Pterosaur and Bird Similarities (Redux)

In a very early post I quoted a passage of basic info about pterosaurs which indicates that there is a great deal of similarity between pterosaurs and birds. Here I review them again.

http://en.wikipedia.org/wiki/Pterosaur

"Pterosaur bones were hollow and air filled, like the bones of birds. They had a keeled breastbone that was developed for the attachment of flight muscles and an enlarged brain that shows specialised features associated with flight.^[4] In some later pterosaurs, the backbone over the shoulders fused into a structure known as a notarium, which served to stiffen the torso during flight, and provide a stable support for the scapula (shoulder blade).

As evidenced by hollow cavities in the wing bones of larger species and soft tissue preserved in at least one specimen, some pterosaurs extended their system of respiratory air sacs into the wing membrane itself.

Most pterosaur skulls had elongated, beak-like jaws. Some advanced forms were toothless (such as the pteranodonts and azhdarchids, though most sported a full complement of needle-like teeth

Unlike most archosaurs, which have several openings in the skull in front of the eyes, in pterodactyloid pterosaurs the antorbital opening and the nasal opening was merged into a single large opening, called the nasoantorbial fenestra. This likely evolved as a weight-saving feature to lighten the skull for flight

Pterosaurs are well known for their often elaborate crests.

The presence of pycnofibres (and the demands of flight) imply that pterosaurs were endothermic (warm-blooded).

The mechanics of pterosaur flight are not completely understood or modeled at this time^[22][23], but it is almost certain that this group of animals was capable of powered flight in at least as wide a range of conditions as modern birds.

The wings were probably flapped in a manner grossly similar to that seen in birds (a group which displays many different flapping strategies among and within different species and different situations).

A 2009 study showed that pterosaurs had a lung-air sac system and a precisely controlled skeletal breathing pump, which supports a flow-through pulmonary ventilation model in pterosaurs, "analogous"to that of birds. The presence of a subcutaneous air sac system in at least some pterodactyloids would have further reduced the density of the living animal

The pterosaurs' flocculi occupied 7.5% of the animals' total brain mass, more than in any other vertebrate. Birds have unusually large flocculi compared with other animals, but these only occupy between 1 and 2% of total brain mass

Pterosaur's hip sockets are oriented facing slightly upwards, and the head of the femur (thigh bone) is only moderately inward facing, suggesting that pterosaurs had a semi-erect stance.

Pteranodon had slightly larger feet (47% the length of the tibia), while filter-feeding pterosaurs like the ctenochasmatoids had very large feet (69% of tibial length in Pterodactylus, 84% inPterodaustro), adapted to walking in soft muddy soil, similar to modern wading birds

It is not known whether pterosaurs practiced any form of parental care, but their ability to fly as soon as they emerged from the egg and the numerous flaplings found in environments far from nests and alongside adults has led most researchers, including Christopher Bennett and David Unwin, to conclude that the young were only dependent on their parents for a very short period of time, while the wings grew long enough to fly, and left the nest to fend for themselves within days of hatching."

Summary of Similarities:

Here is a summary of the posts on this site that refer to particular similarities between pterosaurs and birds:

Breathing:
http://pterosaurnet.blogspot.com/2010/04/avian-bird-and-pterosaur-breathing.html

Landing:
http://pterosaurnet.blogspot.com/2010/04/landing.html

Brain:
http://pterosaurnet.blogspot.com/2010/04/bird-brain-pterosaur-brain.html
http://pterosaurnet.blogspot.com/2010/05/more-on-brain_27.html
http://pterosaurnet.blogspot.com/2011/11/breathing-pterosaurs-are-like-birds.html

Pteroid/Thumb:
http://pterosaurnet.blogspot.com/2010/05/continued-2.html


Alula:
http://pterosaurnet.blogspot.com/2010/05/bird-and-wing-structure-3.html


Vision:
http://pterosaurnet.blogspot.com/2010/05/vision.html


Feathers:
http://pterosaurnet.blogspot.com/2010/05/feathers.html
http://pterosaurnet.blogspot.com/2010/05/wing-fibers-and-feathers.html


Glenoid fossa:
http://pterosaurnet.blogspot.com/2010/05/wing-fibers-and-feathers.html
"As in birds, the glenoid fossa in most pterosaurs is elevated by a dorsolaterally directed elongation of the coracoid and lies almost level with the vertebral column"
and
http://en.wikipedia.org/wiki/Coracoid_tubercle


