Daemonosaurus
Encyclopedia
Daemonosaurus is a genus
of theropod dinosaur
from the Late Triassic
of New Mexico
. Fossils have been found from deposits in the Chinle Formation
, which is latest Triassic
in age. While theropods had diversified into several specialized groups by this time, Daemonosaurus is a basal
theropod that lies outside the clade
Neotheropoda. Daemonosaurus is unusual among early theropods in that it had a short skull and long protruding teeth. The type species
of Daemonosaurus, D. chauliodus, was described in the journal Proceedings of the Royal Society B in 2011. Because the description has not yet been published, the genus is considered a nomen nudum
. The generic name means "demon reptile" in Greek, while the specific name, derived from Greek χαυλιόδους, means "prominent toothed" in reference to its procumbent front teeth.
, CM 76821, consisting of a skull, some vertebrae, and ribs collected from the Ghost Ranch
quarry in New Mexico in the 1980s. Ghost Ranch is famous for an abundance of fossils of the similar theropod Coelophysis
. Fossils of Coelophysis were present on the same block that contained the skull of Daemonosaurus, which was uncovered by a volunteer at the State Museum of Pennsylvania
.
Based on the proportions of related theropods, Daemonosaurus is estimated to have been around 1.5 m (5 feet) long. The skull of Daemonosaurus differs considerably from all other Triassic theropods. The snout is short and bears large premaxilla
ry and maxilla
ry teeth in the upper jaw. Procumbent teeth project forward from the tips of the upper and lower jaws, which is highlighted in the species name chauliodis that roughly means "buck-toothed".
and Herrerasaurus
from South America
. A phylogenetic analysis conducted in its original description found D. chauliodus to be closely related to Tawa hallae
, a theropod that was described from Ghost Ranch in 2009, and the Neotheropoda. Although the two theropods are closely related, Tawa was found in a quarry that is slightly older than Ghost Ranch. Below is a cladogram
showing the phylogenetic relationships of Daemonosaurus:
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 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 Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
of New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
. Fossils have been found from deposits in the Chinle Formation
Chinle Formation
The Chinle is a geologic formation that is spread across the U.S. states of northern Arizona, Nevada, Utah, western New Mexico, and western Colorado. The Chinle is controversially considered to be synonymous to the Dockum Group in eastern Colorado, eastern New Mexico, southwestern Kansas, the...
, which is latest Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
in age. While theropods had diversified into several specialized groups by this time, Daemonosaurus is 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:...
theropod that lies outside the clade
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...
Neotheropoda. Daemonosaurus is unusual among early theropods in that it had a short skull and long protruding teeth. 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...
of Daemonosaurus, D. chauliodus, was described in the journal Proceedings of the Royal Society B in 2011. Because the description has not yet been published, the genus is considered a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
. The generic name means "demon reptile" in Greek, while the specific name, derived from Greek χαυλιόδους, means "prominent toothed" in reference to its procumbent front teeth.
Description
Daemonosaurus is known from a single 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...
, CM 76821, consisting of a skull, some vertebrae, and ribs collected from the Ghost Ranch
Ghost Ranch
Ghost Ranch is a retreat and education center located close to the village of Abiquiu in Rio Arriba County in north central New Mexico. The conference center and lodgings at Ghost Ranch are run by the Presbyterian Church but open to the general public.-History:Ghost Ranch is part of Piedra...
quarry in New Mexico in the 1980s. Ghost Ranch is famous for an abundance of fossils of the similar theropod Coelophysis
Coelophysis
Coelophysis , meaning "hollow form" in reference to its hollow bones , is one of the earliest known genera of dinosaur...
. Fossils of Coelophysis were present on the same block that contained the skull of Daemonosaurus, which was uncovered by a volunteer at the State Museum of Pennsylvania
State Museum of Pennsylvania
The State Museum of Pennsylvania is a non-profit museum at 300 North Street in downtown Harrisburg, run by the Commonwealth of Pennsylvania through the Pennsylvania Historical and Museum Commission to preserve and interpret the region's history and culture. It is a part of the Pennsylvania State...
.
Based on the proportions of related theropods, Daemonosaurus is estimated to have been around 1.5 m (5 feet) long. The skull of Daemonosaurus differs considerably from all other Triassic theropods. The snout is short and bears large 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 teeth in the upper jaw. Procumbent teeth project forward from the tips of the upper and lower jaws, which is highlighted in the species name chauliodis that roughly means "buck-toothed".
Classification
Daemonosaurus lies outside the clade Neotheropoda, a group that includes more advanced Triassic theropods like Coelophysis and their descendants. With such a basal position, it represents a lineage that extended from the earliest radiation of dinosaurs in the Middle Triassic with forms such as EoraptorEoraptor
Eoraptor was one of the world's earliest dinosaurs. It was a two-legged saurischian, close to the ancestry of theropods and sauropodomorphs. It lived ca. 231.4 million years ago, in what is now the northwestern region of Argentina...
and Herrerasaurus
Herrerasaurus
Herrerasaurus was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in rocks of late Ladinian age in northwestern Argentina...
from South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. A phylogenetic analysis conducted in its original description found D. chauliodus to be closely related to Tawa hallae
Tawa (dinosaur)
Tawa is a genus of theropod dinosaur from the Late Triassic period. It is estimated to have been 2 m long...
, a theropod that was described from Ghost Ranch in 2009, and the Neotheropoda. Although the two theropods are closely related, Tawa was found in a quarry that is slightly older than Ghost Ranch. Below is a cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
showing the phylogenetic relationships of Daemonosaurus: