According to a Brazilian football confederation statement on Saturday, Liverpool's Firmino was omitted from the squad due to "bruising". But reports in the British press said the 24-year-old had suffered a hamstring strain, reports Xinhua.
Jonas, who has not represented Brazil's national team since 2012, is Benfica's top scorer this season with 30 goals from 34 matches. The 31-year-old has scored twice in eight matches for the Selecao.
Brazil will play Uruguay in Recife on March 25 before facing Paraguay in Asuncion four days later.
Dunga's side is currently third in the South American zone World Cup qualifying standings with seven points from four matches. Ecuador leads with 12 points, three points ahead of second-paced Uruguay.Published 20 Mar 2016, 21:00 IST