Development theories about the resurrection stories usually start with the observation that, if the longer ending of Mark is non-canonical, Mark "doesn't have" any appearance stories. This assumes, further, that Mark originally ended after verse 8 (which I'd say is probably false). But it also treats the alleged absence of appearance stories as if Mark was *denying* appearances. Not only is this the worst kind of argument from silence, it also runs contrary to other indications right in the undeniably canonical text of Mark itself.
The Lydia McGrew Podcast