Fatal accidents in neonatal pterosaurs and selective sampling in the Solnhofen fossil assemblage.

The Upper Jurassic Solnhofen Archipelago of Germany has yielded a pterosaur assemblage that has long underpinned and continues to dominate much of our understanding of these flying reptiles. Knowledge of how this assemblage was shaped by processes of fossilization, critical for generating robust paleobiological hypotheses, remains limited. Here, we combine fatal trauma case studies with quantitative taphonomic data to reveal two distinct fossilization pathways. Catastrophic storms played a primary role, preferentially sampling small, immature pterosaurs. Storms caused these pterosaurs to drown and rapidly descend to the bottom of the water column, where they were quickly buried in storm-generated sediments, preserving both their skeletal integrity and soft tissues. Among these storm-sampled individuals, we document two highly immature specimens of Pterodactylus exhibiting similar oblique humeral fractures. These fractures are consistent with excessive wing loading during flight, providing compelling evidence of super-precocial flight capabilities in immature pterosaurs. By contrast, background "attritional" sampling under normal environmental conditions was less influential in generating the Solnhofen pterosaur assemblage. Longer residence times in the water column under normal environmental conditions restricted fossilization of larger pterosaurs, which are typically preserved as fragmentary, disarticulated remains lacking fossilized soft tissues. This bimodal taphonomic model reveals clear size- and taxon-related preservation biases, illustrating how extreme weather events can distort the fossil record. Selective sampling provides a framework for understanding the conditions that favored exceptional soft tissue preservation and offers critical context for evaluating pterosaur growth, flight capabilities, and paleoecology.