Kelmayisaurus
Encyclopedia
Kelmayisaurus is an extinct genus
of carcharodontosaurid
theropod dinosaur
from the early Cretaceous
. Its name refers to the petroleum-producing city of Karamay
in the Xinjiang
province of western China
near where it was found.
and only specimen IVPP V 4022. It consists of a complete left dentary (lower jaw with teeth) and partial left maxilla
. The specimen was found in the Lianmugin Formation
of the Tugulu Group
, dating to the ?Valanginian
-Albian
stages
, around 140 to 100 million years ago. The discovery locality is near Wuerho in the Junggar Basin. It was first named and described by Chinese paleontologist
Dong Zhiming
in 1973
and the type species
is Kelmayisaurus petrolicus. A supposed second species, K. "gigantus", was mentioned by Grady in a children book in 1993 as a gigantic vertebral column coming from a 22 m long specimen, but is a nomen nudum
and probably does not pertain to Kelmayisaurus. It may be a sauropod instead.
due to its scanty remains, and its phylogenetic position was uncertain. It has usually been regarded as a basal
tetanuran of uncertain affinities. However, Kelmayisaurus is diagnosable by the form and presence of a deeply-inset accessory groove on the lateral
side of the dentary, the main toothbearing bone of the lower jaw. Some of its features are like those of carcharodontosaurians, but they are also seen in large megalosauroids
like Megalosaurus
and Torvosaurus
.
In 2011, a redescription of the holotype by Stephen L. Brusatte, Roger B. J. Benson and Xing Xu found Kelmayisaurus to be valid genus of Carcharodontosauridae
with a single autapomorphy
. A phylogenetic analysis of Tetanurae
recovered K. petrolicus as a basal carcharodontosaurid in a trichotomy
with Eocarcharia
and a clade comprising more derived
carcharodontosaurids.
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 carcharodontosaurid
Carcharodontosauridae
Carcharodontosaurids were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria...
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 early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. Its name refers to the petroleum-producing city of Karamay
Karamay
Karamay, Qaramay or Kelamayi is a prefecture-level city in the north of the Xinjiang Uygur Autonomous Region, in northwestern China...
in the Xinjiang
Xinjiang
Xinjiang is an autonomous region of the People's Republic of China. It is the largest Chinese administrative division and spans over 1.6 million km2...
province of western 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...
near where it was found.
Discovery and species
Kelmayisaurus is known from the holotypeHolotype
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 specimen IVPP V 4022. It consists of a complete left dentary (lower jaw with teeth) and partial left 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 specimen was found in the Lianmugin Formation
Lianmugin Formation
The Lianmuqin Formation is an Early Cretaceous geologic formation composed of "interbedded red green and yellow variegated mudstones and siltstones [sic]".. Dinosaur remains have been recovered from the it.-Dinosaurs:-Pterosaurs:-Crurotarsans:...
of the Tugulu Group
Tugulu Group
The Tugulu Group is a geological formation in Xinjiang, China whose strata date back to the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Dinosaurs:-Pterosaurs:-Crurotarsans:-References:...
, dating to the ?Valanginian
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma...
-Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
stages
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
, around 140 to 100 million years ago. The discovery locality is near Wuerho in the Junggar Basin. It was first named and described by Chinese paleontologist
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
Dong Zhiming
Dong Zhiming
Dong Zhiming , from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, is one of China's leading paleontologists. He began working at the IVPP in 1962, learning from Yang Zhongjian who was director at the time...
in 1973
1973 in paleontology
-Insects:-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-New taxa:-Non-mammalian:...
and 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...
is Kelmayisaurus petrolicus. A supposed second species, K. "gigantus", was mentioned by Grady in a children book in 1993 as a gigantic vertebral column coming from a 22 m long specimen, but is a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
and probably does not pertain to Kelmayisaurus. It may be a sauropod instead.
Classification
Kelmayisaurus has been thought to be a nomen dubiumNomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
due to its scanty remains, and its phylogenetic position was uncertain. It has usually been regarded as a basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
tetanuran of uncertain affinities. However, Kelmayisaurus is diagnosable by the form and presence of a deeply-inset accessory groove on the lateral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
side of the dentary, the main toothbearing bone of the lower jaw. Some of its features are like those of carcharodontosaurians, but they are also seen in large megalosauroids
Megalosauroidea
Megalosauroidea is a group of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period.-Classification:...
like Megalosaurus
Megalosaurus
Megalosaurus is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Europe...
and Torvosaurus
Torvosaurus
Torvosaurus is a genus of large theropod dinosaur that lived during the Late Jurassic period...
.
In 2011, a redescription of the holotype by Stephen L. Brusatte, Roger B. J. Benson and Xing Xu found Kelmayisaurus to be valid genus of Carcharodontosauridae
Carcharodontosauridae
Carcharodontosaurids were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria...
with a single autapomorphy
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
. A phylogenetic analysis of 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:...
recovered K. petrolicus as a basal carcharodontosaurid in a trichotomy
Polytomy
A polytomy , meaning many temporal based branches, is a section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies. In a phylogenetic tree, a polytomy is represented as a node which has more than two immediate descending branches...
with Eocarcharia
Eocarcharia
Eocarcharia is a genus of carcharodontosaurid theropod dinosaur from the Early Cretaceous Elrhaz Formation that lived in the Sahara 112 million years ago, in what today is the country of Niger. It was discovered in 2000 on an expedition led by University of Chicago paleontologist Paul Sereno. The...
and a clade comprising more derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
carcharodontosaurids.
External links
- Kelmayisaurus from DinoData.org