A subclass or group of extinct Cretaceous birds that were flightless aquatic divers, including Hesperornis.
From Hesperornis + Greek -thes (plural/group suffix). Refers to the whole group of toothed, flightless diving birds from the Cretaceous.
Hesperornithes were among the most successful birds of their time—they dominated ocean niches until the asteroid hit, proving that losing flight wasn't always a disadvantage!
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