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88-509: Gorgosaurus ( / ˌ ɡ ɔːr ɡ ə ˈ s ɔːr ə s / GOR -gə- SOR -əs ; lit.   ' dreadful lizard ' ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period ( Campanian ), between about 76.5 and 75  million years ago . Fossil remains have been found in the Canadian province of Alberta and

176-458: A Gila monster's). Neither of these specimens was associated with any particular bone or specific body area. In the Encyclopedia of Dinosaurs Kenneth Carpenter pointed out that traces of skin impressions from the tail of Gorgosaurus showed similar small rounded or hexagonal scales. Gorgosaurus is classified in the theropod subfamily Albertosaurinae within the family Tyrannosauridae. It

264-419: A certain size threshold. The discovery of this specimen indicated that tyrannosaurids probably did not hunt in multigenerational packs, since its prey size is too small to share with the conspecifics. It is also a direct dietary evidence that reinforces the theory of 'ontogenetic dietary shift' for tyrannosaurids, as previously inferred by ecological modeling and anatomical features among different age groups. Only

352-610: A few species like Hypacrosaurus , and albertosaurines and centrosaurines had gone extinct. However, in the case of the centrosaurines, they had thrived in Asia with genera like Sinoceratops . While albertosaurine remains have been found in the Hell Creek Formation , it is most likely these are indeterminate remains belonging to a species of Tyrannosaurus . [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Genus The composition of

440-414: A fifth skeleton ( AMNH  5664), which Charles H. Sternberg had collected in 1917 and sold to their museum. It was smaller than other Gorgosaurus specimens, with a lower, lighter skull and more elongate limb proportions. Many sutures between bones were unfused in this specimen as well. Matthew and Brown noted that these features were characteristic of juvenile tyrannosaurids, but still described it as

528-407: 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

616-489: A juvenile skull from the Dinosaur Park Formation with several tyrannosaur bite marks, was previously believed to be Daspletosaurus sp. but was later assigned to Gorgosaurus libratus . TMP 2017.012.0002, is a Gorgosaurus right maxilla with 5 raised scars; healed injuries from face biting by conspecifics . TMP91.36.500 is a very complete sub-adult Gorgosaurus with preserved face bite injuries and also has

704-643: 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

792-621: 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,

880-555: A maximum growth rate of about 50 kg (110 lb) per year during the rapid growth phase, slower than in tyrannosaurines like Daspletosaurus and Tyrannosaurus , but comparable to Albertosaurus . Gorgosaurus spent as much as half its life in the juvenile phase before ballooning up to near-maximum size in only a few years. This, along with the complete lack of predators intermediate in size between huge adult tyrannosaurids and other small theropods, suggests that these niches may have been filled by juvenile tyrannosaurids. This pattern

968-478: A new species. One specimen from Montana ( TCMI 2001.89.1), housed in the Children's Museum of Indianapolis , shows evidence of severe pathologies , including healed leg, rib, and vertebral fractures , osteomyelitis (infection) at the tip of the lower jaw resulting in permanent tooth loss, and possibly a brain tumor . Several species were incorrectly assigned to Gorgosaurus in the 20th century. A complete skull of

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1056-485: A rarer species of tyrannosaurid, Daspletosaurus . This is one of the few examples of two tyrannosaur genera coexisting. Similar-sized predators in modern predator guilds are separated into different ecological niches by anatomical, behavioral or geographical differences that limit competition. Niche differentiation between the Dinosaur Park tyrannosaurids is not well understood. In 1970, Dale Russell hypothesized that

1144-409: 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

1232-960: A skull, discovered in 1913 by Charles M. Sternberg . This specimen was the first tyrannosaurid found with a complete hand. It was found in the Dinosaur Park Formation of Alberta and is housed in the Canadian Museum of Nature in Ottawa . Prospectors from the American Museum of Natural History in New York City were active along the Red Deer River in Alberta at the same time, collecting hundreds of spectacular dinosaur specimens, including four complete G. libratus skulls, three of which were associated with skeletons. Matthew and Brown described four of these specimens in 1923. Matthew and Brown also described

1320-532: A small tyrannosaurid ( CMNH 7541), found in the younger, late Maastrichtian -age Hell Creek Formation of Montana, was named Gorgosaurus lancensis by Charles Whitney Gilmore in 1946. This specimen was renamed Nanotyrannus by Bob Bakker and colleagues in 1988. Currently, many paleontologists regard Nanotyrannus as a juvenile Tyrannosaurus rex . Similarly, Evgeny Maleev created the names Gorgosaurus lancinator and Gorgosaurus novojilovi for two small tyrannosaurid specimens ( PIN 553-1 and PIN 552–2) from

