Please advise on my sentence structure.

[Mzjanet]

Please tell me if these sentences are grammatically correct.

The creature sat upright and tugged at the shackles binding his ankles, Frankenstein uttered a piercing scream.


Richard III supposedly had the young princes murdered. Found out what really happened to them.

As of December 1, Ira and Sandy will have been going together for three years.

[Mister Micawber]

'
1-- a comma splice error: a conjunction is needed after the comma, or the comma should be replaced by a semicolon.

2-- The second sentence is not one; it is a fragment, needing (I suppose) a subject, like 'no one'.

3-- OK, so long as December 1st is in the future.
.

[Mzjanet]

Mister Micawber
Thank you!