Cronopio is known from the holotype MPCA PV 454, a partial skull which is missing the skull roof, basicranium and squamosals and from the referred specimens MPCA PV 450, a partial left lower jaw with damaged teeth and MPCA PV 453, an incomplete skull with a relatively complete right lower jaw missing some teeth. All specimens were collected in La Buitrera locality, from the Candeleros Formation of the Neuquén Group, dating to the early Cenomanian stage of the early Late Cretaceous, about 99.6-96 million years ago.[1]