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137-474: Dilophosaurus ( / d aɪ ˌ l oʊ f ə ˈ s ɔːr ə s , - f oʊ -/ dy- LOH -fə- SOR -əs, -⁠foh- ) is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic , about 186 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserved were collected in 1942. The most complete specimen became

274-666: A Eubrontes trackway and resting trace (SGDS 18.T1) from the St. George dinosaur discovery site in the Moenave Formation of Utah, though the dinosaur itself is not known from the formation, which is slightly older than the Kayenta Formation. Weems stated in 2019 that Eubrontes tracks do not reflect the gracile feet of Dilophosaurus , and argued they were instead made by the bipedal sauropodomorph Anchisaurus . Welles found that Dilophosaurus did not have

411-411: A Navajo councilor. Further specimens have since been found, including an infant. Fossil footprints have also been attributed to the animal, including resting traces. Another species, Dilophosaurus sinensis from China, was named in 1993, but was later found to belong to the genus Sinosaurus . At about 7 m (23 ft) in length, with a weight of about 400 kg (880 lb), Dilophosaurus

548-405: A diastema , a gap in the tooth row (which has also been called a "notch"). Within the subnarial gap was a deep excavation behind the toothrow of the premaxilla, called the subnarial pit, which was walled by a downwards keel of the premaxilla. The outer surface of the premaxilla was covered in foramina (openings) of varying sizes. The upper of the two backward-extending processes of the premaxilla

685-410: A kangaroo . In 2005, paleontologists Phil Senter and James H. Robins examined the range of motion in the forelimbs of Dilophosaurus and other theropods. They found that Dilophosaurus would have been able to draw its humerus backward until it was almost parallel with the scapula, but could not move it forwards to a more than vertical orientation. The elbow could approach full extension and flexion at

822-662: A neck frill , and was depicted as smaller than the real animal. In the summer of 1942, the paleontologist Charles L. Camp led a field party from the University of California Museum of Paleontology (UCMP) in search of fossil vertebrates in Navajo County in northern Arizona . Word of this was spread among the Native Americans there, and the Navajo Jesse Williams brought three members of

959-575: A "coelophysoid stage" in their early evolution. In 2007, paleontologist Nathan D. Smith and colleagues found the crested theropod Cryolophosaurus to be the sister species of Dilophosaurus , and grouped them with Dracovenator and Sinosaurus . This clade was more derived than the Coelophysoidea, but more basal than the Ceratosauria, thereby placing basal theropods in a ladder-like arrangement. In 2012, Carrano and colleagues found that

1096-445: A 2021 article, paleontologist Matthew A. Brown and Rowe stated that these remains showed that Dilophosaurus had jaws strong enough to puncture bone. The fleshy air sacs from its respiratory system that grew into the vertebrae both strengthened and lightened the skeleton, and allowed unidirectional airflow through its lungs, similar to birds and crocodiles, and thereby more oxygen than a bidirectional respiratory system of mammals (wherein

1233-468: A developmental anomaly. Dilophosaurus is known from the Kayenta Formation , and lived alongside dinosaurs such as Scutellosaurus and Sarahsaurus . It was designated as the state dinosaur of Connecticut based on tracks found there. Dilophosaurus was featured in the novel Jurassic Park and its movie adaptation , where it was given the fictional abilities to spit venom and expand

1370-558: A direct descendant of Coelophysis . Paul also considered the possibility that spinosaurs were late-surviving dilophosaurs, based on similarity of the kinked snout, nostril position, and slender teeth of Baryonyx . In 1994, paleontologist Thomas R. Holtz placed Dilophosaurus in the group Coelophysoidea, along with but separate from the Coelophysidae. He placed the Coelophysoidea in the group Ceratosauria. In 2000, paleontologist James H. Madsen and Welles divided Ceratosauria into

1507-596: A distance of ~12 millimeters (0.47 in). The preserved part of the crest in UCMP 77270 is tallest around the midpoint of the antorbital fenestra's length. UCMP 77270 preserves the concave shelf between the bases of the crests, and when seen from the front, they are projected upwards and to the sides at an ~80° angle. Welles found the crests reminiscent of a double-crested cassowary , while Marsh and Rowe stated they were probably covered in keratin or keratinized skin. They pointed out that by comparison with helmeted guineafowl ,

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1644-618: A fenestra at the front of the maxilla and a reduced number of teeth in the maxilla. They suggested that the cranial crests of Cryolophosaurus and Sinosaurus had either evolved convergently , or were a feature inherited from a common ancestor. The following cladogram is based on that published by Hendrickx and colleagues, itself based on earlier studies: Coelophysidae Liliensternus Zupaysaurus Dilophosaurus Dracovenator Ceratosauria Cryolophosaurus Sinosaurus Monolophosaurus Orionides In 2019, paleontologists Marion Zahner and Winand Brinkmann found

1781-447: A good match for Dilophosaurus . The paleontologist Spencer G. Lucas and colleagues stated in 2006 that virtually universal agreement existed that Eubrontes tracks were made by a theropod like Dilophosaurus , and that they and other researchers dismissed Weems' claims. In 2006, Weems defended his 2003 assessment of Eubrontes , and proposed an animal like Dilophosaurus as the possible trackmaker of numerous Kayentapus trackways of

