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111-490: Ankylosaurus is a genus of armored dinosaur . Its fossils have been found in geological formations dating to the very end of the Cretaceous Period , about 68–66 million years ago, in western North America, making it among the last of the non-avian dinosaurs . It was named by Barnum Brown in 1908; it is monotypic , containing only A. magniventris . The generic name means "fused" or "bent lizard", and

222-557: A species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in 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 ,

333-651: A tribe the authors named Ankylosaurini ), Arbour and Currie suggested that earlier North American ankylosaurids had gone extinct by the late Albian or Cenomanian ages of the Middle Cretaceous . Ankylosaurids thereafter recolonized North America from Asia during the Campanian or Turonian ages of the Late Cretaceous, and there diversified again, leading to genera such as Ankylosaurus , Anodontosaurus , and Euoplocephalus . The theory explains

444-540: A 30-million-year gap in the fossil record of North American ankylosaurids between the ages. Like other ornithischians, Ankylosaurus was herbivorous . Its wide muzzle was adapted for non-selective low- browse cropping, although not to the extent seen in some related genera, especially Euoplocephalus . Though ankylosaurs may not have fed on fibrous and woody plants , they may have had a varied diet, including tough leaves and pulpy fruits. Ankylosaurus probably fed on abundant ferns and low-growing shrubs . Assuming it

555-459: A keel across the midline. Like other ankylosaurids, Ankylosaurus had cervical half-rings (armor plates on the neck), but these are known only from fragments, making their exact arrangement uncertain. Carpenter suggested that when seen from above, the plates would have been paired, creating an inverted V-shape across the neck, with the midline gap probably being filled with small ossicles (round bony scutes) to allow for movement. He believed

666-651: 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

777-429: A length of 8 m (26 ft) instead. Arbour and Mallon estimated a weight of 4.78 t (5.27 short tons) for AMNH 5214, and tentatively estimated the weight of CMN 8880 at 7.95 t (8.76 short tons). The three known Ankylosaurus skulls differ in various details; this is thought to be the result of taphonomy (changes happening during decay and fossilization of the remains) and individual variation . The skull

888-628: 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,

999-485: A partial skull and osteoderms) as part of the family. Due to the fragmentary condition of the remains, Brown was unable to fully distinguish between Euoplocephalus and Ankylosaurus . Having for comparison only a few, incomplete members of the family, he believed the group was part of the suborder Stegosauria . In 1923 Osborn coined the name Ankylosauria , thereby placing the ankylosaurids in their own suborder. Ankylosauria and Stegosauria are now grouped together within

1110-409: 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

1221-448: A role in thermoregulation as in modern crocodilians . The tail club of Ankylosaurus seems to have been an active defensive weapon, capable of producing enough of an impact to break the bones of an assailant. The tendons of the tail were partially ossified and were not very elastic, allowing great force to be transmitted to the club when it was used as a weapon. Coombs suggested in 1979 that several hindlimb muscles would have controlled

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1332-427: 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. ;

1443-455: 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

1554-461: Is a junior synonym of Cancer grammarius Linnaeus, 1758 . Although the International Code of Nomenclature for algae, fungi, and plants does not contain the same explicit statement, examples make it clear that the original name is used, so that the "type species" of a genus name need not have a name within that genus. Thus in Article 10, Ex. 3, the type of the genus name Elodes is quoted as

1665-429: Is a backlog of untypified names defined in older publications when it was not required to specify a type. A type species is both a concept and a practical system that is used in the classification and nomenclature (naming) of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus,

1776-430: Is a member of the family Ankylosauridae, and its closest relatives appear to be Anodontosaurus and Euoplocephalus . Ankylosaurus is thought to have been a slow-moving animal, able to make quick movements when necessary. Its broad muzzle indicates it was a non-selective browser . Sinuses and nasal chambers in the snout may have been for heat and water balance or may have played a role in vocalization. The tail club

1887-612: 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

1998-411: Is estimated to have been between 6 and 8 m (20 and 26 ft) long and to have weighed between 4.8 and 8 t (5.3 and 8.8 short tons). It was quadrupedal , with a broad, robust body. It had a wide, low skull, with two horns pointing backward from the back of the head, and two horns below these that pointed backward and down. Unlike other ankylosaurs, its nostrils faced sideways rather than towards

