Dilophosaurus was one of the largest carnivorous dinosaurs of the Early Jurassic Period. Dilophosaurus gets its name from the two thin crests of bone on the top of its head. These were probably used as a display for courtship purposes. (Its frill and ability to spit venom at its prey is actually made up and there is no proof if it had such abilities) Dilophosaurus has been found in Northern Arizona.
As a more primitive predatory dinosaur, Dilophosaurus didn't have forward facing eyes to give it stereo vision. It may have used scent as an integral part of its hunting technique. It had long and slender, rear-curving teeth in long jaws and strong front arms which would have been effective in grabbing prey. It was fast - probably with a top speed of about 30-mph. Footprints attributed to Dilophosaurus appear in groups, so it may have hunted in small packs. It shares the same overall body configuration as Coelophysis even though Dilophosaurus is currently classified as a member of a different group of theropods rather than Coelophysis and its relatives.
History of discovery[]
Map showing localities in northern Arizona where Dilophosaurus fossils have been collected (squares)
In the summer of 1942, the American 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 32 kilometers (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 meters (30 ft) 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 vertebra fragments. The first good skeleton was encased in a block of plaster after ten 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.
Description[]
Size of the largest known (left) and holotype (right) specimens compared to a human
Dilophosaurus measured around 6 metres (20 ft) long and may have weighed half a ton. Fossils of the animal have been found at the Navajo Indian Reservation, just west of Tuba City, Arizona, USA and in the Kayenta Formation. Just a few tens of feet below the level of the bones, large footprints of carnivorous dinosaurs were found and these may belong to Dilophosaurus. It lived in the Early Jurassic Period, from the Sinemurian to the Pliensbachian stages (193-183 million years ago), and was more primitive than later carnivores of the Jurassic, such as Ceratosaurus or Allosaurus.
The original description was published in 1954, by the renowned paleontologist Samuel Welles. However, at the time, it was thought to be another genus of theropod (Megalosaurus). In 1970, it was recognized to be distinct and given its own generic name Dilophosaurus. Welles later redescribed the entire taxon in 1984, in a more comprehensive paper. Dilophosaurus may be a primitive member of the clade containing both ceratosaurian and tetanuran theropods. Alternatively, some paleontologists classify this genus as a large coelophysoid. Recent Dilophosaurus 'skin imprints', associated with a set of footprints, seemed to suggest that it had feathers but further study revealed these to be impressions of plant material.
Footprints of a Dilophosaurus-like predator have been discovered in the Lavini di Marco area, near Rovereto (Trentino, northern Italy).
Meanehile the Dilophosaurus true diet is unknown; it is assumed that the animal had probably a mixed diet of both terrestrial and aquatic prey; similiar to spinosaurids, as its speculated to be large enough to hunt large prosauropods as well as smaller dinosaurs including the local species of coelophysis (C. kayentakae) and Sarahsaurus. Latest research also concluded the possiblity of fish-hunting on rivers and delta's.
Classification[]
Cast of Coelophysis, with which Dilophosaurus has often been grouped, Redpath Museum
In 1954 Welles thought that Dilophosaurus was a megalosaur, but later in 1970 revised his opinion because he discovered Dilophosaurus had crests. By 1974 Welles and paleontologist Robert A. Long found Dilophosaurus to be a ceratosauroid, and in 1984 he found that Dilophosaurus exhibited features of both Coelurosauria and Carnosauria, the two main groups into which theropods had hitherto been divided, based only on body size, and he suggested this division was inaccurate. Welles found Dilophosaurus to be closest to the theropods that were placed in Halticosauridae, especially Liliensternus.
In 1988 Gregory Paul classified halticosaurs as a subfamily of the family Coelophysidae, and proposed that Dilophosaurus could have been a direct descendant of Coelophysis. He also considered the possibility that spinosaurs were late-surviving dilophosaurs, based off the similar nostril position, kinked snouts, and slender teeth of Baryonyx. In the year 1994, paleontologist Thomas R. Holtz placed Dilophosaurus in the Superfamily Coelophysoidea, along with but separate from the Coelophysidae. Thomas Holtz placed Coelophysoidea in Ceratosauria, and in 2000, paleontologist James H. Madsen and Welles divided Ceratosauria into the families Ceratosauridae and Dilophosauridae.
In 1998 Lamanna and colleagues pointed out 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, thus, not unique to the genus, and of limited use for determining interrelationships within the group. Paleontologist Adam M. Yates described the genus Dracovenator from South Africa in 2005, finding it closely related to Dilophosaurus and Zupaysaurus. His cladistic analysis suggested they did not belong in the Coelophysoidea, but instead in Neotheropoda, a more derived (or '"advanced"') group.
He suggested that if Dilophosaurus was more derived than the Coelophysoidea, the features it had with this grouping may have been inherited from basal (or '"primitive"') theropods, indicating that theropods may have passed through a "coelophysoid stage" in their early evolution.