1918-651: 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

2055-628: 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,

2192-400: A partial immature Dilophosaurus specimen. Marsh and Rowe suggested in 2020 that many of the features that distinguished Dilophosaurus from earlier theropods were associated with increased body size and macropredation (preying on large animals). While Marsh and Rowe agreed that Dilophosaurus could have fed on fish and small prey in the fluvial system in its environment, they pointed out that

2329-450: A powerful bite, due to weakness caused by the subnarial gap. He thought that it used its front premaxillary teeth for plucking and tearing rather than biting, and the maxillary teeth further back for piercing and slicing. He thought that it was probably a scavenger rather than a predator, and that if it did kill large animals, it would have done so with its hands and feet rather than its jaws. Welles did not find evidence of cranial kinesis in

2466-409: 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

2603-513: A right angle, but not achieve it completely. The fingers do not appear to have been voluntarily hyperextensible (able to extend backwards, beyond their normal range), but they may have been passively hyperextensible, to resist dislocation during violent movements by captured prey. A 2015 article by Senter and Robins gave recommendations for how to reconstruct the fore limb posture in bipedal dinosaurs, based on examination of various taxa, including Dilophosaurus . The scapulae were held very horizontally,

2740-547: A similar size. A 2005 beam-theory study by the palaeontologist François Therrien and colleagues found that the bite force in the mandible of Dilophosaurus decreased rapidly hindwards in the tooth-throw. This indicates that the front of the mandible, with its upturned chin, " rosette " of teeth, and strengthened symphyseal region (similar to spinosaurids), was used to capture and manipulate prey, probably of relatively smaller size. The properties of its mandibular symphysis were similar to those of felids and crocodilians that use

2877-427: 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. ;

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3014-455: 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

3151-414: A very large Dilophosaurus individual, but found that unlikely, as they estimated the trackmaker would have been 2.83–2.99 m (9 ft 3 + 1 ⁄ 2  in – 9 ft 9 + 3 ⁄ 4  in) tall at the hips, compared to the 1.50–1.75 m (4 ft 11 in – 5 ft 9 in) of Dilophosaurus . The paleontologist Gerard Gierliński examined tridactyl footprints from

3288-542: Is a paleontology museum located on the campus of the University of California, Berkeley . The museum is within the Valley Life Sciences Building (VLSB), designed by George W. Kelham and completed in 1930. Its collections are primarily intended for research and are, thus, not accessible to the public. A limited number of fossils from the collection is on display in the VLSB. Although located on

3425-454: Is a cast of a large footprint catalogued as UCMP 79690-4, with casts of three other prints included in the hypodigm. In 1984, Welles conceded that no way had been found to prove or disprove that the footprints belonged to Dilophosaurus . In 1996, the paleontologists Michael Morales and Scott Bulkey reported a trackway of the ichnogenus Eubrontes from the Kayenta Formation made by a very large theropod. They noted it could have been made by

3562-455: Is considered a nomen nudum , an invalidly published name, and Gay pointed out in 2005 that no significant differences exist between D . "breedorum" and other D. wetherilli specimens. In 2012, Carrano and colleagues found differences between the 1964 specimen and the holotype specimen, but attributed them to variation between individuals rather than species. Paleontologists Christophe Hendrickx and Octávio Mateus suggested in 2014 that

3699-612: 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

3836-460: 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,

3973-474: 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

4110-459: Is the modern crocodile that eats the most fish. The nasal openings were also retracted back on the jaws, similar to spinosaurids, which have even more retracted nasal openings, and this may have limited water splashing into the nostrils during fishing. Both groups also had long arms with well-developed claws, which could help when catching fish. Lake Dixie, a large lake that extended from Utah to Arizona and Nevada, would have provided abundant fish in

4247-704: The Holy Cross Mountains in Poland and concluded in 1991 that they belonged to a theropod like Dilophosaurus . He named the new ichnospecies Grallator ( Eubrontes ) soltykovensis based on them, with a cast of footprint MGIW 1560.11.12 as the holotype. In 1994 Gierliński also assigned footprints from the Höganäs Formation in Sweden discovered in 1974 to G. (E.) soltykovensis . In 1996, Gierliński attributed track AC 1/7 from

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4384-621: 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

4521-824: 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;

4658-604: The Turners Falls Formation of Massachusetts, a resting trace he believed to show feather impressions, to a theropod similar to Dilophosaurus and Liliensternus , and assigned it to the ichnotaxon Grallator minisculus . The paleontologist Martin Kundrát agreed that the track showed feather impressions in 2004, but this interpretation was disputed by the paleontologist Martin Lockley and colleagues in 2003 and

4795-415: The holotype of a new species in the genus Megalosaurus , named M. wetherilli by Samuel P. Welles in 1954. Welles found a larger skeleton belonging to the same species in 1964. Realizing it bore crests on its skull, he assigned the species to the new genus Dilophosaurus in 1970, as Dilophosaurus wetherilli . The genus name means "two-crested lizard", and the species name honors John Wetherill,

4932-419: 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 ,

5069-404: 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,

5206-413: The ulna (lower arm bone) was stout and straight, with a stout olecranon . The hands had four fingers: the first was shorter but stronger than the following two fingers, with a large claw, and the two following fingers were longer and slenderer, with smaller claws. The claws were curved and sharp. The third finger was reduced, and the fourth was vestigial (retained, but without function). The crest of

