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= Atrociraptor =
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Introduction
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'Atrociraptor' () is a genus of dromaeosaurid dinosaur that lived
during the Late Cretaceous in what is now Alberta, Canada. The first
specimen, a partial skull, was discovered in 1995 by the fossil
collector Wayne Marshall in the Horseshoe Canyon Formation, about
from the Royal Tyrrell Museum of Palaeontology, where it was brought
for preparation. In 2004, the specimen became the holotype of the new
genus and species 'Atrociraptor marshalli'; the generic name is Latin
for "savage robber", and the specific name references Marshall. The
holotype consists of the (frontmost bones of the upper jaw), a (main
bone of the upper jaw), the (tooth-bearing bones of the lower jaw),
associated teeth, and other skull fragments. Isolated teeth from the
same formation have since been assigned to 'Atrociraptor'.
Estimated to have measured about in length and weighed ,
'Atrociraptor' was a relatively small dromaeosaurid. As a
dromaeosaurid, it would have had a large sickle-claw on the second toe
and had pennaceous feathers. 'Atrociraptor' differs from its
contemporary relatives in that its face is much deeper, and its teeth
are more strongly inclined backwards than in most other dromaeosaurids
and are almost all the same size. It also differed from most relatives
in details of the skull, such as the part of the premaxilla below the
nostril being taller than long, and in that its maxillary fenestra was
larger. The fragmentary nature of the holotype has made the exact
relations of 'Atrociraptor' uncertain; it was initially thought to be
a velociraptorine, but is now considered a saurornitholestine.
'Atrociraptor' is thought to have been specialised for attacking
larger prey than other dromaeosaurids, due to its deep snout. Various
ideas for how dromaeosaurids used their sickle-claws have been
proposed, and 21st-century studies suggest they used them to grasp and
restrain struggling prey while dismembering them with the mouth. The
holotype specimen is known from the Horsethief Member of the
Horseshoe Canyon Formation, which dates to the Maastrichtian age, and
ranges from around 72.2-71.5 million years ago. Assigned teeth from
other parts of the formation indicate it survived for over 2 million
years and across a wide geographic area.
Discovery
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In 1995, the part-time fossil collector Wayne Marshall discovered a
partial skull of a dromaeosaurid (commonly called "raptor") dinosaur
in the Horseshoe Canyon Formation of Drumheller in Alberta, Canada,
about west of the Royal Tyrrell Museum of Palaeontology. Marshall had
previously worked in the museum's mounting shop, helping to construct
exhibits until the museum opened in 1985, and reported fossils to
museum staff as he found them over the years. Jaw fragments and teeth
eroding from the hillside led to the discovery of the dromaeosaur
specimen; Marshall collected the loose fossil fragments and delivered
them to the palaeontologist Philip J. Currie at the museum, and the
remaining parts were later collected. Much of the specimen was in a
relatively hard block of sandstone, and preparation revealed the right
(main bone of the upper jaw) exposed in outer side-view and the right
(tooth-bearing bone of the lower jaw) exposed in inner side view, and
both of these bones were left in the block.
In 2004, Currie and the palaeontologist David Varricchio made the
specimen (catalogued as RTMP 95.166.1) the holotype of the new genus
and species 'Atrociraptor marshalli'. The generic name is derived from
the Latin words , which means , and , . The specific name references
Marshall, the discoverer, and the full name can be translated as
"Marshall's savage robber". Since then, Marshall has led the museum
staff to many important finds. In all, the holotype preserves both
(frontmost bone of the upper jaw, freed from the rock matrix), a right
maxilla, both dentaries (the left one is incomplete), associated teeth
(some having fallen out of their sockets prior to fossilisation), and
numerous bone fragments from the skull. The specimen was not fully
prepared by the time of its original description, so in 2022, the
palaeontologist Mark J. Powers and colleagues used computed tomography
to visualise further details of the skull. Numerous isolated teeth
from the Horseshoe Canyon Formation (some of which had originally been
assigned to 'Saurornitholestes') have since been assigned to
'Atrociraptor'. Some of these were found in a bonebed in Dry Island
Buffalo Jump Provincial Park, which also preserves multiple
'Albertosaurus' individuals.
