Cryolophosaurus
Encyclopedia
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 Antarctica's Early Jurassic (Pliensbachian
stage) Hanson Formation (former the upper Falla Formation) by paleontologist Dr. William Hammer
in 1991. It is the first carnivorous
dinosaur to be discovered in Antarctica and the first dinosaur of any kind from the continent to be officially named (other than birds). Dating from the Early Jurassic
Period, it was originally described as the earliest known tetanuran, though subsequent studies have found that it is probably a dilophosaurid
. Nesbitt (et al., 2009) using the characters of Tawa
found it to be a neither dilophosaurid nor averostran neotheropod but the sister group of a clade composed of dilophosaurids and averostrans
The holotype
and only known individual of Cryolophosaurus is estimated as 6.5 metres (21.3 ft) long and weighing 465 kilograms (1,025.1 lb); this individual may represent a sub-adult and thus not fully grown, however.
A high, narrow skull was discovered, 65 centimeters (25 inches) long. The peculiar nasal crest runs just over the eyes, where it rises up perpendicular to the skull and fans out. It is furrowed, giving it a comb
-like appearance. It is an extension of the skull bones, near the tear ducts, fused on either side to horns which rise from the eye sockets (orbital horns). While other theropods like the Monolophosaurus
have crests, they usually run along the skull instead of across it.
Classification is difficult because Cryolophosaurus has a mix of primitive and advanced characteristics. The leg bone (femur) has traits of early theropods, while the skull resembles much later species of the clade
Tetanurae
, like China's Sinraptor
and Yangchuanosaurus
. Originally, Hammer and colleagues suspected that Cryolophosaurus might be a ceratosaur
or even an early abelisaur, with some traits convergent
with those of more advanced tetanurans, but ultimately concluded that it was itself the earliest known member of the tetanuran group. While a subsequent study by Hammer (along with Smith and Currie) again recovered Cryolophosaurus as a tetanuran, a later (2007) study by the same authors found that it was more closely related to Dilophosaurus
and Dracovenator
than to tetanurans.
in the Beardmore Glacier
region of the Transantarctic Mountains
, by William R. Hammer
, professor at Augustana College
, and his team. The fossils were found in the siliceous siltstone
of the Hanson Formation (formerly the upper Falla Formation) and dated to the Pliensbachian stage of the early Jurassic
.
In 1991, both Hammer and the Ohio State University geologist David Elliot had excavated separate outcroppings near Beardmore Glacier, sharing logistical expenses. Elliot's team first came across the remains of Cryolophosaurus in a rock formation (altitude 13,000 feet (4,000 m) and 400 miles (643.7 km) from the South Pole), and notified Hammer. Over the next three weeks, Hammer excavated 5,000 pounds (2300 kg) of fossil-bearing rock. The team recovered over 100 fossil bones, including those of Cryolophosaurus.
The remains included part of a partially-crushed skull
, a jaw bone (mandible
), parts of the backbone (30 vertebrae), hip bones (the ilium
, ischium, and pubis
), leg bones (femur
and fibula), an ankle bone (tibiotarsus) and foot bones (metatarsals
). These specimens were formally named and described in 1994 by Hammer and William J. Hickerson, in the journal Science
. The name Cryolophosaurus ellioti was derived from the Greek
κρυος (meaning 'cold' or 'frozen'), λοφος (meaning 'crest') and σαυρος (meaning 'lizard'). Hammer and Hickerson named the species C. ellioti after David Elliot, who had made the initial discovery of the fossils.
During the 2003 season, a field team returned and collected more material from the original site. In addition, a second locality was discovered about 30 meters higher in the section on Mt. Kirkpatrick.
The remains of the Cryolophosaurus were found in the Hanson Formation with the remains of Glacialisaurus
(a large basal sauropodomorph), a small pterosaur
, a mammal-like reptile (a tritylodon
t, which is a type of synapsid
about the size of a rat), and another unknown theropod. There were also fossilized tree trunk
s two meters away. The site is about 4,000 meters (13,000 feet) above sea level.
This supports the idea that, even at high altitudes, early Jurassic Antarctica had forest
s populated by a diverse range of species
, at least along the coast. Even though Antarctica was closer to the equator
and the world was considerably warmer than today, the climate
was still cool temperate
. Recent models of Jurassic air flow indicate that coastal areas probably never dropped much below freezing, although more extreme conditions existed inland. Cryolophosaurus was found about 650 kilometres (403.9 mi) from the South Pole
but, at the time it lived, this was about 1000 km (621 mi) or so farther north.
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
dinosaur
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...
, with a crest on its head that looked like a Spanish comb. Due to the resemblance of this feature to Elvis Presley
Elvis Presley
Elvis Aaron Presley was one of the most popular American singers of the 20th century. A cultural icon, he is widely known by the single name Elvis. He is often referred to as the "King of Rock and Roll" or simply "the King"....
