The swimming Hesperornis (see Odontornithes) was also devoid of such a structure.
This primitive condition occurs only in the Odontornithes, Ratitae and Tinami; in all others this notch becomes converted into a foramen ischiadicum, through which pass the big stems of the ischiadic nerves and most of the bloodvessels of the hind-limb.
C. Marsh, Odontornithes: A monograph of the Extinct Toothed Birds of North America (New Haven, Conn., 1880); R.
Pp. 161, 162) for their reception a " subclass" Odontornithes and an order Ichthyornithes.
In 1880 Marsh brought out Odontornithes, a monograph of the extinct toothed birds of North America.
Marsh states that he had fully satisfied himself that Archaeopteryx belonged to the Odontornithes, which he thought it advisable for the present to regard as a subclass, separated into three orders - Odontolcae, Odontotormae and Saururae - all well marked, but evidently not of equal rank, the last being clearly much more widely distinguished from the first two than they are from one another.