1408-399: A suture, and the joint bends around a peg on the astragalus, which fits into a socket in the calcaneum . The shells of most molluscs are made of calcium carbonate (the main constituent of limestone and chalk ), and of conchiolin , a protein. For more information, see Mollusc shell . In cephalopod mollusks , which have external shells (e.g. Nautilus , ammonites ), the shell

1496-427: 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. ;

1584-459: A third metacarpal is known in some specimens, the vestigial remains of the third digit seen in other theropods. Gorgosaurus had four digits on each hindlimb, including a small first toe ( hallux ) which did not contact the ground. Tyrannosaurid hindlimbs were long relative to overall body size compared with other theropods. The largest known Gorgosaurus femur measured 105 cm (41 in) long. In several smaller specimens of Gorgosaurus ,

1672-409: A thoroughly healed fracture in the right fibula. Also present was a healed fracture in the dentary and what the authors describing the specimen referred to as "a mushroom-like hyperostosis of a right pedal phalanx." Ralph Molnar has speculated that this may be the same kind of pathology afflicting an unidentified ornithomimid discovered with a similar mushroom shaped growth on a toe bone. TMP91.36.500

1760-455: 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

1848-465: A wide range of animals, in both invertebrates and vertebrates . Sutures are found in animals with hard parts from the Cambrian period to the present day. Sutures were and are formed by several different methods, and they exist between hard parts that are made from several different materials. The skeletons of vertebrate animals (fish, amphibians, reptiles, birds, and mammals) are made of bone , in which

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1936-598: Is also preserved in a characteristic death pose . Most specimens of Gorgosaurus libratus have been recovered from the Dinosaur Park Formation in Alberta. This formation dates to the middle of the Campanian , between 76.5 and 74.8  million years ago , and Gorgosaurus libratus fossils are known specifically from the lower to middle section of the formation, between 76.6 and 75.1 million years ago. The Two Medicine Formation and Judith River Formation of Montana have also yielded possible Gorgosaurus remains. At this time,

2024-420: Is around 12,200 to 21,800 newtons. In 2022, Sakamoto estimated that Gorgosaurus had an anterior bite force of 6,418 newtons and a posterior bite force of 13,817 newtons. In 2023, a juvenile Gorgosaurus (TMP 2009.12.14) with its in situ stomach contents containing two Citipes juveniles about a year old intact was reported from the Dinosaur Park Formation . This juvenile would have been 5-7 years old at

2112-596: 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

2200-436: Is divided into compartments by septa (partitions). The septa are joined to the external shell by sutures formed by repeated invagination (they interlock like pieces of a jigsaw puzzle ). The sutures are visible from the outside and often form complex and elaborate patterns. Nearly all snail shells (except for the shells of limpets , abalone , sea hares , etc.) can be visualized as a tube of increasing diameter, closed at

2288-472: Is divided into three major sections: a cephalon (head section) with eyes, mouthparts and sensory organs such as antennae; a thorax of multiple segments which are similar to each other; and a pygidium, or tail section. In many species, the cephalon had sutures running from back to front round the outside edges of the eyes. These sutures divided the cephalon into three pieces. The sutures in trilobites' cephalons were unusual because it seems their main function

2376-468: Is most closely related to the slightly younger Albertosaurus . These are the only two definite albertosaurine genera that have been described, although other undescribed species may exist. Appalachiosaurus was described as a basal tyrannosauroid just outside Tyrannosauridae, although American paleontologist Thomas Holtz published a phylogenetic analysis in 2004 which indicated it was an albertosaurine. More recent, unpublished work by Holtz agrees with

2464-562: Is seen in modern Komodo dragons , whose hatchlings start off as tree-dwelling insectivores and slowly mature into massive apex predators capable of taking down large vertebrates. Other tyrannosaurids, including Albertosaurus , have been found in aggregations that some have suggested to represent mixed-age packs , but there is no evidence of gregarious behavior in Gorgosaurus . The discovery of two exceptionally preserved juvenile skulls from Gorgosaurus suggests that Gorgosaurus underwent

