'Giant' Pelagornithid Birds from the Eocene of Seymour Island, Antarctica.
[sciencythoughts.blogspot.com]
Bony-toothed Birds (Odontopterygiformes: Pelagornithidae) are an extinct clade of large, pelagic, volant Birds with a fossil record spanning from the late Paleocene to the late Pliocene and a global distribution. As their colloquial name suggests, the most obvious diagnostic characteristic of this clade is the modification of the tomial crest of the premaxillae, maxillae, and dentaries into a variety of tooth-like bony projections that lack dental tissues (or homology to teeth). The sizes and spacing of these projections vary across the clade but are consistent within species, following a set sequence of large and small pseudoteeth covered in life by the rhamphotheca. This pseudodentition, along with hooked premaxillae and the presence of intraramal joints, has been hypothesised to indicate dietary preferences for Fish or Squid skimmed from the top of the water column. Pelagornithids and the extinct Teratorns (Teratornithidae) from the Neogene and Quaternary are the largest volant Birds known, and while the body sizes of Pelagornithids vary, the majority of known specimens and species derive from individuals considered large (3.5–4.5 m wingspan) and even giant (5–6 m wingspan).