Sinornithosaurus was an early member of the dromaeosaur family. As this beautiful fossil shows, its entire body was covered from head to tail with feathers. Sinornithosaurus means “Chinese bird lizard,” but this species wasn’t a true bird, since it was probably too heavy to fly, although like other dromaeosaurs it may have evolved from a flying ancestor.
■ When: 130–125 million years ago (Early Cretaceous)
■ Fossil location: China
■ Habitat: Woodlands
■ Length: 3 ft (1 m)
■ Diet: Probably omnivorous
Several well-preserved fossils of Sinornithosaurus have been found in China since 1999, including the amazingly complete fossil shown here (nicknamed “Dave”), which shows the precise distribution of feathers on the body. Sinornithosaurus was a ground-dwelling predator that hunted small animals, including other dinosaurs.
Although it couldn’t fly, some scientists think it could climb trees.
Venomous or not?
In 2009, scientists noticed something strange about Sinornithosaurus: it had unusually long, fanglike teeth with prominent grooves, similar to those of venomous snakes and lizards today. They suggested that Sinornithosaurus was venomous (able to inject poison into prey with a bite or a sting). Other scientists disagree with this theory, saying that these grooves could simply be normal wear and tear, and that other dinosaurs had grooved teeth, too.
The fluffy feathers on its body may have helped in trapping heat. Long feathers on its arms were perhaps used for show or for protecting its young.