I just found your post today, so sorry it took me this long to read it.
From my research it seems that THURSA J. PIERCE was the oldest child of Thomas S. Pierce and his wife Elizabeth. Thomas ws born 1826 in Kentucky and died April 1881 in Bates County, Missouri probably near the town of Foster, MO. He is burried in the Salem Cermetery at Foster, Missouri. His first wife Elizabeth was born 8 Aug 1828 and died 3 Feb 1872 and is buried in the Woodfin Cemetery near Foster. Their daughter THURSA J. PIERCE was born 22 November 1853 in Missouri and died 8 July 1873 in Bates County, Missouri, Thursa J. Pierce COX is buried in the Woodfin Cemetery next to her mother, Elizabeth. Thursa J. Pierce COX married my Great Grandpa Garland Wesley Cox on 7 July 1870 in Bates County Missouri near Foster in the home of her father, Thomas Pierce. She was around the age of 16 when she married. I have determend that they had no children, unles they died as babies or stillborn. I have not found an obituary for her, and no death certificate. So do not know why she died so young, my guess would be due to childbirth.
Thomas S. Pierce second wife was Mary A. She was born 25 August 1820 and died and is buried in the Salem Cemetery next to Thomas S. Pierce. I thought I had the maiden names of Thomas' wives, but did not find them today. I know my cousin Jarrott has their last names. Thomas and Elizabeth other children were: Mary E, b. 1860 in MO, James William, b. 1861 in MO, Dockey H. b. 1863 in MO. There was a Hiram Pierce living with Thomas in 1880, probably a brother or cousin. There was a M. J. Pierce living with them in 1860, could be a brother, also.
An interesting item is that when My G-Grandfather (Garland Wesley COX) married his second wife Margaret Mary Walls, he married her in the home of his first father-in-law, Thomas S. Pierce.
Let me know if this COX is mentioned anywhere in your PIERCE Family Line!!!
Jeanette COX Searl