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Feathered ancestor of T. rex unearthed

It's true: see http://www.nature.com/news/2004/041004/full/041004-11.html, a news brief published in the journal, _Nature_. A reconstruction of the skeleton is included. You need not be a subscriber to access this article. It appears that the opening paragraph of the description paper is also accessible to non-subscribers by clicking on "Article" at the bottom of the page.

The paper, "Basal tyrannosaurids from China and evidence for protofeathers in tyrannosauroids," by XU, Norell, Kuang, Wang, Zhao, & Jia, in _Nature_, Vol. 431, 7 October 2004, pp. 680-684, describes the Early Cretaceous tyrannosauroid, _Dilong paradoxus_ (Chinese "di" meaning emperor + "long" meaning dragon; "the specific name refers to the surprising characters of this animal"). The following text, which includes the opening paragraph, is at http://www.nature.com/doifinder/10.1038%2Fnature02855. If the following text does not display, it is probably because it is not in plain text.

Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids

1 Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
2 American Museum of Natural History, New York 10024, USA
3 Tianjin Museum of Natural History, Tianjin 300074, China
* Present address: American Museum of Natural History, Central Park West at 79th Street, New York City, New York 10024, USA

Correspondence and requests for materials should be addressed to X.X. (xu@amnh.org or xingxu@vip.sina.com) or M.A.N. (norell@amnh.org).

Tyrannosauroids are one of the last and the most successful large-bodied predatory dinosaur groups, but their early history remains poorly understood. Here we report a new basal tyrannosauroid from the Early Cretaceous Yixian Formation of western Liaoning, China, which is small and gracile and has relatively long arms with three-fingered hands. The new taxon is the earliest known unquestionable tyrannosauroid found so far. It shows a mosaic of characters, including a derived cranial structure resembling that of derived tyrannosauroids and a primitive postcranial skeleton similar to basal coelurosaurians. One of the specimens also preserves a filamentous integumentary covering similar to that of other coelurosaurian theropods from western Liaoning. This provides the first direct fossil evidence that tyrannosauroids had protofeathers.

The holotype is a semi-articulated skeleton including an almost complete skull. A nearly complete skull with associated presacral vertebrae and a partial skull are also referred to this taxon, as is yet another specimen (IVPP V11579 from the 125 million year old grey shale of the Yixian Formation of Zhangjiagou locality, Beipiao, western Liaoning) which served as the basis for the skeletal reconstruction, although it is noted that the latter specimen may in fact represent a distinct but closely related taxon.

The fossils were found in Lujiatun, Beipiao, western Liaoning. They were situated in the fine sand beds of the lower part of the Yixian Formation which are between 139 and 128 million years old.

The largest individual would have been approximately 1.6 meters long, and the three-fingered forelimbs were long enough to facilitate grasping prey. The skull resembles juvenile tyrannosauroid skulls; the gracile postcranial skeleton is somewhat similar to those of basal coelurosaurians. The referred specimen cited above sports branched filamentous protofeathers as in other coelurosaurians. Protofeathers from the dorsal edge of distal caudal vertebrae are represented in photographs and drawings. Aside from this, the paper does not describe the distribution of the protofeathers.

"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology