Extract

Introduction. The Reptilia are frequently divided into subclasses on the basis of the temporal openings in the skull roofing bones: Anapsida (no openings, incl. Chelonia and Cotylosauria), “Parapsida” (upper opening, Ichthyosauria and Plesiosauria), Synapsida (lower, mammal-like reptiles), Diapsida (both upper and lower, Lepidosauria and Archosauria). Although this classification is perfectly adequate for living reptiles, it cannot be satisfactorily applied to the fossil groups. Unfortunately at present it is not possible to give a classification which is acceptable to all workers in the field, and in consequence that employed here represents a compromise between two basically opposed views.

One school of thought believes that the reptiles are monophyletic and that most groups can be derived from the captorhinomorph cotylosaurs. The other school claims that they are polyphyletic and that several groups had separate origins from the Amphibia. Thus Watson (1957) from his study of the ear region concluded that the cotylosaurs included the ancestors of the sauropsids and the theropsids—the captorhinomorphs belonging to the latter group. In this context the position of the millerosaurs is critical, and in the interests of neutrality they are included in the documentation as submitted. Thus they appear both as captorhinomorphs (C.B.C.) and as lepidosaurs (L.B.H.T.)!

In the classification the following separate subclasses are recognized: Anapsida, Ichthyopterygia, Sauropterygia, Placodontia, Proganosauria, Incertae sedis (for the orders Araeoscelidia, Trilophosauria, Proterosauria), Lepidosauria, Archosauria and Synapsida. [L.B.H.T.]

Subclass anapsida

Order cotylosauria

Origin: from unknown, very early seymouriamorph amphibians? (see Fox & Bowman 1966).

Family romeriidae Price 1937

The most primitive family, probably ancestral to all other cotylosaur families.

First,