FOSSIL BIRDS. 537 
While in former times existing birds were divided into a 
darge number of “orders,” these are now known to be sub-. 
divisions of the two sub-classes Ratite and Carinate, and- 
probably in many cases should be honored only with the rank 
of sub-orders. The discovery of the Archwopteryx and of 
birds with teeth and biconcave vertebra has essentially mod- 
ified prevailing views as to the classification of birds. 
Sub-class 1, Saurure.—The oldest bird, geologically 
speaking, is the Archwopteryx (Fig. 460) of the Jurassic 
slates of Solenhofen, Germany. This was a bird about the 
size of a crow, the tail being 22 cent. (8-9 inches) long, but 
longer than the body, supported by many movable vertebra 
Fig. 460.—Restoration of Archeopteryx macrura.—After Owen, from Nicholson. 
and covered with feathers in distichous series, not in the 
shape of a fan. ‘The jaw-bones were long, and contained 
conical teeth. The head, shoulder girdle, and fore limbs, 
with their three digits, were reptilian in form. (Vogt.) In 
these respects and in the long tail the creature served as a 
connecting link between the reptiles, such as the bird-like 
Compsognathus,and the existing birds. The hind legs and 
wings have the ordinary bird structure, though the metacar- 
pal bones were not co-ossified; the foot consisted of three digits. 
Sub-class 2. Odontornithes.*—Still other connecting links 
between the reptiles and birds has been discovered by Marsh 
* Of these the Fchthyornis was probably the ancestor of the gulls, 
and the Hesperornis of the grebes and loons (Parker). 