2109-423: Is fixed, in theory, to a type specimen. For example, the type species for the land snail genus Monacha is Helix cartusiana , the name under which the species was first described, known as Monacha cartusiana when placed in the genus Monacha . That genus is currently placed within the family Hygromiidae . The type genus for that family is the genus Hygromia . The concept of the type species in zoology

2220-567: Is heavily worn, leading Carpenter to suggest that ankylosaurids in general or at least the young did not swallow their food whole but employed some sort of chewing. Since adult Ankylosaurus did little chewing of its food, it would have spent less time in the day foraging than an elephant. Based on the broadness of the ribcage, the digestion of unchewed food may have been facilitated by hindgut fermentation like in modern herbivorous lizards, which have several chambers in their enlarged colon . In 1969, paleontologist Georg Haas concluded that despite

2331-460: 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,

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2442-474: 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

2553-734: Is thought to have been used in defense against predators or in intraspecific combat . Specimens of Ankylosaurus have been found in the Hell Creek , Lance , Scollard , Frenchman , and Ferris formations, but it appears to have been rare in its environment. Although it lived alongside a nodosaurid ankylosaur, their ranges and ecological niches do not appear to have overlapped, and Ankylosaurus may have inhabited upland areas. Ankylosaurus also lived alongside dinosaurs such as Tyrannosaurus , Triceratops , and Edmontosaurus . In 1906, an American Museum of Natural History expedition led by American paleontologist Barnum Brown discovered

2664-621: 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

2775-824: 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;

2886-670: The Scollard Formation by the Red Deer River in Alberta, Canada. This specimen included a complete skull, mandibles, the first and only tail club known of this genus, as well as ribs, vertebrae, limb bones, and armor. In 1947 the American fossil collectors Charles M. Sternberg and T. Potter Chamney collected a skull and mandible (specimen CMN 8880, formerly NMC 8880), 1 kilometer ( 5 ⁄ 8 mile) north of where

2997-537: The Tyrannosaurus specimen as the now synonymous genus Dynamosaurus in 1905. More recent examination has shown them to be similar to those of Ankylosaurus ; it seems that Brown had compared them with some Euoplocephalus osteoderms, which had been erroneously cataloged as belonging to Ankylosaurus at the AMNH. In 1910, another AMNH expedition led by Brown discovered an Ankylosaurus specimen (AMNH 5214) in

3108-426: The choanae (internal nostrils), and the air passage was looped. The maxillae expanded to the sides, giving the impression of a bulge, which may have been due to the sinuses inside. The maxillae had a ridge that may have been the attachment site for fleshy cheeks; the presence of cheeks in ornithischians is controversial, but some nodosaurs had armor plates that covered the cheek region, which may have been embedded in

3219-476: The dental occlusion (contact between the teeth) of ankylosaur specimens found that the ability for backwards (palinal) jaw movement evolved independently in different ankylosaur lineages , including Late Cretaceous North American ankylosaurids like Ankylosaurus and Euoplocephalus . The retracted position of the nostrils of Ankylosaurus were compared to those of fossorial (digging) worm lizards and blind snakes by Arbour and Mallon in 2017, and though it

3330-444: The larynx , not the nostrils, and that reduction in weight was minimal, as the spaces only accounted for a small percent of the skull volume. He also considered a gland unlikely and noted that the sinuses may not have had any specific function. It has also been suggested that the respiratory passages were used to perform a mammal-like treatment of inhaled air, based on the presence and arrangement of specialized bones . A 2011 study of

3441-587: The manus would have limited fossorial activity. Ankylosaurs were likely to have been slow-moving and sluggish animals, though they may have been capable of quick movements when necessary. The squamosal horns of the largest Ankylosaurus specimen are blunter than those of the smallest specimen, which is also the case in Euoplocephalus , and this may represent ontogenetic variation (related to growth development). Studies of specimens of Pinacosaurus of different ages found that during ontogenetic development,

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3552-404: 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,

