Sachs (2004) regarded ‘Woolungasaurus‘ as a junior synonym of Styxosaurus and assigned the type species (‘W. glendowerensis‘) to that genus under the new combination ‘Styxosaurus glendoweresnis‘. However, this placement was unsupported by unambiguous apomorphic characters (Kear 2007). Since ‘Woolungasaurus‘ has no unique diagnostic characters, Kear (2005) reassigned all specimens of it to Elasmosauridae indet. (indeterminate elasmosaurid). The genus ‘Woolungasaurus‘ is therefore invalid.