An international team of paleontologists has discovered a new species of feathered dinosaur in southern Germany.
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.
“This is a surprising find from the cradle of feathered dinosaur work, the very formation where the first feathered dinosaur Archaeopteryx was collected over 150 years ago,” said Dr Mark Norell, chair of the Division of Paleontology at the American Museum of Natural History and senior author of a paper in the Proceedings of the National Academy of Sciences.
Theropods are bipedal, mostly carnivorous dinosaurs. In recent years, scientists have discovered that many extinct theropods had feathers. But this feathering has only been found in theropods that are classified as coelurosaurs, a diverse group including animals like T. rex and birds.
Sciurumimus – identified as a megalosaur, not a coelurosaur— is the first exception to this rule. The new species also sits deep within the evolutionary tree of theropods, much more so than coelurosaurs, meaning that the species that stem from Sciurumimus are likely to have similar characteristics.
“All of the feathered predatory dinosaurs known so far represent close relatives of birds,” said lead author Dr Oliver Rauhut, a paleontologist at the Bayerische Staatssammlung für Paläontologie und Geologie. “Sciurumimus is much more basal within the dinosaur family tree and thus indicates that all predatory dinosaurs had feathers.”
The fossil, which is of a baby Sciurumimus, 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.
“Under ultraviolet light, remains of the skin and feathers show up as luminous patches around the skeleton,” said co-author Dr Helmut Tischlinger of the Jura Museum Eichstatt.
Sciurumimus is not only remarkable for its feathers. The skeleton, which represents the most complete predatory dinosaur ever found in Europe, allows a rare glimpse at a young dinosaur. Apart from other known juvenile features, such as large eyes, the new find also confirmed other hypotheses.
“It has been suggested for some time that the lifestyle of predatory dinosaurs changed considerably during their growth,” Dr Rauhut said. “Sciurumimus shows a remarkable difference to adult megalosaurs in the dentition, which clearly indicates that it had a different diet.”
“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,” Dr Norell said. “At this point it will surprise no one if feather like structures were present in the ancestors of all dinosaurs.
Bibliographic information: Rauhut O et al. 2012. Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany. PNAS. Published online before print July 2, 2012; doi: 10.1073/pnas.1203238109