3663-471: The type specimen of Ankylosaurus magniventris (AMNH 5895) in the Hell Creek Formation , near Gilbert Creek, Montana . The specimen (found by collector Peter Kaisen) consisted of the upper part of a skull, two teeth, part of the shoulder girdle, cervical, dorsal, and caudal vertebrae, ribs, and more than thirty osteoderms (armor plates). Brown scientifically described the animal in 1908;

3774-566: The 1910 specimen was found. This is the largest-known Ankylosaurus skull, but it is damaged in places. A section of caudal vertebrae (specimen CCM V03) was discovered in the 1960s in the Powder River drainage, Montana, part of the Hell Creek Formation. In addition to these five incomplete specimens, many other isolated osteoderms and teeth have been found. In 1990, American paleontologist Walter P. Coombs pointed out that

3885-463: The American paleontologist Samuel Wendell Williston criticized the skeletal reconstruction as being based on too few remains, and claimed that Ankylosaurus was merely a synonym of the genus Stegopelta , which Williston had named in 1905. Williston also stated that a skeletal reconstruction of the related Polacanthus by Hungarian paleontologist Franz Nopcsa was a better example of how ankylosaurs would have appeared in life. The claim of synonymy

3996-473: The French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or 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

4107-457: The Glossary, type species is defined as The nominal species that is the name-bearing type of a nominal genus or subgenus. The type species permanently attaches a formal name (the generic name) to a genus by providing just one species within that genus to which the genus name is permanently linked (i.e. the genus must include that species if it is to bear the name). The species name in turn

4218-486: The back. The neural spines had ossified (turned to bone) tendons , which also overlapped some of the vertebrae. The ribs of the last four back vertebrae were fused to the diapophyses and parapophyses (the structures that articulated the ribs with the vertebrae), and the ribcage was very broad in this part of the body. The caudal vertebrae had centra that were slightly amphicoelous, meaning they were concave on both sides. A prominent feature of Ankylosaurus

4329-417: The back. There may have been four longitudinal rows of osteoderms on the flanks. Unlike some basal ankylosaurs and many nodosaurs, ankylosaurids do not appear to have had co-ossified pelvic shields above their hips. Some osteoderms without keels may have been placed above the hip region of Ankylosaurus , as in Euoplocephalus . Ankylosaurus may have had three or four transverse rows of circular osteoderms over

4440-442: 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

4551-466: The biological type specimen (or specimens). A similar concept is used for suprageneric groups and called a type genus . In botanical nomenclature , these terms have no formal standing under the code of nomenclature , but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen (or, rarely, an illustration) which is also the type of a species name. The species name with that type can also be referred to as

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4662-420: The body. The front part of the neural spines had well-developed entheses, which was common among adult dinosaurs, and indicates the presence of large ligaments , which helped support the massive head. The dorsal vertebrae had centra (or bodies) that were short relative to their width, and their neural spines were short and narrow. The dorsal vertebrae were tightly spaced, which limited the downwards movement of

4773-402: The bone tissue, a feature unique to ankylosaurids. This would have provided the ankylosaurids with an armor covering that was both lightweight and highly durable, being resistant to breakage and penetration by the teeth of predators. The palpebral bones over the eyes may have provided additional protection for them. Carpenter suggested in 1982 that the heavily vascularized armor may also have had

4884-592: The clade Thyreophora . This group first appeared in the Sinemurian age, and survived for 135 million years until disappearing in the Maastrichtian . They were widespread and inhabited a broad range of environments. As more complete specimens and new genera have been discovered, theories about ankylosaurian interrelatedness have become more complex, and hypotheses have often changed between studies. In addition to Ankylosauridae, Ankylosauria has been divided into

4995-399: The elongated nasal passages of saiga antelope and the looping trachea of cranes and swans . Reconstructions of the inner ear suggest adaptation to hearing at low frequencies, such as the low-toned resonant sounds possibly produced by the nasal passages. They disputed the possibility that the looping is related to olfaction (sense of smell) as the olfactory region is pushed to the sides of

5106-471: The enlarged opening of the nostrils, giving a bulbous appearance. The nostrils also had an intranarial septum , which separated the nasal passage from the sinus. Each side of the snout had five sinuses, four of which expanded into the maxilla bone. The nasal cavities (or chambers) of Ankylosaurus were elongated and separated by a septum at the midline, which divided the inside of the snout into two mirrored halves. The nasal chambers had two openings, including