's pompadour
Pompadour (hairstyle)
Pompadour is a tall style of men's haircut which takes its name from Madame de Pompadour.There are Latin variants of the hair style more associated with European and Argentine tango fashion trends and occasionally with late 20th century musical genres such as rockabilly and country.The pompadour...
haircut from the 1950s, this dinosaur was at one point informally known as "Elvisaurus".
Cryolophosaurus was excavated from Antarctica's Early Jurassic (Pliensbachian
Pliensbachian
The Pliensbachian is an age of the geologic timescale or stage in the stratigraphic column. It is part of the Early or Lower Jurassic epoch or series and spans the time between 189.6 ± 1.5 Ma and 183 ± 1.5 Ma . The Pliensbachian is preceded by the Sinemurian and followed by the Toarcian.The...
stage) Hanson Formation (former the upper Falla Formation) by paleontologist Dr. William Hammer
William R. Hammer
Dr. William Roy Hammer is a professor at Augustana College in Rock Island, Illinois. He is credited with the discovery of the Cryolophosaurus in 1991. He is originally from Detroit, Michigan.- References :...
in 1991. It is the first carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
dinosaur to be discovered in Antarctica and the first dinosaur of any kind from the continent to be officially named (other than birds). Dating from 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, it was originally described as the earliest known tetanuran, though subsequent studies have found that it is probably a dilophosaurid
Dilophosauridae
Dilophosauridae is a family of early carnivorous dinosaurs. They are well-known for their distinctive head crests, which were probably used for mating displays, or to intimidate rivals. The family was proposed by Alan Charig and Andrew Milner in 1990 to contain only the type genus, Dilophosaurus...
. Nesbitt (et al., 2009) using the characters of Tawa
Tawa (dinosaur)
Tawa is a genus of theropod dinosaur from the Late Triassic period. It is estimated to have been 2 m long...
found it to be a neither dilophosaurid nor averostran neotheropod but the sister group of a clade composed of dilophosaurids and averostrans
Description
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
and only known individual of Cryolophosaurus is estimated as 6.5 metres (21.3 ft) long and weighing 465 kilograms (1,025.1 lb); this individual may represent a sub-adult and thus not fully grown, however.
A high, narrow skull was discovered, 65 centimeters (25 inches) long. The peculiar nasal crest runs just over the eyes, where it rises up perpendicular to the skull and fans out. It is furrowed, giving it a comb
Comb
A comb is a toothed device used in hair care for straightening and cleaning hair or other fibres. Combs are among the oldest tools found by archaeologists...
-like appearance. It is an extension of the skull bones, near the tear ducts, fused on either side to horns which rise from the eye sockets (orbital horns). While other theropods like the Monolophosaurus
Monolophosaurus
Monolophosaurus was a genus of theropod dinosaur from the Middle Jurassic of the Shishugou Formation in what is now Xinjiang, China. It was named for the single crest on top of its skull. The type and only known individual is estimated at...
have crests, they usually run along the skull instead of across it.
Classification
- "Cryolophosaurus is also of significance because it represents the oldest known tetanuran from any continent — it is the only one from the Early Jurassic."
- —William R. Hammer
William R. HammerDr. William Roy Hammer is a professor at Augustana College in Rock Island, Illinois. He is credited with the discovery of the Cryolophosaurus in 1991. He is originally from Detroit, Michigan.- References :...
Clade
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...
Tetanurae
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:...
, like China's Sinraptor
Sinraptor
Sinraptor is a genus of theropod dinosaur from the Late Jurassic. The name Sinraptor comes from the Latin prefix "Sino", meaning Chinese, and "Raptor" meaning thief. The specific name dongi honours Dong Zhiming...
and Yangchuanosaurus
Yangchuanosaurus
Yangchuanosaurus was a theropod dinosaur that lived in China during the late Oxfordian stage of the Late Jurassic, and was similar in size and appearance to its North American contemporary, Allosaurus...
. Originally, Hammer and colleagues suspected that Cryolophosaurus might be a ceratosaur
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...
or even an early abelisaur, with some traits convergent
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
with those of more advanced tetanurans, but ultimately concluded that it was itself the earliest known member of the tetanuran group. While a subsequent study by Hammer (along with Smith and Currie) again recovered Cryolophosaurus as a tetanuran, a later (2007) study by the same authors found that it was more closely related to Dilophosaurus
Dilophosaurus
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...
and Dracovenator
Dracovenator
Dracovenator is the name of a genus of dinosaur from the Early Jurassic. It was a theropod which lived in what is now South Africa.The type species, Dracovenator regenti, was formally described by A.M. Yates in 2006. The genus name is a contraction of the Latin draco, "dragon", and venator, "hunter"...
than to tetanurans.
