How did they know that it had feathers?
It is quite possible our view of dinosaurs as a leathery clad lizard-type of creature may be a lot more shortsighted as it is possible that they ALL may been feathered creatures and the development into smaller, more efficient types may have resulted in their ability to survive the Chicxulub event in the Yucatan.
Bird have long been thought to be related to some hollow-boned dinosaurs, yet the explaination of the 'evolvement' of feathers has been dubious at best.
Recent fossil discoveries and probably future ones will show that some of the species were feathered in some form or fashion and the changes made the smaller, more efficient types more likely to survive because of the need for less food, area for development and the ability to adapt more easily to catastrophic change.
Just my two cents on all this.