5217-965: The families Nodosauridae, and sometimes Polacanthidae (these families lacked tail clubs). Ankylosaurus is considered part of the subfamily Ankylosaurinae (members of which are called ankylosaurines) within Ankylosauridae. Ankylosaurus appears to be most closely related to Anodontosaurus and Euoplocephalus . The following cladogram is based on a 2015 phylogenetic analysis of the Ankylosaurinae conducted by Arbour and Currie: Crichtonpelta Tsagantegia Zhejiangosaurus Pinacosaurus Saichania Tarchia Zaraapelta Dyoplosaurus Talarurus Nodocephalosaurus Ankylosaurus Anodontosaurus Euoplocephalus Scolosaurus Ziapelta Because Ankylosaurus and other Late Cretaceous North American ankylosaurids were grouped with Asian genera (in

5328-401: The flesh. Specimen AMNH 5214 has 34–35 dental alveoli (tooth sockets) in the maxilla. The tooth rows in the maxillae of this specimen are about 20 centimeters (7.9 in) long. Each alveolus had a foramen (opening) near its side where a replacement tooth could be seen. Compared to other ankylosaurs, the mandible of Ankylosaurus was low in proportion to its length, and, when seen from

5439-446: 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

5550-487: The fragments represented the remains of two cervical half-rings, which formed two semi-circular plates of armor around the upper part of the neck, as in the closely related Anodontosaurus and Euoplocephalus . Arbour and Mallon elaborated on this idea, describing the shape of these half-rings as "continuous U-shaped yokes" over the upper part of the neck, and suggested that Ankylosaurus had six keeled osteoderms with oval bases on each half-ring. The first osteoderms behind

5661-411: The front of the snout between the nostrils, which had a loreal caputegulum on each side, an anterior and posterior supraorbital caputegulum above each orbit, and a ridge of nuchal caputegulae at the back of the skull. The snout region of Ankylosaurus was unique among ankylosaurs, and had undergone an "extreme" transformation compared to its relatives. The snout was arched and truncated at the front, and

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5772-403: The front. The front part of the jaws was covered in a beak, with rows of small, leaf-shaped teeth farther behind it. It was covered in armor plates, or osteoderms, with bony half-rings covering the neck, and had a large club on the end of its tail. Bones in the skull and other parts of the body were fused, increasing their strength, and this feature is the source of the genus name. Ankylosaurus

5883-737: 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,

5994-574: The generic name is derived from the Greek words αγκυλος ankulos ('bent' or 'crooked'), referring to the medical term ankylosis , the stiffness produced by the fusion of bones in the skull and body, and σαυρος sauros ('lizard'). The name can be translated as "fused lizard", "stiff lizard", or "curved lizard". The type species name, magniventris, is derived from the Latin : magnus ('great') and Latin : venter ('belly'), referring to

6105-534: The genus in 2004. In 2017 the Canadian paleontologists Victoria M. Arbour and Jordan Mallon redescribed the genus in light of newer ankylosaur discoveries, including elements of the holotype that had not been previously mentioned in the literature (such as parts of the skull and the cervical half-rings). They concluded that though Ankylosaurus is the best-known member of its group, it was bizarre in comparison to related ankylosaurs, and therefore not representative of

6216-410: The great width of the animal's body. The skeletal reconstruction accompanying the 1908 description restored the missing parts in a fashion similar to Stegosaurus , and Brown likened the result to the extinct armored mammal Glyptodon . In contrast to modern depictions, Brown's stegosaur-like reconstruction showed robust forelimbs, a strongly arched back, a pelvis with prongs projecting forwards from

6327-401: The group. In spite of its familiarity, it is known from far fewer remains than its closest relatives. Ankylosaurus was the largest-known ankylosaurine dinosaur and possibly the largest ankylosaurid. In 2004 Carpenter estimated that the individual with the largest-known skull (specimen CMN 8880), which is 64.5 cm (2 ft 1.4 in) long and 74.5 cm (2 ft 5.3 in) wide,

6438-432: 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 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

