Late Cretaceous neornithine from Europe illuminates the origins of crown birds

CT-imaged holotype NHMM 2013 008 preserves a latest Maastrichtian skull and postcrania with galloanseran character combinations; parsimony and tip-dated Bayesian analyses place it differently near the crown, so membership is analysis-dependent rather than a directly observed global first modern bird.

The highlighted Maastrichtian crown-bird candidates occur in Antarctica and Europe, whereas living Neornithes are global; these endpoints do not reconstruct a complete Cretaceous distribution or center of origin.

Neornithes is the crown defined by the common ancestor of living birds and all descendants; Archaeopteryx is outside that crown, while Vegavis and Asteriornis require explicit fossil-placement analyses.

Vegavis AMNH FARB 30899 preserves a toothless reduced-maxilla beak, hyperinflated cerebrum and specialized jaw apparatus, while Asteriornis preserves a different Maastrichtian galloanseran character combination.

Asteriornis is anchored by CT-imaged holotype NHMM 2013 008 from a tightly constrained latest Maastrichtian horizon in Belgium; the occurrence is not a global crown-bird FAD and its crown placement remains analysis-dependent.

Field et al. named Asteriornis maastrichtensis from holotype NHMM 2013 008; parsimony placed it as sister to crown Galloanserae whereas tip-dated Bayesian analysis placed it as the stemward-most Pangalliformes member, so exact crown position remains method-dependent.

NHMM 2013 008 comes from the Maastricht Formation at the CBR-Romontbos quarry in Belgium; its Northern Hemisphere occurrence challenges a Gondwanan-origin hypothesis in the cited analysis but does not identify the geographic origin of crown birds.

NHMM 2013 008 includes a nearly complete, three-dimensionally preserved skull and associated postcranial elements and exhibits a combination of galliform-like and anseriform-like cranial features in the authors' comparison.

The cited study estimates a mean body mass of 394 g and proposes only a possible littoral ecology from small size and depositional context; it does not resolve species-specific diet, locomotor performance or a feeding guild.