Huaxiagnathus
Encyclopedia
Huaxiagnathus is a genus
of theropod dinosaur
from the Lower Cretaceous
of China
. It was a compsognathid
, large for that group at about half a meter longer than Compsognathus
and larger specimens of Sinosauropteryx
, with the largest specimen about 1.8 meters (6 feet) in length.
The name Huaxiagnathus is derived from the Chinese Hua Xia, 華夏, a traditional word for "China", and from the Greek
gnathos, Latinised into gnathus, meaning "jaw."
The holotype
(CAGS-IG-02-301, Chinese Academy of Geological Sciences, Beijing
) specimen was collected from the Yixian Formation
(Jehol Group, Aptian
) at Dabangou Village, Sihetun area, near Beipiao City, in western Liaoning
Province. The holotype consists of an essentially complete skeleton, lacking only the end of the tail, preserved on five large slabs. Another, larger specimen of Huaxiagnathus was discovered earlier in the Yixian Formation of the Sihetun area (NGMC 98-5-003, National Geological Museum of China, Beijing), but damage and mistakes made during its preparation rendered it unsuitable as a holotype.
Cladistic analysis indicates that Huaxiagnathus is the basalmost known compsognathid, as indicated by its unspecialized forearm.
Hwang et al. (2004, pp. 14–15) diagnosed this genus as follows: differing from all other known compsognathids in having a very long posterior process of the premaxilla
that overlaps the antorbital fossa
, a manus equal to the combined lengths of the humerus
and radius
, large manual unguals I and II which are subequal in length and 167% the length of manual ungual III, a first metacarpal which has a smaller proximal transverse width than the second metacarpal, and the presence of a reduced olecranon
process on the ulna
.
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 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 Lower 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 China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. It was a compsognathid
Compsognathidae
Compsognathidae is a family of small carnivorous dinosaurs, generally conservative in form, from the Jurassic and Cretaceous Periods. Compsognathids lie at or near the origin of feathers—skin impressions are known from four genera, Compsognathus, Sinosauropteryx, Sinocalliopteryx, and Juravenator...
, large for that group at about half a meter longer than Compsognathus
Compsognathus
Compsognathus was a small, bipedal, carnivorous theropod dinosaur. The animal was the size of a turkey and lived around 150 million years ago, the early Tithonian stage of the late Jurassic Period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany...
and larger specimens of Sinosauropteryx
Sinosauropteryx
Sinosauropteryx was the first genus of dinosaur outside of Avialae to be found with evidence of feathers. They were covered with "furry" coats of very simple filament-like feathers...
, with the largest specimen about 1.8 meters (6 feet) in length.
The name Huaxiagnathus is derived from the Chinese Hua Xia, 華夏, a traditional word for "China", and from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
gnathos, Latinised into gnathus, meaning "jaw."
Description
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...
(CAGS-IG-02-301, Chinese Academy of Geological Sciences, Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...
) specimen was collected from the Yixian Formation
Yixian Formation
The Yixian Formation is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans 11 million years during the early Cretaceous period...
(Jehol Group, Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
) at Dabangou Village, Sihetun area, near Beipiao City, in western Liaoning
Liaoning
' is a province of the People's Republic of China, located in the northeast of the country. Its one-character abbreviation is "辽" , a name taken from the Liao River that flows through the province. "Níng" means "peace"...
Province. The holotype consists of an essentially complete skeleton, lacking only the end of the tail, preserved on five large slabs. Another, larger specimen of Huaxiagnathus was discovered earlier in the Yixian Formation of the Sihetun area (NGMC 98-5-003, National Geological Museum of China, Beijing), but damage and mistakes made during its preparation rendered it unsuitable as a holotype.
Cladistic analysis indicates that Huaxiagnathus is the basalmost known compsognathid, as indicated by its unspecialized forearm.
Hwang et al. (2004, pp. 14–15) diagnosed this genus as follows: differing from all other known compsognathids in having a very long posterior process of the 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....
that overlaps the antorbital fossa
Fossa (anatomy)
In anatomical terminology, fossa has come to mean a depression or hollow, in general, in a bone. Other parts of the body may be involved, for example, the antecubital fossa...
, a manus equal to the combined lengths of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
and radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
, large manual unguals I and II which are subequal in length and 167% the length of manual ungual III, a first metacarpal which has a smaller proximal transverse width than the second metacarpal, and the presence of a reduced olecranon
Olecranon
The olecranon is a large, thick, curved bony eminence of the forearm that projects behind the elbow.It is situated at the upper end of the ulna, one of the two bones in the forearm...
process on the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
.