6549-427: The ilium and pubis, as well as a short, drooping tail without a tail club , which was unknown at the time. Brown also reconstructed the armor plates in parallel rows running down the back; this arrangement was purely hypothetical. Brown's reconstruction became highly influential, and restorations of the animal based on his diagram were published as late as the 1980s. In a 1908 review of Brown's Ankylosaurus description,

6660-439: The large size of ankylosaur skulls, the associated musculature was relatively weak. He also thought jaw movement was limited to up and down movements. Extrapolating from this, Haas suggested that ankylosaurs ate relatively soft non-abrasive vegetation. Later research on Euoplocephalus indicates that forward and sideways jaw movement was possible in these animals, the skull being able to withstand considerable forces. A 2016 study of

6771-633: 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,

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6882-539: The largest specimen may have been 57 cm ( 22 + 1 ⁄ 2  in) wide. The tail club of Ankylosaurus was semicircular when seen from above, similar to those of Euoplocephalus and Scolosaurus but unlike the pointed club osteoderms of Anodontosaurus or the narrow, elongated club of Dyoplosaurus . The last seven tail vertebrae formed the "handle" of the tail club. These vertebrae were in contact, with no cartilage between them, and were sometimes co-ossified, which made them immobile. Ossified tendons attached to

6993-417: The latest Cretaceous (including Ankylosaurus ) had jaws with low mechanical advantage, whereas those of earlier relatives were high to moderate. These late ankylosaurids also had tooth occlusion and complex biphasal jaw mechanisms, features shared with some Late Cretaceous nodosaurids, but those instead have jaws with high mechanical advantage. This indicates that while the two groups converged in some features,

7104-418: 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. Type species In zoological nomenclature , a type species ( species typica ) is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains

7215-439: The main airway. According to Carpenter, the shape of the nasal chambers of Ankylosaurus indicate that airflow was unidirectional (looping through the lungs during inhalation and exhalation), although it may also have been bidirectional in the posterior nasal chamber, with air directed past the olfactory lobes . The enlarged olfactory region of ankylosaurids indicates a well-developed sense of smell. Though hindwards retraction of

7326-426: The mandibles has not yet been found. Like other ankylosaurs, Ankylosaurus had small, phylliform (leaf-shaped) teeth, which were compressed sideways. The teeth were mostly taller than they were wide, and were very small; their size in proportion to the skull meant that the jaws of Ankylosaurus could accommodate more teeth than other ankylosaurines. The teeth of the largest Ankylosaurus skull are smaller than those of

7437-403: 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

7548-428: 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

7659-416: The nasal chambers. The American paleontologist Kenneth Carpenter accepted the teeth as belonging to A. magniventris in 2004, and that all the specimens belonged to the same species, noting that the teeth of other ankylosaurs are highly variable. Most of the known Ankylosaurus specimens were not scientifically described at length, though several paleontologists planned to do so until Carpenter redescribed

7770-401: The nasal passages of Euoplocephalus by paleontologist Tetsuto Miyashita and colleagues supported their function as a heat and water balancing system, noting the extensive blood vessel system and an increased surface area for the mucosa membrane (used for heat and water exchange in modern animals). The researchers also supported the idea of the loops acting as a resonance chamber, comparable to

7881-443: The nodosaurs had higher relative bite force , which suggests diverging jaw mechanics and dietary partitioning between the two. In 1977, paleontologist Teresa Maryańska proposed that the complex sinuses and nasal cavities of ankylosaurs may have lightened the weight of the skull, housed a nasal gland , or acted as a chamber for vocal resonance . Carpenter rejected these hypotheses, arguing that tetrapod animals make sounds through

7992-435: The nostrils is seen in aquatic animals and animals with a proboscis , it is unlikely either possibility applies to Ankylosaurus , as the nostrils tend to be reduced or the premaxilla extended. In addition, though the widely separated nostrils may have allowed for stereo-olfaction (where each nostril senses smells from different directions), as has been proposed for the moose , little is known about this feature. The position of

8103-422: The nostrils were elliptical and were directed downward and outward, unlike in all other known ankylosaurids where they faced obliquely forward or upward. Additionally, the nostrils were not visible from the front because the sinuses were expanded to the sides of the premaxilla bones, to a larger extent than seen in other ankylosaurs. Large loreal caputegulae—strap-like, side osteoderms of the snout—completely roofed