2552-460: 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,

2640-474: 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

2728-428: Is the stage when their bite force increases exponentially and when they begin to pursuit large prey. Several pathologies have been documented in the Gorgosaurus libratus holotype , NMC 2120. These include the third right dorsal rib, as well as healed fractures on the 13th and 14th gastralia and left fibula. Its fourth left metatarsal bore roughened exostoses both in the middle and at the far end. The third phalanx of

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2816-517: Is usually regarded as a nomen dubium today. Additional likely synonyms of G. libratus and/or D. horridus include Laelaps falculus , Laelaps hazenianus , Laelaps incrassatus , and Dryptosaurus kenabekides . Several tyrannosaurid skeletons from the Two Medicine Formation and Judith River Formation of Montana probably belong to Gorgosaurus , although it remains uncertain whether they belong to G. libratus or

2904-621: 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

2992-799: 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;

3080-641: The Nemegt Formation of Mongolia in 1955. Kenneth Carpenter renamed the smaller specimen Maleevosaurus novojilovi in 1992, but both are now considered juveniles of Tarbosaurus bataar . Gorgosaurus was smaller than Tyrannosaurus or Tarbosaurus , close in size to Albertosaurus . Adults reached 8 to 9 m (26 to 30 ft) in length from snout to tail, and weighed 2–3 metric tons (2.2–3.3 short tons) in body mass. The largest known skull measures 99 cm (39 in) long, just slightly smaller than that of Daspletosaurus . As in other tyrannosaurids,

3168-467: The U.S. state of Montana . Paleontologists recognize only the type species , G. libratus , although other species have been erroneously referred to the genus. Like most known tyrannosaurids, Gorgosaurus was a large bipedal predator , measuring 8–9 metres (26–30 ft) in length and 2–3 metric tons (2.2–3.3 short tons) in body mass. Dozens of large, sharp teeth lined its jaws, while its two-fingered forelimbs were comparatively small. Gorgosaurus

3256-422: The apex of the shell to the aperture ; this line is the suture. Details of the suture are often useful in discriminating one species from another, for example, sometimes the suture is channeled. The suture also provides a sort of geographic marker from which one can refer to the positioning of patterning or sculpture , where that is relevant: for example some species have a darker or lighter subsutural band on

3344-414: The dentary bones of the lower jaw. This number of teeth is similar to Albertosaurus and Daspletosaurus but is fewer than those of Tarbosaurus or Tyrannosaurus . Gorgosaurus shared its general body plan with all other tyrannosaurids. Its massive head was perched on the end of an S -shaped neck. In contrast to its large head, its forelimbs were very small. The forelimbs had only two digits, although

3432-743: The enantiornithine bird Avisaurus lived on the ground alongside multituberculate , metatherian and eutherian mammals . A number of species of terrestrial lizards were also present, including whiptails , skinks , monitors and alligator lizards . Dinosaur fossils in particular are found with unrivaled abundance and diversity. Huge herds of ceratopsids roamed the floodplains alongside equally large groups of saurolophine and lambeosaurine hadrosaurs . Other herbivorous groups like ornithomimids , therizinosaurs , pachycephalosaurs , small ornithopods , nodosaurids and ankylosaurids were also represented. Small predatory dinosaurs like oviraptorosaurs , troodonts and dromaeosaurs hunted smaller prey than

3520-419: 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 ,

3608-404: 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,

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3696-402: The tibia was longer than the femur, a proportion typical of fast-running animals. The two bones were of equal length in the largest specimens. The long, heavy tail served as a counterweight to the head and torso and placed the center of gravity over the hips. In 2001, paleontologist Phil Currie reported skin impressions from the holotype specimen of G. libratus . He originally reported

3784-534: The Bearpaw Sea, is recorded by the marine sediments of the massive Bearpaw Shale . The Dinosaur Park Formation preserves a great wealth of vertebrate fossils. A wide variety of fish swam the rivers and estuaries , including gars , sturgeons , sharks and rays , among others. Frogs , salamanders , turtles , crocodilians and champsosaurs also dwelled in the aquatic habitats. Azhdarchid pterosaurs and ornithuran birds like Apatornis flew overhead, while

