The discovery of a fantastically preserved, bushy-tailed fossil theropod has cloaked the dinosaur world in feathers. Named Sciurumimus -- Latin for "squirrel-mimic" -- albersdoerferi, the dinosaur lived 150 million years ago in what is now Germany. When it died, it came to rest in sediments so fine-grained that they preserved an almost photographic impression of the filaments covering its body. Other feathered theropods, the taxonomic clade including all two-legged dinosaurs and their bird descendants, have been found previously, inspiring fantastic artist renditions and speculation that plumes rather than scales were the dinosaur norm. Those fossils, however, belonged to a relative latecomer group known as coelurosaurs. Whether most theropods were feathered, or just a few recent evolutionary offshoots, was an open question. The new fossil find, described July 3 in Proceedings of the National Academy of Sciences and led by paleontologist Oliver Rauhut of Germany's Ludwig Maximilian University, gives a resounding answer. Compared to the coelurosaurs, S. albersdoerferi was "significantly more basal in the evolutionary tree of theropods," or a trunk rather than a branch, wrote Rauhut and colleagues. If it had feathers, so did the rest of the theropods. The plumage didn't end there. Other paleontologists have found feathers in beaked, quadrupedal dinosaurs. Combine those observations with S. albersdoerferi's taxonomic significance, and "a filamentous body covering obviously represents the plesiomorphic state for dinosaurs in general," wrote Rauhut's team. Plesiomorphic is another way of saying "ancestrally typical." In short, it was feathers all the way down. Above: The Fossil Feathers aside, S. albersdoerferi is one of the most beautifully preserved dinosaurs in existence. On the following pages are photographs of the fossil. Image: H. Tischlinger/Jura Museum Eichstätt Citation: "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany." By Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell. Proceedings of the National Academy of Sciences, Vol. 109 No. 27, July 3, 2012.

Skull Skull under ultraviolet light. Though named after a squirrel, S. albersdoerferi was carnivorous and large: Just a juvenile, this skeleton was 28 inches long. Full-grown, it would probably have been 20 feet long from nose to tail. Image: Rauhut et al./PNAS Citation: "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany." By Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell. Proceedings of the National Academy of Sciences, Vol. 109 No. 27, July 3, 2012.

Skin Under ultraviolet light, fossilized bone glows green and soft tissue glows yellow. In this section of S. albersdoerferi's tail, the yellow area represents a patch of skin. Image: Rauhut et al./PNAS Citation: "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany." By Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell. Proceedings of the National Academy of Sciences, Vol. 109 No. 27, July 3, 2012.

Feathers Long, fine filaments at the tail's base. Unlike stereotypical modern bird feathers, which are optimized for flight, early dinosaur feathers likely served as insulation. Image: Rauhut et al./PNAS Citation: "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany." By Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell. Proceedings of the National Academy of Sciences, Vol. 109 No. 27, July 3, 2012.

Follicles Magnified section of S. albersdoerferi's ridged back shows what appear to be follicles anchoring the feathers. Image: Rauhut et al./PNAS Citation: "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany." By Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell. Proceedings of the National Academy of Sciences, Vol. 109 No. 27, July 3, 2012.

Forelimb S. albersdoerferi forelimb under ultraviolet light. Image: Rauhut et al./PNAS Citation: "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany." By Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell. Proceedings of the National Academy of Sciences, Vol. 109 No. 27, July 3, 2012.