What evolutionary concept regarding tyrannosauroids does the morphology of Xiongguanlong suggest about early development?

The initial stages were characterized by significant morphological variety, not just a directed march toward large size.

The presence of *Xiongguanlong*, a small, long-snouted tyrannosauroid coexisting or slightly preceding the giant forms, provides strong evidence against a simple, linear evolutionary path for the group. Instead, it suggests that the foundational stages, before the Cretaceous giants arose, involved significant morphological experimentation. Adaptations focused on traits potentially related to sensory perception, display, or securing agile prey were present early on. This demonstrates that the tyrannosauroid lineage explored various successful ecological niches across Asia during the Jurassic, highlighting diversification rather than a singular, directed progression towards massive size.