5343-450: The "best worst-known dinosaur", since the animal was poorly understood despite having been discovered 80 years earlier. A major problem was that previous studies of the specimens did not make clear which parts were original fossils and which were reconstructed in plaster, yet subsequent researchers only had Welles' 1984 monograph to rely on for subsequent studies, muddling understanding of the dinosaur's anatomy. Marsh spent seven years studying

5480-498: The "post-cataclysmic", biologically more impoverished world that followed the Triassic–Jurassic extinction event (wherein about three quarters of life on Earth vanished), 5 to 15 million years before Dilophosaurus appeared. In 2018, Marsh and Rowe reported that the holotype specimen of the sauropodomorph Sarahsaurus bore possible tooth marks scattered across the skeleton that may have been left by Dilophosaurus ( Syntarsus

5617-408: The 1964 specimen was an adult, about one-third larger than the others. Welles later recalled that he thought the crests were as unexpected as finding "wings on a worm". Welles and an assistant subsequently corrected the wall mount of the holotype specimen based on the new skeleton, by restoring the crests, redoing the pelvis, making the neck ribs longer, and placing them closer together. After studying

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5754-493: The 1964 specimen, since he thought it belonged to a different genus. Dilophosaurus was the first well-known theropod from the Early Jurassic, and remains one of the best-preserved examples of that age. In 2001, the paleontologist Robert J. Gay identified the remains of at least three new Dilophosaurus specimens (this number is based on the presence of three pubic bone fragments and two differentially sized femora) in

5891-637: The Berkeley campus, the museum is the primary locality for storing fossils collected statewide. The original fossils, around which the current collection has grown, were those gathered as part of the California Geological Survey from 1860 to 1867. UCMP was one of the first museums to have its own website in the early 1990s, due to its location within a technology-oriented university with a good Internet connection. The site has been applauded for its use of visually appealing graphics,

6028-535: The Culpeper Quarry in Virginia. Weems suggested rounded impressions associated with some of these trackways to represent hand impressions lacking digit traces, which he interpreted as a trace of quadrupedal movement. Milner and colleagues used the new combination Kayentapus soltykovensis in 2009, and suggested that Dilophosauripus may not be distinct from Eubrontes and Kayentapus . They suggested that

6165-568: The Dilophosauridae to include Dilophosaurus and Dracovenator in 2015, and noted that while general uncertainty exists about the placement of this group, it appears to be slightly more derived than the Coelophysoidea, and the sister group to the Averostra . The Dilophosauridae share features with the Coelophysoidea such as the subnarial gap and the front teeth of the maxilla pointing forwards, while features shared with Averostra include

6302-452: The Kayenta Formation of northern Arizona, on two levels 14 m (45 ft) and 112 m (367 ft) below where the original Dilophosaurus specimens were found. The lower footprints were tridactyl (three-toed), and could have been made by Dilophosaurus ; Welles created the new ichnogenus and species Dilophosauripus williamsi based on them, in honor of Williams, the discoverer of the first Dilophosaurus skeletons. The type specimen

6439-543: The age of the Kayenta Formation (it had been suggested to be Late Triassic in age, whereas Welles thought it was Early to Middle Jurassic ), and discovered another skeleton about 400 m ( 1 ⁄ 4  mi) south of where the 1942 specimens had been found. The nearly complete specimen (catalogued as UCMP 77270) was collected with the help of William J. Breed of the Museum of Northern Arizona and others. During preparation of this specimen, it became clear that it

6576-442: The air flows in and out of the lungs). Unidirectional breathing indicates relatively high metabolic rates and therefore high levels of activity, indicating that Dilophosaurus was likely a fast, agile hunter. Brown and Rowe considered Dilophosaurus to have been an apex predator in its ecosystem , and not a scavenger. Welles envisioned Dilophosaurus as an active, clearly bipedal animal, similar to an enlarged ostrich . He found

6713-432: The articulation between the premaxilla and maxilla of the upper jaw was immobile and much more robust than previously thought, and that large-bodied prey could have been grasped and manipulated with the forelimbs during predation and scavenging. They considered the large bite marks on Sarahsaurus specimens alongside shed teeth and the presence of a Dilophosaurus specimen within the same quarry as support for this idea. In

6850-442: 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

6987-399: The base, lenticular (lens-shaped) above, and slightly concave on their outer and inner sides. The largest tooth of the maxilla was either in or near the fourth alveolus, and the height of the tooth crowns decreased hindwards. The first tooth of the maxilla pointed slightly forwards from its alveolus because the lower border of the premaxilla process (which projected backward towards the maxilla)

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7124-404: The belly and feet, similar to down . Other researchers instead interpret these impressions as sedimentological artifacts created as the dinosaur moved, though this interpretation does not rule out that the track-maker could have borne feathers. The skull of Dilophosaurus was large in proportion to the overall skeleton, yet delicate. The snout was narrow in front view, becoming narrower towards

7261-436: The best match for Dilophosaurus . The attribution to Dilophosaurus was primarily based on the wide angle between digit impressions three and four shown by these tracks, and the observation that the foot of the holotype specimen shows a similarly splayed-out fourth digit. Also in 2003, paleontologist Emma Rainforth argued that the splay in the holotype foot was merely the result of distortion, and that Eubrontes would indeed be

