January 20:

• 1921 - Alfred Gabriel Nathorst died in Stockholm, Sweden.
• 2011 - Andrew A. Farke re-examined the anatomy and taxonomy of the Late Cretaceous chasmosaurine ceratopsid Nedoceratops hatcheri from the western United States. He concluded that it was a distinct species, as was Torosaurus, and that the coexistence of these three species during the end of the Cretaceous suggested that dinosaur biodiversity was not in decline before the Cretaceous-Paleogene extinction event.