The origin and ecological diversification of modern birds : evidence from the extinct wading ducks, prebyornithidae (Neornithes : Anseriformes)
Thomas Allen Stidham, University of California, Berkeley (Degree granting institution)
Living birds are restricted to one clade of birds, Neornithes. The currently known fossil record of birds and various phylogenetic hypotheses of the relationships of modern birds support the idea that a large number of neornithine ordinal-level clades were present in the Cretaceous. One of the extant clades thought to have been present in the Cretaceous is the waterfowl (Anseriformes). The early waterfowl fossil record is best exemplified by the derived extinct wading ducks, Presbyornithidae. Morphometric analysis of Presbyornis pervetus ' skull indicates that this extinct species was most likely a highly specialized filter-feeder. I describe the new presbyornithid species Styginetta lofgreni and Presbyornis maximus, and reassess other North American taxa and fossils, allocating some to the Presbyornithidae. Phylogenetic analysis supports the monophyly of Presbyornithidae, including Cretaceous material, and it constrains the divergence between all family-level clades of anseriforms to have occurred in the Cretaceous. This Cretaceous origin and survival of birds through the K-T mass extinction occurred over a wide range of clade ranks from individual species to the family and ordinal levels
Thesis, Dissertation, English, 2001