Дилофозавр: Ерте юра дәуірінен табылған хищник динозавр

Genus of theropod dinosaur from Early Jurassic

Dilophosaurus (/d//aɪ/,/l//oʊ//f//ə/'/s//ɔːr//ə//s//, // //f//oʊ// / dyLOHfəSORəs, 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 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, 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 in length, with a weight of about , Dilophosaurus 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 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; 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 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 per year early in life. The holotype specimen had multiple paleopathologies, including healed injuries and signs of 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 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 the expedition to some fossil bones he had discovered in 1940. The area was part of the Kayenta Formation, about 20 mile (32 km) north of Cameron near Tuba City in the Navajo Indian Reservation. Three dinosaur skeletons were found in purplish shale, arranged in a triangle, about 30 feet (9 m) long at one side. The first was nearly complete, lacking only the front of the skull, parts of 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 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 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 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 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 later recalled that he thought the crests were as unexpected as finding "wings on a worm".

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 was unknown in Dilophosaurus. 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 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 the specimens either. In 1998, 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 was one of the earliest large predatory dinosaurs, a medium sized theropod, though small compared to some of the later theropods. The largest known specimen weighed about , measured about in length, and its skull was long. The smaller holotype specimen weighed about , was long, with a hip height of about , and its skull was long. A resting trace of a theropod similar to Dilophosaurus and Liliensternus has been interpreted by some researchers as showing impressions of feathers around 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 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 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 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. Dilophosaurus bore a pair of high, thin, and arched (or plate shaped) crests longitudinally on the skull roof. The crests (termed the nasolacrimal crests) began as low ridges on the premaxillae and were mainly formed by the upwards expanded and 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 boss, forming an arc at 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 a distance of ~. 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, 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. In 1984 Welles found that Dilophosaurus exhibited features of both Coelurosauria and Carnosauria, 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 2000, paleontologist James H. Madsen and Welles divided Ceratosauria into 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. 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 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. In 2019, paleontologists Marion Zahner and Winand Brinkmann found 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 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. In 1984, Welles conceded that no way had been found to prove or disprove that the footprints belonged to Dilophosaurus. The paleontologist Gerard Gierliński examined tridactyl footprints from 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 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 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 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 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 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. Weems stated in 2019 that Eubrontes tracks do not reflect the gracile feet of Dilophosaurus, and argued they were instead made by the bipedal sauropodopormph Anchisaurus.

Welles found that Dilophosaurus did not have 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 the skull of Dilophosaurus, a feature that allows individual bones of the skull to move in relation to each other. In 1988, Paul dismissed the idea that Dilophosaurus 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 a similar 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 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 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. 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 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.

