''Tugulusaurus'' (meaning "Tugulu 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 ...

coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrann ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

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 belongs to the

Alvarezsauroidea Alvarezsauroidea is a group of small maniraptoran dinosaurs. Alvarezsauroidea, Alvarezsauridae, and Alvarezsauria are named for the historian Gregorio Álvarez, not the more familiar physicist Luis Alvarez, or his son geologist Walter Alvarez ...

. It is known from the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

Tugulu Group The Tugulu Group () is a geological Group in Xinjiang, China whose strata date back to the Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major ...

in the Urhe area of the

People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. It was one of the first members of Alvarezsauria ever discovered.

Discovery

From 1964 dinosaur fossils were excavated in the

Junggar Basin The Junggar Basin () is one of the largest sedimentary basins in Northwest China. It is located in Xinjiang, and enclosed by the Tarbagatai Mountains of Kazakhstan in the northwest, the Altai Mountains of Mongolia in the northeast, and the Heaven ...

Xinjiang Xinjiang, SASM/GNC: ''Xinjang''; zh, c=, p=Xīnjiāng; formerly romanized as Sinkiang (, ), officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwest ...

. In 1973 a number of these were described by paleontologist

Dong Zhiming Dong Zhiming (Chinese: 董枝明, Pinyin: ''Dǒng Zhimíng''; born January 1937) is a Chinese vertebrate paleontologist formerly employed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. He began working at the ...

, among them the bones of a small theropod which he named ''Tugulusaurus faciles''. The generic name refers to the Tugulu Group. The specific name is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''facilis'', here with the meaning of "easily moving", referring to the agility of the animal as indicated by its "delicate bones". 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 ...

, IVPP V4025, was found in layers of the

Lianmuqin Formation The Lianmuqin Formation, also transcribed as Lianmugin Formation,

dating from the Barremian–Albian. It consists of a partial skeleton including four partial tail

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e, much of the left leg and part of the right, the first fingers of both hands, and a rib. 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 ...

has a length of about . The left first

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ...

is very short: . The skeleton represents the only remains of the species that have ever been discovered.

Classification

''Tugulusaurus'' was originally classified by Dong in 1973 as a member of the

Ornithomimidae Ornithomimidae (meaning "bird-mimics") is a family of theropod dinosaurs which bore a superficial resemblance to modern ostriches. Ornithomimids were fast, omnivorous or herbivorous dinosaurs known mainly from the Late Cretaceous Period of Lauras ...

, within the

Coelurosauria Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrann ...

. In the years that followed, the genus was often considered a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

''. However, in 2005

Oliver Rauhut Oliver may refer to: Arts, entertainment and literature Books * ''Oliver the Western Engine'', volume 24 in ''The Railway Series'' by Rev. W. Awdry * '' Oliver Twist'', a novel by Charles Dickens Fictional characters * Ariadne Oliver ...

and Xu Xing concluded that it is a valid genus of basal coelurosaurian of unknown affinities. In their cladistic analysis of the newly described taxa ''

Bannykus ''Bannykus'' is an alvarezsaur from the Early Cretaceous of the Bayin-Gobi Formation of Inner Mongolia, China. It includes one species, ''Bannykus wulatensis''. It is large for an alvarezsaur, with an estimated weight of 24 kg based on fe ...

'' and ''

Xiyunykus ''Xiyunykus'' (meaning "western claw"; "xiyu" is Mandarin for "west" and refers to Western China where it was found) is an alvarezsaur from the Early Cretaceous of the Tugulu Group of China. It includes one species, ''Xiyunykus pengi''. Paleo ...

'', Xu et al. (2018) recovered ''Tugulusaurus'' as a member of

Alvarezsauria Alvarezsauroidea is a group of small maniraptoran dinosaurs. Alvarezsauroidea, Alvarezsauridae, and Alvarezsauria are named for the historian Gregorio Álvarez, not the more familiar physicist Luis Alvarez, or his son geologist Walter Alvarez ...

.Xing Xu; Jonah Choiniere; Qingwei Tan; Roger B.J. Benson; James Clark; Corwin Sullivan; Qi Zhao; Fenglu Han; Qingyu Ma; Yiming He; Shuo Wang; Hai Xing; Lin Tan (2018). "Two Early Cretaceous fossils document transitional stages in alvarezsaurian dinosaur evolution". Current Biology. Online edition. .

References

{{Taxonbar, from=Q946990 Alvarezsaurs Early Cretaceous dinosaurs of Asia Taxa named by Dong Zhiming Fossil taxa described in 1973 Paleontology in Xinjiang