Final answer:
The Swing Era bassist described is Slam Stewart, recognized for his duo with Slim Gaillard and his role in the Art Tatum trio, as well as his scat-singing alongside bowed bass lines.
Step-by-step explanation:
The Swing Era bassist described in the question is Slam Stewart. He was well-known for being part of a duo with singer-guitarist-humorist Slim Gaillard. Moreover, as a member of the Art Tatum trio, he was famous not only for his exceptional bass playing but also for scat-singing along to his bowed solo lines, which was a distinctive feature of his performances. Neither Oscar Pettiford, Milt Hinton, nor Ray Brown are known for this particular combination of characteristics and collaborations.