Garudimimus
Encyclopedia
Garudimimus is a basal ornithomimosaurian
theropod dinosaur
from the Upper Cretaceous
of Mongolia
.
, a theropod skeleton was discovered at Baishin Tsav in Ömnögovi Province
. The same year this specimen was named and described by Rinchen Barsbold as the type species
Garudimimus brevipes. The generic name combines a reference to the Garuda, winged creatures from Mongolian Buddhist mythology
, with a Latin
mimus, "mimic". The specific name is derived from Latin brevis, "short", and pes, "foot", referring to the short metatarsus
.
The holotype
specimen, GIN 100/13, was uncovered in sediments
of the Upper Cretaceous Bayan Shireh Formation
the stratification
of which is uncertain; its possible age ranges from the Cenomanian
to the Campanian
. It consists of a rather complete and articulated skeleton including the skull but lacking the shoulder girdle, forelimbs and tail end, of a subadult individual. The specimen is today usually seen as the only fossil known of Garudimimus, though Philip Currie
once claimed that part of the Archaeornithomimus
material belonged to Garudimimus. The skeleton was for the first time described in detail in works by Yoshitsugu Kobayashi from 2004 and 2005.
estimated its adult length at 2.5 metres, the weight at thirty kilogrammes. The length of the femur
is 371 millimetres.
Garudimimus, an early ornithomimosauria
n, appears to have not been as adapted for speed as more derived
ornithomimids. It had relatively short legs, heavy feet, and in the hip, shorter ilia
, the latter indicating that the musculature of the legs was not as well-developed as in most ornithomimids. The foot had four toes and a vestige of the first digit, whereas all (other) ornithomimids were three-toed with the first and fifth toe lost. The toothless skull has very straight jaws ending in a more rounded snout tip than that of others of the group, and larger eyes.
Previously it was thought that this "primitive" member of Ornithomimosauria possessed a lacrimal
horn at the top of the skull, in front of the eye socket. However, recent studies have shown that this "horn" was simply the shifted pointed back end of the nasal bone
. Another early mistake was the suggestion by Thomas Holtz that the foot had been incorrectly reconstructed and would in fact have been arctometatarsalian, with the top of the third metatarsal excluded from the front surface of the metatarsus, proving a close relationship of the Ornithomimosauria with the Tyrannosauroidea
which show the same condition. Kobayashi concluded that the original description of Barsbold had been correct on this point.
close to the Ornithomimidae or a basal position in the Ornithomimidae itself.
.
Comparisons between the scleral ring
s of Garudimimus and modern birds and reptiles indicate that it may have been cathemeral
, active throughout the day at short intervals.
Ornithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
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 Upper 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...
of Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
.
Discovery and naming
In 1981, during a Soviet-Mongolian expedition to the Gobi DesertGobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
, a theropod skeleton was discovered at Baishin Tsav in Ömnögovi Province
Ömnögovi Province
Ömnögovi is an aimag of Mongolia, located in the south of the country, in the Gobi Desert. Ömnögovi is Mongolia's largest aimag. The capital is Dalanzadgad....
. The same year this specimen was named and described by Rinchen Barsbold as 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...
Garudimimus brevipes. The generic name combines a reference to the Garuda, winged creatures from Mongolian Buddhist mythology
Buddhist mythology
Buddhist mythology operates within the Buddhist belief system. It is a relatively broad mythology, as it was adopted and influenced by several diverse cultures such as Gandhara which was the capital of Bactria. Later on, it also came to incorporate aspects from countries such as China and Japan...
, with a 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...
mimus, "mimic". The specific name is derived from Latin brevis, "short", and pes, "foot", referring to the short metatarsus
Metatarsus
The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...
.
The 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...
specimen, GIN 100/13, was uncovered in sediments
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
of the Upper Cretaceous Bayan Shireh Formation
Bayan Shireh Formation
The Bayan Shireh Formation is a geological formation in Burkhant, Mongolia, that dates to the late Cretaceous period...
the stratification
Stratification
Stratification is the building up of layers. Stratified is an adjective referring to the arranging of layers, and is also the past form of the verb stratify, to separate or become separated into layers...
of which is uncertain; its possible age ranges from the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
to the Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
. It consists of a rather complete and articulated skeleton including the skull but lacking the shoulder girdle, forelimbs and tail end, of a subadult individual. The specimen is today usually seen as the only fossil known of Garudimimus, though 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...
once claimed that part of the Archaeornithomimus
Archaeornithomimus
Archaeornithomimus is a genus of ornithomimosaurian theropod dinosaur from the Late Cretaceous of China, 70 million years ago....
material belonged to Garudimimus. The skeleton was for the first time described in detail in works by Yoshitsugu Kobayashi from 2004 and 2005.
Description
Garudimimus was a rather small ornithomimosaur. In 2010, Gregory S. PaulGregory 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 adult length at 2.5 metres, the weight at thirty kilogrammes. The length of the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
is 371 millimetres.
Garudimimus, an early ornithomimosauria
Ornithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
n, appears to have not been as adapted for speed as 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...
ornithomimids. It had relatively short legs, heavy feet, and in the hip, shorter ilia
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
, the latter indicating that the musculature of the legs was not as well-developed as in most ornithomimids. The foot had four toes and a vestige of the first digit, whereas all (other) ornithomimids were three-toed with the first and fifth toe lost. The toothless skull has very straight jaws ending in a more rounded snout tip than that of others of the group, and larger eyes.
Previously it was thought that this "primitive" member of Ornithomimosauria possessed a lacrimal
Lacrimal
The term Lacrimal can refer to:*In typography:** A type of Stroke ending *In anatomy** Lacrimal apparatus** Lacrimal artery** Lacrimal bone...
horn at the top of the skull, in front of the eye socket. However, recent studies have shown that this "horn" was simply the shifted pointed back end of the nasal bone
Nasal bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....
. Another early mistake was the suggestion by Thomas Holtz that the foot had been incorrectly reconstructed and would in fact have been arctometatarsalian, with the top of the third metatarsal excluded from the front surface of the metatarsus, proving a close relationship of the Ornithomimosauria with the Tyrannosauroidea
Tyrannosauroidea
Tyrannosauroidea is a superfamily of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period...
which show the same condition. Kobayashi concluded that the original description of Barsbold had been correct on this point.
Phylogeny
Garudimimus was by Barbold assigned to a separate Garudimimidae in 1981. Modern cladistic analyses recover either a basal position in the OrnithomimosauriaOrnithomimosauria
The Ornithomimosauria, ornithomimosaurs or ostrich dinosaurs were theropod dinosaurs which bore a superficial resemblance to modern ostriches. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia...
close to the Ornithomimidae or a basal position in the Ornithomimidae itself.
Paleobiology
Garudimimus may have been an omnivoreOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
.
Comparisons between the scleral ring
Sclerotic ring
Sclerotic rings are rings of bone found in the eyes of several groups of vertebrate animals, except for mammals and crocodilians. They can be made up of single bones or small bones together. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical,...
s of Garudimimus and modern birds and reptiles indicate that it may have been cathemeral
Cathemeral
A cathemeral organism is one that has sporadic and random intervals of activity during the day or night in which food is acquired, socializing with other organisms occurs, and any other activities necessary for livelihood are performed...
, active throughout the day at short intervals.