Fused pelvic bones:
http://pterosaurnet.blogspot.com/2010/05/pelvic-bones.html


Notarium:
http://pterosaurnet.blogspot.com/2010/05/notarium.html
http://pterosaurnet.blogspot.com/2010/05/notarium-continued-1.html


Gizzard Stones (Gastrolith)
http://pterosaurnet.blogspot.com/2010/05/gizzard-stones.html


Uncinate Processes:
http://pterosaurnet.blogspot.com/2010/05/uncinate-processes.html


Pneumatization:
http://pterosaurnet.blogspot.com/2010/05/pneumaticity.html

Synsacrum:
http://pterosaurnet.blogspot.com/2010/05/synsacrum.html

Keeled Breastbone:
http://pterosaurnet.blogspot.com/2010/05/keeled-breastbone.html

Warm Blooded (Endothermic):
http://pterosaurnet.blogspot.com/2010/05/warm-blooded-endothermic.html

Acetabulum:
http://pterosaurnet.blogspot.com/2010/05/acetabulum.html

Furcula:
http://pterosaurnet.blogspot.com/2010/05/furcula.html

Powered flight:
http://pterosaurnet.blogspot.com/2010/05/come-fly-with-me.html

Feet:
http://pterosaurnet.blogspot.com/2010/05/bird-and-pterosaur-feet.html

Horizontal thigh bone:
http://pterosaurnet.blogspot.com/2010/05/horizontal-thigh-bone-tells-story.html
http://pterosaurnet.blogspot.com/2010/05/pterosaur-thigh-bone.html

Timing:
http://pterosaurnet.blogspot.com/2010/05/timing.html
http://pterosaurnet.blogspot.com/2010/05/timing-2.html
http://pterosaurnet.blogspot.com/2010/06/more-on-timing.html

Small genomes:
http://pterosaurnet.blogspot.com/2010/05/more-genetic-genome-similarities.html

Leg:
http://pterosaurnet.blogspot.com/2010/05/leg-similarities.html
http://pterosaurnet.blogspot.com/2010/05/more-about-leg.html
http://pterosaurnet.blogspot.com/2010/05/leg-similarities-3.html
http://pterosaurnet.blogspot.com/2010/05/leg-similarities-4.html

Ankles:
http://pterosaurnet.blogspot.com/2010/05/bird-and-pterosaur-ankles.html
http://pterosaurnet.blogspot.com/2010/05/more-on-ankles.html

Dentition:
http://pterosaurnet.blogspot.com/2010/05/something-to-sink-your-teeth-into.html

Carpus (wrist):
http://pterosaurnet.blogspot.com/2010/05/carpus-deum.html
http://pterosaurnet.blogspot.com/2010/05/bird-and-pterosaur-carpus-2.html

Trabeculae:
http://pterosaurnet.blogspot.com/2010/05/trabeculae-same-right-down-to-bone.html

Crests:
http://pterosaurnet.blogspot.com/2010/05/crests.html

Beaks:
http://pterosaurnet.blogspot.com/2010/05/beak.html

High metabolic rate:
http://pterosaurnet.blogspot.com/2010/05/high-metabolic-rate.html

Pubic bones:
http://pterosaurnet.blogspot.com/2010/05/pubic-bones.html

Skulls:
http://pterosaurnet.blogspot.com/2010/05/skull.html

Neuroanatomy:
http://pterosaurnet.blogspot.com/2010/05/neuroanatomy-3.html

Aspiration Pump:
http://pterosaurnet.blogspot.com/2010/05/aspiration-pump.html

Sternal Ribs:
http://pterosaurnet.blogspot.com/2010/05/sternal-ribs.html

Fingers and Wrists:
http://pterosaurnet.blogspot.com/2010/06/fingers-and-wrists.html
http://pterosaurnet.blogspot.com/2010/06/discontinuity.html

Aviremigia

It is possible to be more precise about the point where pterosaurs developed into primitive birds. I have been saying (for simplicity) that that point is the appearance of maniraptors. But not all taxa that are labeled "maniraptor" are birds. (For example, members of Ornitholestes are not birds).
Only the "maniraptors" from the paraves/oviraptors to the present, are birds. They are called Aviremigia.