'Atrociraptor' was featured in the 2022 film 'Jurassic World
Dominion', with the director describing it as more "brutish" than
'Velociraptor' as it appears in the film. A '/Film' writer commented
that while 'Atrociraptor' "might sound like another made-up hybrid
dinosaur invented for the 'Jurassic World' films ... it's a very real
dino with its own Wiki page and everything".
Description
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'Atrociraptor' was a relatively small dromaeosaurid, comparable to
'Velociraptor' in size, and is estimated to have measured about in
length and weighed . As a dromaeosaur, it would have had large arms, a
long tail with vertebrae encased in rod-like extensions, and a large
sickle-claw on the robust, hyper-extendible second toe. Fossils of
other dromaeosaurids, such as 'Zhenyuanlong', show that even
relatively large members of the group had pennaceous feathers, with
large wings on the arms and long feathers on the tail. 'Atrociraptor'
does not have autapomorphies (unique diagnostic features) that can be
used to distinguish it, but it has a unique combination of features
that is so far unknown in relatives. 'Atrociraptor' mainly differs
from its contemporary relatives 'Bambiraptor', 'Saurornitholestes',
and 'Velociraptor' in that its face is much deeper, and in that its
maxillary teeth are more strongly inclined backwards than in most
other dromaeosaurids, and in the teeth being almost all the same size.
The relatively deep premaxillae have four teeth each, the same number
as in other dromaeosaurids. The part of the premaxilla below the
nostril is taller than long from front to back, as in 'Deinonychus',
'Utahraptor', and perhaps 'Dromaeosaurus', while the opposite is the
case for 'Bambiraptor', 'Saurornitholestes', and 'Velociraptor'. There
is an elongated extension below the nostril, the subnarial process,
that is wedged between the and the maxilla, as in other
dromaeosaurids. The almost parallel subnarial and internarial (above
the nostrils) processes are oriented more upwards than hindwards due
to the depth of the snout, unlike in other dromaeosaurids where the
opposite is true. The shallow depression on the side of the premaxilla
that marks the lower front limit of the nostril opening is nested
between the subnarial and internarial processes, while it extends
further to the front in 'Velociraptor'.
The second tooth of the premaxilla is the largest of the four therein,
based on the size of the , as in some relatives. As in
'Saurornitholestes', the front is on the inner hind edge of the
tooth, but more forwards positioned than the hind cutting edge. The
teeth look more J-shaped than D-shaped in cross section. The on the
front and hind cutting edges of the premaxillary teeth have almost the
same basal diameter, though those on the front are taller. There are
2.3-3.0 serrations per 1 mm.
The , an opening in the front of the antorbital fossa (a depression
around the antorbital fenestra, the large opening in front of the
eye), is positioned right under the maxillary fenestra, another
opening. In relatives where both these fenestrae are known, the
promaxillary fenestra is well in front of and below the maxillary
fenestra. The maxilla is roughly triangular and relatively deeper than
in other dromaeosaurids. The height between the maxillary fenestra and
the tooth-bearing margin of the maxilla is more than twice the height
of the largest tooth in 'Atrociraptor', whereas it is less than twice
in other dromaeosaurids. If the teeth can be assumed to have had the
same relative height among dromaeosaurids, the short and deep
appearance of the maxilla of 'Atrociraptor' could be due to the snout
having an increased depth rather than because the snout was shortened.
The antorbital fenestra of 'Atrociraptor' was relatively small
compared to in other dromaeosaurids, with the portion in the maxilla
taking up less than 43% its length, and the antorbital fossa also
appears to have been relatively smaller. The rounded maxillary
fenestra is larger than in relatives, and had a diameter of about 1 cm
when complete. In front of a depression on the side at the back of the
maxilla, the margin of the antorbital fossa slopes forwards and up at
a higher angle than in other dromaeosaurids. Right above the margin of
the tooth sockets, the maxilla has a row of neurovascular foramina
(which supplied blood). The lower margin of the maxilla is strongly
convex when seen from the side.
The maxilla contains eleven teeth (comparable to most other
dromaeosaurids), which are closely packed in their sockets with no
gaps between them. The maxillary teeth are narrow from side to side,
blade-like, and have a distinct inclination towards the back and down;
only the teeth of 'Bambiraptor' and 'Deinonychus' are similarly
inclined. The maxillary dentition is almost isodont (the teeth being
of similar size), and, unusually for dromaeosurids, there are no gaps
left by shed teeth in the holotype. The teeth vary little in overall
height, while in 'Velociraptor' every other tooth is noticeably longer
than those next to it. The maxillary teeth have larger serrations on
their hind cutting edge, 3-4.5 per mm, than their front, 5-8 per mm.
