Macro-Siouan languages
In the 19th century, Robert Latham suggested that the Siouan languages are related to the Caddoan and Iroquoian languages. In 1931, Louis Allen presented the first list of systematic correspondences between a set of 25 lexical items in Siouan and Iroquoian. In the 1960s and 1970s, Wallace Chafe further explored the link between Siouan and Caddoan languages. In the 1990s, Marianne Mithun compared the morphology and syntax of all the three families. At present, the Macro-Siouan hypothesis based on relations among Siouan, Caddoan, and Iroquoian is not universally accepted as proven.
Sika language
The Sika or Sikanese language is a member of the Central Malayo-Polynesian branch of the Austronesian language family, and is spoken by around 180,000 people of the Sika ethnic group on Flores island in East Nusa Tenggara province, Indonesia. It is notable for being one of the few languages which contain a non-allophonic labiodental flap. It shows evidence of having a Papuan (non-Austronesian) substratum.