The obituary of James Robert Black states that he came to Utah with his mother and stepfather in 1854. He did come to Utah in 1854, but just came with his mother. She married John Atkinson in 1857 after she arrived in Utah. Further research is needed to determine the name of the pioneer company they traveled with.
His name is listed as "Jas. R. Atkinson" in the 1860 Utah Census, and as "James R. Atkinson" in the 1870 Utah census.