7398-436: The bones separating them were sometimes paper-thin. The centra were plano-concave, flat to weakly convex at the front and deeply cupped (or concave) at the back, similar to Ceratosaurus . This indicates that the neck was flexible, though it had long, overlapping cervical ribs, which were fused to the centra. The cervical ribs were slender and may have bent easily. The atlas bone (the first cervical vertebra which attaches to

7535-552: The collection belonged to an infant specimen (MNA P1.3181), the youngest known example of this genus, and one of the earliest known infant theropods from North America, only preceded by some Coelophysis specimens. The juvenile specimen includes a partial humerus, a partial fibula, and a tooth fragment. In 2005, paleontologist Ronald S. Tykoski assigned a specimen (TMM 43646-140) from Gold Spring, Arizona, to Dilophosaurus , but in 2012, paleontologist Matthew T. Carrano and colleagues found it to differ in some details. In 2020,

7672-542: The collections of the Museum of Northern Arizona. The specimens were found in 1978 in the Rock Head Quadrangle, 190 km (120 mi) away from where the original specimens were found, and had been labeled as a "large theropod". Though most of the material is damaged, it is significant in including elements not preserved in the earlier specimens, including part of the pelvis and several ribs. Some elements in

7809-467: The expedition of the fossils. Welles placed the new species in Megalosaurus due to the similar limb proportions of it and M. bucklandii , and because he did not find great differences between them. At the time, Megalosaurus was used as a " wastebasket taxon ", wherein many species of theropods were placed, regardless of their age or locality. Welles returned to Tuba City in 1964 to determine

7946-494: The expedition to some fossil bones he had discovered in 1940. The area was part of the Kayenta Formation , about 32 km (20 mi) north of Cameron near Tuba City in the Navajo Indian Reservation . Three dinosaur skeletons were found in purplish shale , arranged in a triangle, about 9.1 m (30 ft) long at one side. The first was nearly complete, lacking only the front of the skull, parts of

8083-490: The families Ceratosauridae and Dilophosauridae , with Dilophosaurus as the sole member of the latter family. Lamanna and colleagues pointed out in 1998 that since Dilophosaurus was discovered to have had crests on its skull, other similarly crested theropods have been discovered (including Sinosaurus ), and that this feature is, therefore, not unique to the genus, and of limited use for determining interrelationships within their group. Paleontologist Adam M. Yates described

8220-512: The fingers diverged during flexion, and were very hyperextensible. 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 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

8357-442: The first sacral vertebra articulated with the preacetabular process of the ilium, a distinct feature. The centra of the caudal vertebrae were very consistent in length, but their diameter became smaller towards the back, and they went from elliptical to circular in cross-section. The scapulae (shoulder blades) were moderate in length and concave on their inner sides to follow the body's curvature. The scapulae were wide, particularly

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8494-676: The first was short but strong and bore a large claw, the two following fingers were longer and slenderer with smaller claws; the fourth was vestigial . The thigh bone was massive, the feet were stout, and the toes bore large claws. Dilophosaurus has been considered a member of the family Dilophosauridae along with Dracovenator , a group placed between the Coelophysidae and later theropods, but some researchers have not found support for this grouping. Dilophosaurus would have been active and bipedal, and may have hunted large animals; it could also have fed on smaller animals and fish. Due to

8631-411: The forelimbs to have been powerful weapons, strong and flexible, and not used for locomotion. He noted that the hands were capable of grasping and slashing, of meeting each other, and reaching two-thirds up the neck. He proposed that in a sitting posture, the animal would rest on the large "foot" of its ischium, as well as its tail and feet. In 1990, paleontologists Stephen and Sylvia Czerkas suggested that

8768-446: 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

8905-451: The front edges, and 29 to 33 were on the back. At least the second and third teeth of the premaxilla had serrations, but the fourth tooth did not. The teeth were covered in a thin layer of enamel , 0.1 to 0.15 mm (0.0039 to 0.0059 in) thick, which extended far towards their bases. The alveoli were elliptical to almost circular, and all were larger than the bases of the teeth they contained, which may therefore have been loosely held in

9042-419: The front of the skull. The antorbital fenestra was continuous with the side of the crests, which indicates the crests also had air sacs (a ridge of bone forms a roof over the antorbital fenestrae in most other theropods). The orbit was oval, and narrow towards the bottom. The jugal bone had two upwards-pointing processes, the first of which formed part of the lower margin of the antorbital fenestra, and part of

9179-464: The front of their jaws to deliver a powerful bite when subduing prey. The loads exerted on the mandibles were consistent with struggle of small prey, which may have been hunted by delivering slashing bites to wound it, and then captured with the front of the jaws after being too weakened to resist. The prey may then have been moved further back into the jaws, where the largest teeth were located, and killed by slicing bites (similar to some crocodilians) with

9316-437: The front, and smoother than the rest of the maxilla. A foramen called the preanteorbital fenestra opened into this recess at the front bend. Large foramina ran on the side of the maxilla, above the alveoli. A deep nutrient groove ran backward from the subnarial pit along the base of the interdental plates (or rugosae) of the maxilla. Dilophosaurus bore a pair of high, thin, and arched (or plate-shaped) crests longitudinally on

9453-737: 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,

9590-566: The genus Dracovenator from South Africa in 2005, and found it closely related to Dilophosaurus and Zupaysaurus . His cladistic analysis suggested they did not belong in the Coelophysoidea, but rather in the Neotheropoda , a more derived (or "advanced") group. He proposed that if Dilophosaurus was more derived than the Coelophysoidea, the features it shared with this group may have been inherited from basal (or "primitive") theropods, indicating that theropods may have passed through

