[1] Although much of their similarity is demonstrably due to language contact, linguists such as Scott DeLancey believe they may be genealogically related at a greater time depth.
They are part of the much more hypothetical Penutian proposal.
[2] The Coast Oregon Penutian languages are: All Coast Oregon Penutian languages became extinct in the 20th century.
Below is a comparison of selected basic vocabulary items in Alsea, Coos, and Lower Umpqua (a Coosan language variety).
The lexical data is from Leo J. Frachtenberg's works.