From this episode and SITL this surely means that Alex Kingston plays River in her last regeneration. However this doesn't stop the Doctor meeting River in an incarnation before Alex played by a different actress and for her to regenerate into Ms Kingston at the end of the story... Hence there could be lots of other river's out there for the Doctor to come across. [After all there are many rivers to cross ]

I have a feeling, she cant change her face, her timelord DNA just brings her back to life, like Jenny didnt change face.

Ah, but Jenny was only a few hours old, so her body was able to self-repair. Notice how she gave off the same 'fairy dust' effect as Ten did in The Christmas Invasion?

We don't know if Jenny actually regenerated though. It looked like she was brought back by that stuff that brought the planet back. (I call it 'that stuff' because I can't remember fully. ) So it's possible River can regenerate.

Ooo I have a theory on this one...I shall pop it in spoilers, just in case as I don't want to upset anyeone!!! ...not saying incidentally that this is defo true, I don't have a scoobie, its just an idea...feel free to debunk at leisure!!

If River is enough of a Time Lord to be able to regenerate, how come the Doctor has never "felt her presence"?

And if "River" is Melody how come she hasn't been known as Melody all along considering the name River Song is only a translation onto a prayer leaf. The Doctor's and River's timelines became united at the point of reveal so surely logically, it would have been when River realised who she was too!

Personally, I reckon we'll see three Rivers - the baby/the little girl, who then regenerates in DoTM into a second incarnation, which will grow up and we'll meet later on. She'll eventually die and regenerate into a third and final River which will be the Alex Kingston one.

SITL:

River mentions that the Doctor can't fry so she does it in his place, it would kill him and not give him enough time to regenerate. Ergo, she can't regenerate.

That's easy - timelines. She had to change her name (and even then she technically hasn't) so that when she met the Doctor before he knew who she was so that he wouldn't find out her name before the "proper" time and cause all sorts of timey wimey problems. She kept the name River Song because that is her name - just translated from a language where there is no word for pond.

The impression I got was that River grew up at least partly with the Gamma Forest people, and the translation of the name stuck.
And/or...
It could be to protect her identity from her kidnappers, changing her name to make her harder to find?

Is there a reason to think their timelines became united at that point? I think there will come a time when they get halfway between their first and last meetings and will be in sync, but I'm not convinced it was this episode.

Edit to add:
I think the opening post is right...UNLESS the Doctor finds a way of bringing River out of CAL's memory and back into reality.

As a fan of both the RTD and Moffat eras, that's one of the new things i personally don't agree with. I always enjoyed moments in the Classic series when the Doctor didn't know a Time Lord was nearby until they revealed themselves or he discovered their TARDIS. The Master disguised himself numerous times to fool the Doctor, and the Rani's first appearance saw her disguised as an old woman. So i hope Moffat either takes this ability away from the Doctor somehow or quietly drops it. That way, he can introduce Time Lords into the series without having the Doctor "feel" their presence and give the game away.

Just my opinion.

Capt Apollo

When the Doctor finally meets the young River, he probably gives her that name in order to conceal her identity from his earlier self.

Doesn't he sense that they exist, but not where they are? He doesn't sense River because she's human. With The Master apparently gone (timelocked in the Time War as of The End of Time), the only other proper Time Lord would be Jenny, his cloned daughter.

Yes, he senses Time Lords and recognises them on sight. I think this takes away from the thrill of discovering that a character is a Time Lord if even the Doctor doesn't know until it's revealed either in dialogue or through actions. This would also explain why he never knew River was a Time Lord or part-Time Lord (i prefer full Time Lord, which is what i also consider Jenny to be - since she has two hearts)

Capt Apollo

Jenny is certainly full Time Lord, she's a clone of the Doctor after all. But River is a human with one heart... although whether she'd get a second heart if she regenerated is another matter, since she has some Time Lord DNA. River is what Marvel Comics calls a mutant.

I like this. It would explain how Lorna met him - causing mayhem in the 30 seconds he came to pick up River.

Gary

Has it been mentioned in any episode that she has only one heart?
I'm not being confrontational here, i just want to clarify if River or Melody have been stated as having one/two hearts?
Donna used a stethoscope to confirm that Jenny had two hearts (and therefore, in my opinion, is a full Time Lord with the ability to regenerate)
Has anyone stated in any episode that River/Melody have/don't have two hearts?

Apollo1

Actually I was given to understand that Jenny was half timelord as the Doctors DNA was spliced with human DNA that was in the cloning system. Didn't she only have one heart? Maybe I need to re watch as its been a while.....

Not even remotely confontational - a perfectly sensible question.

It hasn't been stated one way or the other but it would be seriously stretching credulity to suggest that someone scanned that baby right to her DNA without spotting an extra heart - or another major non-human attributes - along the way so I'd say it's incredibly unlikely that she is anything but human in every other way.

No, if you watch the episode, Donna uses a stethoscope and clearly states that Jenny has two hearts. At the end, when she has seemingly been killed she wakes up, expelling the same glowing energy from her mouth as the Doctor has done after his last two regenerations. Doctor 10 replaced his severed hand just after his regeneration, pointing out that he was within his regeneration cycle. Since Jenny was only a few hours old, many people have interpreted that her body repaired itself in a similar fashion and that she now has the ability to regenerate.

Capt Apollo

I'm pretty sure she will regenerate. Not for any story reasons but because Alex Kingston doesn't want to do a full series, so the doctor will have one of her previous regenerations as a companion.

She expelled glowing energy alright, but it was ambiguous as there was definitely an element of the terraforming energy in there.

The Doctor made the point that it takes more than just having two hearts to be a Time Lord. It may be that he was just referring to the education and cultural history, or it may that he's referring to the augmented DNA that was also present in Melody - perhaps this didn't transfer in the cloning process that created Jenny.

Either way, if it's this extra DNA that's necessary for regeneration, then Jenny may or may not have the ability.

River's body was vaporised, so there wasn't anything left to regenerate, besides river was saved, her mind was transferred to the library database

It doesn't even need to be a previous regeneration (as we don't know either way with that...). We have had it established that the Doctor gets to see progressively younger versions of River, as they travel in two different directions. This means that they could just cast similar looking actresses who are younger than Alex to play the character. They could even have it that the Doctor misses out a huge chunk of her life (due to unforseen circumstances), and then the next time we see River she's 20.

I think it could be great if their romance actually only started because from her point of view she hadn't seen the Doctor for such a long time, and she had built up her emotions to such a level - and due to it being later in the Doctor's personal time line, he's already started kissing her (we saw her final one with him, it was his first with her, though), so it seems reciprocated. Therefore, it could be that the last time we see Alex play River, it will be an emotional journey for the Doctor: from how she greets him - that she's missed him so much, kind of thing - he would have the knowledge that the romance part of their meetings would be over. And this would be like how River felt after kissing the Doctor for her last time...