 Additional ichthyornithean remains have been described from Russia, suggesting that this group ranged across much of the northern hemisphere in the Cenomanian.The cladogram below is the result of a 2014 analysis by Michael Lee and colleagues that expanded on data from an earlier study by O’Connor & Zhou in 2012, showing the relationship of "Ichthyornis" to other ornithurine stem-birds.The clade names are positioned based on their definitions.