''Adasaurus'' ( ; meaning "Ada lizard") is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
dromaeosaurid
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
that lived in
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
during the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
period about 70 million years ago. The genus is known from two partial specimens found in the
Nemegt Formation of
Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
that were partially described in 1983 by the paleontologist
Rinchen Barsbold.
''Adasaurus'' was a large dromaeosaurid that was about long weighing . Unlike other dromaeosaurids, ''Adasaurus'' developed a rather small and blunt sickle claw that likely had a reduced use, and a recurved
lacrimal bone; this latter trait is also shared with ''
Austroraptor
''Austroraptor'' ( ) is a genus of large dromaeosaurid dinosaur that lived during the Late Cretaceous Period in what is now Argentina.
''Austroraptor'' was a large-sized, moderately-built, ground-dwelling, bipedal carnivore, estimated at in len ...
''. Though reduced, the sickle claw retained the characteristic rounded articulation of most dromaeosaurids.
''Adasaurus'' was originally regarded as a
dromaeosaurine
Dromaeosaurinae is a subfamily of the theropod group Dromaeosauridae. The earliest dromaeosaurine is ''Utahraptor'', dating back to the Early Cretaceous period in North America, however, some isolated teeth seems to represent an indeterminate spe ...
by Barsbold, a group that includes robust dromaeosaurs with deep jaws. Revisions made to the specimens have showed that this dromaeosaurid belongs to the
Velociraptorinae which is composed of more lightly built animals like ''Velociraptor''.
History of discovery
![Cretaceous-aged dinosaur fossil localities of Mongolia](https://upload.wikimedia.org/wikipedia/commons/c/c5/Cretaceous-aged_dinosaur_fossil_localities_of_Mongolia.PNG)
''Adasaurus'' was first figured in
1977
Events January
* January 8 – Three bombs explode in Moscow within 37 minutes, killing seven. The bombings are attributed to an Armenian separatist group.
* January 10 – Mount Nyiragongo erupts in eastern Zaire (now the Democratic R ...
by the
Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
n
paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Rinchen Barsbold on a pelvic comparison with other
theropods, but it would remain as an informally named taxon until a proper description. In 1983, Barsbold published a large comparative revision of the known
Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
n theropod
taxa at the time where he formally named ''Adasaurus'' and the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
''A. mongoliensis'', which was based on two partial specimens. The
generic name, ''Adasaurus'', is taken from the
Mongolian word (, meaning
evil spirit
Evil, in a general sense, is defined as the opposite or absence of good. It can be an extremely broad concept, although in everyday usage it is often more narrowly used to talk about profound wickedness and against common good. It is generally ...
), and the
Greek word (, meaning lizard). The
specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
for the
single species, ''mongoliensis'', refers to the country of discovery Mongolia. Barsbold briefly described ''Adasaurus'' as a dromaeosaurid and noted that this new taxon possessed a notably reduced second pedal ungual. Given that this trait contrasted to the large, sharply-developed ungual of most members, Barsbold listed it as a
unique character for ''Adasaurus''.
[Translated paper]
/ref> However, the authenticity of this unusual reduction was disputed in 2010 by Phil Senter, who claimed that the supposed ungual did not pertain to the specimen. Nevertheless, in the revised diagnosis conducted by Turner and colleagues in 2012, this character is still considered as authentic,[ which has been widely followed by other authors.]
''Adasaurus'' is known from the holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
MPC-D 100/20, which represents an adult individual comprising a partial skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
missing its anterior region, the right scapulocoracoid and a sternal
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
plate, 8 cervical vertebrae, 11 partial dorsal vertebrae, the sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30.
The sacrum situates at the upper, back part ...
, 7 caudal vertebrae, partial hindlimbs with the right foot, and a nearly complete right pelvic girdle comprising the ilium, and pubis. A second specimen is represented by the less complete paratype MPC-D 100/21 that includes two caudal vertebrae and a nearly complete right foot. Both specimens were unearthed from the Nemegt Formation at the locality of Bügiin Tsav, in the Gobi Desert
The Gobi Desert (Chinese: 戈壁 (沙漠), Mongolian: Говь (ᠭᠣᠪᠢ)) () is a large desert or brushland region in East Asia, and is the sixth largest desert in the world.
