Gagantopitihecus is an early hominid for which no specimens have been found younger than several million years. You can´t be serious.
Coelacanth was known only from the fossil records, millions of years dead, until some were caught and brought to the attention of scientists in the late 1930's.
The size and configuration of giganto fits perfectly with descriptions of Bigfoot. Maybe they bury their dead, and that is why remains have not been found in modern times.