8214-410: The orbits of Ankylosaurus suggest some stereoscopic vision . Reconstructions of ankylosaur forelimb musculature made by Coombs in 1978 suggest that the forelimbs bore the majority of the animal's weight, and were adapted for high force delivery on the front feet, possibly for food gathering. In addition, Coombs suggested that ankylosaurs may have been capable diggers, though the hoof-like structure of

8325-459: The pelvic region, which were smaller than those on the rest of the body, as in Scolosaurus . Smaller, triangular osteoderms may have been present on the sides of the pelvis. Flattened, pointed plates resemble those on the sides of the tail of Saichania , and may have been distributed similarly on Ankylosaurus . Osteoderms with oval keels could have been placed on the upper side of the tail or

8436-541: 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

8547-417: The result of remodeling of the skull itself. This obliterated the sutures between skull elements, which is common for adult ankylosaurs. The caputegulum pattern of the skull was variable between specimens, though some details are shared. The caputegulae are named according to their position on the skull, and those of Ankylosaurus include a relatively large, hexagonal (or diamond-shaped) nasal caputegulum at

8658-408: The ribs of juvenile ankylosaurs fused with their vertebrae. The forelimbs strongly increased in robustness while the hindlimbs did not become larger relative to the rest of the skeleton, further evidence that the arms bore most of the weight. In the cervical half-rings, the underlying bone band developed outgrowths connecting it with the underlying osteoderms, which simultaneously fused to each other. On

8769-432: The second cervical half-ring would have been similar in shape to those in the first half-ring, and the osteoderms on the back probably decreased in diameter hindwards. The largest osteoderms were probably arranged in transverse and longitudinal rows across most of the body, with four or five transverse rows separated by creases in the skin. The osteoderms on the flanks would probably have had a more square outline than those on

8880-417: The side of the limbs. Compressed, triangular osteoderms found with Ankylosaurus specimens may have been placed on the sides of the pelvis or the tail. Ovoid, keeled, and teardrop-shaped osteoderms are known from Ankylosaurus , and may have been placed on the forelimbs, like those known from Pinacosaurus , but it is unknown whether the hindlimbs bore osteoderms. The tail club (or tail knob) of Ankylosaurus

8991-406: The side, the tooth row was almost straight instead of arched. The mandibles are completely preserved only in the smallest specimen (AMNH 5214) and are about 41 centimeters (16 in) long. The incomplete mandible of the largest specimen (CMN 8880) is the same length. AMNH 5214 has 35 dental alveoli in the left dentary bone () and 36 in the right, for a total of 71. The predentary bone of the tip of

9102-436: The sides from the back of the skull. The crest and horn were probably separate elements originally, as seen in the related Pinacosaurus and Euoplocephalus . Below the upper horns, jugal horns were present, which pointed backward and down. The horns may have originally been osteoderms that fused to the skull. The scale -like cranial ornamentation on the surfaces of ankylosaurs skulls is called " caputegulae ", and were

9213-509: The skeleton of Ankylosaurus , including most of the pelvis , tail, and feet, is still unknown. It was quadrupedal , and its hind limbs were longer than its forelimbs. In the holotype specimen, the scapula (shoulder blade) measures 61.5 cm (2 ft 1 ⁄ 4  in) long and was fused with the coracoid (a rectangular bone connected to the lower end of the scapula). It also had entheses (connective tissue) for various muscle attachments. The humerus (upper arm bone) of AMNH 5214

9324-505: The skull, the middle bone plates first ossified at the snout and the rear rim, with ossification gradually extending towards the middle regions. On the rest of the body, ossification progressed from the neck backward in the direction of the tail. The osteoderms of ankylosaurids were thin in comparison to those of other ankylosaurs, and appear to have been strengthened by randomly distributed cushions of collagen fibers. Structurally similar to Sharpey's fibres , they were embedded directly into

