I googled Brad's name and here is what it said about him in reference to America (keep in mind this is the internet so everything is guaranteed to be 100% accurate and error free by Al Gore):
In 1981 Brad Palmer, who had worked with Andrew Gold and Wendy Waldman in the past, joined AMERICA as their new bass player. For the next recordings all members of AMERICA went to the recording studio, but Dewey Bunnell and Gerry Beckley also used many session musicians for the recordings. The same was repeated for all of the studio recordings of the eighties. If one listens to the live recordings, which were recorded during the eighties ("King Biscuit Flower Hour Presents America In Concert" 1982 and "America In Concert" 1985), it is difficult to understand the reasons for this decision, as the live recordings in most cases sounded better than the studio recordings. After 1985 AMERICA seemed to have retired. There still were a few concerts but it should remain quiet till 1993. Rhino Records had asked AMERICA to record some new songs for a "Best Of..." compilation, which they were planning. "Encore" featured some new recordings. The five musicians really enjoyed their new cooperation in the studio and so they decided to become active again. In 1994 they released their first new album in almost ten years - "Hourglass". The next album was released in 1998 under the title "Human Nature". In 2000 Rhino released a 3-CD-retrospective covering the whole career of the group. The compilation even had some unreleased demo recordings. In 2001 another "Best of..." album was released and again this album had some new recordings. In 2002 AMERICA returned to their well known creativity. During the summer they recorded a christmas album together with Andrew Gold. Andrew Gold did not only produce the album but he also played all of the instruments.
Brad Palmer was obviously a bloody good bass player and singer to have played for America for as long as he did. The old chat folder though; I remember there was a bit of talk surrounding his departure.