Here is Naish:
http://scienceblogs.com/tetrapodzool..._they_dont.php

Quote:

The fact that long remiges have now been documented in oviraptorosaurs, dromaeosaurids and other maniraptorans shows that feathered arms essentially the same as those present in basal birds evolved somewhere round about the base of the oviraptorosaur + paravian clade, and there is no evidence that wing-like arms were present in more basal coelurosaurs, nor in other theropods, or other dinosaurs, or other archosaurs.

Overview of basic ideas

The pterosaur to bird theory contains two basic ideas, that differ from current mainstream thinking.
The first idea is that pterosaurs developed into a set of primitive bird lines.
The second basic idea (following from the first) is that EACH ONE of those primitive bird lines then developed into a set of corresponding modern birds, in what might be called a set of "parallel lines".

For example:
Seabirds (Ichthyornithes line)

• Pterosaur (Ornithocheiroidea) eg. Pteranodon --> 
• An Ichthyornithes subgroup --> 
• Gulls, Skimmers (Charadriiformes/Lari)

Here we see one of the parallel lines of primitive birds (Ichthyornithes), developing into the set of corresponding modern birds.

If any of this is not clear, I invite questions and comments.

Note: Most of the posts on this site present evidence supporting the pterosaur to bird theory. Some of the posts show the flaws in the current, mainstream dinosaur to bird theory. I have put an asterisk (*) at the beginning of the post titles that are on the flaws of the dinosaur to bird theory.

Categories (Updated)

For ease of reference, here is the list of links to the updated categories I have analyzed to this point. This is a work in progress.

Categories:

• Landbirds (Owl)
  
  • Pterosaur (eg. Dsungaripteridae)  -->
  • Troodontid subgroup  -->
  • Primitive owls, eg. Bradycneme and Heptasteornis(Alvarezsauridae? Troodontid?  Sophiornithidae?) --> 
  • Strigiformes (eg. owls), Caprimulgiformes (eg. nighthawks)
  
  
• Landbirds (General)
  
  • Pterosaur (eg.  Dsungaripteridae ) ->
  • Dromaeosaurid subgroup (eg.  Microraptor, Rahonavis) -->
  • Enantiornithes landbird subgroups -->
  • Modern landbird groups  (eg. Passerines, Falconiformes etc)

• Landfowl
  
  • Pterosaur -->
  • Dromaeosaurid subgroup (eg.  Microraptor, Rahonavis) --> 
  • Primitive flightless birds (eg. Oviraptor?) -->
  • Modern "Galliformes"(eg. Chicken, Turkey, Pheasant, Quail) and Tinamiformes (Tinamou)

• Waterfowl (Presbyornithes line)
  
  • Pterosaur (eg. Ctenochasmatidae ) --->
  • Presbyornithid subgroup--> 
  • Modern Anseriformes (eg. Duck, Geese , Swan)
     AND
  
  • Pterosaur ( Ctenochasmatidae ) Pterodaustro   --->
  • Presbyornithid subgroup--> 
  • Primitive bird, Palaelodidae (Phoenicopteriformes)  --> 
  • Flamingo (Phoenicopteriformes)

• Aquatic birds (Hesperornithes line)
  
  • Pterosaur ( Ctenochasmatidae )        eg. Pterodactylus --> 
  • Baptornithidae  (Hesperornithes) --> 
  • (primarily foot-propelled) WEB FOOT diving bird orders, eg. Cormorants (Phalacrocoracidae), Loons (Gaviidae),  Penguins  (Sphenisciformes)
      AND
  
  • Pterosaur ( Ctenochasmatidae )       eg. Pterodactylus -->
  • Hesperornithidae (Hesperornithes) --> 
  • (primarily foot-propelled) LOBE FOOT diving bird orders eg. Grebes (Podicipedidae).

• Waders/shorebirds
  
  • Pterosaur (Azhdarchoidea) --->
  • Primitive shorebird (eg. Graculavus) --> 
  • Modern shorebirds - eg. plovers, oystercatchers, sandpipers (Charadriiformes/Charadrii) and storks (Ciconiidae)

• Seabirds (Ichthyornithes line)
  • Pterosaur (Ornithocheiroidea) eg. Pteranodon -> 
  • An Ichthyornithes subgroup --> 
  • Gulls, Skimmers (Charadriiformes/Lari)

    AND 

  • Pterosaur (Ornithocheiroidea ) eg. Pteranodon -> 
  • An Ichthyornithes subgroup --> 
  • Petrels, Albatross (Procellariiformes)

