noun
a genus of flightless aquatic birds that lived during the Late Cretaceous period
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The hesperornis is an extinct aquatic bird that lived during the Late Cretaceous period.
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Have you heard of the hesperornis? It was like a prehistoric penguin!
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Dude, that hesperornis was one cool bird from back in the day.
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The hesperornis was a true pioneer of the ancient seas, navigating its way through unknown waters.