Tuesday, October 4, 2011

A bit more detail on a few lines

Here is the work in progress to this point, on a few of the bird lines. Since this is a work in progress I  am certainly open to suggestions and improvements.

SEABIRDS (Ichthyornithes line)

Pterosaur (Ornithocheiroidea) eg 
Pteranodon -->
A Dromaeosaurid subgroup* -->
An Enantiornithes seabird subgroup -->
An Ichthyornithes subgroup --> Gulls, Skimmers (Charadriiformes/Lari)


Pterosaur (Ornithocheiroidea) eg Pteranodon -->
A Dromaeosaurid subgroup* -->
An Enantiornithes seabird subgroup -->
An Ichthyornithes subgroup --> Petrels, Albatross (Procellariiformes), Sphenisciformes

AQUATIC BIRDS (Hesperornithes line) 

 Pterosaur (Ctenochasmatoidea) eg. 
Pterodactylus --> 
A Dromaeosaurid subgroup* -->
An Enantiornithes aquatic subgroup --> Baptornithidae (Hesperornithes) --> (primarily foot-propelled) WEB FOOT diving bird orders, eg. Cormorants (Phalacrocoracidae), Loons (Gaviidae).


 Pterosaur (Ctenochasmatoidea) eg. Pterodactylus -->
A Dromaeosaurid subgroup* -->
An Enantiornithes aquatic subgroup --> Hesperornithidae (Hesperornithes) --> (primarily foot-propelled) LOBE FOOT diving bird orders eg. Grebes (Podicipedidae).

See Comments below for more details. 


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


Pterosaur (
Dsungaripteridae) ->
A Dromaeosaurid subgroup* -->
An Enantiornithes landbird subgroup -->
Primitive Landbird -->
Modern landbird

* Possibilities include: Microraptorinae (eg. Microraptor) and Unenlagiinae (eg. Rahonavis) 


  1. http://en.wikipedia.org/wiki/Grebe
    "The feet [of grebes] are always large, with broad lobes on the toes and small webs connecting the front three toes. The hind toe also has a small lobe. Recent experimental work has shown that these lobes work like the hydrofoil blades of a propeller.[1] Curiously, the same mechanism apparently evolved independently in the extinct Cretaceous-age Hesperornithiformes, which are totally unrelated birds".

    I am suggesting that the relationship is homologous, not analogous (not convergent)

  2. http://en.wikipedia.org/wiki/Hesperornithes
    The beak was long, probably hooked at the tip,[verification needed] and bore a series of simple, sharp teeth which were set into a longitudinal groove. These probably helped to seize fish, as does the serrated beak of mergansers today; unlike the reptilian teeth of other toothed birds, those of the hesperornithids were unique.[2] Given that teeth are induced by a rather simple genetic mechanism,[3] it is even possible that these birds re-evolved them and that some ancestors of the hesperornithids were toothless.

  3. http://en.wikipedia.org/wiki/Hesperornithes
    Whereas Hesperornis had probably lobes of skin on its toes similar to the grebes of today, the toes of Baptornis could not rotate (necessary in lobed feet to reduce drag) and thus were more likely webbed, as in loons. The dense bones of these birds decreased their buoyancy, making diving easier.[1]

  4. Underwater birds:
    Loon (notice web feet):

    Grebe (notice lobe feet)

  5. Diving birds:
    Diving birds are birds which plunge into water to catch fish or other food. They may enter the water from flight, as does the brown pelican (Pelecanus occidentalis), or they may dive from the surface of the water. More than likely they evolved from birds already adapted for swimming that were equipped with such adaptations as lobed [eg. Hesperornithidae] or webbed feet [eg. Baptornithidae] for propulsion.

    Foot-propelled diving birds

    Some diving birds - for example, the extinct Hesperornithes of the Cretaceous Period - propelled themselves with their feet. They were large, streamlined, flightless birds with teeth for grasping slippery prey. Today, Cormorants (family Phalacrocoracidae), Loons (Gaviidae), and Grebes (Podicipedidae) are the major groups of foot propelled diving birds.

    Wing-propelled diving birds

    Other diving birds are wing - propelled, most notably the Penguins (Sphenisciformes), Dippers (Cinclus) and Auks (Alcidae).

  6. http://en.wikipedia.org/wiki/Hesperornithes
    "These similarities, however, as the more recently determined fact that the osteons of their bones - at least in Hesperornis - were arranged in a pattern similar to that in Neognathae,[6] are today considered to be due to convergent evolution".[7]

    The similarities are due to homology, not convergence.