9727-429: The ground, but the third skeleton was almost gone. The nearly complete first specimen was cleaned and mounted at the UCMP under supervision of the paleontologist Wann Langston , a process that took three men two years. The skeleton was wall-mounted in bas relief , with the tail curved upwards, the neck straightened, and the left leg moved up for visibility, but the rest of the skeleton was kept in its burial position. As

9864-425: The group of crested theropods proposed by Smith and colleagues was based on features that relate to the presence of such crests, but that the features of the rest of the skeleton were less consistent. They instead found that Dilophosaurus was a coelophysoid, with Cryolophosaurus and Sinosaurus being more derived, as basal members of the group Tetanurae . Paleontologist Christophe Hendrickx and colleagues defined

10001-439: The hand. The third toe was the stoutest, and the smaller first toe (the hallux ) was kept off the ground. Welles thought Dilophosaurus a megalosaur in 1954, but revised his opinion in 1970 after discovering that it had crests. By 1974, Welles and the paleontologist Robert A. Long found Dilophosaurus to be a ceratosauroid . In 1984 Welles found that Dilophosaurus exhibited features of both Coelurosauria and Carnosauria ,

10138-402: The humerus. Pronation and supination of the wrists (crossing the radius and ulna bones of the lower arm to turn the hand) was prevented by the radius and ulna joints not being able to roll, and the palms, therefore, faced medially, towards each other. The inability to pronate the wrists was an ancestral feature shared by theropods and other dinosaur groups. The wrist had limited mobility, and

10275-427: The ilium was highest over the ilial peduncle (the downwards process of the ilium), and its outer side was concave. The foot of the pubic bone was only slightly expanded, whereas the lower end was much more expanded on the ischium , which also had a very thin shaft. The hind legs were large, with a slighter longer femur (thigh bone) than tibia (lower leg bone), the opposite of, for example, Coelophysis . The femur

10412-430: The jaws. Though the number of alveoli in the dentary would seem to indicate that the teeth were very crowded, they were rather far apart, due to the larger size of their alveoli. The jaws contained replacement teeth at various stages of eruption. The interdental plates between the teeth were very low. Dilophosaurus had 10 cervical (neck), 14 dorsal (back), and 45 caudal (tail) vertebrae, and air sacs grew into

10549-415: The keratin on the crests of Dilophosaurus could have enlarged them much more than what is indicated by the bone. As only one specimen preserves much of the crests, whether they differed between individuals is unknown. CT scans show that air sacs (pockets of air that provide strength for and lighten bones) were present in the bones that surrounded the brain, and were continuous with the sinus cavities in

10686-449: The known specimens might represent two species of Dilophosaurus based on different skull features and stratigraphic separation, pending thorough description of assigned specimens. Marsh and Rowe concluded in 2020 that there was only one taxon among known Dilophosaurus specimens, and that differences between them were due to their different degree of maturity and preservation. They did not find considerable stratigraphic separation between

10823-633: 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,

10960-494: The limited range of movement and shortness of the forelimbs, the mouth may instead have made first contact with prey. The function of the crests is unknown; they were too weak for battle, but may have been used in visual display , such as species recognition and sexual selection . It may have grown rapidly, attaining a growth rate of 30 to 35 kg (66 to 77 lb) per year early in life. The holotype specimen had multiple paleopathologies , including healed injuries and signs of

11097-420: 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. University of California Museum of Paleontology 37°52′16.18″N 122°15′43.24″W  /  37.8711611°N 122.2620111°W  / 37.8711611; -122.2620111 The University of California Museum of Paleontology ( UCMP )

11234-409: The long claw marks that were used to distinguish Dilophosauripus may be an artifact of dragging. They found that Gigandipus and Anchisauripus tracks may likewise also just represent variations of Eubrontes . They pointed out that differences between ichnotaxa may reflect how the trackmaker interacted with the substrate rather than taxonomy. They also found Dilophosaurus to be a suitable match for

11371-559: The lower jaw. In the phylogenetic analysis accompanying their 2020 redescription, Marsh and Rowe found all specimens of Dilophosaurus to form a monophyletic group, sister to Averostra, and more derived than Cryolophosaurus . Their analysis did not find support for Dilophosauridae, and they suggested cranial crests were a plesiomorphic (ancestral) trait of Ceratosauria and Tetanurae. Various ichnotaxa (taxa based on trace fossils ) have been attributed to Dilophosaurus or similar theropods. In 1971, Welles reported dinosaur footprints from

11508-407: The lower margin of the orbit. A projection from the quadrate bone into the lateral temporal fenestra (opening behind the eye) gave this a reniform (kidney-shaped) outline. The foramen magnum (the large opening at the back of the braincase ) was about half the breadth of the occipital condyle, which was itself cordiform (heart-shaped), and had a short neck and a groove on the side. The mandible

11645-468: The members of the Dilophosauridae to be successive basal sister taxa of the Averostra rather than a monophyletic clade (a natural group), but noted that some of their analyses did find the group valid, containing Dilophosaurus , Dracovenator , Cryolophosaurus , and possibly Notatesseraeraptor as the basal-most member. They therefore provided a diagnosis for the Dilophosauridae, based on features in

