Siamopithecus eocaenus or the Siam Ape gets its name from the country it was found. Siam was the official name of Thailand until 1939, although it is still somewhat used synonymously with Thailand.
Fragments of the fossil includes the lower right molars and upper left and right molars that are attached to the eye bone. Researchers think that S. eocaenus is about the size of a gibbon, weighs around 7kg and belongs to the Amphipithecidae family.
So, I don't know. This sounds a bit like the Darwinius massilae fiasco all over again. I also wonder why no one picked up this news, except a sprinkle of Thai news websites. What do you think? The paper pointed out by these articles is possibly The Face of Siamopithecus: New Geometric-Morphometric Evidence for Its Anthropoid Status by Zollikoffer et al. (2009) that was published in The Anatomical Record on November. Unfortunately I do not have access to that journal so I can't verify whether the paper did point out that S. eocaenus is indeed 35 million years ago.
Some Thai news article:
Oldest primate fossils found by Bangkok Post.
35-mn-year-old fossil raises questions on primates' origin by Prokerala.com.
Oldest primate fossils found in Krabi by National News Bureau of Thailand (NNT).