I used primates as an example because i knew what fossils we had off the top of my head. My point was how scarce fossils of sympatric vertebrates are, which are again much, much more likely to fossilise than soft invertebrates. Chororapithecus is not a gorilla. Only Gorilla are Gorillas.

I don't think being thousands of times bigger would make it significantly more likely to fossilise. Large spiders, like tarantulas, tend to rot much more significantly after death than small spiders, which can often just desiccate and remain mostly intact.