9435-541: The small teeth may have been adapted for handling, could also have provided supplemental nutrition. Fossils of Ankylosaurus teeth exhibit wear on the face of the crown rather than on the tip of the crown, as in nodosaurid ankylosaurs. In 1982 Carpenter ascribed to baby Ankylosaurus two very small teeth that originate from the Lance and Hell Creek Formations and measure 3.2 to 3.3 mm ( 1 ⁄ 8 to 17 ⁄ 128  in) in length, respectively. The smaller tooth

9546-449: The smallest skull in the absolute sense. Some teeth from behind in the tooth row curved backwards, and tooth crowns were usually flatter on one side than the other. Ankylosaurus teeth are diagnostic and can be distinguished from the teeth of other ankylosaurids based on their smooth sides. The denticles were large, their number ranging from six to eight on the front part of the tooth, and five to seven behind. The structure of much of

9657-414: The smallest specimen of Ankylosaurus , its skull is still larger than those of any other ankylosaurins. A few other ankylosaurs reached about 6 m (20 ft) in length. Because the vertebrae of AMNH 5214 are not significantly larger than those of other ankylosaurines, Arbour and Mallon considered their upper range estimate of nearly 10 meters (33 ft) for large Ankylosaurus too long, and suggested

9768-399: The specific name means "great belly". A handful of specimens have been excavated to date, but a complete skeleton has not been discovered. Though other members of Ankylosauria are represented by more extensive fossil material, Ankylosaurus is often considered the archetypal member of its group, despite having some unusual features. Possibly the largest known ankylosaurid , Ankylosaurus

9879-497: 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,

9990-412: 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

10101-417: The swinging of the tail, and that violent thrusts of the club would have been able to break the metatarsal bones of large theropods . Genus The composition of 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

10212-403: 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

10323-473: The teeth of two skulls assigned to A. magniventris differed from those of the holotype specimen in some details, and though he expressed a "considerate temptation" to name a new species of Ankylosaurus for these, he refrained from doing so, as the range of variation in the species was not completely documented. He also raised the possibility that the two teeth associated with the holotype specimen perhaps did not belong to it, as they were found in matrix within

10434-399: The type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, and some higher-rank names based on genus names, have such types. In bacteriology , a type species is assigned for each genus. Whether or not currently recognized as valid , every named genus or subgenus in zoology is theoretically associated with a type species. In practice, however, there

10545-405: The type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species. The term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological Nomenclature , which defines a type species as the name-bearing type of the name of a genus or subgenus (a " genus-group name "). In

10656-474: The underside. Compared to Euoplocephalus , the osteoderms of Ankylosaurus were smoother. Many smaller osteoderms and ossicles probably occupied the space between the larger ones, as in other ankylosaurids. The osteoderms covering the body were very flat, though with a low keel at one margin. In contrast, the nodosaurid Edmontonia had high keels stretching from one margin to the other on the midline of its osteoderms. Ankylosaurus had some smaller osteoderms with

10767-576: 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

10878-400: The vertebrae in front of the tail club, and these features together helped strengthen it. The interlocked zygapophyses (articular processes) and neural spines of the handle vertebrae were U-shaped when seen from above, whereas those of most other ankylosaurids are V-shaped, which may be due to the handle of Ankylosaurus being wider. The larger width may indicate that the tail of Ankylosaurus

10989-429: 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

11100-400: The weight for AMNH 5214 at 4.78 t (5.27 short tons) in 2014. In 2017, based on comparisons with more complete ankylosaurines, Arbour and Mallon estimated a length of 7.56 to 9.99 m (24 ft 9 + 1 ⁄ 2  in to 32 ft 9 + 1 ⁄ 2  in) for CMN 8880, and 6.02 to 7.95 m (19 ft 9 in to 26 ft 1 in) for AMNH 5214. Though the latter is

11211-466: The width of this armor belt was too wide to have fitted solely on the neck, and that it covered the base of the neck and continued onto the shoulder region. Arbour and the Canadian paleontologist Philip J. Currie disagreed with Carpenter's interpretation in 2015 and pointed out that the cervical half-ring fragments of the holotype specimen did not fit together in the way proposed by Carpenter (though this could be due to breakage). They instead suggested that

