I strongly suspect that Groening and co were screwing with us more than normal with the episode Jurassic Bark. In the scene where Fry realises that he has been duped, he tosses the pizza on the desk. What's that moving in the waste paper basket? Could it be Nibbler? And if so, what's he doing there? I hope that there will be a sequel episode. If they brought back Fry's girlfriend, the least they can do is bring back his beloved pet...
Merry Christmas everybody,
~Leon