I don’t know about Newton Thomas Pettus, but I do know about Thomas Newton Pettus who was the son, b. about 1815, of William Pettus and his wife Mary Knox of South Carolina. William was born in Hanover Co., Va., and migrated to South Carolina to live with his brother George L. Pettus, who had preceded him to that state.
William was the son of Stephen Pettus II, son of Stephen Pettus, son of Thomas Pettus II, son of Thomas Pettus (b. 1598 in England). The last of these men is the one you identified as the “famous Pettus.” The link between Thomas Pettus II and the first Stephen Pettus has been the subject of some controversy, but vol. II of my Pettus book, which I am now proofreading, presents previously unreported evidence that, in my opinion, establishes the relationship between the two men. Vol. I of my Pettus book has extensive biographical information on all the Pettuses mentioned above and on all the related Pettuses in in England. Copies of vol. I are available from me by direct order. If you are interested, please e-mail me at my own URL (click on my name at the top of this message), and I will send you an order form.
Thomas was a cousin of Rolphe Pettus, son of William Pettus of Norwich and London, England, and his wife Elizabeth Rolfe. Elizabeth was related to John Rolfe, who married Pocahontas at Jamestown. Pocahontas's portrait was in an old Pettus home in Norfolk Co., England. I only recently learned that Pocahontas had previously been married to Okoum and had a daughter Ka-Lee. According to the legend, Ka-Lee married a Pettus who was close kin to Thomas. I am still exploring the possibilities of who Ka-Lee’s husband might have been. One theory is that he was Theodore Pettus, Thomas's younger brother. Another is that he was "Thomas Pettus, Jr.," whose name was given as a headright for a patent issued to Thomas in 1644. The identity of Thomas, Jr., is uncertain, but he was not Thomas II, mentioned above.