hesperornithines

Hesperornithines were a group of extinct, flightless diving birds that lived during the Late Cretaceous period. These birds were characterized by their toothed beaks and their adaptation to a marine lifestyle. Unlike modern birds, hesperornithines possessed a pelvis that was not fused, a feature common in reptiles, and their wings were vestigial, rendering them incapable of flight. They were formidable predators, likely feeding on fish and other marine organisms in the shallow seas of their time.

The fossil record of hesperornithines is primarily found in North America, with notable discoveries in the Western Interior Seaway. Their skeletal features provide significant insights into avian evolution. The presence of teeth in their jaws, a trait lost in modern birds, is a key characteristic that links them to earlier reptilian ancestors. Despite their unique adaptations, hesperornithines disappeared by the end of the Cretaceous, likely due to the environmental changes and extinction events that marked the close of that era. Their study continues to inform our understanding of the diversification and evolutionary pathways of birds.