Dilophosaurus
Encyclopedia
Dilophosaurus was a theropod dinosaur
from the Sinemurian
stage of the Early Jurassic
Period, about 193 million years ago. The first specimens were described in 1954, but it was not until over a decade later that the genus received its current name. It is one of the earliest known Jurassic theropods and one of the least understood.
Dilophosaurus has appeared several times in popular culture, such as in the 1993 film Jurassic Park
.
Dilophosaurus measured around six meters (20 ft) long and may have weighed half a ton.
The most distinctive characteristic of Dilophosaurus is the pair of rounded crests on its skull, possibly used for display. Studies by Robert Gay show no indication that sexual dimorphism
was present in the skeleton of Dilophosaurus, but says nothing about crest variation. The teeth of Dilophosaurus are long, but have a fairly small base and expand basally. Another skull feature was a notch behind the first row of teeth, giving Dilophosaurus an almost crocodile-like appearance, similar to the putatively piscivorous spinosaurid dinosaurs. This "notch" existed by virtue of a weak connection between the premaxilla
ry and maxilla
ry 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.
containing both ceratosauria
n and tetanuran
theropods. Alternatively, some paleontologists classify this genus as a large coelophysoid.
The first Dilophosaurus specimens were discovered by Sam Welles in the summer of 1942 in Arizona
. The specimen was brought back to Berkeley
for cleaning and mounting, where it was given the name Megalosaurus wetherilli. Returning to the same formation a decade later to determine from which time period the bones dated, Welles found a new specimen not far from the location of the previous discovery. The specimens were later renamed Dilophosaurus, based on the double crest clearly visible in the new skeleton.
There is another species of Dilophosaurus (D. sinensis), which may or may not belong to this genus. It is possibly closer to the 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.
A third species, D. breedorum, was coined by Samuel Welles through Welles and Pickering (1999). This species was based upon crested specimen UCMP 77270. Welles' original material lacked well-preserved crests, and he suggested that the crested specimens pertained to a different species. He was unable to complete a manuscript describing this during his lifetime, and the name eventually came out in a private publication distributed by Pickering. This species has not been accepted as valid in other reviews of the genus.
on a humerus. A Dilophosaurus wetherilli is also known with an unusually small left humerus compared to a very robust right arm, a possible example of "fluctuating asymmetry". Fluctuating asymmetry
results from developmental disturbances and is more common in populations under stress and can therefore be informative about the quality of conditions a dinosaur lived under.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 60 foot bones referred to Dilophosaurus were examined for signs of stress fracture
, but none were found.
, in which a member of the genus kills a member of Parliament
.
Dilophosaurus is prominently featured in both Michael Crichton
's 1990 novel Jurassic Park and its 1993 movie adaptation
. It is depicted spitting blinding poison, aiming for the eyes to blind and paralyze its prey (much like a spitting cobra
); in the film, it also has a retractable neck frill
around its neck (much like a frill-necked lizard
). There is no evidence to support either the frill or the venom spitting, which was acknowledged by Crichton as creative license. In the film, Steven Spielberg
also reduced the size of Dilophosaurus to 3 foot (0.9144 m) tall and 5 feet (1.5 m) long in order to avoid confusion with the Velociraptor
s. Jurassic Park merchandise, including toys and video games (such as Jurassic Park: Operation Genesis
, Telltale's Jurassic Park: The Game
and the arcade games The Lost World: Jurassic Park
and Jurassic Park III), often include Dilophosaurus.
Despite its inaccuracies, the Jurassic Park depiction of Dilophosaurus has been taken up by others. Several other video games, such as ParaWorld
, Jurassic: The Hunted
, Nanosaur
and Ice Age: Dawn of the Dinosaurs
, feature Dilophosaurus modeled after the representations in Jurassic Park, and The Whitest Kids U'Know sketch "Dinosaur Rap" (a music video for Trevor Moore
's "Gettin' High With Dinosaurs") features a Dilophosaurus, complete with a short frill. A more accurately restored Dilophosaurus was featured in the documentary When Dinosaurs Roamed America
, killing an Anchisaurus
and scaring off a pack of Syntarsus
(now known as Megapnosaurus
). More accurately-sized, yet slightly larger Dilophosaurus wetherilli also make an appearance in the 2008 video game Turok.
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
stage of the Early Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
Period, about 193 million years ago. The first specimens were described in 1954, but it was not until over a decade later that the genus received its current name. It is one of the earliest known Jurassic theropods and one of the least understood.
Dilophosaurus has appeared several times in popular culture, such as in the 1993 film Jurassic Park
Jurassic Park (film)
Jurassic Park is a 1993 American science fiction adventure film directed by Steven Spielberg. The film is based on the novel of the same name by Michael Crichton. It stars Sam Neill, Laura Dern, Jeff Goldblum, Richard Attenborough, Martin Ferrero, and Bob Peck...
.
