Shuvuuia

*Shuvuuia deserti*

***Shuvuuia*** is a genus of bird-like theropod dinosaur from the late Cretaceous period of Mongolia. It is a member of the family Alvarezsauridae, small coelurosaurian dinosaurs which are characterized by short but powerful forelimbs specialized for digging. The type (and only known) species is *Shuvuuia deserti*, or "desert bird". The name *Shuvuuia* is derived from the Mongolian word *shuvuu* (шувуу) meaning "bird".

## Description

Shuvuuia was a small and lightly built animal. Only reaching lengths of around 60 cm (2 ft) in length, it is one of the smallest known dinosaurs. The skull is lightly built with long and slender jaws and minute teeth. *Shuvuuia* is unique among non-avian theropods in the skull's ability to perform prokinesis, that is, it could flex its upper jaw independently of its braincase.

The hindlimbs of *Shuvuuia* were long, slender, and short-toed, which may indicate significant running capabilities. The forelimbs, however, were unusually short and powerfully constructed. Although originally *Shuvuuia* and other alvarezsaurids were thought to have only a single digit on the front limb, newer specimens show the presence of reduced second and third fingers in addition to the massively enlarged thumb known from previous specimens. Like other alverezsaurids, *Shuvuuia* may have used its forelimbs to open insect nests, and its slender, unusually mobile jaws to probe after such prey.

 Fossils of *Shuvuuia* are currently known from two locations within the Djadochta Formation: Ukhaa Tolgod and Tögrögiin Shiree. These sites are thought to be about 75 million years old (late Campanian age). Contemporary genera included Velociraptor and Protoceratops.

## Paleobiology

### Nocturnal adaptations

Like other alvarezsaurids, *Shuvuuia* may have used its forelimbs to open insect nests, and its slender, unusually mobile jaws to probe after such prey. However, new research based on analysis of the theropod's ears suggests that it was actually an owl-like, nocturnal hunter which used its strong legs to run down prey, and its arms to dig small prey such as insects and mammals out of burrows and shrubs; its lagena is about the same size as that of barn owls, giving it superb hearing in addition to its fantastic night vision (analyzed by looking at its scleral ring) allowing it to potentially hunt in complete darkness, unlike other theropods to which it has been compared, such as the apparently diurnal *Dromaeosaurus* and *Tyrannosaurus*.

A recent study in May 6, 2021, suggests that Shuvuuia might've been a primarily nocturnal hunter due to its incredibly sensitive hearing and enlarged eyes suggesting a very developed night vision. The study also included Haplocheirus, a similar coelurusaur.

### Feathers

*Shuvuuia* was the fourth non-avian dinosaur genus that demonstrated direct evidence of feathers. The type specimen was found surrounded by small, hollow, tube-like structures resembling the rachis (central vane) of modern bird feathers. Though highly deteriorated and poorly preserved, biochemical analyses later showed that these structures contain decay products of the protein beta-keratin, and more significantly, the *absence* of alpha-keratin. While beta-keratin is found in all integumentary (skin and feather) cells of reptiles and birds, only bird feathers completely lack alpha-keratin. These findings show that, though poorly preserved, *Shuvuuia* likely possessed a coat of feathers.

## JPInstitute.com Description

Shuvuuia was a small dinosaur that a lot in common with modern birds, including its jaw and feathers. While Shuvuuia appears to have been capable of bursts of speedy movement, scientists think that it spent most of its time searching for small, hidden or burrowing prey, such as nesting insects.

It is noteworthy that Shuvuuia is the only alvarezsaurid that is known from a complete skull. Some fossil material previously thought to have been Mononykus have been assigned to Shuvuuia. These bird-like dinosaur fossils have created one of the most intense fields of study within paleontology and have contributed to many new theories.

## Dinosaur Field Guide Description

Shuvuuia ("bird") is one of the strangest theropods, or meat-eating dinosaurs, ever found. It is one of the alvarezsaurs, a group of small bird-like dinosaurs of the Late Cretaceous Period. Shuvuuia has a pointed, beaky snout, with jaws holding many very tiny teeth. It has a long neck, a compact body, a fairly short tail (for a dinosaur), and long legs built for running fast. One of the oddest parts about it is its arms. While most advanced theropods had three working fingers and the tyrant dinosaurs had two alvarezsaurs had only one working finger the thumb. Also, although the arms of Shuvuuia are short-like its larger relatives-they were extremely strong. Scientists do not know how Shuvuuia used these arms, but they certainly had some function. Perhaps it used them to dig into insect nests? Shuvuuia and the other alvarezsaurs are a bit of a puzzle in the dinosaur family tree. In some ways they seem like the ostrich dinosaurs, in others they are similar to primitive birds, and in still other ways they are like troodonts. Paleontologists are still trying to determine the closest relatives to these bizarre little dinosaurs.

### Fun Facts

A skeleton of Shuvuvia is on display at the American Museum of Natural History in New York City.

### Trivia

A full-grown Shuvuuia was only the size of a chicken, but it was bigger
than most of the mammals that lived in its environment.

## Links

http://web.archive.org/web/20040214162912fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_shuvu.html

## References

1. ↑ Chiappe, L.M., Norell, M. A., and Clark, J. M. (1998). "The skull of a relative of the stem-group bird *Mononykus*." *Nature*, **392**(6673): 275-278.
2. ↑ https://scitechdaily.com/shuvuuia-extraordinary-dinosaurs-that-hunted-in-the-dark/
3. ↑ https://www.usatoday.com/story/news/nation/2021/05/06/little-bird-like-dinosaur-hunted-night-study-suggests/4975565001/
4. ↑ https://theconversation.com/nocturnal-dinosaurs-night-vision-and-superb-hearing-in-a-small-theropod-suggest-it-was-a-moonlight-predator-160152
5. ↑ https://www.newscientist.com/article/2276926-owl-like-dinosaurs-had-remarkably-good-hearing-and-night-vision/
6. ↑ Schweitzer, M.H., J.A. Watt, R. Avci, L. Knapp, L. Chiappe, M. Norell & M. Marshall. (1999). "Beta-keratin specific immunological reactivity in feather-like structures of the Cretaceous alvarezsaurid, *Shuvuuia deserti*." *Journal of Experimental Zoology* (Mol Dev Evol), **285**: 146-157.