Welles envisioned Dilophosaurus as an active, clearly bipedal animal, similar to an enlarged ostrich. He found 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. Paul depicted Dilophosaurus bouncing on its tail while lashing out at an enemy, similar to 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 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, 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 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 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 the fingers diverged during flexion, and were very hyperextensible. The Dilophosauripus footprints reported by Welles in 1971 were all on the same level, and were described as a "chicken yard hodge podge" of footprints, with few forming a trackway. The footprints had been imprinted in mud, which allowed the feet to sink down The prints were sloppy, and the varying breadth of the toe prints indicates that mud had clung to the feet. The impressions varied according to differences in the substrate and the manner in which they were made; sometimes, the foot was planted directly, but often a backward or forward slip occurred as the foot came down. The positions and angles of the toes also varied considerably, which indicate they must have been quite flexible. The Dilophosauripus footprints had an offset second toe with a thick base, and very long, straight claws that were in line with the axes of the toe pads. One of the footprints was missing the claw of the second toe, perhaps due to injury. In 2011 the paleontologists Kevin Padian and John R. Horner proposed that "bizarre structures" in dinosaurs in general (including crests, frills, horns, and domes) were primarily used for species recognition, and dismissed other explanations as unsupported by evidence. They noted that too few specimens of cranially ornamented theropods, including Dilophosaurus, were known to test their evolutionary function statistically, and whether they represented sexual dimorphism or sexual maturity. In a response to Padian and Horner the same year, the paleontologists Rob J. Knell and Scott D. Sampson argued that species recognition was not unlikely as a secondary function for "bizarre structures" in dinosaurs, but that sexual selection (used in display or combat to compete for mates) was a more likely explanation, due to the high cost of developing them, and because such structures appear to be highly variable within species. In 2013, paleontologists David E. Hone and Darren Naish criticized the "species recognition hypothesis", and argued that no extant animals use such structures primarily for species recognition, and that Padian and Horner had ignored the possibility of mutual sexual selection (where both sexes are ornamented). Marsh and Rowe agreed in 2020 that the crests of Dilophosaurus likely had a role in species identification or intersexual/intrasexual selection, as in some modern birds. In 2005 Gay found no evidence of the sexual dimorphism suggested by Paul (but supposedly present in Coelophysis), and attributed the variation seen between Dilophosaurus specimens to individual variation and ontogeny (changes during growth). There was no dimorphism in the skeletons, but he did not rule out that there could have been in the crests; more data was needed to determine this. Based on the tiny nasal crests on a juvenile specimen, Yates had tentatively assigned to the related genus Dracovenator, he suggested that these would have grown larger as the animal became adult. Welles found that the replacement teeth of Dilophosaurus and other theropods originated deep inside the bone, decreasing in size the farther they were from the alveolar border. There were usually two or three replacement teeth in the alveoli, with the youngest being a small, hollow crown. The replacement teeth erupted on the outer side of the old teeth. When a tooth neared the gum line, the inner wall between the interdental plates was resorbed and formed a nutrient notch. As the new tooth erupted, it moved outwards to center itself in the alveolus, and the nutrient notch closed over. A 2001 study conducted by paleontologist Bruce Rothschild and colleagues examined 60 Dilophosaurus foot bones for signs of stress fractures (which are caused by strenuous, repetitive actions), but none were found. Such injuries can be the result of very active, predatory lifestyles. In 2016 Senter and Sara L. Juengst examined the paleopathologies of the holotype specimen and found that it bore the greatest and most varied number of such maladies on the pectoral girdle and forelimb of any theropod dinosaur so far described, some of which are not known from any other dinosaur. Only six other theropods are known with more than one paleopathology on the pectoral girdle and forelimbs. The holotype specimen had eight afflicted bones, whereas no other theropod specimen is known with more than four. On its left side, it had a fractured scapula and radius, and fibriscesses (like abscesses) in the ulna and the outer phalanx bone of the thumb. On the right side it had torsion of its humeral shaft, three bony tumors on its radius, a truncated articular surface of its third metacarpal bone, and deformities on the first phalanx bone of the third finger. This finger was permanently deformed and unable to flex. The deformities of the humerus and the third finger may have been due to osteodysplasia, which had not been reported from non avian dinosaurs before, but is known in birds. Affecting juvenile birds that have experienced malnutrition, this disease can cause pain in one limb, which makes the birds prefer to use the other limb instead, which thereby develops torsion. Senter and Sullivan found that the pathologies significantly altered the range of motion in the right shoulder and right third finger of the holotype, and that estimates for range of motion may therefore not match those made for a healthy forelimb. The Kayenta Formation is part of the Glen Canyon Group that includes formations in northern Arizona, parts of southeastern Utah, western Colorado, and northwestern New Mexico. It is composed mostly of two facies, one dominated by siltstone deposition and the other by sandstone. The siltstone facies is found in much of Arizona, while the sandstone facies is present in areas of northern Arizona, southern Utah, western Colorado, and northwestern New Mexico. The formation was primarily deposited by rivers, with the siltstone facies as the slower, more sluggish part of the river system. Kayenta Formation deposition was ended by the encroaching dune field that would become the Navajo Sandstone. The environment was seasonally dry, with sand dunes migrating in and out of the wet environments where animals lived, and has been likened to a river oasis; a waterway lined with conifers and surrounded by sand. Most organisms known so far are vertebrates. Non vertebrates include microbial or "algal" limestone, petrified wood, plant impressions, freshwater bivalves and snails, and invertebrate trace fossils. the frog Prosalirus, the caecilian Eocaecilia, the turtle Kayentachelys, a sphenodontian reptile, lizards, and several early crocodylomorphs including Calsoyasuchus, Eopneumatosuchus, Kayentasuchus, and Protosuchus, and the pterosaur Rhamphinion. Apart from Dilophosaurus, several dinosaurs are known, including the theropods Megapnosaurus, the sauropodomorph Sarahsaurus, a heterodontosaurid, and the thyreophoran Scutellosaurus. Synapsids include the tritylodontids Dinnebitodon, Kayentatherium, and Oligokyphus, morganucodontids,