11782-403: 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

11919-428: 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

12056-435: The neck, a unique feature. The neural spines of the dorsal vertebrae were also low and expanded front and back, which formed strong attachments for ligaments . Uniquely for this genus, additional laminae emanated from the middle trunk vertebrae's anterior centrodiapophyseal laminae and posterior centrodiapophyseal laminae. The sacral vertebrae which occupied the length of the ilium blade did not appear to be fused. The rib of

12193-459: The new genus in a brief note, rather than wait until the publication of a detailed description. In 1970, Welles coined the new genus name Dilophosaurus , from the Greek words di ( δι ) meaning "two", lophos ( λόφος ) meaning "crest", and sauros ( σαυρος ) meaning "lizard": "two-crested lizard". Welles published a detailed osteological description of Dilophosaurus in 1984, but did not include

12330-512: The outer side of the dentary. The side surface of the surangular bone had a unique pyramidal process in front of the articulation with the quadrate, and this horizontal ridge formed a shelf. The retroarticular process of the mandible (a backwards projection) was long. Dilophosaurus had four teeth in each premaxilla, 12 in each maxilla, and 17 in each dentary. The teeth were generally long, thin, and recurved, with relatively small bases. They were compressed sideways, oval in cross-section at

12467-437: The paleontologist Anthony J. Martin and colleagues in 2004, who considered them as sedimentological artifacts. Martin and colleagues also reassigned the track to the ichnotaxon Fulicopus lyellii . Gierliński and Karol Sabath responded at a conference talk in 2005, pointing out that the algae mat imprint would not only have been present on the stomach, but also the footprints. Based on detailed photos and experiments, they found

12604-502: The paleontologist Matthew C. Lamanna and colleagues found D. sinensis to be identical to Sinosaurus triassicus , a theropod from the same formation, named in 1940. This conclusion was confirmed by paleontologist Lida Xing and colleagues in 2013, and though paleontologist Guo-Fu Wang and colleagues agreed the species belonged in Sinosaurus in 2017, they suggested it may be a separate species, S. sinensis . Dilophosaurus

12741-431: The paleontologists Adam D. Marsh and Timothy B. Rowe comprehensively redescribed Dilophosaurus based on the by then known specimens, including specimen UCMP 77270 which had remained undescribed since 1964. They also removed some previously assigned specimens, finding them too fragmentary to identify, and relocated the type quarry with the help of a relative of Jesse Williams. In an interview, Marsh called Dilophosaurus

12878-423: The pelvis, and some vertebrae. The second was very eroded, included the front of the skull, lower jaws, some vertebrae, limb bones, and an articulated hand. The third was so eroded that it consisted only of vertebral fragments. The first good skeleton was encased in a block of plaster after 10 days of work and loaded onto a truck, the second skeleton was easily collected, as it was almost entirely weathered out of

13015-541: 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

13152-404: The range of motion is greater in elbows covered in soft tissue (such as cartilage , ligaments, and muscles) than what would be indicated by manipulation of bare bones. They found that the humerus of Dilophosaurus could be retracted into a position that was almost parallel with the scapula, protracted to an almost vertical level, and elevated 65°. The elbow could not be flexed past a right angle to

13289-490: The resting orientation of the elbow would have been close to a right angle, and the orientation of the hand would not have deviated much from that of the lower arm. In 2018, Senter and Corwin Sullivan examined the range of motion in the fore limb joints of Dilophosaurus by manipulating the bones, to test hypothesized functions of the fore limbs. They also took into account that experiments with alligator carcasses show that

13426-409: The right crest was right of the midline, and was concave along its middle length. This discovery led to re-examination of the holotype specimen, which was found to have bases of two thin, upwards-extended bones, which were crushed together. These also represented crests, but they had formerly been assumed to be part of a misplaced cheek bone. The two 1942 specimens were also found to be juveniles , while

13563-412: The rounded top. The premaxilla (front bone of the upper jaw) was long and low when seen from the side, bulbous at the front, and its outer surface became less convex from snout to naris (bony nostril). The nostrils were placed further back than in most other theropods. The premaxillae were in close articulation with each other, and while the premaxilla only connected to the maxilla (the following bone of

13700-470: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or

13837-408: 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

13974-492: The sideways-compressed teeth. The authors suggested that if Dilophosaurus indeed fed on small prey, possible hunting packs would have been of limited size. Milner and paleontologist James I. Kirkland suggested in 2007 that Dilophosaurus had features that indicate it may have eaten fish. They pointed out that the ends of the jaws were expanded to the sides, forming a "rosette" of interlocking teeth, similar to those of spinosaurids, known to have eaten fish, and gharials , which

14111-481: The skeletons of North American and European theropods, Welles realized that the dinosaur did not belong to Megalosaurus , and needed a new genus name. At that time, no other theropods with large longitudinal crests on their heads were known, and the dinosaur had therefore gained the interest of paleontologists. A mold of the holotype specimen was made, and fiberglass casts of it were distributed to various exhibits; to make labeling these casts easier, Welles decided to name

14248-501: The skeletons, preliminarily described and named this dinosaur as a new species in the existing genus Megalosaurus , M. wetherilli . The nearly complete specimen (catalogued as UCMP 37302) was made the holotype of the species, and the second specimen (UCMP 37303) was made the paratype . The specific name honored John Wetherill, a Navajo councilor whom Welles described as an "explorer, friend of scientists, and trusted trader". Wetherill's nephew, Milton, had first informed

