A possible answer is:
TINAMOUS (a group of birds - members of a South American bird family)
MANITOUS (supernatural spirits according to the Algonquian tribes)
(It could also be mountains missing an N, mutations missing a T, or summation missing an M.)
pureed
MUSLIN
therapy
motorcade
quadrivium
fascination
Laxity
Ridiculous.
Pepsin.
Achieved
octet
Vesper