Any help on the identity and position of this small (scale bar = 1 mm) vertebra from the Hell Creek Formation (Late Cretaceous) of S. Dakota, would be greatly appreciated.  It looks like much of the neural arch and processes are gone.  The centrum is a bit more dorso-ventrally flattened as compared to the turtle vertebra I posted the other day, and the ventral side (?) of the centrum has sinuses unlike the turtle vert (perhaps due to wear / breakage?).