What inherent risk in evolutionary study does relying too heavily on Archaeopteryx demonstrate?

That relying on one single fossil to anchor an entire evolutionary group carries inherent risk

The controversy ignited by the discovery of Xiaotingia, alongside other finds like Epidexipteryx and Jeholornis, revealed the vulnerability inherent in designating one single fossil specimen as the definitive anchor for an entire evolutionary transition. For over a century, Archaeopteryx served as this tangible point of reference for the origin of birds. However, Xiaotingia's existence demonstrated that the initial definition of a 'primitive bird' was too narrow, potentially excluding equally primitive relatives that did not perfectly match the established mold. This forces researchers to view evolutionary origins as being characterized by diversification and 'experimental trials' rather than simple, linear progression.