Discovery
Cryolophosaurus was originally collected during the 1990-91 austral summer on Mount KirkpatrickMount Kirkpatrick
Mount Kirkpatrick is a lofty, generally ice-free mountain in Antarctica's Queen Alexandra Range. Located 8 km west of Mount Dickerson, Mt. Kirkpatrick is the highest point in the Queen Alexandra Range, as well as in its parent range, the Transantarctic Mountains...
in the Beardmore Glacier
Beardmore Glacier
The Beardmore Glacier in Antarctica is one of the largest glaciers in the world, with a length exceeding 160 km . The glacier is one of the main passages from the Ross Ice Shelf through the Queen Alexandra and Commonwealth ranges of the Transantarctic Mountains to the Antarctic Plateau, and was one...
region of the Transantarctic Mountains
Transantarctic Mountains
The three largest mountain ranges on the Antarctic continent are the Transantarctic Mountains , the West Antarctica Ranges, and the East Antarctica Ranges. The Transantarctic Mountains compose a mountain range in Antarctica which extend, with some interruptions, across the continent from Cape Adare...
, by William R. Hammer
William R. Hammer
Dr. William Roy Hammer is a professor at Augustana College in Rock Island, Illinois. He is credited with the discovery of the Cryolophosaurus in 1991. He is originally from Detroit, Michigan.- References :...
, professor at Augustana College
Augustana College (Illinois)
Augustana College is a private liberal arts college located in Rock Island, Illinois, United States. The college enrolls approximately 2,500 students. Covering of hilly, wooded land, Augustana is adjacent to the Mississippi River...
, and his team. The fossils were found in the siliceous siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
of the Hanson Formation (formerly the upper Falla Formation) and dated to the Pliensbachian 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...
.
In 1991, both Hammer and the Ohio State University geologist David Elliot had excavated separate outcroppings near Beardmore Glacier, sharing logistical expenses. Elliot's team first came across the remains of Cryolophosaurus in a rock formation (altitude 13,000 feet (4,000 m) and 400 miles (643.7 km) from the South Pole), and notified Hammer. Over the next three weeks, Hammer excavated 5,000 pounds (2300 kg) of fossil-bearing rock. The team recovered over 100 fossil bones, including those of Cryolophosaurus.
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, a jaw bone (mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
), parts of the backbone (30 vertebrae), hip bones (the ilium
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
, ischium, and pubis
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
), leg bones (femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
and fibula), an ankle bone (tibiotarsus) and foot bones (metatarsals
Metatarsus
The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...
). These specimens were formally named and described in 1994 by Hammer and William J. Hickerson, in the journal Science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
. The name Cryolophosaurus ellioti was derived from the Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
κρυος (meaning 'cold' or 'frozen'), λοφος (meaning 'crest') and σαυρος (meaning 'lizard'). Hammer and Hickerson named the species C. ellioti after David Elliot, who had made the initial discovery of the fossils.
During the 2003 season, a field team returned and collected more material from the original site. In addition, a second locality was discovered about 30 meters higher in the section on Mt. Kirkpatrick.
Paleoecology
Glacialisaurus
Glacialisaurus is a genus of massospondylid sauropodomorph dinosaur. It lived during the Early Jurassic period in what is now central Transantarctic Mountains of Antarctica. It is known from the holotype FMNH PR1823, a partial hind limb and from the referred material FMNH PR1822, a left...
(a large basal sauropodomorph), a small pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
, a mammal-like reptile (a tritylodon
Tritylodon
Trityldon was a genus of tritylodont, one of the most advanced group of cynodont therapsids. They lived in the Early Jurassic and possibly Late Triassic periods along with dinosaurs. They also shared a lot of characteristics with mammals, and were once considered mammals because of overall...
t, which is a type of synapsid
Synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...
about the size of a rat), and another unknown theropod. There were also fossilized tree trunk
Petrified wood
Petrified wood is the name given to a special type of fossilized remains of terrestrial vegetation. It is the result of a tree having turned completely into stone by the process of permineralization...
s two meters away. The site is about 4,000 meters (13,000 feet) above sea level.
This supports the idea that, even at high altitudes, early Jurassic Antarctica had forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s populated by a diverse range of species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, at least along the coast. Even though Antarctica was closer to the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
and the world was considerably warmer than today, the climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
was still cool temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
. Recent models of Jurassic air flow indicate that coastal areas probably never dropped much below freezing, although more extreme conditions existed inland. Cryolophosaurus was found about 650 kilometres (403.9 mi) from the South Pole
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
but, at the time it lived, this was about 1000 km (621 mi) or so farther north.
External links
- Transantarctic Vertebrate Paleontology Project, official website for the NSF project conducting research on Cryolophosaurus and related fauna (photos, research information, publication list, geology, project members...)
- Fryxell Geology Museum (photos, information)