In the year 2007, Nathan D. Smith and colleagues found the crested theropod Cryolophosaurus to be a 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, as a result of that placing basal theropods in a ladder-like arrangement. In 2012, paleontologist 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.
The paleontologist Christophe Hendrickx, and colleagues defined the Dilophosauridae to include Dilophosaurus and Dracovenator in 2015, noting 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. Dilophosauridae share features with the Coelophysoidea such as the subnarial gap and the front teeth of the maxilla pointing forwards, whilst features shared with Averostra include 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.
In 2019, Marion Zahner and Winand Brinkmann found the members of the Dilophosauridae to be a 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 then provided a diagnosis for Dilophosauridae, based on features in the lower jaw. In the phylogenetic analysis accompanying their 2020 redescription, Rower and Marsh found all specimens of Dilophosaurus to form a monophyletic group, sister to Averostra, and to be more derived than Cryolophosaurus. Their analysis did not find support for Dilophosauridae, and then suggested cranial crests were a plesiomorphic (ancestral) trait of Ceratosauria and Tetanurae.
Ichnology[]
Multiple ichnotaxa (taxa based on trace fossils) have been assigned to Dilophosaurus or other similar theropods. Welles in 1971, reported dinosaur footprints from 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.
Skull and Crests[]
The most distinctive characteristic of Dilophosaurus was the pair of rounded crests on its skull, probably used for display. Studies by Rob Gay (2001) show that these crests may have been larger in one sex than in the other. Another curious skull feature was a notch behind the first row of teeth, giving it an almost crocodile-like appearance. This "notch" existed by virtue of a weak connection between the premaxillary and maxillary bones of the skull. This conformation led to the early hypothesis that Dilophosaurus scavenged off dead carcasses, with the front teeth being too weak to bring down and hold large prey. A similar notch is present in most other species of coelophysoid.
Species[]
There is another species of Dilophosaurus (D. sinensis), which may or may not belong to this genus. It is possibly closer to the bizarre Antarctic theropod Cryolophosaurus, based on the fact that the anterior end of the jugal does not participate in the internal antorbital fenestra and that the maxillary tooth row is completely in front of the orbit and ends anterior to the vertical strut of the lacrimal. This species was recovered from the Yunnan Province of China in 1987, with the prosauropod Yunnanosaurus and later described and named in 1993 by Shaojin Hu.
Paleobiology[]
Reconstructed skull in semi-profile, American Museum of Natural History; note the subnarial gap, large upper teeth, and slender mandible
Meanwhile despite generally depicted as a carnivore; the high potential for a more varied diet; fish, in addition to normal prey items has been recently established by paleontologists. Whereas Some paleontologists have interpreted that Dilophosaurus could be more derived compared to regular theropods.
Latest research has put the possibility that Dilophosaurus could be potential macropredators of their time . Dilophosaurus might have wandered the Early Jurassic landscapes, hunting for small animals and fish. Studies suggest Dilophosaurus did not have a strong bite force, based on weakness on the subnarial gap. Both theories remain intact, although based on fossil bitemarks evidence found on prosauropod remains might indicate the generalist predator interpretation could be more valid. A 2022 study using results from a physics class finds that a Dilophosaurus (if placed in a 100-meter-sprint with Usain Bolt) would have lost by 2 seconds, based on biomechanics and physics.
Paleoecology[]
Restoration of Dilophosaurus chasing Scutellosaurus
Dilophosaurus is known from the Kayenta Formation (which was once primarily deposited by silt-rich rivers with slow-moving water), inhabiting the western North America during the Early Jurassic period, around 201 to 182 million years ago. There, it lived alongside prosauropods (such as Achisaurus) and the armoured Scutellosaurus, as well as an Early Jurassic species of Coelophysis (known as Syntarsus kayentakatae, which coincidentally also bore head crests), once one of the most abundant predators in the Late Triassic. As one of the largest carnivores of its environment, Dilophosaurus is likely to have preyed on large herbivores – although it may also have eaten fish and small reptiles.
JPInstitute.com Description[]
Dilophosaurus was the largest meat-eater of the early Jurassic. It was made famous by the movie Jurassic Park, but the movie did not present an accurate picture of this dinosaur. Because it was the biggest and most ferocious of its time, it would not have needed to be poisonous (it was probably not a "spitter" like in the movie). It is also much larger than the movie version.
Dilophosaurus gets its name from the two thin crests of bone on the top of its head. These were probably used as a display for courtship purposes (scientists don't believe it had a frill on its neck like the movie version). Dilophosaurus has been found in both the U.S. and China, which, although part of the same huge landmass, were still quite a long distance from each other.