14385-406: The skull of Dilophosaurus , a feature that allows individual bones of the skull to move in relation to each other. In 1986, the paleontologist Robert T. Bakker instead found Dilophosaurus , with its massive neck and skull and large upper teeth, to have been adapted for killing large prey, and strong enough to attack any Early Jurassic herbivores. In 1988, Paul dismissed the idea that Dilophosaurus

14522-408: The skull roof. The crests (termed the nasolacrimal crests) began as low ridges on the premaxillae and were mainly formed by the upwards expanded nasal and lacrimal bones . These bones were coossified together (fusion during bone tissue formation), so the sutures between them cannot be determined. The lacrimal bone expanded into a thick, rugose preorbital boss, forming an arc at

14659-409: The skull was crushed, it was reconstructed based on the back of the skull of the first specimen and the front of the second. The pelvis was reconstructed after that of Allosaurus , and the feet were also reconstructed. At the time, it was one of the best-preserved skeletons of a theropod dinosaur, though incomplete. In 1954, the paleontologist Samuel P. Welles , who was part of the group who excavated

14796-451: The skull) had a small, cubic centrum, and had a concavity at the front where it formed a cup for the occipital condyle (protuberance that connects with the atlas vertebra) at the back of the skull. The axis bone (the second cervical vertebra) had a heavy spine, and its postzygapophyses (the processes of the vertebrae that articulated with the prezygapophyses of a following vertebrae) were met by long prezygapophyses that curved upwards from

14933-497: 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,

15070-626: The specimens either. A nearly complete theropod skeleton (KMV 8701) was discovered in the Lufeng Formation , in Yunnan Province , China, in 1987. It is similar to Dilophosaurus , with a pair of crests and a gap separating the premaxilla from the maxilla, but differs in some details. The paleontologist Shaojin Hu named it as a new species of Dilophosaurus in 1993, D. sinensis (from Greek Sinai , referring to China). In 1998,

15207-399: The specimens to clarify the issues surrounding the dinosaur, including two specimens found two decades earlier by Rowe, his Ph.D. advisor. In 1984, Welles suggested that the 1964 specimen (UCMP 77270) did not belong to Dilophosaurus , but to a new genus, based on differences in the skull, vertebrae, and femora. He maintained that both genera bore crests, but that the exact shape of these

15344-412: 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

15481-403: 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

15618-407: The teeth there were attached) had an up-curved rather than pointed chin. The chin had a large foramen at the tip, and a row of small foramina ran in rough parallel with the upper edge of the dentary. On the inner side, the mandibular symphysis (where the two halves of the lower jaw connected) was flat and smooth, and showed no sign of being fused with its opposite half. A Meckelian foramen ran along

15755-453: The third cervical vertebra. The centra and neural spines of the cervical vertebrae were long and low, and the spines were stepped in side view, forming "shoulders" at the front and back, as well as taller, central "caps" that gave the appearance of a Maltese cross (cruciform) when seen from above, distinctive features of this dinosaur. The posterior centrodiapophyseal lamina of the cervicals showed serial variation, bifurcating and reuniting down

15892-444: The traces similar to those left by the fibrous feathers (semiplumes) of modern birds, and different from those left by a scaly body. The paleontologist Robert E. Weems proposed in 2003 that Eubrontes tracks were not produced by a theropod, but by a sauropodomorph similar to Plateosaurus , excluding Dilophosaurus as a possible trackmaker. Instead, Weems proposed Kayentapus hopii , another ichnotaxon named by Welles in 1971, as

16029-449: The two main groups into which theropods had hitherto been divided, based on body size, and he suggested this division was inaccurate. He found Dilophosaurus to be closest to those theropods that were usually placed in the family Halticosauridae , particularly Liliensternus . In 1988, paleontologist Gregory S. Paul classified the halticosaurs as a subfamily of the family Coelophysidae , and suggested that Dilophosaurus could have been

16166-401: The upper front border of the orbit (eye socket), and supported the bottom of the back of the crest. Uniquely for this genus, the rim above the orbit continued hindwards and ended in a small, almost triangular process behind the orbit, which curved slightly outwards. Since only a short part of the upper surface of this process is unbroken, the rest of the crest may have risen above the skull over

16303-463: The upper jaw) at the middle of the palate, with no connection at the side, they formed a strong joint through the robust, interlocking articulation between the hindwards and forwards directed processes of these bones. Hindwards and below, the premaxilla formed a wall for a gap between itself and the maxilla called the subnarial gap (also termed a "kink"). Such a gap is also present in coelophysoids , as well as other dinosaurs. The subnarial gap resulted in

16440-416: The upper part, which was rectangular (or squared off), a unique feature. The coracoids were elliptical, and not fused to the scapulae. The lower hind portions of the coracoids had a "horizontal buttress" next to the biceps tuber, unique for this genus. The arms were powerful, and had deep pits and stout processes for attachment of muscles and ligaments. The humerus (upper arm bone) was large and slender, and

16577-576: 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

16714-453: The vertebrae. It had a long neck, which was probably flexed nearly 90° by the skull and by the shoulder, holding the skull in a horizontal posture. The cervical vertebrae were unusually light; their centra (the "bodies" of the vertebrae) were hollowed out by pleurocoels (depressions on the sides) and centrocoels (cavities on the inside). The arches of the cervical vertebrae also had pneumatic fossae (or chonoses), conical recesses so large that

