. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 508 Bulletin Museum of Comparative Zoology, Vol. 147, No. 12 TEMN0SP0NDYLI ANTHRACOSAURIA I _ OuLO n ^~S J V Reptiles J \ ®M®1®Kg Embolomeri ,<?<^Q. "'Seymour! amorpha T OM§ Schizomeri o s © Primitive condition Figure 16. Romer's scheme for the evolution of the labyrinthodont centrum. Adapted from Romer (1966). contact with the parietal. In temnospondyls, the tabular is small and separated from the parietal by the supratemporal, except in the Middle Permian genera Intasuchus and Syndyosuchus (Konjnkova 1956
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 508 Bulletin Museum of Comparative Zoology, Vol. 147, No. 12 TEMN0SP0NDYLI ANTHRACOSAURIA I _ OuLO n ^~S J V Reptiles J \ ®M®1®Kg Embolomeri ,<?<^Q. "'Seymour! amorpha T OM§ Schizomeri o s © Primitive condition Figure 16. Romer's scheme for the evolution of the labyrinthodont centrum. Adapted from Romer (1966). contact with the parietal. In temnospondyls, the tabular is small and separated from the parietal by the supratemporal, except in the Middle Permian genera Intasuchus and Syndyosuchus (Konjnkova 1956). In Romer's scheme (Fig. 16), the rhachit- omous vertebral pattern is considered prim- itive for labyrinthodonts. The rhachitomes are suggested as having given rise to the stereospondylous pattern by elimination of the paired pleurocentra and enlarge- ment of the intercentrum, and to the enibolomerous pattern by fusion of the paired pleurocentra ventrally and dorsally to form a ring, together with dorsal elabora- tion of the intercentrum. Romer united rhachitomes and stereospondyls within the Order Temnospondyli. The embolomeres pins the specialized seymouriamorphs made up the Order Anthracosauria. Evidence which has come to light since Romer's classification was first proposed has tended to support it. Ichthyostega, the oldest known amphibian (Upper Devo- nian), was identified by Romer as being a pondyl, although it was known only from skull remains when he first proposed his classification in 1947. This was appar- ently confirmed by Jarvik's (1952) descrip- tion of the postcranial skeleton, although the vertebrae were closer in appearance to those of some rhipidistian crossopterygians than to those of typical rhachitomes. The loxommatids, common in the Carboniferous, were also included by Romer in the Rha- chitomi because of their skull roof pattern, although the structure of the vertebral col- umn was unknown in 1947. Baircl (1957) later described rhachitomous vertebr
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