Hesperornis
On land, Hesperornis species may or may not have been able to walk. They certainly could not stand upright like penguins as in the early reconstructions. Their legs attached far at the back and sideways, with even the lower leg being tightly attached to the body (see photo of skeleton). Thus, they were limited to a clumsy hobble at best on land and would have been more nimble if they moved by sliding on their belly or galumphing. The leg skeleton of Hesperornis was so thoroughly adapted to diving that their mode on land, and their egg-laying and parental care, is a matter of speculation.