Nephila jurassica, the freshly found fossil orb-weaver spider from the Daohugou Beds of Mongolia dating back aroung 165 million years. Modern golden orb-weaver spiders are big enough to catch small birds and bats and eat them once in a while, though they normally target large insects.
Nephila jurassica was around the same size class as it's modern relatives and certainly big enough to catch and kill an occasional unlucky feathered dinosaur. Here it's shown attacking a young Scansoriopteryx.
A very quickly made reconstruction drawn with markers and colored digitally. I just heard about the find this morning and made this in a couple of hours. I'm not fully satisfied with this, but just consider it a speed painting thing.
And there were dinosaur-eating mammals, dinosaur-eating snakes and all that. No wonder they learned to fly, when every thing that crawls on land wants to eat them.