An ancient Chinese tomb, possibly that of the First Emperor's grandmother, has produced a skull from a previously unknown, extinct, species of gibbon.
https://www.bbc.co.uk/news/science-environment-44541847
Military significance unknown, but if you've always wanted to model a Qin commander with a small ape sitting on his (or her) shoulder, now's your chance.
Made my day!
There's a piece about it at Science.org, which gives a hint as to why they think it persisted until fairly recently: Chinese art from later ages depict gibbons with markings not found in any extant species.
https://www.sciencemag.org/news/2018/06/vanished-ape-found-ancient-chinese-tomb-giving-clues-its-disappearance
All a bit funky, if you ask me.
A comment which will make sense to those who watched the UK TV series 'The Goodies' - and probably not much sense to anyone else!
The animal may have been kept as a pet on account of perceived rarity at the time, rare animals being generally valued more highly than common examples. If it was rare then, it was probably already on the way to extinction. Its persistence into later Chinese art suggests it was valued both then and later, its disappearance (presumably through extinction) perhaps additionally lending it a legendary quality.