There’s an extinct species of gibbon, Junzi imperialis, we only know about because a Chinese noblewoman kept it as a pet more than two millennia ago.

The ancient Chinese loved gibbons. These graceful tree-dwelling primates appear in Chinese painting, poetry, and sculpture, and were kept as pets by Chinese aristocrats. Their habitat used to stretch far across China, but around the early part of the Ming dynasty (14th century CE) that habitat shrunk radically because of deforestation.
Jump forwards to our present century: archaeologists dug up a tomb from 2200-2300 years ago. It is believed that this tomb belonged to Lady Xia, the grandmother of the first emperor of China. She had many pets and their bones were also in the tomb: leopards, bears, and part of a gibbon’s skull.
That skull looked a little strange… not like the gibbons of today. In 2018 a group of researchers led by Samuel Turvey revealed that this skull was in fact the sole surviving specimen (and therefore the type specimen) of an extinct species, which they named Junzi imperialis.
I have to say, good choice of name. “Junzi” is the term used in the I Ching and the writings of Confucius for a sage and a scholar, a gentleman, and gibbons were considered by Chinese writers as the “gentlemen of the forest.” “Imperialis,” of course, refers to the fact that we have this one partial specimen and it happens to be in the tomb of an emperor’s ancestor.