Dilophosaurus‭ (‬Two crested lizard‭)

Short Info

Dilophosaurus‭ (‬Two crested lizard‭)

Phonetic : Di-lo-fo-sore-us.

Named By : Samuel Paul Welles‭ ‬-‭ ‬1970

Diet : Carnivore

Size : Estimated 6 meters long

Type of Dinosaur : Large Theropod

Type Species : D.‭ ‬wetherilli‭ (‬type‭)

Found in : USA,‭ ‬Arizona – Kayenta Formation

When it Lived : Early Jurassic, 190 million years ago

Dilophosaurus (/daI,loUf@’so:r@s [1di-LOHF-oSOR-@s) is the name of a species that belongs to theropod dinosaurs which resided in what is now North America during the Early Jurassic approximately 193 million year ago. Three skeletons were found in the northern part of Arizona in the year 1940 and the two most well preserved ones were discovered in 1942. The most complete specimen was the holotype for a brand new species belonging to the Genus Megalosaurus that was known as M. wetherilli by Samuel P. Welles in 1954. Welles discovered a bigger skull belonging to that same species, in. Noting that it had skull crests and torso, he classified the species into the new Genus Dilophosaurus in the year 1970. It was named Dilophosaurus wetherilli. The name of the genus translates to “two-crested lizard”, and the name of the species honors John Wetherill, a Navajo councilor. Additional specimens have been discovered and include an infant. Footprints have also been linked by the creature, such as the remains of a resting animal. A different species of animal, Dilophosaurus sinensis of China was identified in 1993, however it was later confirmed to be part of the Genus Sinosaurus.

DilophosaurusROM1Eduard Solà, CC BY-SA 3.0, via Wikimedia Commons

With a length of 7 meters (23 feet) in length, and a the weight of around 400 kilograms (880 pounds), Dilophosaurus was one of the first large predatory dinosaurs. It was also the largest known land-based animal in North America at the time. It was thin and well constructed, and the skull was massive, however, it was a delicate. The snout was small and the jaw’s upper part was slender and had a Kink beneath the nostril. The skull had two arched, longitudinal crests that were on the skull. Their exact shape is not known however they are likely increased by the keratin. The mandible was thin and delicate in the front, while it was it was deep in the back. The teeth were long, curving slim, and compressed on the sides. Teeth in the lower jaw were smaller than those in those in the top jaw. The majority of teeth had serrations along their back and front edges. The neck was lengthy, and the vertebrae were hollow and extremely lightweight. The arms were strong with a long, slender the upper arm bone. The hands were equipped with four fingers. The initial was short , but strong and had a big claw. The next two fingers were larger and slimmer with smaller claws. The fourth finger was a slender and weak. Thigh bones were huge and the feet were strong and toes had massive claws.

Dilophosaurus is part of the family Dilophosauridae together with Dracovenator the group which is located between Coelophysidae and theropods later. Dilophosaurus is believed to be active and bipedal. It could have hunted large mammals as well as eaten smaller animals and fish. Because of the restricted mobility and the shortness of the forelimbs, the mouth could rather have been the first to come into contact with the prey. The purpose of the crests remains unclear as they were not strong enough for combat, but could be utilized in visual displays, like the recognition of species and sexual selection. They could have grown extremely fast and reached a in the range of 30-35 kilograms (66 to 77 pounds) annually in early the life of. The holotype specimen showed numerous paleopathologies, which included wounds that healed and indications of an anomaly in development. Dilophosaurus was a species found in the Kayenta Formation which was found with dinosaurs like Megapnosaurus as well as Sarahsaurus. Dilophosaurus was prominent as a character in the novel Jurassic Park and its movie adaptation, in which it was granted the ability to spit out venom and grow the neck frill in addition to being smaller than the actual creature. It was named the official dinosaur for Connecticut in reference to tracks that were found in the state.

