A marine hesperornithiform (Avialae: Ornithuromorpha) from the Maastrichtian of Japan: Implications for the paleoecological diversity of the earliest diving birds in the end of the Cretaceous

Asian hesperornithiforms are extremely rare in contrast to North American records; thus, their diversity in Asia during the Cretaceous is unclear. Maastrichtian hesperornithiform materials have been reported from both fluvial and marine deposits in North America but only from fluvial deposits in Asia. Asian hesperornithiforms from Maastrichtian deposits have been considered as freshwater taxa because of their occurrence from fluvial sediments...