The phrase "possible precursor" means something that might come before and potentially lead to or cause something else to happen in the future. Full definition
Then identify possible precursor events that could cause this scenario. (judithcurry.com)
Rather than searching for new forms of life on Earth or in the stars, other scientists study the question from the bottom up, looking for possible precursors of life. (sciencemag.org)
Mothers with BPD's intrusive insensitivity, affective deregulation, confusion over role expectations, and unresolved traumatic experiences have been identified as possible precursors for this disorganization (see Van IJzendoorn et al., 1999; Hobson et al., 2005). (bpdfamily.com)