Geography
The Gobi measures from southwest to northeast an ...
of Mongolia. In 2004, Philip J. Currie
Philip John Currie (born March 13, 1949) is a Canadian palaeontologist and museum curator who helped found the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta and is now a professor at the University of Alberta in Edmonton. In the ...
and David J. Varricchio referred another two specimens to ''Adasaurus'' labelled as IGM 100/22 and IGM 100/23. Supposedly, the specimens were recovered from the same locality of the holotype. However, these specimens are actually known from the Shine Us Khuduk and Tel Ulan Chaltsai localities (respectively) of the Bayan Shireh Formation
The Bayan Shireh Formation (also known as Baynshiree/Baynshire, Baynshirenskaya Svita or Baysheen Shireh) is a geological formation in Mongolia, that dates to the Cretaceous period. It was first described and established by Vasiliev et al. 1959. ...
and thus, they are older than the remains of ''Adasaurus'' from the younger Nemegt Formation. They represent a different and new taxon that differs from ''Adasaurus''.[
]
Description
''Adasaurus'' was a rather large-sized dromaeosaurid. The holotype has an estimated length of with a weight of . The comparatively larger pedal elements of the paratype indicate a gently bigger size in this latter specimen which is estimated around long and in body mass. Aside from the reduced pedal ungual II, ''Adasaurus'' can be recognised by the following additional traits: expanded projection of the maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
ry; recurved lacrimal; lower jaw with a prominent surangular ; irregular triangular projection on the quadrate
Quadrate may refer to:
* Quadrate bone
* Quadrate (heraldry)
* Quadrate lobe of liver
* Quadrate tubercle
The quadrate tubercle is a small tubercle found upon the upper part of the femur. It serves as a point of insertion of the quadratus femori ...
shaft; pleurocoel
Skeletal pneumaticity is the presence of air spaces within bones. It is generally produced during development by excavation of bone by pneumatic diverticula (air sacs) from an air-filled space, such as the lungs or nasal cavity. Pneumatization is h ...
s are present on the anterior sacral vertebrae
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30.
The sacrum situates at the upper, back part ...
; and the anterior border of the anterior blade in the ilium is relatively shortened.[
]
Skull
On the right side of the skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
, the lower portion of the jugal is expanded from the top to the bottom. The quadrate is a large and vertical bone with a large triangular projection
Projection, projections or projective may refer to:
Physics
* Projection (physics), the action/process of light, heat, or sound reflecting from a surface to another in a different direction
* The display of images by a projector
Optics, graphic ...
on its lateral border. This triangular projection is located on the quadrate shaft and bent to the top. The top surface of the right ectopterygoid—a smalle bone of the palate—is flattened to the palate. As in other dromaeosaurids, the lacrimal has an inverted L-shape, but the thin body of this bone is curved, which is also seen in ''Austroraptor
''Austroraptor'' ( ) is a genus of large dromaeosaurid dinosaur that lived during the Late Cretaceous Period in what is now Argentina.
''Austroraptor'' was a large-sized, moderately-built, ground-dwelling, bipedal carnivore, estimated at in len ...
''.[
]
Skeleton
The scapula
The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...
and coracoid of the holotype are completely fused giving form to the scapulocoracoid, and the suture between them is not present.[ ]Pneumatic
Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air.
Pneumatic systems used in Industrial sector, industry are commonly powered by compressed air or compressed inert gases. A central ...
foramina are present in the holotypic anterior sacral vertebrae.[ The ]femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
and tibia
The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...
of the holotype measure and long, respectively,[ and the fourth trochanter is a prominent and rugose ridge that is located on the posterior inner surface of the upper region of the femoral shaft. The femur itself is very similar to that of the indeterminate dromaeosaur DGBU-78. The anterior surface of the lower end of the femoral shaft is convex in shape, and the lateral tubercle of the upper end of the tibia-fibula articulation is a compact structure.] The presence of a rounded pit on the inner surface of the lower tibiotarsus
The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia.
A similar structure also occurred in the Mesozoic Heterodontosauridae. These sm ...
is often documented in dromaeosaurids, however, this feature is not verifiable in ''Adasaurus'' since the astragalus region is covered with sediments.[
]
The posterior top border of the ilium is proportionally more thickened than that of ''Achillobator
''Achillobator'' ( ; meaning "Achilles hero") is a genus of large dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous period about 96 million to 89 million years ago in what is now the Bayan Shireh Formation. The genus is curren ...
