Xixiasaurus (Xixia lizard)
Xixiasaurus (Xixia lizard)
Named By : J. Lü, L. Xu, Y. Liu, X. Zhang, S. Jia, & Q. Ji. 2010
Diet : Carnivore
Size : Estimated 1.5 meters long
Type of Dinosaur : Small Theropod
Type Species : X. henanensis (type)
Found in : China, Henan Province, Xixia County - Majiacun Formation
When it Lived : Late Cretaceous, 86 million years ago
Xixiasaurus (/,Si:Si@’so:r@sThe Xixiasaurus (/,Si:Si@’so) is one of the genus belonging to the troodontid dinosaurs that lived in the Late Cretaceous Period in what is today China. The only specimen known was found at Xixia County, Henan Province located in central China which was later made the holotype of the newly discovered species and genus Xixiasaurus Henanensis in the year 2010. These names are a reference to regions of discoveryand could refer to “Henan Xixia lizard”. The specimen comprises an almost entire skull (except for the posterior portion) and a portion from the jaw’s lower part teeth, as well being a forelimb that is partially right.
Xixiasaurus was believed to have measured 1.5 metres (5 feet) in length and weighted 8 kilograms (18 lbs). A troodontid was like a bird and light-built with hands that could grasp as well as a large sickle-shaped claw that was located on the second toe. The skull was long with a low, long snout which was shaped into an U-shape with a tapering shape when viewed from below. The frontal jaw bone appeared to be dome-shaped in the view from side that suggests it was an enlarged braincase. The troodontids differed from the rest by the fact that the front bone in lower jaws was flipped down. Contrary to the majority of troodontids their teeth from Xixiasaurus had no serrations. Instead, the carinae (front and back edges) were sharp and smooth. This was different from troodontids by having 22 teeth per maxilla (in other genera, the maxillary tooth count was greater or less).
The exact relationships between Xixiasaurus to other troodontids is not clear, but it has some resemblances with Byronosaurus. While troodontids that had teeth without abrasion were previously thought to form an edifice however the taxonomic value of this characteristic has been debated. Troodontids had brains that were large, sharp senses, and were likely adept. There is debate over the diet they ate, with certain scientists suggesting that they were carnivores as well as others claiming that they were herbivores or omnivores. The absence or serrated teeth found in Xixiasaurus as well as other troodontids suggests that they were herbivores as they lost the ability to cut meat. Xixiasaurus is identified from the Majiacun Formation and the precise time of its existence is unknown. These sedimentary rocks were laid down by braided streams as well as meandering streams. They are known for their abundance of dinosaur eggs.
The Holotype of the specimen (catalogued by the name of HGM 41HIII-0201 at the Henan Geological Museum, Zhengzhou) was found close to Songgou Village, which is located in northeastern Xixia County, in Henan Province of central China. The area in the Xixia Basin exposes the Majiacun Formation. The specimen was discovered in 2010. was identified as the newly discovered species and genus Xixiasaurus of Henanensis by palaeontologist Lu Junchang and colleagues. The generic name is a reference to Xixia County coupled with saurus which means “lizard”, while the specific name is a reference to Henan Province. The full name may translate as “Henan Xixia lizard”. The remains of troodontids are uncommon in comparison to other dinosaurs of the small theropod range (only 13 troodontid species were identified at the time that Xixiasaurus was first named) They are mainly been discovered in Asia.
The Holotype specimen is the sole known Xixiasaurus fossil and is composed of a skull that is almost complete aside from the hindmost region as well as the right forelimb is only partially visible. The connective tissue to the forehead (forehead bones) and the nasal (bone running along the top of the snout) bones is broken, and a part of the skullcase has been removed. A large portion of the snout has been preserved and the dentition of the right side well-preserved. The front portion of the right dentary bones (tooth-bearing mandible bone) and a few broken teeth have been preserved. Although there are a few missing teeth in both jaws the original numbers can be found from the lower jaw because their sockets remain. Forelimb (of which all the remaining components are articulated) is comprised of the middle portion of the ulna and radius (bones that form the arm’s lower part) as well as the outermost part of the third and second metacarpals (hand bones) as well as the entire first finger, as well as one of the first bones in the phalanx of second finger. In 2014 the Palaeontologist Takanobu Tsuihiji and his colleagues reported that the bone that Lu and colleagues initially thought was Vomer (part of the mouth) in Xixiasaurus was actually one of the premaxillae, or maxillae (the major teeth of the upper jaw) in examination of its vomer in the troodontid with a more complete Gobivenator.