Wow...I cannot believe I just typed all of the those words in the title together. Today's issue of Nature magazine includes an article on a new heterodontosaurid ornithischian (Tianyulong confuciusi) from the Cretaceous of China. Not only are heterodontosaurs pretty much unknown from the Cretaceous (previously restricted to the Latest Triassic (?) and early-middle Jurassic only), this one is covered with patches of filaments similar to the protofeathers found in many saurischian taxa.
These filaments are already known from the basal ceratopsian Psittacosaurus; however, a heterodontosaurid with feathers pushes this occurence to the base of Ornithischia (Butler et al. 2008).
It is not entirely clear whether the ornithischian filaments and saurischian protofeathers are the same, but if they are this would strongly suggest that protofeathers may be plesiomorphic for Dinosauria, and it is even hypothetical now that the successive ornithodiran outgroups to the dinosaurs may have also possessed this character. Now we just need a silesaurid from these Chinese deposits now or some better preservation in the Triassic! You can read more about this here, here, and here.
Butler, R., Upchurch, P., & Norman, D. (2007). The phylogeny of the ornithischian dinosaurs Journal of Systematic Palaeontology, 6 (01) DOI: 10.1017/S1477201907002271
Zheng, X., You, H., Xu, X., & Dong, Z. (2009). An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures Nature, 458 (7236), 333-336 DOI: 10.1038/nature07856
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