[inferiorhuman]

Of the more than 100 poop complaints I've filed with 311 the majority have been human sized. The one with a string/tapeworm coming out of it was ambiguously sized and spread out over like three blocks.

Yesterday I submitted one of bloody handprints smeared all over a building on Mission St. Pretty sure those weren't dog handprints. I called it graffiti since I didn't see anything more suited towards "blood smeared all over someone's building".

http://mobile311.sfgov.org/reports/11720974

This was voluminous enough that I think it was probably human:

http://mobile311.sfgov.org/reports/11019074

Out in the western neighborhoods this size was more common (and I'd assume was dog sourced):

http://mobile311.sfgov.org/reports/11541986

[kbenson]

And that is a useful set of information to add to the discussion.

I'm not sure how accurate size is as an indicator of species for feces, given that some dogs are quite large with large feces (and some many humans have small feces for dietary reasons), but it's not like the original commenter explained in much detail how they classified the feces either (other than indicating it was through images for many).

Edit: Regarding your second link, I have a pair of 65 pound dogs, and their poop is generally about 1/3 to 3/4 that size. I assume it could be a ~100 lb dog, but agree it's more likely from a person.