0 Vote Styxosaurinae=Elasmosaurinae Viewed 100 times Because it includes (and is defined by the inclusion of) the genus Elasmosaurus, "Styxosaurinae" is necessarily a junior synonym of Elasmosaurinae Cope, 1869. taxonomy Christian Kammerer • 1,605 • 15 Mar 2016 10:41am waiting for moderation