3872-715: The Two Medicine Formation of Montana and in southwestern North America during the Campanian, while centrosaurines and lambeosaurines dominate in northern latitudes. Holtz has suggested this pattern indicates shared ecological preferences between tyrannosaurines, chasmosaurines and saurolophines. At the end of the later Maastrichtian stage, tyrannosaurines like Tyrannosaurus rex , saurolophines like Edmontosaurus and Kritosaurus and chasmosaurines like Triceratops and Torosaurus were widespread throughout western North America, while lambeosaurines were rare, consisting of

3960-546: The area was a coastal plain along the western edge of the Western Interior Seaway , which divided North America in half. The Laramide Orogeny had begun uplifting the Rocky Mountains to the west, from which flowed great rivers that deposited eroded sediment in vast floodplains along the coast. The climate was subtropical with marked seasonality, and periodic droughts sometimes resulted in massive mortality among

4048-442: 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

4136-574: The edge of an inland sea . It was an apex predator , preying upon abundant ceratopsids and hadrosaurs . In some areas, Gorgosaurus coexisted with another tyrannosaurid, Daspletosaurus . Although these animals were roughly the same size, there is some evidence of niche differentiation between the two. Gorgosaurus is the best-represented tyrannosaurid in the fossil record, known from dozens of specimens. These plentiful remains have allowed scientists to investigate its ontogeny , life history and other aspects of its biology . Gorgosaurus libratus

4224-424: The family. The eye socket was circular rather than oval or keyhole-shaped as in other tyrannosaurid genera. A tall crest rose from the lacrimal bone in front of each eye, similar to Albertosaurus and Daspletosaurus . Differences in the shape of bones surrounding the brain set Gorgosaurus apart from Albertosaurus . Gorgosaurus teeth were typical of all known tyrannosaurids. The eight premaxillary teeth at

4312-446: 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

4400-413: The front of the snout were smaller than the rest, closely packed and D -shaped in cross section . In Gorgosaurus , the first tooth in the maxilla was also shaped like the premaxillary teeth. The rest of the teeth were oval in cross section, rather than blade-like as in most other theropods. Along with the eight premaxillary teeth, Gorgosaurus had 26 to 30 maxillary teeth and 30 to 34 teeth in

4488-727: 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,

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4576-493: The great herds of dinosaurs, as represented in the numerous bonebed deposits preserved in the Dinosaur Park Formation. Conifers formed the forest canopy , while the understory plants consisted of ferns , tree ferns and angiosperms . Around 73 million years ago, the seaway began to expand, transgressing into areas formerly above sea level and drowning the Dinosaur Park ecosystem. This transgression, called

4664-557: The holotype of a new species, G. sternbergi . Today's paleontologists regard this specimen as a juvenile G. libratus . Dozens of other specimens have been excavated from the Dinosaur Park Formation and are housed in museums across the United States and Canada. G. libratus is the best-represented tyrannosaurid in the fossil record, known from a virtually complete growth series. In 1856, Joseph Leidy described two tyrannosaurid premaxillary teeth from Montana. Although there

4752-443: The huge tyrannosaurids; Daspletosaurus and Gorgosaurus , which were two orders of magnitude larger in mass. Intervening predatory niches may have been filled by young tyrannosaurids. A Saurornitholestes dentary has been discovered in the Dinosaur Park Formation that bore tooth marks left by the bite of a young tyrannosaur, possibly Gorgosaurus . In the middle stages of the Dinosaur Park Formation, Gorgosaurus lived alongside

4840-472: The large known adult individuals. The study's results likewise indicate that there is a dissociation between body size and cranial development in tyrannosaurs, while simultaneously allowing better identification of juvenile remains that may have been misidentified in museum fossil collections. It is estimated that an ontogenetic dietary shift of Gorgosaurus and Albertosaurus occurs when the mandibular length reaches 58 cm (1.90 ft), indicating that this

4928-628: 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,

5016-460: The late juvenile stage. In 2012, Jovannelly and Lane estimated that Gorgosaurus could exert a bite force of at least 22,000, possibly up to 42,000 newtons. Other paleontologists have produced significantly lower bite force estimates. In 2021, given that the largest known Gorgosaurus had a similar bite force to the similar-sized Tyrannosaurus , Therrien and colleagues proposed that the maximum bite force that could be produced by adult albertosaurines

5104-409: 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. Suture (anatomical) In anatomy , a suture is a fairly rigid joint between two or more hard elements of an organism, with or without significant overlap of the elements. Sutures are found in the skeletons or exoskeletons of