'',[ and the anterior border of the anterior blade of the ilium has a similar shape to that of '']Saurornitholestes
''Saurornitholestes'' ("lizard-bird thief") is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta) and the United States (Montana, New Mexico, Alabama, North Carolina, and South Carolina).
Two spec ...
''. This anterior border has a notched appearance that is characteristic to ''Adasaurus''. As a whole, the top border is straightened in shape. The pubic peduncle—a robust anterior extension that articulates with the pubis—is wide and developed to the bottom. A large supratrochanteric (above the trochanter of the femur) extension is absent on the ilium. Like other dromaeosaurids, the pubis is elongated with an expanded pubic boot (lower end) and features an opisthopubic (backwards directed) condition.[ The digit II ungual is not hypertrophied (elongated) as in most dromaeosaurids,][ and though ''Adasaurus'' features a similar metatarsal II-III ratio to that of '' Balaur'', this is due to the reduced sickle claw of digit II instead of an elongated ungual of digit I. Metatarsal III of the paratype shows that a ]tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projection ...
is present on the extensor surface and this tuberosity likely originates the insertion of the muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
''tibialis cranialis''.[ The lower tarsals and upper ends of the metatarsals are somewhat fused.][
]
Classification
''Adasaurus'' is a member of Dromaeosauridae, a group that is closely related to living birds
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
. When erected by Barsbold in 1983, Velociraptorinae was conceived as a group containing ''Velociraptor
''Velociraptor'' (; ) is a genus of small dromaeosaurid dinosaur that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in the pa ...
'' and closely related species that were characterized by their smaller size and long-narrow snouts. However, Barsbold did not include ''Adasaurus'' in the group, instead, he placed it within the Dromaeosaurinae.[ It was not until 1998 that this group was defined as a clade by ]Paul Sereno
Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago and a National Geographic "explorer-in-residence" who has discovered several new dinosaur species on several continents, including at sites ...
. Sereno defined the group as all dromaeosaurids more closely related to ''Velociraptor'' than to ''Dromaeosaurus
''Dromaeosaurus'' (, "running lizard") is a genus of dromaeosaurid theropod dinosaur which lived during the Late Cretaceous period (middle late Campanian and Maastrichtian), sometime between 80 and 69 million years ago, in Alberta, Canada and the ...
''. Kubota and Barsbold in 2006 during their rexamination of ''Adasaurus'' found this taxon to be more closely related to ''Velociraptor'' than other dromaeosaurids.[ The traditional view of the Velociraptorinae commonly included ''Velociraptor'', '']Tsaagan
''Tsaagan'' (meaning "white") is a genus of dromaeosaurid dinosaur from the Djadokhta Formation of the Late Cretaceous of Mongolia.
Discovery and naming
The holotype of ''Tsaagan'' was discovered in 1996 and first identified as a specimen of '' ...
'' and ''Linheraptor
''Linheraptor'' is a genus of dromaeosaurid dinosaur which lived in what is now China in the Late Cretaceous. It was named by Xu Xing and colleagues in 2010, and contains the species ''Linheraptor exquisitus''. This bird-like dinosaur was less ...
'', which are known from complete skulls, however, most analyses vary widely regarding which species are actually velociraptorines and which are dromaeosaurines. Turner and colleagues in 2012 supported a traditional, monophyletic composition of Velociraptorinae.[ However, some studies found a very different group of dromaeosaurids in Velociraptorinae, such as Longrich and Currie in 2009, which recovered '' Deinonychus'' outside of the Velociraptorine and Dromaeosaurinae. Traditionally, ''Adasaurus'' was assigned to the Dromaeosaurinae, which includes giant, heavily built animals such as '']Achillobator
''Achillobator'' ( ; meaning "Achilles hero") is a genus of large dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous period about 96 million to 89 million years ago in what is now the Bayan Shireh Formation. The genus is curren ...
'' and ''Utahraptor
''Utahraptor'' (meaning "Utah's thief") is a genus of large dromaeosaurid dinosaur that lived in North America during the Early Cretaceous period. It was a heavy-built, ground-dwelling, bipedal carnivore. It contains a single species, ''Utahrap ...
'' but several analyses have suggested that it belongs to the Velociraptorinae instead.
