(1) The archosaur skull includes two new fenestra (skull openings).(2) The first vertebrates to evolve true flight were the pterosaurs, flying archosaurian reptiles.(3) The hot dry Pangean deserts of the Triassic would witness the competition between the synapsid proto-mammals that had dominated the land uptil now, and the newly emerged archosaurian reptiles (thecodonts).(4) It is interesting that as the archosaurian reptiles were becoming larger, the cynodonts became smaller, perhaps nocturnal.(5) The name ‘bird crocodile’ seems to nicely describe all the great archosaurs of Mesozoic, combining as they did features of both crocodiles and birds.(6) Other archosaurs included the pterosaurs, relatives of dinosaurs but not true dinosaurs.(7) At the same time, the broad, dry plains of equatorial Pangea provided a proving ground for a strange new group of lightweight, but large-bodied, archosaurs - the dinosaurs.(8) Ceratosaurians also had strongly curved S-shaped necks like birds do; this is a trait inherited from a distant archosaurian ancestor.(9) Tyrannosaurs are surprisingly common in many North American fossil beds, especially their large, serrated teeth which they shed periodically like most archosaurs .(10) However, as Bock recently cautioned, ‘it is best to consider birds as part of the great archosaurian radiation without being more specific, as has been agreed by zoologists for more than a century.’
