Okay, look, it's clear that I'm not the BEST guy to go to when it comes to this subject. I don't have the same access to primary literature that many of you do, I certainly haven't seen many actual specimens of Triceratops OR Torosaurus, my knowledge of stratigraphy is poor, and bone histeology is still very new to me.
I'm not trying to overturn anybody or make a serious case against Scannella and/or Horner. I'm not trying to bogart anybody's future or current research. I'm sorry if I've hit any nerves or didn't read the right papers...well enough.
That said, on morphological grounds alone, I think that known specimens of Torosaurus differ significantly from known specimens of Triceratops, either T. prorsus or T. horridus (although T. horridus looks a bit more like Torosaurus). Several things lack decent explaination. Among them:
Why don't any specimens of Torosaurs have "adult" nasal horn morphology of Triceratops? What other ceratopsid goes through such a radical late-stage morphological change?
How do we know that a solid frill is a juvenile trait, and not a derived trait?
Why aren't there any (AFAIK) Triceratops skulls with small fenestrae besides Nedoceratops, which itself is a contentious specimen?
I liked Haikaru's example in the comments for the 2nd Toroceratops post: if you found a humpback whale and a blue whale as fossils, you might assume that the latter is the adult of the former. Again, I'm not saying that Scannella and/or Horner are WRONG, I'm saying that their conclusion is not completely solid based on that paper alone. And you know what? Few papers are. Further research into post-cranial anatomy, histeology, stratigraphy, and morphology will doubtlessly illuminate this topic further, and I welcome that research.
I didn't mean to step on any toes or insult anybody. My posts were meant to suggest that further research was needed, and that alternatives to Toroceratops are possible.
And that's the last I'll say on the subject...at least until more data is published.