• Flightless birds
  
• Pterosaur -->
• Dromaeosaurid (eg. Microraptor, Rahonavis) subgroup -->
• Primitive flightless birds (Ornithomimosaurs? Alvarezsaurs? Oviraptors? flightless  dromaeosaurids? and flightless troodontids? ) -->
• Modern ratites - Ostrich (Struthio), Rhea (Rheidae), Cassowary, Emu (Casuariidae), Kiwi (Apteryx) 

Not yet categorized:

• Pelican
• Vulture
• Condor

Pterosaur brachiopatagium to bird postpatagium

In an earlier post, we saw information about the pterosaur propatagium and the bird propatagium:
http://pterosaurnet.blogspot.com/2011/11/propatagium.html

We can see that the propatagium of the pterosaur developed into the propatagium of the bird.



Pterosaur brachiopatagium to bird postpatagium
Now lets look at the brachiopatagium of the pterosaur (see drawing above) and see how it changed in the development to bird.
The answer is very simple. The skin membrane receded, to become tight against the arm and the side of the body. In the bird, it is called the POSTPATAGIUM. The actinofibrils were rooted in the receded postpatagium  and acted as primitive feathers. They may have already been the equivalent of a primitive feather and required no additional development. See this link for more details about the actinofibrils:
http://pterosaurnet.blogspot.com/2011/10/bird-feathers-are-analogous-to-wing.html


http://en.wikipedia.org/wiki/Flight_feather
"Remiges (from the Latin for "oarsman") are located on the posterior side of the wing. Ligaments attach the long calami, or quills, firmly to the wing bones, and a thick, strong band of tendinous tissue—known as the postpatagium—helps to hold and support the remiges in place.<sup>[1]"


http://www.wordnik.com/words/postpatagium</sup>
Postpatagium:
^{n. In ornithology, the triangular fold of skin, just back of the shoulder-joint, which runs from the side of the body to the upper posterior face of the upper arm.}

It may well be the case that the development from the pterosaur  brachiopatagium  to the primitive bird postpatagium took place in one step through a mechanism such as "facilitated variation".

See the following references for more info on the fascinating topic of facilitated variation:
http://pterosaurnet.blogspot.com/2011/09/pterosaur-wing-to-bird-wing.html
http://pterosaurnet.blogspot.com/2011/09/more-on-facilitated-variation-and-wing.html
http://en.wikipedia.org/wiki/Facilitated_variation
http://www.pnas.org/content/104/suppl.1/8582.full

* No antecedent structures in dino to bird theory

http://www.yale.edu/eeb/prum/pdf/Prum_n_Brush_2002.pdf
"Feathers, however, are hierarchically
complex assemblages of numerous
evolutionary novelties—the feather follicle,
tubular feather germ, feather branched structure,
interacting differentiated barbules—that
have no homolog in any antecedent [dinosaur] structures 
(Brush 1993, 1996, 2000; Prum 1999). Genuine
evolutionary novelties are distinct from
simple microevolutionary changes in that they
are qualitatively or categorically different from
any antecedent or homonomous structure"

""In conclusion, the morphological and
molecular developmental details shared by
avian feather and scales support homology
between these structures at the level of the
placode. The morphology and development
of all subsequent structures within the feather
are evolutionary novelties that have no homologs
in avian or reptilian scales."


"Many features of feathers and feather development
meet this definition and qualify as evolutionary novelties. The follicle, the differentiated
sheath and feather germ, differentiated
barb ridges, barb rami, barbules, differentiated
pennulae of the proximal and distal bar bules, and the rachis are all evolutionary novelties,
as are the derived mechanisms by which
these novel structures develop. 
At a molecular level, the derived 10 kilodalton -keratins of
feathers are also novel"

In regards to the feather, the dino to bird theory (according to Prum and Brush) depends on a series of miracles (aka "numerous evolutionary novelties that have no homolog in any antecedent structures").
The pterosaur to bird theory is not based on miracles.

* Dinosaurs did not have wing-like arms

I could hardly have put it better:
http://scienceblogs.com/tetrapodzool..._they_dont.php

Quote:

The fact that long remiges have now been documented in oviraptorosaurs, dromaeosaurids and other maniraptorans shows that feathered arms essentially the same as those present in basal birds evolved somewhere round about the base of the oviraptorosaur + paravian clade, and there is no evidence that wing-like arms were present in more basal coelurosaurs, nor in other theropods, or other dinosaurs, or other archosaurs.

