Kingdom Animalia
Phylum Chordata
Superclass Tetrapoda
Class Reptilia
Subclass Diapsida
Superorder Dinosauria
Order Saurischia
Suborder Theropoda
Family Dromaeosauridae
Subfamily Microraptorinae
Genus Sinornithosaurus
1st Species Sinornithosaurus millenii
Other attributes
Time Range 124.6-122 mya
Location China
Name Meaning Chinese bird reptile
Physical Dimensions 1.2 meters long
Dietary Classification Carnivore

Sinornithosaurus is a dromaeosaurid theropod dinosaur from the Early Cretaceous of China. It was named in 1999 by Xu Xing, Wang Xiao-Lin, and Wu Xiao-Chun. It was another of the first confirmed feathered non-avian dinosaurs to be found, and, as time went on, would prove to be among the more interesting.


Similar to its close relative Microraptor, Sinornithosaurus was a very bird-like theropod with a sleek, streamlined body, long legs with a sickle-shaped claw on each foot, a moderately long tail, a moderately long neck, and a long, bird-like head with a mouth containing lots of teeth; along with this, its arms were long, feathery, bird-like wings that it flew around with (similarly to Microraptor), although it did not have the large leg wings that Microraptor had. Most of its body (excluding its feet and snout) would have been covered in long, vaned feathers; its body would have been different shades of reddish-brown, yellow, black, and gray in color (which body part was what color is yet to be known).


Sinornithosaurus was a predator, preying on lizards, small mammals, and possibly primitive birds. Its teeth had knife-like serrations from back to back, and its sickle claw was used for restraining smaller prey.


Similarly to the later Microraptor, Sinornithosaurus had large, feathery wings that it used to fly through the air with, and, like its later relative, would have possibly taken to the air by running up a steep slope while flapping its wings before entering an airborne phase. However, Sinornithosaurus lacked the large leg wings that Microraptor had, meaning that it would not have been as adept in the air as its later relative, while conversely being considerably more agile on the ground; this indicates that Sinornithosaurus was either a more primitive microraptorine, or was part of a lineage of microraptorines that secondarily started to evolve to fit a more ground-based niche. For a while, it has been suspected that Sinornithosaurus had a venomous bite similarly to a snake, based on the notion that the upper teeth were long and fang-like, had prominent grooves running down their outer surface, and were situated just under a cavity that could have housed a venom gland; however, this has been disproved, as the teeth weren't nearly that long in life (they may have partially slid from their sockets), the grooves weren't unique to the species (as many other theropods had them), and the cavity just above the upper teeth was, in fact, not actually existant. A comparison of its sclerotic rings to those of modern reptiles and birds indicates that it was cathemeral.

In popular cultureEdit

Sinornithosaurus was featured in the 2nd episode of the 2011 documentary Planet Dinosaur, where it is shown chasing a Microraptor (which itself was attempting to eat a small lizard) through the air and attempting to eat it; in reality, this kind of scenario would not have happened, as Sinornithosaurus went extinct 2 million years before Microraptor evolved. The show also erroneously depicts it with a venomous bite, which it utilizes (along with hunting in packs) to take down a juvenile ornithopod.

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