.8 m (25.6 ft). Its mass is estimated to have been 1,350 kg (1.33 long tons; 1.49 short tons), 1,500 kg (1.5 long tons; 1.7 short tons), 2,000 kg (2.0 long tons; 2.2 short tons), 2,100 kg (2.1 long tons; 2.3 short tons), and 1,306–1,743 kg (1.285–1.715 long tons; 1.440–1.921 short tons) in separate studies that used different estimation methods. Carnotaurus

9292-409: Was longer than high in related forms such as Skorpiovenator and Majungasaurus . The antorbital fenestra was bounded by a larger depression, the antorbital fossa , which was formed by recessed parts of the maxilla in front and the lacrimal behind. As in all abelisaurids, this depression was small in Carnotaurus . The lower front corner of the antorbital fossa contained a smaller opening,

9393-661: Was not closely related to either genus, and instead proposed Ilokelesia as its sister taxon . Juan Canale and colleagues, in 2009, erected the new clade Brachyrostra to include Carnotaurus but not Majungasaurus ; this classification has been followed by a number of studies since. Carnotaurus is eponymous for two subgroups of the Abelisauridae: the Carnotaurinae and the Carnotaurini . Paleontologists do not universally accept these groups. The Carnotaurinae

9494-561: Was only a quarter the size of the upper arm. There were no carpalia in the hand, so that the metacarpals articulated directly with the forearm. The hand showed four basic digits, though apparently only the middle two of these ended in finger bones, while the fourth consisted of a single splint-like metacarpal that may have represented an external 'spur'. The fingers themselves were fused and immobile, and may have lacked claws. Carnotaurus differed from all other abelisaurids in having proportionally shorter and more robust forelimbs, and in having

9595-455: Was probably well adapted for running and was possibly one of the fastest large theropods. The only skeleton ( holotype MACN -CH 894) was unearthed in 1984 by an expedition led by Argentinian paleontologist José Bonaparte . This expedition also recovered the peculiar spiny sauropod Amargasaurus . It was the eighth expedition within the project named "Jurassic and Cretaceous Terrestrial Vertebrates of South America", which started in 1976 and

9696-543: Was proportionally shorter and deeper than in any other large carnivorous dinosaur. The snout was moderately broad, not as tapering as seen in more basal theropods like Ceratosaurus , and the jaws were curved upwards. A prominent pair of horns protruded obliquely above the eyes. These horns, formed by the frontal bones, were thick and cone-shaped, internally solid, somewhat vertically flattened in cross-section, and measured 15 cm (5.9 in) in length. Bonaparte, in 1990, suggested that these horns would probably have formed

9797-536: Was restricted to the lower jaw, while the thickened skull roof and the ossification of several cranial joints suggest that the skull had no or only little kinesis. Robert Bakker (1998) found that Carnotaurus mainly fed upon very large prey, especially sauropods . As he noted, several adaptations of the skull—the short snout, the relatively small teeth and the strong back of the skull ( occiput )—had independently evolved in Allosaurus . These features suggest that

9898-490: Was sponsored by the National Geographic Society . The skeleton is well-preserved and articulated (still connected together), with only the posterior two thirds of the tail, much of the lower leg, and the hind feet being destroyed by weathering . The skeleton belonged to an adult individual, as indicated by the fused sutures in the braincase . It was found lying on its right side, showing

9999-427: Was subrectangular and directed sidewards and forwards, but was not sloping in side view as in some other ceratosaurs such as Ceratosaurus . This opening was formed by the nasal and premaxilla only, while in some related ceratosaurs the maxilla also contributed to this opening. Between the bony nostril and the orbit (eye opening) was the antorbital fenestra . In Carnotaurus , this opening was higher than long, while it

10100-474: Was tall, short, and kidney-shaped, while the supratemporal fenestra was short and square-shaped. Another opening, the mandibular fenestra , was located in the lower jaw – in Carnotaurus , this opening was comparatively large. On each side of the upper jaws there were four premaxillary and twelve maxillary teeth, while the lower jaws were equipped with fifteen dentary teeth per side. The teeth had been described as being long and slender, as opposed to

10201-475: Was the latest South American abelisaurid known. By the Late Cretaceous, South America was already isolated from both Africa and North America. The La Colonia Formation is exposed over the southern slope of the North Patagonian Massif . Most vertebrate fossils, including Carnotaurus , come from the formation's middle section (called the middle facies association ). This part likely represents

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