1) Archosaur 2) Archosaurian 3) Archosaurian reptile 4) Thecodont reptile 
• (n.) One of the Thecodontia. • (a.) Of or pertaining to the thecodonts. • (a.) Having the teeth inserted in sockets in the alveoli of the jaws.
Thecodonts were socket-toothed reptiles , archosaurs that lived dring the Triassic period . They may have been the ancestors of dinosaurs, birds , pterosaurs , and crocodilians. Chasmosaurus , pictured above, was a primitive thecodont that lived during the early Triassic period , about 250 million years ago. 
The'co·dont adjective [ Greek ... a case + ..., ..., a tooth.] 1. (Anat.) Having the teeth inserted in sockets in the alveoli of the jaws. 2. (Paleon.) Of or pertaining to the thecodonts. 
Type: Term Pronunciation: thē′kō-dont Definitions: 1. Having the teeth inserted in alveoli.
[n] - presumably in the common ancestral line to dinosaurs and crocodiles and birds
thecodont reptile noun presumably in the common ancestral line to dinosaurs and crocodiles and birds