The serrations on the hind edge have relatively straight shafts with
hooked tips, and are taller than the serrations at the front. The
front and hind cutting edges lie on the midline of the maxillary teeth
like in relatives but unlike 'Dromaeosaurus', and the teeth are
generally comparable to those of 'Bambiraptor', 'Deinonychus',
'Saurornitholestes', and 'Velociraptor'.
The dentary of 'Atrociraptor' is similar to those of other
dromaeosaurids. The upper and lower margins are almost parallel,
though the height decreases somewhat towards the back of the
tooth-bearing part. The (an opening at the side of the lower jaw)
appears to have been small and set low as in relatives, and the
dentary has two rows of nutritive foramina. The dentary is thin from
side to side, the Meckelian canal is shallow, the dental shelf narrow,
and the dental plates are fused to each other and to the dentary's
margin, as in relatives. The complete number of tooth sockets in the
dentary is unknown; there are ten sockets in the right dentary and six
in the left. The complete number is estimated to have been twelve or
thirteen. The teeth of the dentary appear to be generally smaller than
those in the maxilla, and they are not as strongly inclined backwards.
Like the maxillary teeth, they are narrow and as blade-like. The
serrations at the front are smaller and more numerous, 5-8 per mm,
than those behind, 3.5-5.
Classification
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Within Dromaeosauridae, 'Atrociraptor' is a member of Eudromaeosauria
(or "true dromaeosaurids"), a group that includes the subfamilies
Saurornitholestinae, Velociraptorinae, and Dromaeosaurinae. Below is
a cladogram showing the position of Eudromaeosauria within
Dromaeosauridae.
The pattern of eudromaeosaur dispersal is controversial among
scientists. Some researchers have suggested that saurornitholestines
are the earliest-diverging members of this group. If that is the case,
it suggests a North American origin for Eudromaeosauria. However, if
saurornitholestines are more closely related to velociraptorines, then
they may have immigrated to North America from Asia closer to the end
of the Cretaceous. The general uncertainty of the internal
classification of Eudromaeosauria complicates discussion of the
placement of 'Atrociraptor'. This is compounded by the incompleteness
of the known remains (four skull bones and several teeth). The skull
and teeth of 'Atrociraptor' bear similarities to many dromaeosaur taxa
including 'Dromaeosaurus', 'Shri', 'Saurornitholestes', and 'Kuru'.
For this reason, some studies fully omit 'Atrociraptor' from the
presentation of their findings in order to improve the clarity of the
interrelationships they found in their phylogenetic analyses.
When 'Atrociraptor' was first described in 2004, it was found to be
closely related to 'Deinonychus' and assigned to the dromaeosaurid
subfamily Velociraptorinae, a group known predominantly from the Late
Cretaceous of Asia. This was based on the difference in size between
the front and back serrations on the maxillary teeth and the size of
the second premaxillary tooth. The describers cautioned that this
position might change if more fossil material was found. A 2009
analysis by the palaeontologist Nicholas Longrich and Currie instead
grouped 'Atrociraptor' with 'Saurornitholestes' as part of a new
subfamily: Saurornitholestinae. By 2012, the palaeontologist Alan H.
Turner and colleagues stated that the three phylogenetic analyses
featuring 'Atrociraptor' so far had such disparate results that there
was no consensus regarding its affinity to other dromaeosaurids.
In their 2013 description of 'Acheroraptor', the palaeontologist David
Evans and colleagues suggested that 'Atrociraptor' was the sister
taxon of the much older genus 'Deinonychus' in a clade more advanced
than Saurornitholestinae but outside of both Velociraptorinae and
Dromaeosaurinae. This analysis used the same phylogenetic data set as
the earlier analysis by Longrich and Currie, but included additional
taxa which had been described in the interim. The analysis that
accompanied the 2015 description of 'Dakotaraptor' by the
palaeontologist Robert DePalma and colleagues suggested that
'Atrociraptor' was a member of Dromaeosaurinae, alongside
'Deinonychus', although they did not directly comment on the placement
of 'Atrociraptor' in their analysis. A similar result to DePalma and
colleagues was found by the palaeontologists William and Kristen
Parsons later in 2015.