Welles outlined the taphonomy of the original specimens, changes that happened during their decay and fossilization. The holotype skeleton was found lying on its right side, and its head and neck were recurvedcurved backwardsin the "death pose" in which dinosaur skeletons are often found. This pose was thought to be opisthotonus (due to death spasms) at the time, but may instead have been the result of how a carcass was embedded in sediments. The back was straight, and the hindmost dorsal vertebrae were turned on their left sides. The caudal vertebrae extended irregularly from the pelvis, and the legs were articulated, with little displacement. Welles concluded that the specimens were buried at the place of their deaths, without having been transported much, but that the holotype specimen appears to have been disturbed by scavengers, indicated by the rotated dorsal vertebrae and crushed skull. Gay noted that the specimens he described in 2001 showed evidence of having been transported by a stream. As none of the specimens were complete, they may have been transported over some distance, or have lain on the surface and weathered for some time before transport. They may have been transported by a flood, as indicated by the variety of animals found as fragments and bone breakage. In a 1994 book, Welles said Williams had come back some days later with two Navajo women saying "that's no man's work, that's squaw's work". Dilophosaurus was proposed as the state dinosaur of Arizona by a nine year old boy in 1998, but lawmakers suggested Sonorasaurus instead, arguing that Dilophosaurus was not unique to Arizona. A compromise was suggested that would recognize both dinosaurs, but the bill died when it was revealed that the Dilophosaurus fossils had been taken without permission from the Navajo Reservation, and because they did not reside in Arizona anymore (an 11 year old boy again suggested Sonorasaurus as Arizona's state dinosaur in 2018). Navajo Nation officials subsequently discussed how to get the fossils returned. According to Mayor, one Navajo stated that they do not ask to get the fossils back anymore, but wondered why casts had not been made so the bones could be left, as it would be better to keep them in the ground, and a museum built so people could come to see them there. The geologist J. Bret Bennington noted in 1996 that though Dilophosaurus probably did not have a frill and could not spit venom like in the movie, its bite could have been venomous, as has been claimed for the Komodo dragon. He found that adding venom to the dinosaur was no less allowable than giving a color to its skin, which is also unknown. If the dinosaur had a frill, there would have been evidence for this in the bones, in the shape of a rigid structure to hold up the frill, or markings at the places where the muscles used to move it were attached. He also added that if it did have a frill, it would not have used it to intimidate its meal, but rather a competitor (he speculated it may have responded to a character in the movie pulling a hood over his head). In a 1997 review of a book about the science of Jurassic Park, the paleontologist Peter Dodson likewise pointed out the wrong scale of the film's Dilophosaurus, as well as the improbability of its venom and frill. Bakker pointed out in 2014 that the movie's Dilophosaurus lacked the prominent notch in the upper jaw, and concluded that the movie makers had done a good job at creating a frightening chimaera of different animals, but warned it could not be used to teach about the real animal. Brown and Marsh stated that while these traits were fictitious, they were made believable by being based on the biology of real animals.