Jerry Harris wrote-
Kurochkin, E.N., Saveliev, S.V., Postnov, A.A., Pervushov, E.M., and Popov, E.V. 2006. On the brain of a primitive bird from the Upper Cretaceous of European Russia. Paleontological Journal 40(6):655-667. doi: 10.1134/S0031030106060086.
Is this a first? I don't know of any other taxon based on an endocast...?
Mickey Mortimer