By the 2020s, dromaeosaurid systematics included several unique
phylogenetic datasets which have produced slightly different results.
One of these datasets is the so-called "TWiG matrix" (an abbreviation
for the Theropod Working Group), developed by the palaeontologists
Steven Brusatte, Andrea Cau, Mark Norell, and several other
researchers, which contains data for most named coelurosaurian taxa
and is updated regularly by new authors. Other matrices include the
matrix published by Mark Powers, the one published by Scott Hartman
and colleagues, and one produced by Philip Currie and David Evans. In
many of the most updated analyses for each of these matrices,
including data from recently described taxa, 'Atrociraptor' has been
consistently found to be a member of Saurornitholestinae.
The results of two analyses, displaying two of the possible hypotheses
of the affinities of 'Atrociraptor', are shown below.
;Evans, Larson, & Currie 2013
{{clade| style=font-size:85%; line-height:85%
|label1=Eudromaeosauria
|1={{clade
|label1=Saurornitholestinae
|1=
|2={{clade
|1=
|2={{clade
|label1=Dromaeosaurinae
|1=
|label2=Velociraptorinae
|2=
}}
}}
}}
}}
;Czepiński 2023
{{clade| style=font-size:85%; line-height:85%
|label1=Eudromaeosauria
|1={{clade sequential
|1='Adasaurus'
|label2=Velociraptorinae
|2={{clade
|1='Kuru'
|2=
}}
|3={{clade
|label1=Dromaeosaurinae
|1=
|label2=Saurornitholestinae
|2={{clade
|1='Deinonychus'
|2=
}}
}}
}}
}}
Palaeobiology
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The palaeontologist Gregory S. Paul suggested in 2016 that
'Atrociraptor' was able to attack relatively large prey and to wound
it more than its relatives with its strong head and teeth. Powers and
colleagues noted in 2022 that all dromaeosaurids with their deep
maxillae are considered to have been predators, based on their
relatively large size, few yet large serrated teeth, recurved claws
including their sickle-claws, and a very developed olfactory system
(sense of smell). The development of deep snouts in addition was
probably an adaptation for handling vertebrate prey; velociraptorines
with their elongated snouts that allowed for rapid biting at the cost
of power perhaps specialised in smaller prey in their desert
environments, and the small-bodied 'Acheroraptor' and
'Saurornitholestes' with their intermediate snout dimensions may have
had more generalised diets in their more diverse ecosystems. The
diverse and abundant prey in the environments of 'Atrociraptor' and
'Deinonychus' may have allowed for more specialised diets of
large-bodied prey for these deep-snouted dromaeosaurids.
Dromaeosaurids are thought to have used the large sickle-claws on
their second toes to deal with prey, and theories about how this was
done have ranged from using the claws for slashing to climbing up prey
larger than themselves. A 2011 study by the palaeontologist Denver W.
Fowler and colleagues found these ideas unlikely, and instead
suggested the claws were used like those of modern birds of prey, to
grip and pin down prey, and immobilise it while dismembering it with
the mouth. Fowler and colleagues called this the "Raptor Prey
Restraint" model, and added that the grasping feet showed a shift to
using the feet instead of the hands for restraining prey, as the
forelimbs became increasingly feathered. The forelimbs could instead
have been used for "stability flapping" as seen in birds of prey,
which, along with movement of the tail, would have helped the predator
stay in position when struggling with the prey. In 2019, the
palaeontologist Peter J. Bishop examined the biomechanics of
dromaeosaurid sickle-claws through a musculoskeletal 3D model of the
hindlimb of 'Deinonychus'. The results supported that the claws were
used for grasping and restraining prey smaller than the dromaeosaurid
itself, but did not rule out other behaviours also involving
crouching, such as stabbing and cutting prey at close quarters.
Palaeoenvironment
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The holotype remains of 'Atrociraptor' were found at a locality west
of the Royal Tyrrell Museum of Palaeontology. This locality is part of
the Horsethief Member of the Horseshoe Canyon Formation, which is the
second-oldest member of the formation. The Horsethief Member ranges
from around 72.2-71.5 million years ago, a timespan of about 700,000
years. Teeth from elsewhere in the Horseshoe Canyon Formation have
been assigned to 'Atrociraptor'. If these assignments are valid, it
would mean 'Atrociraptor' had a wide geographic and temporal
distribution. These remains push the latest occurrence of
'Atrociraptor' to the Tolman Member of the formation (about 70.9-69.6
million years ago), suggesting the genus may have existed for over 2
million years.
