7
October 2004
Tyrannosauroids: Feather wait
The early history of the tyrannosauroids, one of the last and most successful dinosaur groups, is still poorly understood. Two fossils from China's Yixian Formation, one a near complete skull with vertebrae and the other a partial skull, will fill in some of the gaps in the story. At 130 million years old they are the oldest known tyrannosauroids, and they reveal similarities to later tyrannosauroids and to another group of carnivores, the coelurosaurians. But there is a surprise too. One of the new fossils, like some coelurosaurians, has a filamentous integumetary covering, or 'protofeathers'. Flying tyrannosauroids are unlikely: these early feather-like structures were probably involved in heat retention.
Basal tyrannosauroids from China and evidence
for protofeathers in tyrannosauroids
XING XU, MARK A. NORELL, XUEWEN KUANG, XIAOLIN WANG,
QI ZHAO & CHENGKAI JIA
Nature 431, 680–684 (2004); doi:10.1038/nature02855
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