The summer of 1942 saw paleontologist Charles L. Camp led an expedition from the University of California Museum of Paleontology (UCMP) to search fossil vertebrates in Navajo County in northern Arizona. The news of the expedition circulated among the Native Americans there, and the Navajo Jesse Williams brought three members of the team to fossil bones that discovered by him in 1940. The region was part of the Kayenta Formation, about 32 km (20 miles) to the north of Cameron close to Tuba City in the Navajo Indian Reservation. The skeletons of three dinosaurs were discovered in shale with a purplish color, which was placed in a triangle roughly 9.1 millimeters (30 feet) in length at one end. The first was close to complete, minus parts of the skull’s front, the parts of the pelvis and some vertebrae. The second was severely damaged, and included the skull’s front as well as lower jaws, vertebrae, limb bones as well as an articulated hand. It was also so degraded that it only contained vertebral fragments. The first solid skeleton was covered in the form of a block made of plaster following 10 days effort and loaded on the truck. The second skeleton was easy to collect because it was nearly completely weathered from the ground, however it was the third that was nearly gone.

The almost complete specimen was cleaned and re-mounted on the UCMP under the supervision of Paleontologist Wann Langston, a process that took three men 2 years. The skeleton was mounted in bas relief with the tail curving upwards and the neck straightened as well as the leg on left moved upwards to increase visibility, however the rest of the skeleton preserved in its burial location. When the skull had been crushed it was rebuilt based on the front on the skull in the original specimen, as well as its frontal part of the other. The pelvis was recreated following the model of Allosaurus as were the feet, which were constructed. In the past, it was considered to be one of the best preserved dinosaur skeletons although it was not complete. In 1954 the paleontologist Samuel P. Welles, who was part of the team who excavated the skeletons preliminary described and named this dinosaur as a novel species belonging to the Genus Megalosaurus, M. wetherilli. The entire sample (catalogued in the form of UCMP 37302) was designated the holotype The second specimen (UCMP 37303) was designated the paratype. The name was chosen to honor John Wetherill, a Navajo councilor who Welles identified as being an “explorer, friend of scientists, and trusted trader”. His nephew, Milton, had first told the expedition about the fossils. Welles put the new species within Megalosaurus because of the similarity in limb proportions between Megalosaurus as well as M. bucklandii, and since he didn’t find significant differences between them. In the past, Megalosaurus could be described as an “wastebasket taxon”, wherein several different species of theropods would be classified regardless of age or geographical location.

Sinosaurus triassicusGhedoghedo, CC BY-SA 3.0, via Wikimedia Commons

Welles visited Tuba City in 1964 to find out its age. Kayenta Formation (it was believed that it was Late Triassic in age, while Welles believed that it could be Early to Middle Jurassic), and found a second skeleton that was located 400 meters (1/4 mile) from the spot the site where the 1942 specimens were discovered. The almost whole piece (catalogued as UCMP 777270) was taken with the assistance of William Breed of the Museum of Northern Arizona as well as other experts. When the specimen was being prepared it was discovered the specimen was an bigger specimen from M. wetherilli, and that it could have two crests at the skull’s top. Since it was a thin piece of bone, the crest was initially believed to be part of the left side missing from the skull, and was ripped out of its location by the predator. After it was realized the crest was indeed a crest it was discovered that the corresponding crest could be on the left side of the skull, since it was located located right of the midline and had a concave shape throughout its middle. The discovery led to the revisiting the holotype specimen. It was found to consist made of two small, upwardly extended bones that were crushed. They also had crests but were thought to belong in a missing cheek bone. The two specimens from 1942 were discovered to be juveniles and one from 1964 was adult and about 1/3 larger than the other specimens. Welles later stated that he believed the crests were as bizarre as discovering “wings on a worm”.

Welles along with an assistant modified an holotype wall mounted, based on the new skeleton in the process of restoring the skull crests and changing the pelvis and neck ribs, making them longer and putting them further apart. After reviewing the skeletons from North American and European theropods, Welles realized that the dinosaur wasn’t part of Megalosaurus and required the creation of a new genus. In the past there were no other theropods that had huge long crests that extended across their heads were recognized and the dinosaur thus attracted the attention of paleontologists. The holotype mold was created and fiberglass molds of it were given to different exhibits. To aid in labelling these casts, Welles decided to name the new genus with short notes, instead of waiting until when he could publish a full description. In the year 1970, Welles coined the new name for the genus Dilophosaurus which is derived from the Greek words di (di) which means “two”, lophos (lophos) meaning “crest”, and sauros (sauros) meaning “lizard”: “two-crested lizard”. Welles published an extensive bone morphological description for Dilophosaurus at the end of 1984 however he was unable to include the specimen from 1964 because he believed it was part of another Genus. Dilophosaurus was one of the first theropods to be well-known from early in Early Jurassic, and remains one of the most preserved examples of the time.

In 2001, Paleontologist Robert J. Gay discovered the remains of at most three brand new Dilophosaurus samples (this quantity is determined by the existence in the pubic bones of three fragments, and two femora of different sizes) within the collection of the Museum of Northern Arizona. The remains were discovered in 1978 within the Rock Head Quadrangle, 190 kilometers (120 miles) far from the place where they were originally discovered and were described as the “large theropod”. Although the majority of the material is damaged, the specimen is notable by containing elements that weren’t preserved in earlier specimens, such as a portion of the pelvis, as well as several ribs. The collection includes a few pieces that were part of one of the specimens that was infant (MNA P1.3181) The most recent specimen from this Genus and among the first known infant theropods in North America, only preceded by a handful of Coelophysis specimens. The juvenile specimen contains the humerus in its partial form and a fibula that is partially encased and an unidentified tooth fragment. In 2005 the paleontologist Ronald S. Tykoski assigned the specimen (TMM 43646-140) from Gold Spring, Arizona, to Dilophosaurus However, in 2012 the paleontologist Matthew T. Carrano and colleagues discovered that it was different in certain aspects.

In the year 2020, paleontologists Adam D. Marsh and Timothy B. Rowe comprehensively revised the description of Dilophosaurus in a manner based on at the time known specimens, such as the specimen UCMP 777270 that had been in obscurity since the year 1964. They also reclaimed previously designated specimens, finding them too fragmented to be identified and then relocated the quarry, with the assistance of a cousin from Jesse Williams. in an interview with Marsh, Marsh declared Dilophosaurus one of the “best worst-known dinosaur”, due to the fact that the animal was not known despite being discovered over 80 years prior. One of the major issues was that prior research on the fossils failed to reveal which of the parts were fossils from the beginning and which were later reconstructed using plaster. However, later researchers had only Welles 1984 monograph to use to conduct subsequent research, which muddy understanding of the anatomy of the dinosaur. Marsh was able to spend seven years studying fossils to resolve the issues around the dinosaur, which included two specimens that were discovered in the past two decades by Rowe the his Ph.D. advisor.

in 1984 Welles claimed that the specimen from 1964 (UCMP 77270) was not part of Dilophosaurus and was instead an entirely new genus because of the differences in skull, vertebrae, as well as the femora. He also claimed that both genera have crests, but the exact form of these was not clear in Dilophosaurus. Welles passed away in 1997 before he was able to name the new dinosaur and the concept that the two genera were distinct genera has been largely dismissed or ignored for a long time. In 1999, paleontologist amateur Stephan Pickering privately published the new name Dilophosaurus “breedorum” based on the 1964 specimen. It was named in the honor of Breed who had helped in the collecting of the specimen. The name is regarded as an invalid nomen nudum or incorrectly published name. Gay has stated in 2005 that there were no substantial differences are evident among D. “breedorum” and other D. wetherilli specimens. The year 2012 was the time that Carrano as well as colleagues discovered some differences among the specimen from 1964 and that of the holotype however, they attributed them to differences among individuals, not species. Paleontologists Christophe Hendrickx and Octavio Mateus have suggested in 2014 that found specimens could represent two distinct species of Dilophosaurus Based on the distinct skull features and stratigraphic distinction, subject to a detailed descriptions of assigned specimens. Marsh and Rowe found in the year 2020, that there existed just one taxon in the known Dilophosaurus specimens and that the differences are due to their distinct levels of maturity and preservation. They didn’t observe any stratigraphic differences between the specimens .

A almost complete skeleton of theropods (KMV 8701.1) was found inside the Lufeng Formation, in Yunnan Province, China, in 1987. It is very similar to Dilophosaurus and has two crests as well as a gap between the maxilla from the premaxilla however, it differs in a few particulars. A paleontologist Shaojin Hu named it as an entirely new type from Dilophosaurus at the time of 1993. D. sinensis (from Greek Sinai, referring to China). In 1998, paleontologist Matthew C. Lamanna and colleagues determined D. sinensis the same as Sinosaurus triassicus, which is a theropod of the same formation designated in 1940. The discovery was confirmed by the paleontologist Lida Xing and her colleagues in 2013, but even while the paleontologist Guo-Fu Wang and colleagues agreed that the species belonged to Sinosaurus in 2017, they suggested that it might be a different kind of species called S. sinensis.

Source: Wikipedia