Feathers didn’t start with birds. Plumage of various sorts — from simple fuzz to the complex structures used for flight — adorned dinosaurs first, and was only later inherited by birds. And if a beautifully preserved juvenile dinosaur unearthed in the Jurassic strata of Germany is any indication, it is possible that all dinosaurs bore patches of filamentous feathers.
Since the discovery of the fluffy theropod Sinosauropteryx in 1996, palaeontologists have recognized more than 30 types of feathered dinosaur. Most of these are coelurosaurs — a disparate group of theropods that includes not only the fearsome tyrannosaurs, sickle-clawed deinonychosaurs and bizarre therizinosaurs, but also birds.
However, there are exceptions to this rule. Palaeontologists have also discovered simple, feather-like structures along the vertebral columns of the dinosaurs Psittacosaurus and Tianyulong. These ornithischians are about as distantly related to birds as dinosaurs can be, and the discoveries hinted that swaths of simplified protofeathers were a common feature among dinosaurs. The discovery of the most recent fossil indicates that feathery body coverings were widespread in these creatures.
The 150-million-year-old theropod Sciurumimus albersdoerferi unearthed in Germany and described today1 was coated in a form of plumage. The filamentous structures have been seen before in other dinosaurs, but what makes Sciurumimus so noteworthy is that this dinosaur was a megalosauroid.
Megalosauroids were a group of archaic sharp-toothed dinosaurs near the base of the theropod family tree, and greatly removed from the various types of feathered dinosaur and early birds recognized so far.