16851-429: 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

16988-501: The weak pelvis of Dilophosaurus could have been an adaptation for an aquatic lifestyle, where the water would help support its weight, and that it could have been an efficient swimmer. They found it doubtful that it would have been restricted to a watery environment, though, due to the strength and proportions of its hind limbs, which would have made it fleet-footed and agile during bipedal locomotion. Paul depicted Dilophosaurus bouncing on its tail while lashing out at an enemy, similar to

17125-530: Was 590 millimeters ( 23 + 1 ⁄ 4  in) long. The smaller holotype specimen weighed about 283 kilograms (624 lb), was 6.03 meters (19 ft 9 + 1 ⁄ 2  in) long, with a hip height of about 1.36 meters (4 ft 5 + 1 ⁄ 2  in), and its skull was 523 millimeters (1 ft 8 + 1 ⁄ 2  in) long. A resting trace of a theropod similar to Dilophosaurus and Liliensternus has been interpreted by some researchers as showing impressions of feathers around

17262-416: Was a larger individual of M. wetherilli , and that it would have had two crests on the top of its skull. Being a thin plate of bone, one crest was originally thought to be part of the missing left side of the skull, which had been pulled out of its position by a scavenger . When it became apparent that it was a crest, it was also realized that a corresponding crest would have been on the left side, since

17399-410: Was a scavenger, and claimed that strictly scavenging terrestrial animals are a myth. He stated that the snout of Dilophosaurus was better braced than had been thought previously, and that the very large, slender maxillary teeth were more lethal than the claws. Paul suggested that it hunted large animals such as prosauropods , and that it was more capable of snapping small animals than other theropods of

17536-400: Was long and low, and formed most of the upper border of the elongated naris. It had a dip towards the font, which made the area by its base concave in profile. The underside of the premaxilla containing the alveoli (tooth sockets) was oval. The maxilla was shallow, and was depressed around the antorbital fenestra (a large opening in front of the eye), forming a recess that was rounded towards

17673-446: Was massive; its shaft was sigmoid -shaped (curved like an 'S'), and its greater trochanter was centered on the shaft. The tibia had a developed tuberosity and was expanded at the lower end. The astragalus bone (ankle bone) was separated from the tibia and the calcaneum , and formed half of the socket for the fibula. It had long, stout feet with three well-developed toes that bore large claws, which were much less curved than those of

17810-476: Was nominated for a Webby Award five times, and received a medal from the Smithsonian Institution . It also had a cameo appearance in the movie Deep Impact , albeit under an incorrect name. Annie Montague Alexander was the first benefactor of the museum, and led some early expeditions. Many notable paleontologists have worked as staff at UCMP. Dates given after each name indicate when

17947-429: Was one of the earliest large predatory dinosaurs , a medium-sized theropod , though small compared to some of the later theropods. It was also the largest known land-animal of North America during the Early Jurassic. Slender and lightly built, its size was comparable to that of a brown bear . The largest known specimen weighed about 400 kilograms (880 lb), measured about 7 meters (23 ft) in length, and its skull

18084-493: Was one of the earliest large predatory dinosaurs and the largest known land-animal in North America at the time. It was slender and lightly built, and the skull was proportionally large, but delicate. The snout was narrow, and the upper jaw had a gap or kink below the nostril. It had a pair of longitudinal, arched crests on its skull; their complete shape is unknown, but they were probably enlarged by keratin . The mandible

18221-414: Was slender and delicate at the front, but deep at the back. The teeth were long, curved, thin, and compressed sideways. Those in the lower jaw were much smaller than those of the upper jaw. Most of the teeth had serrations at their front and back edges. The neck was long, and its vertebrae were hollow, and very light. The arms were powerful, with a long and slender upper arm bone. The hands had four fingers;

18358-470: Was slender and delicate at the front, but the articular region (where it connected with the skull) was massive, and the mandible was deep around the mandibular fenestra (an opening on its side). The mandibular fenestra was small in Dilophosaurus , compared to that of coelophysoids, and reduced from front to back, uniquely for this genus. The dentary bone (the front part of the mandible where most of

18495-428: Was too small to have produced them) scavenging the specimen after it died (the positions of the bones may also have been disturbed by scavenging). An example of such marks can be seen on the left scapula, which has an oval depression on the surface of its upper side, and a large hole on the lower front end of the right tibia. The quarry where the holotype and paratype specimens of Sarahsaurus were excavated also contained

18632-404: Was unknown in Dilophosaurus . Welles died in 1997, before he could name this supposed new dinosaur, and the idea that the two were separate genera has generally been ignored or forgotten since. In 1999, amateur paleontologist Stephan Pickering privately published the new name Dilophosaurus "breedorum" based on the 1964 specimen, named in honor of Breed, who had assisted in collecting it. This name

18769-424: Was upturned. The teeth of the dentary were much smaller than those of the maxilla. The third or fourth tooth in the dentary of Dilophosaurus and some coelophysoids was the largest there, and seems to have fit into the subnarial gap of the upper jaw. Most of the teeth had serrations on the front and back edges, which were offset by vertical grooves, and were smaller at the front. About 31 to 41  serrations were on

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