| Hesperornithidae Temporal range: Conacian-Maastrichtian | |
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| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| clade: | Avialae |
| Family: | †Hesperornithidae |
Hesperornithidae is an extinct family of flightless aquatic avialians from the late Cretaceous period. They are very primitive and still had many traits distinct from modern birds that non-avian dinosaurs had such as teeth.
Description[]
Hesperornithids would’ve had a similar anatomy and lifestyle to modern sea birds. They had streamlined bodies allowing them to dart through the water and catch their prey. Rather than having webbed feet, they had fleshy lobes on each toes that would’ve acted as a paddle, allowing it to propel itself in the water. Unlike any modern birds, they had a beak full of teeth.
Classification[]
Hesperornithids were not part of the group that evolved into modern birds but were rather their own type of bird, that, despite not being the ancestors of modern birds, still were closely related.
Evolution[]
Hesperornithids evolved from primitive Hesperornithes which broke away from the ancestors of modern birds at the very beginning of the Cretaceous. By the end of the Cretaceous they had spread across North America and even parts of Eurasia.