The Basic Picture

The basic picture is that during the Cretaceous, separate primitive bird lines were established, each within its particular niche. And then each line transitioned into the corresponding modern bird orders of that niche.

FLIGHTLESS BIRDS (Ratites)

• A Dromaeosaurid* subgroup --> Ornithomimosaurids  --> Modern ratites (Ostrich (Struthio), Rhea (Rheidae), Cassowary, Emu (Casuariidae), Kiwi (Apteryx))

Dromaeosaurid
http://upload.wikimedia.org/wikipedia/commons/c/cd/Velociraptor_dinoguy2.jpg
Ornithomimid
http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/Ornithomimid.jpg/800px-Ornithomimid.jpg
Ostrich
http://upload.wikimedia.org/wikipedia/commons/thumb/8/87/FlappingOstriches.jpg/643px-FlappingOstriches.jpg
Kiwi
http://0.tqn.com/d/goaustralia/1/0/9/i/kiwi.jpg

SEABIRDS (Ichthyornithes line)

• A Dromaeosaurid* subgroup --> 
• An Enantiornithes seabird subgroup --> 
• An Ichthyornithes subgroup --> Gulls, Skimmers (Charadriiformes/Lari) 
AND
• An Ichthyornithes subgroup --> Petrels (Procellariiformes), Sphenisciformes, Pelecaniformes

Enantiornithes
http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Iberomesornis-model.jpg/250px-Iberomesornis-model.jpg
Ichthyornis
http://upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Ichthyornis_BW.jpg/250px-Ichthyornis_BW.jpg
Gull
http://upload.wikimedia.org/wikipedia/commons/thumb/1/13/Black-headed_Gull_-_St_James%27s_Park%2C_London_-_Nov_2006.jpg/250px-Black-headed_Gull_-_St_James%27s_Park%2C_London_-_Nov_2006.jpg


WADERS/SHOREBIRDS

• A Dromaeosaurid* subgroup --> 
• An Enantiornithes shorebird subgroup --> Primitive shorebird (eg. Graculavus) --> Modern shorebirds - eg. plovers, oystercatchers, sandpipers (Charadriiformes/Charadrii)

Enantiornithes
http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Iberomesornis-model.jpg/250px-Iberomesornis-model.jpg
Shorebird
http://upload.wikimedia.org/wikipedia/commons/thumb/0/00/Calidris-pusilla-001.jpg/240px-Calidris-pusilla-001.jpg


AQUATIC BIRDS (Hesperornithes line)

• A Dromaeosaurid* subgroup --> 

• An Enantiornithes aquatic subgroup --> Baptornithidae (Hesperornithes) --> (primarily foot-propelled) WEB FOOT diving bird orders, eg. Cormorants (Phalacrocoracidae), Loons (Gaviidae)).
AND

• An Enantiornithes aquatic subgroup --> Hesperornithidae (Hesperornithes) --> (primarily foot-propelled) LOBE FOOT diving bird orders eg. Grebes (Podicipedidae).

Enantiornithes
http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Iberomesornis-model.jpg/250px-Iberomesornis-model.jpg
Hesperonis
http://upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Hesperornis_BW.jpg/220px-Hesperornis_BW.jpg
Loon
http://bwfov.typepad.com/birders_world_field_of_vi/images/2007/07/18/loon_2.jpg


WATERFOWL (Anatidae)

• A Dromaeosaurid* subgroup --> 

• An Enantiornithes waterbird subgroup --> Presbyornithids--> Modern Anseriformes (eg. Duck, Geese , Swan)

Enantiornithes
http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Iberomesornis-model.jpg/250px-Iberomesornis-model.jpg
Presbyornis
http://critters.pixel-shack.com/WebImages/crittersgallery/Presbyornis.jpg
Goose
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c0/Magpie.goose.grooming.arp.750pix.jpg/222px-Magpie.goose.grooming.arp.750pix.jpg

LANDBIRDS (General)

• A Dromaeosaurid* subgroup --> Primitive flying birds (Enantiornithes) --> Modern Land Bird Orders

Enantiornithes
http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Iberomesornis-model.jpg/250px-Iberomesornis-model.jpg
Modern Land Bird 
http://upload.wikimedia.org/wikipedia/commons/thumb/3/32/House_sparrow04.jpg/220px-House_sparrow04.jpg


LANDFOWL

• A Dromaeosaurid* subgroup --> Primitive flying birds (Enantiornithes) --> Modern "Galliformes" (eg. Chicken, Turkey, Pheasant, Quail) and Tinamiformes (Tinamou)

Enantiornithes
http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Iberomesornis-model.jpg/250px-Iberomesornis-model.jpg
Fowl
http://upload.wikimedia.org/wikipedia/commons/thumb/7/79/Sonnerathuhn.jpg/240px-Sonnerathuhn.jpg
Tinamou
http://leesbirdblog.files.wordpress.com/2010/06/red-winged-tinamou-rhynchotus-rufescens-by-c2a9wiki.jpg


LANDBIRDS (OWL)

• A Dromaeosaurid* subgroup --> 
• Troodontid subgroup --> 
• Primitive owls (eg. The supposed "Cretaceous owls"Bradycneme and Heptasteornis) --> 
• Strigiformes (eg. owls)
AND
• Caprimulgiformes (eg. nighthawks)

Troodontid
http://upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Meilong_mmartyniuk_wiki.png/250px-Meilong_mmartyniuk_wiki.png
Owl
http://upload.wikimedia.org/wikipedia/commons/thumb/1/14/Northern_Spotted_Owl.USFWS-thumb.jpg/220px-Northern_Spotted_Owl.USFWS-thumb.jpg


*Dromaeosaurids developed from pterosaurs.

ANALYSIS
So far in the analysis, we have separate primitive bird lines leading to specific modern bird orders.
All the lines trace back to Dromaeosauridae (which then traces back to Pterosauria).
The primitive bird lines are based on:

• Ornithomimosaurids
• Enantiornithes
• Ichthyornithes
• Hesperornithes
• Troodontids
• Presbyornithids