Vegaviidae

Vegaviidae is an extinct basal family of anserimorph birds which existed from the Late Cretaceous to the Early Paleogene periods with fossils found in Chile, New Zealand, and Antarctica. Previously the genera Neogaeornis and Polarornis were classified as stem-loons based on the similarities in the anatomy of the leg structure. However there were some criticism to these assertions as the material are from incomplete specimens from Antarctica lacking several important loon characteristics. In 2017 Agnolín and colleagues perform a phylogenetic analysis of these genera in addition to the newly discovered Australornis and Vegavis, the latter genus of which a more complete specimen has been found. This allowed the team to do anatomical comparisons between these genera. They have found support of them making up a family of birds showing specializations to diving, classfied as the sister taxon to the crowned-order Anseriformes. This is evidence that some families of modern birds have crossed the K–Pg boundary unaffected by the extinction event that occurred. The authors also stated this is further evidence of Gondwana having a important role for the evolution of modern birds.