As an early predatory dinosaur, Dilophosaurus did not have forward facing eyes to give it stereo vision. It may have used scent as an integral part of its hunting technique. It had long and slender, rear-curving teeth in long jaws and strong front arms which would have been effective in grabbing prey. It was fast - probably with a top speed of about 30-mph. It also had a long tail that could have been used as a whip in a fight. Footprints attributed to Dilophosaurus appear in groups, so it may have hunted in small packs. It shares the same overall body configuration as its ancestor the Coelophysis.
Dinosaur Field Guide Description[]
Dilophosaurus ("double-crested lizard") was one of the first large meat-eating dinosaurs. It was a close relative of the smaller dinosaur Coelophysis. Little Coelophysis lived in the Late Triassic, when Rauisuchus and other reptiles related to the ancestors of crocodilians were the top predators. At the end of the Triassic, however, there was a series of great extinctions, and the giant crocodile relatives became extinct. Dinosaurs then became the top meat-eaters. In general, Dilophosaurus looks like a shorter-necked, more heavily built version of Coelophysis. Like its little relative, Dilophosaurus has a characteristic "kink" in the front of its snout. This probably helped hold on to struggling victims. One dramatic difference (other than size) between the two is the pair of tall crescent-shaped crests along the top of Dilophosaurus's skull. These were very thin and probably used only for display. Footprints that match the feet of Dilophosaurus are found in many parts of the world, dating from Early Jurassic. Since the continents of the Earth were still mostly attached as the supercontinent of Pangaea at this time (see map on page 151), it is possible that the double-crested hunter lived in most parts of the world.
Fun Facts[]
The state fossil of Connecticut is a dinosaur footprint, very likely the footprint of Dilophosaurus or a close relative.
Trivia[]
When the first skeleton of this dinosaur was found (in 1942), it was thought to be from a new species of Megalosaurus. Only later in the lab did paleontologist Sam Welles discover the pair of crests on its head.
Gallery[]
Appearance in other media[]
Jurassic Park[]
- Dilophosaurus was featured in the 1993 Film Jurassic Park and in the original novel by Michael Crichton (on which the film was based). In the film version, it had a retractable frill around its neck, much like a Frilled Lizard, and was able to shoot venom, like a spitting cobra, aiming for the eyes to blind and paralyze its prey. There is no true fossil evidence to support this representation, which was invented by the author and director to heighten suspense. However, this is explained by saying that this was due to genetic tampering with spitting cobra and Austrailian frilled lizard DNA. In the film the director Steven Spielberg reduced its size, from moderately large to about 3 feet tall and 5 feet long - this was so as not to overshadow the main star of the movie, Tyrannosaurus rex. In the novel, the creature was 10 feet tall with no frill and had poisonous saliva that was used in predation by biting or spitting at its prey. In the novel, this trait was discovered by the researchers at Jurassic Park, who planned to remove the glands containing the poison. This plan was not carried out - an autopsy would have been needed to see how to remove the glands, but it would have required killing a Dilophosaurus, which John Hammond, owner of the park, opposed.
- No Dilophosaurus were known to have been held publicly in Jurassic World, nor were listed on its official website as attractions, but the Innovation Center included it in the Holoscape, along with Velociraptor, Spinosaurus & other dinosaurs created by InGen but not kept on display in the park. The glass of the Gyrosphere is designed to protect visitors even from them, meaning that it could have been in the park at one point. During the second Isla Nublar incident, the holographic display of Dilophosaurus was briefly used by Gray Mitchell to distract Delta the Velociraptor while he, Claire Dearing, Owen Grady, and his brother Zach Mitchell escaped the building.
- While not on screen for Jurassic World: Fallen Kingdom, it has been revealed that there are surviving Dilophosaurus populations on Isla Nublar, but they and many other creatures will now face an impending danger in the form of an erupting volcanic eruption from Mount Sibo. However, during the operation to retrieve a bone from the skeleton of the Indominus rex, a man named Jack was briefly startled by the sound of a Dilophosaurus hooting in the jungle near the mercenaries' Main Street campsite. However he resumed his work without encountering the dinosaur, likely because the approaching T. rex scared the smaller predator away. But it is possible that some Dilophosaurus was saved offscreen. In the museum in Lockwood Manor, a statue Dilophosaurus can be seen fighting a statue brown Velociraptor. The Dilophosaurus in the estate is mainly green with red crests and frill. Dilophosaurus was meant to appear proper in Jurassic World: Fallen Kingdom, but it was cut from the final film.
- Dilophosaurus finally makes a physical appearance for the first time since Jurassic Park in Jurassic World: Dominion.
- Jurassic Park merchandise, including toys and video games (such as Jurassic Park: Operation Genesis, Jurassic World: Evolution, LEGO Jurassic World and the arcade games The Lost World: Jurassic Park and Jurassic Park III), often include Dilophosaurus.
- It appears in Jurassic World: The Game as a rare carnivore. Its frills are relatively large.
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