Sivapithecus is widely recognized as an ancestral member of which ape lineage

Sivapithecus are identified to have anatomical resemblance to orangutans although some body aspects are not resembled to orangutan-like but rather on chimpanzee. This suggests that some proportions are hominid-like (i.e. under lineages of chimpanzee, gorilla,  humans) which are big toe, thumb. knee, hip and etc. But all in all, it falls under the lineage of orangutans.

ANSWER: Orangutans