In the 1800's, and earlier, a child born out of wedlock was not legally entitled to use his or her father's surname. The only legal surname the child could carry was his/her mother's legal surname at the time of his/her birth. The only way a child could legally use his/her father's surname was if the father petitioned the Georgia Legislature to pass a law "legitimizing" the child.
For example -- John Turner Spillers.
On 4 Nov 1818, John Turner of Putnam Co., Georgia, wrote his will. One clause in the will says: “I give to John Turner Spillers late of Sparta, in Hancock [Co., Georgia], two Hundred & fifty dollars out of my Estate."
The obvious question is: Who is John Turner Spillers and why did John Turner include him in the will?
I photocopied the will as it appears in the Will Book in the Probate Court in Putnam Co., Georgia. Fortunately, Putnam Co. also has folders which contain the originals of the wills. And, in reading the original, I discovered that the clerk who transcribed the will into the will book didn't make a complete transcription.
When I looked in the loose estate folders in Putnam Co., I discovered that the original will says, “I give to John Turner Spillers of Baldwin County son of the widow Spillers late of Sparta in Hancock”...
But, this still does nothing to identify John Turner Spillers. I immediately started using the assumption that John Turner Spillers was an illegitimate child, but didn't have any proof of it. On a later trip to the Georgia Archives, I started looking through the microfilm of the Court of Ordinary (i.e., today's Probate Court) and found proof that John Turner Spillers was an illegitimate child of John Turner's:
Putnam Co., GA, Court of Ordinary Minutes, Book AA (1819-1831), p. 71, 6 Jan 1823: “Whereas John Turner Spillers an Illegittemate of John Turner decd came into open court and made choice of William Turner as his guardian It is therefore ordered that the said William Turner be and he is hereby appointed Guardian to the said Illegitimate Child orphan of John Turner decd.” [Photocopied from microfilm (Drawer 1, Box 17), Georgia Department of Archives.]
So, back to the point of all this: John Turner Spillers could not use the TURNER surname of his father because (1) he was born out of wedlock and (2) his father never petitioned the legislature to "legitimize" him. And, he used the surname SPILLERS because that was his mother's LEGAL surname at the time of his birth. And we know that his mother's legal surname was Spillers because she had been married to someone named Spillers (John Turner's original will identified John Turner Spillers as the son of the "widow Spillers.")
I've yet to find proof of the "widow Spillers" maiden name (her given name was Elizabeth) and I haven't discovered proof of the given name of her Spillers husband (who was not John Turner Spillers' father). But, at least, we know the name of his biological father -- or, to be more precise, we know that John Turner accepted paternity of John Turner Spillers.