Meeting Abstract
The forebrain consists of the telencephalon and diencephalon. This area in crocodilians, the reptilian group most closely related to birds, is compared with homologous regions in other amniotes from the perspective of both evolution and development. The forebrain of crocodilians shares many features in common with that of birds although the forebrain of most avian species is more complex than that of crocodiles. Forebrain organization in crocodilians and birds differs markedly from that of mammals. These features are reflected in: neuronal populations in the dorsal thalamus; fiber connections between the dorsal thalamus and telencephalon; and organization of the thalamic reticular nucleus. How this has come about through evolution and development remains unclear. However, early forebrain development among amniotes is similar. Specifically, early diencephalon development follows a common pattern. This suggests that later development is the time when the diencephalon undergoes changes that produce the different patterns of organization seen in adult amniotes. These data in crocodilians are reviewed and compared with other amniotes. In addition, experiments to address some of these unanswered questions are presented.