11322-418: Was endothermic , Ankylosaurus would have eaten 60 kilograms (130 pounds) of ferns per day, similar to the amount of dry vegetation a large elephant would consume. The requirements for nutrition could have been more effectively met if Ankylosaurus ate fruit, which its small, cusp-like teeth and the shape of its beak seem well adapted for, compared to for example Euoplocephalus . Certain invertebrates, which

11433-469: Was about 6.25 m (20 ft 6 in) long and had a hip height of about 1.7 m (5 ft 7 in). The smallest-known skull (specimen AMNH 5214) is 55.5 cm (1 ft 9.9 in) long and 64.5 cm (2 ft 1.4 in) wide, and Carpenter estimated that it measured about 5.4 m (17 ft 9 in) long and about 1.4 m (4 ft 7 in) tall at the hips. The English paleontologist Roger B. J. Benson and colleagues estimated

11544-478: Was composed of two large osteoderms, with a row of small osteoderms at the midline, and two small osteoderms at the tip; these osteoderms obscured the last tail vertebra. As only the tail club of specimen AMNH 5214 is known, the range of variation between individuals is unknown. The tail club of AMNH 5214 is 60 cm ( 23 + 1 ⁄ 2  in) long, 49 cm ( 19 + 1 ⁄ 2  in) wide, and 19 cm ( 7 + 1 ⁄ 2  in) tall. The club of

11655-531: Was introduced by Pierre André Latreille . The International Code of Zoological Nomenclature states that the original name (binomen) of the type species should always be cited. It gives an example in Article 67.1. Astacus marinus Fabricius, 1775 was later designated as the type species of the genus Homarus , thus giving it the name Homarus marinus (Fabricius, 1775) . However, the type species of Homarus should always be cited using its original name, i.e. Astacus marinus Fabricius, 1775 , even though that

11766-519: Was its armor, consisting of knobs and plates of bone known as osteoderms, or scutes, embedded in the skin. These have not been found in articulation, so their exact placement on the body is unknown, though inferences can be made based on related animals, and various configurations have been proposed. The osteoderms ranged from 1 centimeter ( 1 ⁄ 2  in) in diameter to 35.5 cm (14 in) in length, and varied in shape. The osteoderms of Ankylosaurus were generally thin walled and hollowed on

11877-500: Was low and triangular in shape, and wider than it was long; the back of the skull was broad and low. The skull had a broad beak on the premaxillae . The orbits (eye sockets) were almost round to slightly oval and did not face directly sideways because the skull tapered towards the front. The braincase was short and robust, as in other ankylosaurines. Crests above the orbits merged into the upper squamosal horns (their shape has been described as " pyramidal "), which pointed backwards to

11988-506: Was not accepted by other researchers, and the two genera are now considered distinct. Brown had collected 77 osteoderms while excavating a Tyrannosaurus specimen in the Lance Formation of Wyoming in 1900. He mentioned these osteoderms (specimen AMNH 5866) in his description of Ankylosaurus but thought they belonged to the Tyrannosaurus instead. Paleontologist Henry Fairfield Osborn also expressed this view when he described

12099-487: Was probably not a burrowing animal, the snout of Ankylosaurus may indicate earth-moving behavior. These factors, as well as the low rate of tooth formation in ankylosaurs compared to other ornithischians, indicate that Ankylosaurus may have been omnivorous (eating both plant and animal matter). It may also (or alternatively) have dug in the ground for roots and tubers . A 2023 study by paleontologist Antonio Ballell and colleagues found that North American ankylosaurids from

12210-439: Was short, very broad and about 54 cm (1 ft 9 + 1 ⁄ 2  in) long. The femur (thigh bone), also from AMNH 5214, was 67 cm (2 ft 2 + 1 ⁄ 2  in) long and very robust. While the feet of Ankylosaurus are incompletely known, the hindfeet probably had three toes, as is the case in advanced ankylosaurids. The cervical vertebrae had broad neural spines that increased in height towards

12321-451: Was shorter in relation to its body length than those of other ankylosaurids, or that it had the same proportions but with a smaller club. Brown considered Ankylosaurus so distinct that he made it the type genus of a new family , Ankylosauridae, typified by massive, triangular skulls, short necks, stiff backs, broad bodies, and osteoderms. He also classified Palaeoscincus (only known from teeth), and Euoplocephalus (then only known from

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