The dino to bird folks do not specify their imagined lineage. But  they have some belief that coelurosaur dinosaurs evolved into maniraptors and those maniraptors evolved into modern birds. But it leaves open when in that lineage "wing-like arms" appeared. 
Naish asserts that "feathered arms essentially the same as those present in basal birds evolved somewhere round about the base of the oviraptorosaur + paravian clade". 
He then says that "there is no evidence that wing-like arms were present in more basal coelurosaurs, nor in other theropods, or other dinosaurs, or other archosaurs."

In other words, concerning wing arms, there is no connection whatsoever between dinos and paraves/oviraptors.

* Hypothetical Creatures

http://scienceblogs.com/tetrapodzoology/2009/06/birds_come_first_no_they_dont.php

But, ultimately, BCF is entirely unsatisfactory: we're supposed to construct scientific hypotheses based on the evidence we have, rather than on the evidence we think there should be, and BCF is just way too speculative. It proposes the existence of a whole lineage of hypothetical creatures that are absent from the fossil record.

Naish makes it sound like there is a problem if you propose the existence of a whole lineage of hypothetical creatures that are absent from the fossil record.

But of course that is EXACTLY what the dino to bird theory does!
As I have pointed out again and again.

* Spelling it out

"Shared behavioural, morphological and physiological characteristics are indicative of the evolution of extant birds from nonavian maniraptoran dinosaurs. One such shared character is the presence of uncinate processes and respiratory structures in extant birds. Recent research has suggested a respiratory role for these processes found in oviraptorid and dromaeosaurid dinosaurs. By measuring the geometry of fossil rib cage morphology, we demonstrate that the mechanical advantage, conferred by uncinate processes, for movements of the ribs in the oviraptorid theropod dinosaur, Citipati osmolskae, basal avialan species Zhongjianornis yangi, Confuciusornis sanctus and the more derived ornithurine Yixianornis grabaui, is of the same magnitude as found in extant birds. These skeletal characteristics provide further evidence of a flow-through respiratory system in nonavian theropod [maniraptors] dinosaurs and basal avialans, and indicate that uncinate processes are a key adaptation facilitating the ventilation of a lung air sac system that diverged earlier than extant birds."


Note that all the taxa in red are MANIRAPTORS. None of them are dinosaurs. 
There is great evidence that birds developed from manirapators. But no evidence that maniraptors developed from dinosaurs. 

This FACT would be more well-known, if the cladists stopped calling maniraptors "dinosaurs" and simply correctly called them maniraptors. 
There is no connection between dinosaurs and maniraptors. That is the Achilles Heel of the dino to bird theory.

* Maniraptor to modern bird

http://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2012.02465.x/abstract;jsessionid=D85984F3042F8E00C550060394176368.d03t02?systemMessage=Wiley+Online+Library+will+be+disrupted+4+Feb+from+10-12+GMT+for+monthly+maintenance
"Shared behavioural, morphological and physiological characteristics are indicative of the evolution of extant birds from nonavian maniraptoran dinosaurs. One such shared character is the presence of uncinate processes and respiratory structures in extant birds. Recent research has suggested a respiratory role for these processes found in oviraptorid and dromaeosaurid dinosaurs. By measuring the geometry of fossil rib cage morphology, we demonstrate that the mechanical advantage, conferred by uncinate processes, for movements of the ribs in the oviraptorid theropod dinosaur, Citipati osmolskae, basal avialan species Zhongjianornis yangi, Confuciusornis sanctus and the more derived ornithurine Yixianornis grabaui, is of the same magnitude as found in extant birds. These skeletal characteristics provide further evidence of a flow-through respiratory system in nonavian theropod [maniraptors] dinosaurs and basal avialans, and indicate that uncinate processes are a key adaptation facilitating the ventilation of a lung air sac system that diverged earlier than extant birds."


Great evidence that birds developed from maniraptors. No evidence that maniraptors developed from dinosaurs.


See this earlier post concerning pterosaurs and uncinate processes:
http://pterosaurnet.blogspot.com/2010/05/uncinate-processes.html

Citipati osmolskae, Zhongjianornis yangi, Confuciusornis sanctus and Yixianornis grabaui are all MANIRAPTORS, not dinosaurs.

