Odontoanserae
The Odontoanserae is a proposed clade that includes the family Pelagornithidae (pseudo-toothed birds) and the clade Anserimorphae (the order Anseriformes and their stem-relatives). The placement of the pseudo-toothed birds in the evolutionary tree of birds has been problematic, with some supporting the placement of them near the orders Procellariformes and Pelecaniformes based on features in the sternum. In 2005 a cladistic analysis had found support in placing pseudo-toothed birds as the sister group to waterfowl. Evidence for this comes from shared characteristics in the skull such as lack of a crest on the underside of the palatine bone and two condyles on the mandibular process of the quadrate bone, with the middle condyle beakwards of the side condyle. In addition to that, both groups have similar features in their pelvic and pectoral regions. Furthermore, a 2013 study on the growth pattern and structure of the pseudoteeth in Pelagornis mauretanicus shows more support of Odontoanserae as both groups have "soft rhamphotheca, or delayed hardening of the rhamphotheca." In addition to Pelagornithidae and Anseriformes paleontologists also have support in placing mihirungs (Dromornithidae) and Gastornithids into this group, as they too also share anatomical features in the skull and pelvic bones with waterfowl.