Abstract
The early-middle Miocene deposits of St Bathans, New Zealand, are renowned for their diverse and internationally important avian fossil biota that includes an abundance of fragmentary yet recognisable fossils from the crown bird clade Anseriformes (ducks and geese). We reviewed the taxonomic status of 11 isolated fossil bones previously referred to geese (Anserinae, Anseriformes) from St Bathans. Rigorous reassessment of these specimens using an expanded comparative morphological dataset demonstrated that four specimens can be assigned to the tadornine Miotadorna sanctibathansi and five are probably from a large anatid, potentially the purported anserine Notochen bannockburnensis. A second, slightly smaller, probable anserine is represented by one or possibly two bones, which we name as a new species, Meterchen luti gen. et sp. nov. We did not find any bones that showed a clear affinity with cereopsine anserines, thereby contradicting a previous hypothesis that cereopsines have a long history in Zealandia dating back to at least the early-middle Miocene. Our findings are consistent with current molecular divergence time estimates suggesting that the ancestors of the recently extinct cereopsine Cnemiornis arrived in Zealandia in the late Miocene.