Erlikosaurus
Encyclopedia
Erlikosaurus is a genus
of herbivorous theropod dinosaur
from the late Cretaceous Period, belonging to the Therizinosaur
idae. Its fossils, a skull and some post-cranial fragments, were found in the Bayan Shireh Formation
of Mongolia
, dating to around 90 million years ago.
. The type species
, Erlikosaurus andrewsi, was named and described by Altangerel Perle
in 1980, in an article co-authored with Rinchen Barsbold, who however, is not indicated as the name-giver of this particular species. Its generic name was taken from that of the demon king Erlik
from Mongolian mythology and the specific name of the American paleontologist Roy Chapman Andrews
. Confusingly, in 1981 Perle again named the species as if it were new, this time spelling the generic name as a Latinised "Erlicosaurus". It is today generally considered that the original name, Erlikosaurus, is valid.
The holotype
, IGM 100/111, was found in layers dating from the Cenomanian
-Santonian
. It consists of a complete skull with lower jaws, some cervical vertebrae fragments, the left humerus
and the right foot. At the time it was the only known therizinosaur (then called segnosaurs) for which a skull had been discovered. This helped shed light on a puzzling and poorly known group of dinosaurs. It still represents the most completely known therizinosaurian skull.
Some scientists have speculated that Erlikosaurus may be the same animal as Enigmosaurus mongoliensis
named in 1983, since the latter was found in the same geologic formation
, and was only known from part of a hip, whereas the pelvis of Erlikosaurus is unknown. This would make Enigmosaurus a junior synonym of Erlikosaurus. However, since the Enigmosaurus hip did not resemble that of Segnosaurus
as closely as would be expected for the Segnosaurus-like Erlikosaurus remains and there is a considerable size difference, paleontologist Rinchen Barsbold disputed the alleged synonymy. Consequently, Enigmosaurus and Erlikosaurus are generally still considered separate genera.
, a strange group of theropods that ate plants instead of meat, and had a backward facing pubis
like an ornithischian
. Also like an ornithischian, its jaws were tipped by a broad rounded bony beak useful for cropping off plants. Behind the beak, separated by an hiatus, there were per side twenty-three small straight coarsely serrated teeth in the maxilla
. The dentary of the lower jaw had more teeth: thirty-one for a total of hundred-eight. The bony nostrils of Erlikosaurus were very large and elongated. Its braincase was swollen at the back by pneumatised bone. Scientists now know some therizinosaurs were feathered, so it is likely that Erlikosaurus was as well. Erlikosaurus had exceptionally long, with a bone core of up to ten centimetres, and very slender claws on its feet, the purpose of which is unclear; G.S. Paul surmised they were used for self-defence.
As it is only known from very fragmentary material, it has been problematic to determine the size of Erlikosaurus, especially as most of the vertebral column
of the holotype is missing. The skull length is twenty-five centimetres; the humerus is thirty centimetres long. It has been estimated to attain an adult body length of six meters (twenty feet). Erlikosaurus may have been more lightly built than close relative Segnosaurus
. Other estimates are lower: in 2010 Gregory S. Paul
gave a length of 4.5 metres, a weight of half a tonne.
. This is confirmed by later cladistic analyses.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of herbivorous theropod 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...
from the late Cretaceous Period, belonging to the Therizinosaur
Therizinosaur
Therizinosaurs are theropod dinosaurs belonging to the clade Therizinosauria. Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People's Republic of China and Western North America...
idae. Its fossils, a skull and some post-cranial fragments, were found in the Bayan Shireh Formation
Bayan Shireh Formation
The Bayan Shireh Formation is a geological formation in Burkhant, Mongolia, that dates to the late Cretaceous period...
of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
, dating to around 90 million years ago.
Discovery and naming
The remains of Erlikosaurus were discovered in 1972 at Bayshin Tsav, during a Soviet-Mogolian expedition in Ömnögovi ProvinceÖmnögovi Province
Ömnögovi is an aimag of Mongolia, located in the south of the country, in the Gobi Desert. Ömnögovi is Mongolia's largest aimag. The capital is Dalanzadgad....
. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, Erlikosaurus andrewsi, was named and described by Altangerel Perle
Altangerel Perle
Altangerel Perle is a Mongolian palaeontologist.He is employed at the National University of Mongolia. He has described species such as Goyocephale lattimorei, Achillobator giganticus and Erlikosaurus andrewsi. He has been honored by Polish palaeontologist Halszka Osmólska, who named the species...
in 1980, in an article co-authored with Rinchen Barsbold, who however, is not indicated as the name-giver of this particular species. Its generic name was taken from that of the demon king Erlik
Erlik
Erlik, or Erlig, is the god of death and underworld in Turkic and Mongolian mythology.According to Siberian mythology, Erlik was the first creation of Tengri or Ulgan, the creator god, but Erlik's pride led to friction between the two, and he was banished to the underworld.In the myths of the...
from Mongolian mythology and the specific name of the American paleontologist Roy Chapman Andrews
Roy Chapman Andrews
Roy Chapman Andrews was an American explorer, adventurer and naturalist who became the director of the American Museum of Natural History. He is primarily known for leading a series of expeditions through the fragmented China of the early 20th century into the Gobi Desert and Mongolia...
. Confusingly, in 1981 Perle again named the species as if it were new, this time spelling the generic name as a Latinised "Erlicosaurus". It is today generally considered that the original name, Erlikosaurus, is valid.
The holotype
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...
, IGM 100/111, was found in layers dating from the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
-Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
. It consists of a complete skull with lower jaws, some cervical vertebrae fragments, the left humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
and the right foot. At the time it was the only known therizinosaur (then called segnosaurs) for which a skull had been discovered. This helped shed light on a puzzling and poorly known group of dinosaurs. It still represents the most completely known therizinosaurian skull.
Some scientists have speculated that Erlikosaurus may be the same animal as Enigmosaurus mongoliensis
Enigmosaurus
Enigmosaurus is a genus of therizinosauroid theropod dinosaur from the Late Cretaceous of Mongolia, central Asia...
named in 1983, since the latter was found in the same geologic formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
, and was only known from part of a hip, whereas the pelvis of Erlikosaurus is unknown. This would make Enigmosaurus a junior synonym of Erlikosaurus. However, since the Enigmosaurus hip did not resemble that of Segnosaurus
Segnosaurus
Segnosaurus is a genus of herbivorous theropod dinosaur belonging to the Therizinosauridae from the Cretaceous of Mongolia.-Discovery and naming:...
as closely as would be expected for the Segnosaurus-like Erlikosaurus remains and there is a considerable size difference, paleontologist Rinchen Barsbold disputed the alleged synonymy. Consequently, Enigmosaurus and Erlikosaurus are generally still considered separate genera.
Description
Erlikosaurus was a therizinosaurTherizinosaur
Therizinosaurs are theropod dinosaurs belonging to the clade Therizinosauria. Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People's Republic of China and Western North America...
, a strange group of theropods that ate plants instead of meat, and had a backward facing 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....
like an ornithischian
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
. Also like an ornithischian, its jaws were tipped by a broad rounded bony beak useful for cropping off plants. Behind the beak, separated by an hiatus, there were per side twenty-three small straight coarsely serrated teeth in the 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...
. The dentary of the lower jaw had more teeth: thirty-one for a total of hundred-eight. The bony nostrils of Erlikosaurus were very large and elongated. Its braincase was swollen at the back by pneumatised bone. Scientists now know some therizinosaurs were feathered, so it is likely that Erlikosaurus was as well. Erlikosaurus had exceptionally long, with a bone core of up to ten centimetres, and very slender claws on its feet, the purpose of which is unclear; G.S. Paul surmised they were used for self-defence.
As it is only known from very fragmentary material, it has been problematic to determine the size of Erlikosaurus, especially as most of the vertebral column
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
of the holotype is missing. The skull length is twenty-five centimetres; the humerus is thirty centimetres long. It has been estimated to attain an adult body length of six meters (twenty feet). Erlikosaurus may have been more lightly built than close relative Segnosaurus
Segnosaurus
Segnosaurus is a genus of herbivorous theropod dinosaur belonging to the Therizinosauridae from the Cretaceous of Mongolia.-Discovery and naming:...
. Other estimates are lower: in 2010 Gregory S. Paul
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
gave a length of 4.5 metres, a weight of half a tonne.
Phylogeny
Erlikosaurus was by Perle assigned to the Segnosauridae, a group today known as the TherizinosauridaeTherizinosauridae
Therizinosauridae is a family of advanced herbivorous or omnivorous theropod dinosaurs. Therizinosaurid fossil remains have been recovered from mid-late Cretaceous Period deposits from Mongolia, China, and the United States.-Classification:...
. This is confirmed by later cladistic analyses.
External links
- Erlikosaurus in the Dinosaur Encyclopedia
- Therizinosauria from Thescelosaurus!