Below is a cladogram based on the phylogenetic analysis conducted by James G. Napoli and colleagues in 2021:
Paleobiology
Paleopathology
In 1997, Norell and Makovicky stated that the holotype specimen of ''Adasaurus'' represents a largely pathologic
''Pathologic'' ( rus, Мор. Утопия, Mor. Utopiya, ˈmor ʊˈtopʲɪjə, , More. Utopia – a pun on Thomas More's ''Utopia'' and the Russian word for "plague") is a 2005 role-playing and survival game developed by Russian studio Ice-Pick ...
(due to injury
An injury is any physiological damage to living tissue caused by immediate physical stress. An injury can occur intentionally or unintentionally and may be caused by blunt trauma, penetrating trauma, burning, toxic exposure, asphyxiation, o ...
or disease
A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
) individual.[ They reaffirmed this observation in 2004 by claiming the pelvis as pathological. However, during the large revision of the Dromaeosauridae by Turner and colleagues in 2012, the holotype was re-examined and found to be non-pathological. Instead of reflect injured elements, several surfaces may represent the advanced age of the individual, such as the fused upper ends of the metatarsus.][
]
Sickle claw function
Kubota and Barsbold in 2006 stated that the highly reduced sickle claw of ''Adasaurus'' may have been used with less frequency than other deinonychosaurs as the bottom surface of lower heel on the penultimate phalanx has no apparent asymmetrical ridges like other dromaeosaurids
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...
and troodontids.[
In 2011, Denver Fowler and colleagues suggested a new method by which dromaeosaurids may have taken smaller prey. This predation model, "Raptor Prey Restraint" (RPR), proposes that dromaeosaurids killed their prey by leaping onto their quarry, pinning it under their body weight, and gripping it tightly with the large, sickle claws of the pedal digit II—in a manner very similar to extant ]accipitrid
The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-si ...
birds of prey. Like accipitrids, the dromaeosaurid would then begin to feed on the animal while still alive, until it eventually died from blood loss
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...
and organ failure. This proposal is based primarily on comparisons between the morphology and proportions of the feet and legs of dromaeosaurids to several groups of extant birds of prey with fairly known predatory behaviors. Fowler and colleagues found that the feet and legs of dromaeosaurids most closely resemble those of eagle
Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...
s and hawk
Hawks are bird of prey, birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica.
* The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. Th ...
s, especially in terms of having an enlarged second claw and a similar range of grasping motion, but the short metatarsus and foot strength would have been more similar to that of owls. The RPR model would be consistent with other aspects of dromaeosaurid anatomy, such as their unusual dentition and arm morphology. The arms were covered in long feathers and may have been used as flapping stabilizers for balance while atop a struggling prey, along with the stiff counter-balancing tail. Lastly, the comparatively weak jaws would have been useful for eating prey alive but not as useful for forceful dispatch of the prey.
In 2019, Peter Bishop reconstructed the leg skeleton and musculature of '' Deinonychus'' by using three-dimensional models of muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
s, tendon
A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
s, and bone
A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
s. With the addition of mathematical models and equations, Bishop simulated the conditions that would provide maximum force at the tip of the sickle claw and therefore the most likely function. Among the proposed modes of the sickle claw use are: kicking to cut, slash or disembowel prey; for gripping onto the flanks of prey; piercing aided by body weight; to attack vital areas of the prey; to restrain prey; intra
''Intra'' may refer to:
* ''Intra'' (album), a 2005 album by metal band Ram-Zet
* Intra, a city now part of Verbania, Italy
* Intra Airways, British airline
* Intra (software), anti Internet censorship Android app by Google.
* Intra-frame codi ...
- or interspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...
; and digging out prey from hideouts. The results obtained by Bishop showed that a crouching posture increased the claw forces, however, these forces remained relatively weak indicating that the claws were not strong enough to be used in slashing strikes. Rather than being used for slashing, the sickle claws were more likely to be useful in flexed leg angles such as restraining prey and stabbing prey at close quarters. These results are consistent with the Fighting Dinosaurs
The Fighting Dinosaurs is a fossil specimen which was found in the Late Cretaceous Djadokhta Formation of Mongolia. It preserves a ''Protoceratops andrewsi'' and ''Velociraptor mongoliensis'' trapped in combat and provides direct evidence of pre ...
specimen, which preserves a ''Velociraptor
''Velociraptor'' (; ) is a genus of small dromaeosaurid dinosaur that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago. Two species are currently recognized, although others have been assigned in the pa ...
'' and ''Protoceratops
''Protoceratops'' (; ) is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 75 to 71 million years ago. The genus ''Protoceratops'' includes two species: ''P. andrewsi'' and the larger ''P. hellenik ...
