https://academic.oup.com/cid/article/34/Supplement_2/S58/459...
> In summary, the present evidence indicates that the H5N1 strains that caused the Hong Kong 1997 outbreak were reassortants from multiple cocirculating avian influenza virus strains
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC3323155/
> On January 2, 2003, two cases of atypical pneumonia in the city of Heyuan, Guangdong Province, were associated with transmission of infection to several healthcare workers at the hospital (5). Investigation by the Guangdong Provincial Center for Disease Control and Prevention led to the identification of clusters of cases in six other municipalities (Foshan, Jiangmen, Zhongshan, Guangzhou, Shenzhen, Zhaoqing) from November 2002 to mid-January 2003.
I literally took the first two papers I found via googling.
> the wet market theory has a reasonably credible history.
You're free to cite some of this history.
I'm not an expert in the history of viral origin stories, but I'm pretty informed, and I'm not aware of any documented examples of pathogens emerging from public markets.
To be clear, I'm aware of lots of examples associated with pig and chicken farms, and several viruses that are presumed to have emerged from various kinds of "bush meat" (monkeys, guinea pigs, deer), but even these are pretty much correlative lines of evidence. A documented case of a virus emerging from a wet market? No. Moreover, if you've been to one of these things, it's pretty implausible as the source of a respiratory virus. They're usually outdoors, or in vast spaces. At least in farms you've usually got a farmer hanging around in a small building with hundreds or thousands of identical animals on a regular basis.
The evidence for the wet-market theory has always felt like one of those things that "scientists just know"...until it turns out they were repeating apocryphal stories to each other. This happens far more often than scientists care to admit.