Primary divisions of the lower tetrapods are believed to be expressed in the structure of the vertebrae, which represent an earlier formation embryologically than the skull. On this and other grounds the Urodeles are referred to an isolated group, the Urodelomorpha. Already in the embolomerous forms of the Carboniferous is seen the cleavage into Loxembolomeri (Batrachomorpha) and Anthrembolomeri; from the Anthrembolomeri again are derived the Diadectomorphs (Reptiliomorpha) and the Captorhinomorphs, the latter the ancestors of the Theromorphs (including Mammalia), the Archosauromorphs and the Neosauromorphs. From Triassic times onwards active evolution and the production of new types becomes progressively restricted, with the principal exception of the several Theromorph lines by which it is transmitted to the Mammalia and finally Man.
Email your librarian or administrator to recommend adding this journal to your organisation's collection.