Sinusonasus is a genus

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 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 Early 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...

 Period, recovered 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...

. This dinosaur lived in what is now the Liaoning Province 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...

. Sinusonasus was a theropod, specifically a troodontid dinosaur. The name should not be confused with Sinosaurus

Sinosaurus

Sinosaurus was a tetanuran theropod dinosaur which lived during the Late Triassic or Early Jurassic Period. Its fossils were found in the Lufeng Formation, in Yunnan Province, China. It was a bipedal carnivore...

.

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...

, Sinusonasus magnodens, was named and described by Xu Xing and Wang Xiaolin in 2004. The generic name refers to the sinusoid form, in lateral view, of the nasals

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....

. The specific name means "big-toothed" in 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...

. In a later publication the species is referred to as "Sinucerasaurus" but this is a junior objective synonym.

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...

, IVPP V 11527, was found in the Lujiatun Member of the Yixian Formation, dating from the Hauterivian

Hauterivian

The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous epoch or a stage in the Lower Cretaceous series. It spans the time between 136.4 ± 2 Ma and 130 ± 1.5 Ma...

. It consists of a partial skeleton including skull and lower jaw fragments and partial tail, pelvis and hind limbs. The maxillary

Maxilla

The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...

 teeth are large. 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 141 millimetres long. The chevron

Chevron (anatomy)

A chevron is one of a series of bones on the ventral side of the tail in many reptiles, dinosaurs , and some mammals such as kangaroos and manatees....

s on the caudal vertebrae are so wide that they connect, forming a continuous plate at the underside of the tail.