In the early Maastrichtian, the continent of Laramidia (today North
America) was about 8 degrees of latitude further North than North
America is today. Despite this, the average temperature of the area
was almost certainly much warmer than the region is today. The mean
annual temperature in the early Maastrichtian is estimated to have
been around 10 C, compared to 4.5 C today. The lower part of the
Horseshoe Canyon Formation, where the holotype was discovered,
corresponds to poorly-drained sediments which reflect a depositional
setting with a lot of standing water. The sediments of the Horsethief
Member are composed primarily of coal, shales, sandstones, and
mudstones. These sediments are rich with organic materials, which
reflect a highly saturated and humid environment, likely a coastal
plain or fluvial system which was on the margins of the Western
Interior Seaway. This suggests that the region was very humid and
composed primarily of wetlands with a high water table. This is
further corroborated by the presence of a wider variety of turtles in
the lower members of the formation than in the higher members.
As the Maastrichtian stage progressed, the Western Interior Seaway
began to shrink, which is reflected in the palaeoclimatic
reconstructions of the region. Later sediments are believed to have
been further inland and less humid than those of the late Campanian.
This may be responsible for the apparent change in fauna during this
period. How these climatic changes affected 'Atrociraptor' is not
clear, due to the rarity of its remains, but the discovery of teeth
from the geologically younger Tolman Member suggests that the taxon
may have survived through this period. Despite the apparent decline
in temperature and humidity, it is known that major flooding events
continued throughout this period. The 'Albertosaurus' bonebed which
contains teeth referred to 'Atrociraptor', dated to one of the upper
members of the Horseshoe Canyon Formation, was believed to have been
deposited during a major storm. Despite the regression of the Western
Interior Seaway, Cretaceous Alberta became wetter and more humid in
the uppermost part of the formation (around 68 million years ago),
returning to conditions similar to those of the Horsethief Member. No
remains from these youngest sediments have been assigned to
'Atrociraptor', which suggests that either the change in climate
forced the small theropod to move elsewhere or it became extinct.
Contemporary fauna and flora
==============================
The holotype of 'Atrociraptor' is the only fossil discovered from its
locality, so it is not known for certain if any of the animals from
the Horsethief Member directly coexisted with it, but many of them are
known to have been contemporaneous. The Horsethief Member of the
Horseshoe Canyon Formation constitutes the upper part of the so-called
'Edmontosaurus regalis-Pachyrhinosaurus canadensis' zone. As the name
suggests, two common terrestrial herbivores in these lower strata were
'Pachyrhinosaurus' and 'Edmontosaurus'. The lower part of Horseshoe
Canyon also preserves fossils of other ceratopsids including
'Anchiceratops', 'Arrhinoceratops', and several indeterminate
specimens. Ankylosaurs are also well-represented in this member. The
genera 'Edmontonia' and 'Anodontosaurus' have been found alongside
indeterminate ankylosaur remains. Hadrosaurid remains are very common,
but many of these are not confidently assigned to any genera other
than 'Edmontosaurus'. Fragmentary remains of pachycephalosaurids have
also been found.
Theropod remains are also common in the Horsethief Member.
'Ornithomimus' and 'Struthiomimus' are known from several specimens,
and other coelurosaurs are known from a few remains. These include
the troodontid 'Albertavenator' and the caenagnathids 'Apatoraptor'
and 'Epichirostenotes'. Although their remains are not known directly
from the Horsethief Member, 'Dromaeosaurus', 'Paronychodon', and the
poorly-understood taxon 'Richardoestesia' (known only from teeth) are
known from both older and younger deposits, so they are inferred to
have existed at this time as well. The largest theropod in the
Horsethief Member (and the Horseshoe Canyon Formation generally) was
the tyrannosaurid 'Albertosaurus'.
