Artist Zhao Chuang rendered this cool illustration of a newly-discovered Zhenyuanlong. It was over six feet long and had copious feathers, as shown in a beautifully preserved Chinese fossil below.
From the paper by Junchang Lü and Stephen L. Brusatte:
We describe a new specimen of large-bodied, short-armed Liaoning dromaeosaurid, which we designate as a new genus and species, Zhenyuanlong suni. The integument is well preserved and provides the first evidence of feather morphologies and distribution in a short-armed (and probably non-volant) dromaeosaurid, indicating that these rare and aberrant taxa had large wings consisting of pennaceous feathers on the arms and long pennaceous feathers on the tail very similar to their smaller and longer-armed relatives, but potentially lacked vaned feathers on the legs.