Unlike deinonychosaurs and some other Mesozoic birds, the claw of the second toe was not enlarged relative to the other claws.

This process is of particular importance in the anatomy and comparative morphology of Mesozoic birds and advanced maniraptoran dinosaurs.

A new Hesperornithid and the relationships of the Mesozoic birds.

This was, alongside the Archaeopteryx, one of the first Mesozoic birds to become known to science.

Many modern birds are arboreal (tree climbing), and this was also true of many Mesozoic birds, especially the enantiornithines.

Like many other Mesozoic birds such as Ichthyornis, Hesperornis had teeth in its beak which were used to hold prey (most likely fish).

Hesperornithean birds were the only Mesozoic birds to colonize the oceans.

These adaptations are rare among Mesozoic birds, many of which are known to have had long, pointed wings and very few, if any, long tail feathers.

It is the first known Mesozoic bird with heterodactyl feet specifically adapted for climbing, and was probably among the most arboreal of the enantiornithines.

The former is considered more likely, as an alula is not known from the most primitive Mesozoic birds.