5192-410: The main rigid ingredient is calcium phosphate . The skulls of most vertebrates consist of sets of bony plates held together by cranial sutures . These sutures are held together mainly by Sharpey's fibers which grow from each bone into the adjoining one. In the type of crurotarsal ankle, which is found in crocodilians and some other archosaurs , the astragalus is fixed to the tibia by

5280-457: The more common Gorgosaurus actively hunted fleet-footed hadrosaurs , while the rarer and more troublesome ceratopsians and ankylosaurians (horned and heavily armoured dinosaurs) were left to the more heavy built Daspletosaurus . However, a specimen of Daspletosaurus ( OTM 200) from the contemporaneous Two Medicine Formation of Montana preserves the digested remains of a juvenile hadrosaur in its gut region, and another bonebed contains

5368-442: The morphological shift from gracile juveniles to robust adults at an earlier age than Tyrannosaurus , to which it was compared in a study published by Jared Voris et al., suggests that the ontogenetic changes occurred at roughly 5-7 years of age in Gorgosaurus ; much earlier than its larger and later relative. However, both tyrannosaur genera underwent these ontogenetic transformations at a similar percent of skull length relative to

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5456-403: 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

5544-428: 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

5632-512: The original assessment. All other tyrannosaurid genera, including Daspletosaurus , Tarbosaurus and Tyrannosaurus , are classified in the subfamily Tyrannosaurinae. Compared to the tyrannosaurines, albertosaurines had slender builds, with proportionately smaller, lower skulls and longer bones of the lower leg ( tibia ) and feet ( metatarsals and phalanges ). The close similarities between Gorgosaurus libratus and Albertosaurus sarcophagus have led many experts to combine them into one genus over

5720-526: 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

5808-400: The remains of the hindlimbs and caudal vertebrae of juvenile Citipes were present in the tyrannosaurid's stomach cavity, suggesting that a juvenile Gorgosaurus may have had preferential consumption of the muscular hindlimbs. Thomas R. Holtz Jr. , a paleontologist who also previously theorized that tyrannosaurs underwent a big dietary shift with maturation, said that the fossil "looks like it

5896-493: The remains of three Daspletosaurus along with the remains of at least five hadrosaurs. Unlike some other groups of dinosaurs, neither genus was more common at higher or lower elevations than the other. However, Gorgosaurus appears more common in northern formations like Dinosaur Park, with species of Daspletosaurus being more abundant to the south. The same pattern is seen in other groups of dinosaurs. Chasmosaurine ceratopsians and saurolophine hadrosaurs are also more common in

5984-466: 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

6072-408: 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

6160-449: The shell. When an angulation of the whorls occurs, the space between it and the suture above it (i.e. the abaxial edge of the sutural ramp) constitutes the area known as the "shoulder" of the shell. The shoulder angle may be simple or keeled, and may sometimes have nodes or spines A trilobite's carapace consisted of calcite and calcium phosphate deposited on a lattice (framework) of chitin (a polysaccharide ). The trilobite body

6248-726: The situation. Gregory S. Paul has suggested that Gorgosaurus libratus is ancestral to Albertosaurus sarcophagus . Below is the cladogram of Tyrannosauridae based on the phylogenetic analysis conducted by Loewen et al. in 2013. Gorgosaurus libratus Albertosaurus sarcophagus Dinosaur Park tyrannosaurid Daspletosaurus torosus Two Medicine tyrannosaurid Teratophoneus curriei Bistahieversor sealeyi Lythronax argestes Tyrannosaurus rex Tarbosaurus bataar Zhuchengtyrannus magnus Just like other tyrannosaurids, bite force of Gorgosaurus and Albertosaurus increases slowly among young individuals, and then it increases exponentially when they reach

6336-452: The skin as being essentially smooth and lacking the scales found in other dinosaurs, similar to the secondarily featherless skin found in large modern birds. Scales of some sort were present in this specimen, but they are reportedly widely dispersed from each other and very small. Other patches of isolated Gorgosaurus skin shows denser, and larger though still relatively fine scales (smaller than hadrosaurid scales and approximately as fine as

6424-420: The skull was large compared to its body size, although chambers within the skull bones and large openings ( fenestrae ) between bones reduced its weight. Albertosaurus and Gorgosaurus share proportionally longer and lower skulls than Daspletosaurus and other tyrannosaurids. The end of the snout was blunt, and the nasal and parietal bones were fused along the midline of the skull, as in all other members of