'' locked in combat, with the former gripping onto the other with its claws in a non-extended leg posture. Despite the obtained results, Bishop considered that the capabilities of the sickle claw could have varied within taxa given that among dromaeosaurids, ''Adasaurus'' had an unusually smaller sickle claw that retained the characteristic ginglymoid—a structure divided in two parts—and hyperextensible articular surface of the penultimate phalange. He could neither confirm nor disregard that the pedal digit II could have loss or retain its functionally.[
]
Paleoenvironment
''Adasaurus'' is known from the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
Nemegt Formation, the age of which has been considered from the Late Campanian to Early-Middle Maastrichtian
The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...
stages, about 70 million and 68 million years ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds.
Usage
Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...
. The environments that were present on the formation included stream and river channels, mudflats, and shallow lakes. Much of the sedimentation also indicates that a rich habitat existed, offering extensive vegetation in abundant amounts that could sustain most herbivorous dinosaurs. Most fluvial systems functioned as oases
In ecology, an oasis (; ) is a fertile area of a desert or semi-desert environment'ksar''with its surrounding feeding source, the palm grove, within a relational and circulatory nomadic system.”
The location of oases has been of critical imp ...
for oviraptorosaurs.[ Other dinosaurs found in this ]formation
Formation may refer to:
Linguistics
* Back-formation, the process of creating a new lexeme by removing or affixes
* Word formation, the creation of a new word by adding affixes
Mathematics and science
* Cave formation or speleothem, a secondar ...
include the ornithomimosaurs ''Anserimimus
''Anserimimus'' ( ; "goose mimic") is a genus of ornithomimid theropod dinosaur, from the Late Cretaceous Period of what is now Mongolia. It was a lanky, fast-running animal, possibly an omnivore. From what fossils are known, it probably closely ...
'', ''Gallimimus
''Gallimimus'' ( ) is a genus of theropod dinosaur that lived in what is now Mongolia during the Late Cretaceous period, about seventy million years ago (mya). Several fossils in various stages of growth were discovered by Polish-Mongolian exped ...
'', and a taxon that remains unnamed; diverse oviraptorosaurs such as '' Nemegtomaia'', '' Elmisaurus'' and ''Gobiraptor
''Gobiraptor'' is a genus of oviraptorid maniraptoran dinosaur from the Maastrichtian-age Nemegt Formation of Mongolia. The type and only species is ''Gobiraptor minutus'', known from a single incomplete specimen—the holotype MPC-D 102/111. It ...
''; and the troodontid ''Zanabazar
Öndör Gegeen Zanabazar, , , "High Saint Zanabazar"; 1635–1723 (born Eshidorji) was the sixteenth '' Jebtsundamba Khutuktu'' and the first ''Bogd Gegeen'' or supreme spiritual authority, of the Gelugpa (Yellow Hat) lineage of Tibetan Buddhism ...
''. Large
Large means of great size.
Large may also refer to:
Mathematics
* Arbitrarily large, a phrase in mathematics
* Large cardinal, a property of certain transfinite numbers
* Large category, a category with a proper class of objects and morphisms (or ...
dinosaurs in this formation are represented by ''Deinocheirus
''Deinocheirus'' ( ) is a genus of large ornithomimosaur that lived during the Late Cretaceous around 70 million years ago. In 1965, a pair of large arms, shoulder girdles, and a few other bones of a new dinosaur were first discovered in the Ne ...
'', ''Saurolophus
''Saurolophus'' (; meaning "lizard crest") is a genus of large hadrosaurid dinosaur from the Late Cretaceous period of Asia and North America, that lived in what is now the Horseshoe Canyon and Nemegt formations about 70 million to 68 million ...
'', '' Tarbosaurus'' and ''Therizinosaurus
''Therizinosaurus'' (; meaning 'scythe lizard') is a genus of very large therizinosaurid that lived in Asia during the Late Cretaceous period in what is now the Nemegt Formation around 70 million years ago. It contains a single species, ''Therizi ...
''.
See also
* Timeline of dromaeosaurid research
References
External links
Photograph of the holotype skull
{{Taxonbar, from=Q131769
Eudromaeosaurs
Maastrichtian life
Late Cretaceous dinosaurs of Asia
Cretaceous Mongolia
Fossils of Mongolia
Nemegt fauna
Fossil taxa described in 1983
Taxa named by Rinchen Barsbold