Description
The most distinctive characteristic of Dilophosaurus is the pair of rounded crests on its skull, possibly used for display. Studies by Robert Gay show no indication that sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
was present in the skeleton of Dilophosaurus, but says nothing about crest variation. The teeth of Dilophosaurus are long, but have a fairly small base and expand basally. Another skull feature was a notch behind the first row of teeth, giving Dilophosaurus an almost crocodile-like appearance, similar to the putatively piscivorous spinosaurid dinosaurs. This "notch" existed by virtue of a weak connection between the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry and maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
ry 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.
Classification
Dilophosaurus may be a primitive member of the cladeClade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
containing both ceratosauria
Ceratosauria
Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. There is presently no universally agreed upon listing of species or diagnostic characters of Ceratosauria, though they were less derived...
n and tetanuran
Tetanurae
Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:...
theropods. Alternatively, some paleontologists classify this genus as a large coelophysoid.
Discovery and species
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
. The specimen was brought back to Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
for cleaning and mounting, where it was given the name Megalosaurus wetherilli. Returning to the same formation a decade later to determine from which time period the bones dated, Welles found a new specimen not far from the location of the previous discovery. The specimens were later renamed Dilophosaurus, based on the double crest clearly visible in the new skeleton.
There is another species of Dilophosaurus (D. sinensis), which may or may not belong to this genus. It is possibly closer to the Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
theropod Cryolophosaurus
Cryolophosaurus
Cryolophosaurus was a large theropod dinosaur, with a crest on its head that looked like a Spanish comb. Due to the resemblance of this feature to Elvis Presley's pompadour haircut from the 1950s, this dinosaur was at one point informally known as "Elvisaurus".Cryolophosaurus was excavated from...
, based on the fact that the anterior end of the jugal
Jugal
The jugal is a skull bone found in most reptiles, amphibians, and birds. In mammals, the jugal is often called the malar or Zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species....
does not participate in the internal antorbital fenestra
Antorbital fenestra
An antorbital fenestra is an opening in the skull, in front of the eye sockets. This skull formation first appeared in archosaurs during the Triassic Period. Living birds today possess antorbital fenestrae, but the feature has been lost in modern crocodilians...
and that the maxillary tooth row is completely in front of the orbit and ends anterior to the vertical strut of the lacrimal
Lacrimal bone
The lacrimal bone, the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders.-Lateral or orbital surface:...
. This species was recovered from the Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
Province of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
in 1987, with the prosauropod Yunnanosaurus
Yunnanosaurus
Yunnanosaurus is a genus of prosauropod dinosaur from the Early to Middle Jurassic Period, a position in time that makes it one of the last prosauropods. It is closely related to Lufengosaurus...
and later described and named in 1993 by Shaojin Hu.
A third species, D. breedorum, was coined by Samuel Welles through Welles and Pickering (1999). This species was based upon crested specimen UCMP 77270. Welles' original material lacked well-preserved crests, and he suggested that the crested specimens pertained to a different species. He was unable to complete a manuscript describing this during his lifetime, and the name eventually came out in a private publication distributed by Pickering. This species has not been accepted as valid in other reviews of the genus.
Paleopathology
One Dilophosaurus wetherilli specimen shows potential damage "due to injury or crushing" to a vertebra, and a potential abscessAbscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...
on a humerus. A Dilophosaurus wetherilli is also known with an unusually small left humerus compared to a very robust right arm, a possible example of "fluctuating asymmetry". Fluctuating asymmetry
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry.-In organisms:Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension....
results from developmental disturbances and is more common in populations under stress and can therefore be informative about the quality of conditions a dinosaur lived under.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, 60 foot bones referred to Dilophosaurus were examined for signs of stress fracture
Stress fracture
A stress fracture is one type of incomplete fracture in bones. It is caused by "unusual or repeated stress" and also heavy continuous weight on the ankle or leg...
, but none were found.
In popular culture
Dilophosaurus appears in the novel CarnosaurCarnosaur (novel)
Carnosaur is a horror novel written by Australian author John Brosnan, under the pseudonym of Harry Adam Knight. A film adaptation was made in 1993 by Adam Simon....
, in which a member of the genus kills a member of Parliament
Member of Parliament
A Member of Parliament is a representative of the voters to a :parliament. In many countries with bicameral parliaments, the term applies specifically to members of the lower house, as upper houses often have a different title, such as senate, and thus also have different titles for its members,...
.
Dilophosaurus is prominently featured in both Michael Crichton
Michael Crichton
John Michael Crichton , best known as Michael Crichton, was an American best-selling author, producer, director, and screenwriter, best known for his work in the science fiction, medical fiction, and thriller genres. His books have sold over 200 million copies worldwide, and many have been adapted...
's 1990 novel Jurassic Park and its 1993 movie adaptation
Jurassic Park (film)
Jurassic Park is a 1993 American science fiction adventure film directed by Steven Spielberg. The film is based on the novel of the same name by Michael Crichton. It stars Sam Neill, Laura Dern, Jeff Goldblum, Richard Attenborough, Martin Ferrero, and Bob Peck...
. It is depicted spitting blinding poison, aiming for the eyes to blind and paralyze its prey (much like a spitting cobra
Spitting cobra
A spitting cobra is one of several species of cobras that have the ability to eject venom from their fangs when defending themselves against predators. The sprayed venom is harmless to intact skin...
