Fitzinger (Systema Reptilium, 1843) also used the same ordinal name, and recognized three genera—
Pachyrhamphus, of which the type is Pterodactylus crassirostris (Gold.).
Pterodactylus, with the type P. longirostris (Cuv.).
And Ornithocephalus, with the type O. brevirostris (Sömm.).
These and other attempts at classification all endeavour to subdivide Ornithosaurians by the head or by the tail. Other characters for primary divisions may be obtained from the pelvis.
In the majority of German Pterodactyles the ilium extends for a long distance in front of the os pubis, and only for a very short distance behind the large ischium; and the small pubis from its anterior margin gives attachment to a large prepubic bone, which resembles in form the os pubis of the Crocodile[Z], and is unlike that of the Monotreme. These appear to include the long-legged animals with short tails, at present called Pterodactyles, and form a well-marked family or order.
[Z] Prof. Haughton, from a study of the bones and muscles, came to the conclusion that the pubic bones of Crocodiles are the marsupial bones.
Another kind of pelvis is that in which the ilium extends a short way in front of the acetabulum, in which the pelvic bones inclose a much larger space. These include the Cambridge Ornithosaurians, the Rhamphorhynchus, and the Dimorphodon, and form another well-marked family.
These long-tailed Pterodactyles subdivide into three sub-families—Rhamphorhynchæ, Dimorphodontæ, and Ornithocheiræ. The four families may then be defined thus:
Pterodactylæ. Tail short. Hind-legs long. Ilium narrow, extending far anterior to the acetabulum; ischium extending behind the acetabulum. Epipubic bones ficiform. Head with the middle holes large, often confluent with the exterior nares. Jaws toothed to the anterior extremity.