Newly Discovered Dinosaur Implies Greater Prevalence of Feathers

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Skeleton of Sciurumimus as found on a limestone slab
© H. Tischlinger/Jura Museum Eichstätt

A new species of feathered dinosaur discovered in southern Germany is further changing the perception of how predatory dinosaurs looked. The fossil of Sciurumimus albersdoerferi, which lived about 150 million years ago, provides the first evidence of feathered theropod dinosaurs that are not closely related to birds. The fossil is described in a paper published today in the Proceedings of the National Academy of Sciences by researchers at the Museum and at the Bayerische Staatssammlung für Paläontologie und Geologie and Ludwig Maximilians University, both in Germany.

Theropods are bipedal, mostly carnivorous dinosaurs. In recent years, scientists have discovered that feathering was present on many extinct theropods, but only on those that are classified as coelurosaurs, a diverse group including T. rex and birds. Sciurumimus—identified as a megalosaur, not a coelurosaur—is the first exception to this rule. Because the new species sits deep within the evolutionary tree of theropods, the findings suggest that all predatory dinosaurs might have had feathers.

“Everything we find these days shows just how deep in the family tree many characteristics of modern birds go, and just how bird-like these animals were,” says Mark Norell, chair of the Museum’s Division of Paleontology and an author on the paper. “At this point it will surprise no one if feather-like structures were present in the ancestors of all dinosaurs.”

The fossil, which is of a baby Sciurumimus and just about 28 inches long, was found in the limestones of northern Bavaria and preserves remains of a filamentous plumage, indicating that the whole body was covered with feathers. The genus name of Sciurumimus albersdoerferi refers to the scientific name of the tree squirrels, Sciurus, and means “squirrel-mimic”—referring to the especially bushy tail of the animal. The species name honors the private collector who made the specimen available for scientific study.

Mid-tail section of Sciurumimus under ultraviolet light, showing patches of preserved skin (yellow) and fine filaments (bluish lines above the vertebrae).
© H. Tischlinger/Jura Museum Eichstätt

The Sciurumimus skeleton, which represents the most complete predatory dinosaur ever found in Europe, provides a rare glimpse at a young dinosaur. Based on studies on its teeth, the researchers concluded that young Sciurumimus had a much different diet than adults, which reached about 20 feet in length and often weighed more than a ton. The juvenile specimen of Sciurumimus probably hunted insects and other small prey, as evidenced by the slender, pointed teeth in the tip of the jaws.