); in the film, it also has a retractable neck frill
Neck frill
Neck frill is the popular term for the relatively extensive margin seen on the back of the heads of reptiles with either a bony support such as those present on the skulls of dinosaurs of the suborder Marginocephalia or a cartilaginous one as in the Frill-necked Lizard...
around its neck (much like a frill-necked lizard
Frill-necked Lizard
The frill-necked lizard , also known as the frilled lizard or frilled dragon, is found mainly in northern Australia and southern New Guinea. Its name comes from the large frill around its neck, which usually stays folded against the lizard's body. It is largely arboreal, spending the majority of...
). There is no evidence to support either the frill or the venom spitting, which was acknowledged by Crichton as creative license. In the film, Steven Spielberg
Steven Spielberg
Steven Allan Spielberg KBE is an American film director, screenwriter, producer, video game designer, and studio entrepreneur. In a career of more than four decades, Spielberg's films have covered many themes and genres. Spielberg's early science-fiction and adventure films were seen as an...
also reduced the size of Dilophosaurus to 3 foot (0.9144 m) tall and 5 feet (1.5 m) long in order to avoid confusion with the Velociraptor
Velociraptor
Velociraptor is a genus of dromaeosaurid theropod dinosaur that existed approximately 75 to 71 million years ago during the later part of the Cretaceous Period. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis; fossils...
s. Jurassic Park merchandise, including toys and video games (such as Jurassic Park: Operation Genesis
Jurassic Park: Operation Genesis
Jurassic Park: Operation Genesis is a construction and management simulation video game for the PC, Xbox, and PlayStation 2 based on the novel and film series Jurassic Park. The main point of the game is to recreate Jurassic Park - building a 5 star theme park with dinosaurs, and turning John...
, Telltale's Jurassic Park: The Game
Jurassic Park: The Game
Jurassic Park: The Game is an episodic, downloadable third-person adventure video game developed by Telltale Games that is based on the Jurassic Park franchise. The game, which is the latest of several Universal/Telltale deals, was originally announced in June 2010 before being revealed in the...
and the arcade games The Lost World: Jurassic Park
The Lost World: Jurassic Park (arcade game)
The Lost World: Jurassic Park is a light gun arcade game from Sega. It was released in 1997. It was the follow-up to Sega's 1994 rail shooter based on Jurassic Park, itself named Jurassic Park...
and Jurassic Park III), often include Dilophosaurus.
Despite its inaccuracies, the Jurassic Park depiction of Dilophosaurus has been taken up by others. Several other video games, such as ParaWorld
Paraworld
ParaWorld is a real-time strategy PC game released on September 25, 2006. It was developed by the German company SEK , based in Berlin. The game features more than 50 prehistoric animals, especially dinosaurs and Pleistocene mammals...
, Jurassic: The Hunted
Jurassic: The Hunted
Jurassic: The Hunted is a first-person shooter video game developed by Cauldron HQ and published by Activision. The game was announced on October 16, 2009...
, Nanosaur
Nanosaur
Nanosaur is a science fiction third person shooter video game developed by Pangea Software and published by Ideas From the Deep for Mac OS and Microsoft Windows...
and Ice Age: Dawn of the Dinosaurs
Ice Age: Dawn of the Dinosaurs
Ice Age: Dawn of the Dinosaurs, also known as Ice Age 3, is a 2009 3-D computer animated film. It is the third installment of the Ice Age series, produced by Blue Sky Studios and distributed by 20th Century Fox...
, feature Dilophosaurus modeled after the representations in Jurassic Park, and The Whitest Kids U'Know sketch "Dinosaur Rap" (a music video for Trevor Moore
Trevor Moore
Trevor Paul Moore is an American actor, comedian, writer, and director best known as a founding member of the New York City-based comedy troupe The Whitest Kids U' Know, who had their own sketch comedy series on IFC which ran for five seasons...
's "Gettin' High With Dinosaurs") features a Dilophosaurus, complete with a short frill. A more accurately restored Dilophosaurus was featured in the documentary When Dinosaurs Roamed America
When Dinosaurs Roamed America
When Dinosaurs Roamed America is a two-hour American television program that first aired on Discovery Channel in 2001. It was directed by Pierre de Lespinois and narrated by actor John Goodman...
, killing an Anchisaurus
Anchisaurus
Anchisaurus is a genus of basal sauropodomorph, and was an early herbivorous dinosaur. Until recently it was classed as a member of Prosauropoda. The name comes from the Greek αγχι/agkhi...
and scaring off a pack of Syntarsus
Syntarsus
*Syntarsus is a beetle in the Colydiinae subfamily.*Megapnosaurus, a theropod dinosaur, was formerly called Syntarsus, and is occasionally still referred to as such....
(now known as Megapnosaurus
Megapnosaurus
Megapnosaurus was a dinosaur of the theropod family Coelophysidae, formerly called Syntarsus , living during the Early Jurassic. It was renamed by American entomologist Dr. Michael Ivie , Polish Australian Dr...
). More accurately-sized, yet slightly larger Dilophosaurus wetherilli also make an appearance in the 2008 video game Turok.