Teeth found in the higher layers of the Horseshoe Canyon Formation
(the Morrin and Tolman members) suggest that 'Atrociraptor' may have
also been a constituent of the younger 'Hypacrosaurus
altispinus-Saurolophus osborni' zone. This period is typified by the
presence of the hadrosaurids 'Saurolophus' and 'Hypacrosaurus', in
addition to numerous hadrosaur remains that have not yet been assigned
to a particular genus. This time interval extended from 71.5-69.6
million years ago and immediately followed the 'Edmontosaurus
regalis'-'Pachyrhinosaurus canadensis' dinosaur zone. 'Edmontosaurus',
'Pachyrhinosaurus', and 'Edmontonia' that characterise the Horsethief
Member appear to be completely absent from this zone, although these
genera did persist elsewhere in Laramidia. The ceratopsids
'Anchiceratops' and 'Arrhinoceratops' persist into the Morrin Member
and the early layers of the even younger Tolman Member, as does the
ankylosaurid 'Anodontosaurus' and the large predator 'Albertosaurus'.
The aforementioned teeth, which have been assigned to 'Atrociraptor',
suggest that it directly shared its environment in the Tolman Member
with 'Albertosaurus', 'Hypacrosaurus', one or more troodontids,
ornithomimids, and possibly other dromaeosaurids. Small dinosaurs are
also more common in the Tolman Member. These include the
leptoceratopsid 'Montanoceratops', the pachycephalosaurid
'Sphaerotholus', the thescelosaurid 'Parksosaurus', and the
alvarezsaurid 'Albertonykus', in addition to the diverse assemblage of
small theropods known from the Horsethief Member. The absence of these
fossils from the older members does not necessarily mean that these
taxa did not exist at that time, and may simply be reflective of the
fossil bias which makes the preservation of small-bodied animals less
likely.
Remains of animals other than dinosaurs are known from throughout the
Horseshoe Canyon Formation. Fish are common fossils and are
represented by sclerorhynchoids, guitarfish, sturgeons, paddlefishes,
aspidorhynchids, osteoglossomorphs, elopiformes, ellimmichthyiformes,
esocids, and acanthomorphs. Frogs and salamanders are also known from
teeth found in these deposits alongside polyglyphanodontian lizards.
Turtles were also very diverse in the warm and humid climate of the
early Maastrichtian. Fossils of macrobaenids, chelydrids, trionychids,
adocids, and the giant genus 'Basilemys' have been found from the
parts of Horseshoe Canyon Formation that correspond to wetlands. The
choristodere genus 'Champsosaurus' was also a resident of Alberta
during this time.
A wide variety of fossil plants have been found in the Horseshoe
Canyon Formation. The most numerous and diverse of these are the
conifers, which are known from plant body fossils and a diverse array
of seeds. Among the conifers present were pines, redwoods, cypresses,
yellow woods, and yews, as well as some conifers that have not been
confidently identified by paleobotanists. Ginkgoes are also known
from the region during the Cretaceous. Uniquely, fossils of true
cycads - which are otherwise very abundant among Mesozoic flora -
appear to be completely absent from the Horseshoe Canyon Formation.
Seed ferns and false cycads, which are related groups of
spermatophytes, have been found, and some plant remains that resemble
the genus 'Nilssonia' have been suggested to belong to true cycads.
Angiosperms had undergone a significant diversification event during
the Cretaceous Terrestrial Revolution, and by the early Maastrichtian,
they were common components of North American terrestrial ecosystems.
However, in the Horseshoe Canyon Formation, leaf imprints, fossilized
wood, stems, and fruits from angiosperms are rare fossils. Fossilized
leaves and fruits of plane trees, dogwood trees, myrtles, wheel trees,
saxifrages, and katsura have been identified. Most angiosperm remains
so far discovered have been in the form of seeds and pollen. Such
trace fossils from lotuses, laurels, hornworts, witch hazels, elm
trees, buckthorns, beeches, birches, willows, and cashews, among
others, have also been found, but body fossils from these plants are
not yet known from the area.
Fossil remains from non-spermatophytes are rare, and typically only
their spores are preserved. The morphology of these spores is used to
determine the affinities of these plants. From this, it has been
determined that the Horseshoe Canyon Formation was also home to a
diverse assemblage of ferns, tree ferns, water clovers, horsetails,
quillworts, club mosses, mosses, and liverworts.
See also
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* Dinosaurs in 'Jurassic Park'
* List of North American dinosaurs
License
=========
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Original Article: http://en.wikipedia.org/wiki/Atrociraptor