6512-408: The small end, and spirally wrapped around a central axis. For more information, see Gastropod shell . Each complete rotation of this spirally-arranged tube is called a whorl . The whorls of a snail shell usually overlap one another, forming a spire . Where the whorls overlap, there is usually a clear (if narrow) indentation. This indentation forms a visible line, which is continuous and reaches from

6600-497: 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,

6688-605: The specimen had a pseudoarthortic gastralium . Lesions from a bite received to the face were present and showed evidence that the wounds were healing before the animal died. Another specimen has a poorly healed fracture of the right fibula , which left a large callus on the bone. In a 2001 study conducted by Bruce Rothschild and other paleontologists, 54 foot bones referred to Gorgosaurus were examined for signs of stress fracture , but none were found. As with many tyrannosaurids, several Gorgosaurus specimens show evidence of intraspecific face biting. Specimen TMP 1994.143.1,

6776-412: 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

6864-403: 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

6952-419: The third right toe is deformed, as the claw on that digit has been described as "quite small and amorphous". The three pathologies may have been received in a single encounter with another dinosaur. Another specimen cataloged as TMP 94.12.602 bears multiple pathologies. A 10 cm (3.9 in) longitudinal fracture is present in the middle of the right fibula's shaft. Multiple ribs bear healed fractures and

7040-423: The time of death, measuring about 4 metres (13 ft) long and weighing around 335 kilograms (739 lb). It is much larger than the two Citipes juveniles that weigh about 9–12 kilograms (20–26 lb), contrary to the assumption that tyrannosaurids fed on prey of their size once they reached 16–32 kilograms (35–71 lb), indicating that juvenile tyrannosaurids still consumed much smaller prey after exceeding

7128-606: The two greatly expands the geographical and chronological range of the genus Albertosaurus . Other experts maintain the two genera as separate. Canadian paleontologist Phil Currie claims there are as many anatomical differences between Albertosaurus and Gorgosaurus as there are between Daspletosaurus and Tyrannosaurus , which are almost always kept separate. He also notes that undescribed tyrannosaurids discovered in Alaska , New Mexico and elsewhere in North America may help clarify

7216-566: 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

7304-429: 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

7392-448: The years. Albertosaurus was named first, so by convention it is given priority over the name Gorgosaurus , which is sometimes considered its junior synonym . William Diller Matthew and Barnum Brown doubted the distinction of the two genera as early as 1922. Gorgosaurus libratus was formally reassigned to Albertosaurus (as Albertosaurus libratus ) by Dale Russell in 1970, and many subsequent authors followed his lead. Combining

7480-713: Was Thanksgiving," as the juvenile Gorgosaurus was mostly eating the legs of Citipes . Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids using bone histology , which can determine the age of a specimen when it died. A growth curve can be developed when the ages of various individuals are plotted against their sizes on a graph. Tyrannosaurids grew throughout their lives, but underwent tremendous growth spurts for about four years, after an extended juvenile phase. Sexual maturity may have ended this rapid growth phase, after which growth slowed down considerably in adult animals. Examining five Gorgosaurus specimens of various sizes, Erickson calculated

7568-518: Was first described by Lawrence Lambe in 1914. Its name is derived from the Greek γοργος ( gorgos – "fierce" or "terrible") and σαυρος ( saurus – "lizard"). The type species is G. libratus ; the specific epithet "balanced" is the past participle of the Latin verb librare , meaning "to balance". The holotype of Gorgosaurus libratus ( NMC 2120) is a nearly complete skeleton associated with

7656-435: Was most closely related to Albertosaurus , and more distantly related to the larger Tyrannosaurus . Gorgosaurus and Albertosaurus are extremely similar, distinguished mainly by subtle differences in the teeth and skull bones. Some experts consider G. libratus to be a species of Albertosaurus ; this would make Gorgosaurus a junior synonym of that genus. Gorgosaurus lived in a lush floodplain environment along

7744-570: Was no indication of what the animal looked like, the teeth were large and robust, and Leidy gave them the name Deinodon . Matthew and Brown commented in 1922 that these teeth were indistinguishable from those of Gorgosaurus , but in the absence of skeletal remains of Deinodon , opted not to unequivocally synonymize the two genera, provisionally naming a ?Deinodon libratus . Although Deinodon teeth are very similar to those of Gorgosaurus , tyrannosaurid teeth are extremely uniform, so it cannot be said for certain which animal they belonged to. Deinodon

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