Atrociraptor
Encyclopedia
Atrociraptor is a genus
of dromaeosaurid
theropod dinosaur
from the Late Cretaceous
(Lower Maastrichtian
stage
) of Alberta, Canada.
The type
(and only) specimen of Atrociraptor, holotype
RTMP 95.166.1, was in 1995 discovered by Wayne Marshall in layers of the Horseshoe Canyon Formation
, near Drumheller, Alberta
. It consists of parts of the upper and lower jaws — both premaxilla
e, a right maxilla
, both dentaries — teeth and numerous small fragments. The skull appears to have been unusually short and tall. The teeth are relatively straight, but they emerge from the tooth sockets at an angle to the jaw line, resulting in a strongly raked row of teeth. A number of isolated teeth (previously referred to Saurornitholestes
) have also been recovered from the Horseshoe Canyon Formation; they can be recognized by their unusually large serrations.
In 2004 Philip Currie
and David Varricchio named and described the type species
of Atrociraptor: Atrociraptor marshalli. The generic name is derived from Latin
atrox, "savage", and raptor, "seizer". The specific name honours Marshall.
Atrociraptor was about the size of Bambiraptor
. In 2010 Gregory S. Paul
estimated its length at two metres, its weight at fifteen kilogrammes. Atrociraptor differs from Bambiraptor and other velociraptorines in its more isodont dentition — the teeth have different sizes but the same form — and short deep snout. A skull opening, the maxillary fenestra, is relatively large and positioned right above another opening, the promaxillary fenestra, a condition not known from other species.
Atrociraptor was by its describers assigned to the Velociraptorinae
within a larger Dromaeosauridae
. However, in 2009 Currie published a cladistic analysis showing Atrociraptor to be a member of the Saurornitholestinae
.
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 dromaeosaurid
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
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
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...
(Lower Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
stage
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...
) of Alberta, Canada.
The type
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...
(and only) specimen of Atrociraptor, 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...
RTMP 95.166.1, was in 1995 discovered by Wayne Marshall in layers of the Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
, near Drumheller, Alberta
Drumheller, Alberta
Drumheller is a town within the Red Deer River valley in the badlands of east-central Alberta, Canada. It is located northeast of Calgary...
. It consists of parts of the upper and lower jaws — both 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....
e, a right 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...
, both dentaries — teeth and numerous small fragments. The skull appears to have been unusually short and tall. The teeth are relatively straight, but they emerge from the tooth sockets at an angle to the jaw line, resulting in a strongly raked row of teeth. A number of isolated teeth (previously referred to Saurornitholestes
Saurornitholestes
Saurornitholestes is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Alberta, Montana and New Mexico....
) have also been recovered from the Horseshoe Canyon Formation; they can be recognized by their unusually large serrations.
In 2004 Philip Currie
Philip Currie
Philip Henry Wodehouse Currie, 1st Baron Currie GCB , known as Sir Philip Currie between 1885 and 1899, was a British diplomat. He was Ambassador to the Ottoman Empire from 1893 to 1898 and Ambassador to Italy from 1898 to 1902.-Background and education:Currie was the son of Raikes Currie, Member...
and David Varricchio named and described 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 Atrociraptor: Atrociraptor marshalli. The generic name is derived from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
atrox, "savage", and raptor, "seizer". The specific name honours Marshall.
Atrociraptor was about the size of Bambiraptor
Bambiraptor
Bambiraptor is a Late Cretaceous, 75 million year old, bird-like dromaeosaurid theropod dinosaur described by scientists at the University of Kansas, Yale University, and the University of New Orleans....
. 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...
estimated its length at two metres, its weight at fifteen kilogrammes. Atrociraptor differs from Bambiraptor and other velociraptorines in its more isodont dentition — the teeth have different sizes but the same form — and short deep snout. A skull opening, the maxillary fenestra, is relatively large and positioned right above another opening, the promaxillary fenestra, a condition not known from other species.
Atrociraptor was by its describers assigned to the Velociraptorinae
Velociraptorinae
Velociraptorinae is a subfamily of the theropod group Dromaeosauridae. Velociraptorine remains are found mostly in northern hemisphere. In Late Cretaceous, they are mostly present in Mongolia, Romania and China,and in early, in USA. The earliest velociraptorines are probably Nuthetes from the...
within a larger Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...
. However, in 2009 Currie published a cladistic analysis showing Atrociraptor to be a member of the Saurornitholestinae
Saurornitholestinae
Saurornitholestinae is a subfamily of Dromaeosauridae.-Species:...
.
External links
- Atrociraptor at DinoData