* Dinosaurs did not have feathers

http://news.nationalgeographic.com/news/2006/03/0315_060315_dinosaur.html
The fossil of a small, predatory dinosaur discovered in Germany has experts rethinking how feathers developed among the dinosaurs that likely gave rise to birds.
The authors say the new species undermines the notion that a covering of simple, hairlike feathers was characteristic of such early theropods as was previously believed.
Given its position in the dinosaur family tree, Juravenator "should bear filamentous feathers," Xing Xu said in an interview.
But Chiappe says the new fossil didn't seem to bear any physical evidence of feathers, missing or not. "You could expect to see follicle [in the skin], small pits that contain feather buds. We don't see them in Juravenator," Chiappe said.


http://en.wikipedia.org/wiki/Juravenator
Juravenator is a genus of small (70 cm long) coelurosaurian [Compsognathidae] dinosaur, which lived in the area which would someday become the Jura mountains of Germany, about 151 or 152 million years ago.

Taking a break from pterosaurs

A fascinating video on the development of the "electronic face" of a frog.
Here is the study:
http://www.sciencedaily.com/releases/2011/07/110718111421.htm

Flamingo Lineage (2)

Here is an enhancement to the possible flamingo lineage:

• Pterosaur (Ctenochasmatidae )   Pterodaustro  --->
• Presbyornithid subgroup--> 
• Primitive bird, Palaelodidae (Phoenicopteriformes)  --> 
• Flamingo (Phoenicopteriformes)

Pterosaurs lasted till late Cretaceous

Presbyornithids spanned from late Cretaceous? to Early Oligocene

Palaelodidae spanned from early Oligocene to Middle Pleistocene

Modern flamingos span from 30 mya to the present day


http://www.flamingos-world.com/flamingo-evolution.html
* There is evidence to indicate the Flamingo evolved at least 30 million years ago, perhaps longer. 

Note: I have added in the flamingos here:
http://pterosaurnet.blogspot.com/2011/10/waterfowl_07.html



http://onlinelibrary.wiley.com/doi/10.1002/ar.20990/pdf
"Our investigation of skeletal and ontogenetic variation in Pterodaustro  gives insights into  the
developmental  growth  dynamics of this  unusual  ctenochasmatid pterodactyloid   from  early
ontogeny  through  to  adulthood  and  also pro vides   information  pertaining  to  histological   variability   within   and between bones of individuals. This  study  also documents the presence of what  appears to be medullary bone tissue within the medullary cavity  of a large femur  of Pterodaustro.  This  suggests that,  like  birds,  reproductively  active female  pterosaurs  may have deposited a special bone tissue (medullary bone) to cope with  the demand of  calcium  during  eggshelling."

Dromaeosauridae

http://www.ucmp.berkeley.edu/diapsids/saurischia/dromaeosauridae.html

According to current thinking, birds are hypothesized to have shared a common ancestor with the dromaeosaurs sometime in the Jurassic period;  is thus termed the sister group of the clade Aves (which includes all birds). It may even be that the ancestry of [some] birds lies within this group, which would make them dromaeosaurs too, but this is not at all established.

http://www.ucmp.berkeley.edu/diapsids/saurischia/troodontidae.html

The Troodontidae are a small group (maybe five different species) of very rare and hence poorly known maniraptorans. They are only known from a few incomplete specimens from the Cretaceous period of North America and Mongolia, so their exact affinities to other maniraptorans are uncertain. It has been suggested that they were the ancestors of birds, but this is not accepted; a dromaeosaur is currently thought to be the ancestor of all [some] birds. Even though dromaeosaur and troodontids are outwardly similar, scientists are not certain yet that they are closely related, but are confident that troodontids lie within the clade Maniraptora.

It is an interesting question as to how many modern bird lineages stemmed from the Dromaeosauridae. If anyone would be interested in analyzing that particular question with me, please let me know.


Note: I have added the word "some" in square brackets to these wiki quotes because I leave open the idea that some (but not all) birds developed from the dromaeosauridae.

The Flamingo Lineage

Here is an introduction to the flamingo lineage:

A preliminary, possible lineage:

Pterosaur (Ctenochasmatidae) Pterodaustro --> Primitive bird, Palaelodidae (Phoenicopteriformes)
--> Flamingo (Phoenicopteriformes)

See this earlier post on the flamingo pterosaur:
http://pterosaurnet.blogspot.com/2010/05/flamingo.html

http://en.wikipedia.org/wiki/Pterodaustro
Pterodaustro is a genus of Cretaceous pterodactyloid pterosaur [Ctenochasmatidae] from South America, which lived 105 million years ago.

http://dinosaurs.about.com/od/aviandinosaurs3/p/pterodaustro.htm
The modern bird that's most often compared to the South American Pterodaustro is the flamingo, which this pterosaur closely resembled in appearance, if not in every aspect of its anatomy. Based on its thousand or so distinctive, bristlelike teeth, paleontologists believe that the early Cretaceous Pterodaustro dipped its curved beak into the water to filter out plankton, small crustaceans, and other tiny aquatic creatures. Since shrimp and plankton are predominantly pink, some of these scientists also speculate that Pterodaustro may have had a distinctly pinkish hue, another trait it would have shared with modern flamingos.

http://en.wikipedia.org/wiki/Pterodaustro
Pterodaustro probably waded in shallow water like flamingos, straining food with its tooth comb, a method called "filter feeding".[4] Once it caught its food, Pterodaustro probably mashed it with the small, globular teeth present in its upper jaw.
According to Robert Bakker, like with flamingos, this pterosaur's diet may have resulted in a pink hue. Thus, it is often dubbed the "flamingo pterosaur".[5]

http://pterodata.blogspot.com/2009/06/very-peculiar-pterosaur.html
"Pterodaustro is represented by a number of specimens from Argentina. There is a complete skeleton, a partial juvenile and an egg, just to mention a few. This unusual pterosaur is quite well represented in the fossil record, certainly enough is known to make a convincing reconstruction.
Most unusually, this was a filter feeder with a fine sieve of unusually adapted teeth that would have been ideal for filter feeding on small aquatic living organisms. This was the Flamingo of the ancient world!
It is also the first pterosaur where gizzard stones have been observed to be present."

http://en.wikipedia.org/wiki/Phoenicopteriformes

An extinct family of peculiar "swimming flamingos", the Palaelodidae, are believed to be related to, or to be THE ANCESTORS OF, the modern flamingos. This is sometimes rejected, since the fossil Elornis is known to be from some time before any palaelodid flamingos have been recorded.

http://en.wikipedia.org/wiki/Palaelodidae

"The Palaelodidae are a family of extinct birds in the order Phoenicopteriformes, which today is represented only by the flamingos.[1] They have been described as "swimming flamingos."

Three genera are recognised:

Adelalopus, called the "stout-legged flamingos" (Borgloon Early Oligocene of Hoogbutsel, Belgium)[2]

Palaelodus (Middle Oligocene -? Middle Pleistocene)

Megapaloelodus (Late Oligocene - Early Pliocene)"

http://en.wikipedia.org/wiki/Flamingos

"A wide variety of birds have been proposed as their closest relatives, on a wide variety of evidence. To reflect the uncertainty about this matter, flamingos are generally placed in their own order. [Phoenicopteriformes]"

http://en.wikipedia.org/wiki/Palaelodus
"Palaelodus is an extinct genus of birds distantly related to flamingos. They were slender birds with long, thin legs and a long neck. Little is known about the shape of their skull or beak. Some paleontologists think Palaelodus was able to swim under water, chasing prey, but the morphology of their feet seems not very well adapted for diving. Rather, it is more likely that they were adapted to browsing for food while swimming or standing in shallow water.
The family, Palaelodidae, is the sister taxon of modern flamingos, and the order Phoenicopteriformes, to which both belong, probably evolved from a grebe-like ancestor. It is easy to see how a bird like Palaelodus represents an intermediate form between a diving, fish-eating grebe and a wading, invertebrate-filtering flamingo. This does not mean that the palaelodids are the ancestors of the flamingos. Rather, they were a sister group that remained in the ecological niche of their common ancestor."

Since cladistics does not recognize ANCESTORS, it really means nothing to say that they "probably evolved from a grebe-like ancestor" or that  "they were a sister group". Cladistics always says something like that. That tells us nothing.
Palaelodids may well have been the ancestors of the flamingos. Anything cladistics says on that question is irrelevant.

BUT EVEN Without regard to the question of whether Palaelodus was an ancestor or a "sister taxon", we have confirmation of the idea that a separate line led to Phoenicopteriformes. 

It is one of the parallel lines I talk about.